Copyright laws are changing all over the world, be sure to check
the copyright laws for your country before posting these files!!
Please take a look at the important information in this header.
We encourage you to keep this file on your own disk, keeping an
electronic path open for the next readers. Do not remove this.
**Welcome To The World of Free Plain Vanilla Electronic Texts**
**Etexts Readable By Both Humans and By Computers, Since 1971**
*These Etexts Prepared By Hundreds of Volunteers and Donations*
Information on contacting Project Gutenberg to get Etexts, and
further information is included below. We need your donations.
The Descent of Man and Selection in Relation to Sex
by Charles Darwin
August 2000 [Etext #2300]
The Project Gutenberg Etext The Descent of Man by Charles Darwin
******This file should be named dscmn10.txt or dscmn10.zip******
Corrected EDITIONS of our etexts get a new NUMBER, dscmn11.txt
VERSIONS based on separate sources get new LETTER, dscmn10a.txt
This etext was prepared by Sue Asscher
Project Gutenberg Etexts are usually created from multiple editions,
all of which are in the Public Domain in the United States, unless a
copyright notice is included. Therefore, we usually do NOT keep
these books in compliance with any particular paper edition.
We are now trying to release all our books one month in advance
of the official release dates, for time for better editing.
Please note: neither this list nor its contents are final till
midnight of the last day of the month of any such announcement.
The official release date of all Project Gutenberg Etexts is at
Midnight, Central Time, of the last day of the stated month. A
preliminary version may often be posted for suggestion, comment
and editing by those who wish to do so. To be sure you have an
up to date first edition [xxxxx10x.xxx] please check file sizes
in the first week of the next month. Since our ftp program has
a bug in it that scrambles the date [tried to fix and failed] a
look at the file size will have to do, but we will try to see a
new copy has at least one byte more or less.
Information about Project Gutenberg (one page)
We produce about two million dollars for each hour we work. The
fifty hours is one conservative estimate for how long it we take
to get any etext selected, entered, proofread, edited, copyright
searched and analyzed, the copyright letters written, etc. This
projected audience is one hundred million readers. If our value
per text is nominally estimated at one dollar then we produce $2
million dollars per hour this year as we release thirty-six text
files per month, or 432 more Etexts in 1999 for a total of 2000+
If these reach just 10% of the computerized population, then the
total should reach over 200 billion Etexts given away this year.
The Goal of Project Gutenberg is to Give Away One Trillion Etext
Files by the December 31, 2001. [10,000 x 100,000,000=Trillion]
This is ten thousand titles each to one hundred million readers,
which is only ~5% of the present number of computer users.
At our revised rates of production, we will reach only one-third
of that goal by the end of 2001, or about 3,333 Etexts unless we
manage to get some real funding; currently our funding is mostly
from Michael Hart's salary at Carnegie-Mellon University, and an
assortment of sporadic gifts; this salary is only good for a few
more years, so we are looking for something to replace it, as we
don't want Project Gutenberg to be so dependent on one person.
We need your donations more than ever!
All donations should be made to "Project Gutenberg/CMU": and are
tax deductible to the extent allowable by law. (CMU = Carnegie-
Mellon University).
For these and other matters, please mail to:
Project Gutenberg
P. O. Box 2782
Champaign, IL 61825
When all other email fails try our Executive Director:
Michael S. Hart
We would prefer to send you this information by email.
******
To access Project Gutenberg etexts, use any Web browser
to view http://promo.net/pg. This site lists Etexts by
author and by title, and includes information about how
to get involved with Project Gutenberg. You could also
download our past Newsletters, or subscribe here. This
is one of our major sites, please email hart@pobox.com,
for a more complete list of our various sites.
To go directly to the etext collections, use FTP or any
Web browser to visit a Project Gutenberg mirror (mirror
sites are available on 7 continents; mirrors are listed
at http://promo.net/pg).
Mac users, do NOT point and click, typing works better.
Example FTP session:
ftp sunsite.unc.edu
login: anonymous
password: your@login
cd pub/docs/books/gutenberg
cd etext90 through etext99
dir [to see files]
get or mget [to get files. . .set bin for zip files]
GET GUTINDEX.?? [to get a year's listing of books, e.g., GUTINDEX.99]
GET GUTINDEX.ALL [to get a listing of ALL books]
***
**Information prepared by the Project Gutenberg legal advisor**
(Three Pages)
***START**THE SMALL PRINT!**FOR PUBLIC DOMAIN ETEXTS**START***
Why is this "Small Print!" statement here? You know: lawyers.
They tell us you might sue us if there is something wrong with
your copy of this etext, even if you got it for free from
someone other than us, and even if what's wrong is not our
fault. So, among other things, this "Small Print!" statement
disclaims most of our liability to you. It also tells you how
you can distribute copies of this etext if you want to.
*BEFORE!* YOU USE OR READ THIS ETEXT
By using or reading any part of this PROJECT GUTENBERG-tm
etext, you indicate that you understand, agree to and accept
this "Small Print!" statement. If you do not, you can receive
a refund of the money (if any) you paid for this etext by
sending a request within 30 days of receiving it to the person
you got it from. If you received this etext on a physical
medium (such as a disk), you must return it with your request.
ABOUT PROJECT GUTENBERG-TM ETEXTS
This PROJECT GUTENBERG-tm etext, like most PROJECT GUTENBERG-
tm etexts, is a "public domain" work distributed by Professor
Michael S. Hart through the Project Gutenberg Association at
Carnegie-Mellon University (the "Project"). Among other
things, this means that no one owns a United States copyright
on or for this work, so the Project (and you!) can copy and
distribute it in the United States without permission and
without paying copyright royalties. Special rules, set forth
below, apply if you wish to copy and distribute this etext
under the Project's "PROJECT GUTENBERG" trademark.
To create these etexts, the Project expends considerable
efforts to identify, transcribe and proofread public domain
works. Despite these efforts, the Project's etexts and any
medium they may be on may contain "Defects". Among other
things, Defects may take the form of incomplete, inaccurate or
corrupt data, transcription errors, a copyright or other
intellectual property infringement, a defective or damaged
disk or other etext medium, a computer virus, or computer
codes that damage or cannot be read by your equipment.
LIMITED WARRANTY; DISCLAIMER OF DAMAGES
But for the "Right of Replacement or Refund" described below,
[1] the Project (and any other party you may receive this
etext from as a PROJECT GUTENBERG-tm etext) disclaims all
liability to you for damages, costs and expenses, including
legal fees, and [2] YOU HAVE NO REMEDIES FOR NEGLIGENCE OR
UNDER STRICT LIABILITY, OR FOR BREACH OF WARRANTY OR CONTRACT,
INCLUDING BUT NOT LIMITED TO INDIRECT, CONSEQUENTIAL, PUNITIVE
OR INCIDENTAL DAMAGES, EVEN IF YOU GIVE NOTICE OF THE
POSSIBILITY OF SUCH DAMAGES.
If you discover a Defect in this etext within 90 days of
receiving it, you can receive a refund of the money (if any)
you paid for it by sending an explanatory note within that
time to the person you received it from. If you received it
on a physical medium, you must return it with your note, and
such person may choose to alternatively give you a replacement
copy. If you received it electronically, such person may
choose to alternatively give you a second opportunity to
receive it electronically.
THIS ETEXT IS OTHERWISE PROVIDED TO YOU "AS-IS". NO OTHER
WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, ARE MADE TO YOU AS
TO THE ETEXT OR ANY MEDIUM IT MAY BE ON, INCLUDING BUT NOT
LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE.
Some states do not allow disclaimers of implied warranties or
the exclusion or limitation of consequential damages, so the
above disclaimers and exclusions may not apply to you, and you
may have other legal rights.
INDEMNITY
You will indemnify and hold the Project, its directors,
officers, members and agents harmless from all liability, cost
and expense, including legal fees, that arise directly or
indirectly from any of the following that you do or cause:
[1] distribution of this etext, [2] alteration, modification,
or addition to the etext, or [3] any Defect.
DISTRIBUTION UNDER "PROJECT GUTENBERG-tm"
You may distribute copies of this etext electronically, or by
disk, book or any other medium if you either delete this
"Small Print!" and all other references to Project Gutenberg,
or:
[1] Only give exact copies of it. Among other things, this
requires that you do not remove, alter or modify the
etext or this "small print!" statement. You may however,
if you wish, distribute this etext in machine readable
binary, compressed, mark-up, or proprietary form,
including any form resulting from conversion by word pro-
cessing or hypertext software, but only so long as
*EITHER*:
[*] The etext, when displayed, is clearly readable, and
does *not* contain characters other than those
intended by the author of the work, although tilde
(~), asterisk (*) and underline (_) characters may
be used to convey punctuation intended by the
author, and additional characters may be used to
indicate hypertext links; OR
[*] The etext may be readily converted by the reader at
no expense into plain ASCII, EBCDIC or equivalent
form by the program that displays the etext (as is
the case, for instance, with most word processors);
OR
[*] You provide, or agree to also provide on request at
no additional cost, fee or expense, a copy of the
etext in its original plain ASCII form (or in EBCDIC
or other equivalent proprietary form).
[2] Honor the etext refund and replacement provisions of this
"Small Print!" statement.
[3] Pay a trademark license fee to the Project of 20% of the
net profits you derive calculated using the method you
already use to calculate your applicable taxes. If you
don't derive profits, no royalty is due. Royalties are
payable to "Project Gutenberg Association/Carnegie-Mellon
University" within the 60 days following each
date you prepare (or were legally required to prepare)
your annual (or equivalent periodic) tax return.
WHAT IF YOU *WANT* TO SEND MONEY EVEN IF YOU DON'T HAVE TO?
The Project gratefully accepts contributions in money, time,
scanning machines, OCR software, public domain etexts, royalty
free copyright licenses, and every other sort of contribution
you can think of. Money should be paid to "Project Gutenberg
Association / Carnegie-Mellon University".
*END*THE SMALL PRINT! FOR PUBLIC DOMAIN ETEXTS*Ver.04.29.93*END*
This etext was prepared by Sue Asscher
THE DESCENT OF MAN
AND
SELECTION IN RELATION TO SEX
Works by Charles Darwin, F.R.S.
Life and Letters of Charles Darwin. With an Autobiographical Chapter.
Edited by Francis Darwin. Portraits. 3 volumes 36s. Popular Edition.
Condensed in 1 volume 7s 6d.
Naturalist's Journal of Researches into the Natural History and Geology of
Countries Visited during a Voyage Round the World. With 100 Illustrations
by Pritchett. 21s. Popular Edition. Woodcuts. 3s 6d. Cheaper Edition,
2s. 6d. net.
Origin of Species by means of Natural Selection; or, The Preservation of
Favoured Races in the Struggle for Life. Large Type Edition, 2 volumes
12s. Popular Edition, 6s. Cheaper Edition with Portrait, 2s. 6d.
Various Contrivances by which Orchids are Fertilized by Insects. Woodcuts.
7s. 6d.
Variation of Animals and Plants under Domestication. Illustrations. 15s.
Descent of Man, and Selection in relation to Sex. Illustrations. Large
Type Edition, 2 volumes 15s. Popular Edition, 7s 6d. Cheaper Edition, 2s.
6d. net.
Expression of the Emotions in Man and Animals. Illustrations. 12s.
Insectivorous Plants. Illustrations. 9s.
Movements and Habits of Climbing Plants. Woodcuts. 6s.
Cross and Self-Fertilization in the Vegetable Kingdom. Illustrations. 9s.
Different Forms of Flowers on Plants of the Same Species. Illustrations.
7s. 6d.
Formation of Vegetable Mould through the Action of Worms. Woodcuts. 6s.
The above works are Published by John Murray.
Structure and Distribution of Coral Reefs. Smith, Elder, & Co.
Geological Observations on Volcanic Islands and Parts of South America.
Smith, Elder, & Co.
Monograph of the Cirripedia. Illustrations. 2 volumes. 8vo. Ray
Society.
Monograph of the Fossil Lepadidae, or Pedunculated Cirripedes of Great
Britain. Palaeontographical Society.
Monograph of the Fossil Balanidae and Verrucidae of Great Britain.
Palaeontographical Society.
THE DESCENT OF MAN
AND
SELECTION IN RELATION TO SEX
BY
CHARLES DARWIN, M.A., F.R.S.
Uniform with this Volume
The Origin of Species, by means of Natural Selection; or, The Preservation
of Favoured Races in the Struggle for Life. Popular Edition, with a
Photogravure Portrait. Large Crown 8vo. 2s. 6d. net.
A Naturalist's Voyage. Journal of Researches into the Natural History and
Geology of the Countries visited during the Voyage of H.M.S. "Beagle" round
the World, under the Command of Capt. Fitz Roy, R.N. Popular Edition, with
many Illustrations. Large Crown 8vo. 2s. 6d. net.
PREFACE TO THE SECOND EDITION.
During the successive reprints of the first edition of this work, published
in 1871, I was able to introduce several important corrections; and now
that more time has elapsed, I have endeavoured to profit by the fiery
ordeal through which the book has passed, and have taken advantage of all
the criticisms which seem to me sound. I am also greatly indebted to a
large number of correspondents for the communication of a surprising number
of new facts and remarks. These have been so numerous, that I have been
able to use only the more important ones; and of these, as well as of the
more important corrections, I will append a list. Some new illustrations
have been introduced, and four of the old drawings have been replaced by
better ones, done from life by Mr. T.W. Wood. I must especially call
attention to some observations which I owe to the kindness of Prof. Huxley
(given as a supplement at the end of Part I.), on the nature of the
differences between the brains of man and the higher apes. I have been
particularly glad to give these observations, because during the last few
years several memoirs on the subject have appeared on the Continent, and
their importance has been, in some cases, greatly exaggerated by popular
writers.
I may take this opportunity of remarking that my critics frequently assume
that I attribute all changes of corporeal structure and mental power
exclusively to the natural selection of such variations as are often called
spontaneous; whereas, even in the first edition of the 'Origin of Species,'
I distinctly stated that great weight must be attributed to the inherited
effects of use and disuse, with respect both to the body and mind. I also
attributed some amount of modification to the direct and prolonged action
of changed conditions of life. Some allowance, too, must be made for
occasional reversions of structure; nor must we forget what I have called
"correlated" growth, meaning, thereby, that various parts of the
organisation are in some unknown manner so connected, that when one part
varies, so do others; and if variations in the one are accumulated by
selection, other parts will be modified. Again, it has been said by
several critics, that when I found that many details of structure in man
could not be explained through natural selection, I invented sexual
selection; I gave, however, a tolerably clear sketch of this principle in
the first edition of the 'Origin of Species,' and I there stated that it
was applicable to man. This subject of sexual selection has been treated
at full length in the present work, simply because an opportunity was here
first afforded me. I have been struck with the likeness of many of the
half-favourable criticisms on sexual selection, with those which appeared
at first on natural selection; such as, that it would explain some few
details, but certainly was not applicable to the extent to which I have
employed it. My conviction of the power of sexual selection remains
unshaken; but it is probable, or almost certain, that several of my
conclusions will hereafter be found erroneous; this can hardly fail to be
the case in the first treatment of a subject. When naturalists have become
familiar with the idea of sexual selection, it will, as I believe, be much
more largely accepted; and it has already been fully and favourably
received by several capable judges.
DOWN, BECKENHAM, KENT,
September, 1874.
First Edition February 24, 1871.
Second Edition September, 1874.
CONTENTS.
INTRODUCTION.
PART I. THE DESCENT OR ORIGIN OF MAN.
CHAPTER I.
The Evidence of the Descent of Man from some Lower Form.
Nature of the evidence bearing on the origin of man--Homologous structures
in man and the lower animals--Miscellaneous points of correspondence--
Development--Rudimentary structures, muscles, sense-organs, hair, bones,
reproductive organs, etc.--The bearing of these three great classes of
facts on the origin of man.
CHAPTER II.
On the Manner of Development of Man from some Lower Form.
Variability of body and mind in man--Inheritance--Causes of variability--
Laws of variation the same in man as in the lower animals--Direct action of
the conditions of life--Effects of the increased use and disuse of parts--
Arrested development--Reversion--Correlated variation--Rate of increase--
Checks to increase--Natural selection--Man the most dominant animal in the
world--Importance of his corporeal structure--The causes which have led to
his becoming erect--Consequent changes of structure--Decrease in size of
the canine teeth--Increased size and altered shape of the skull--Nakedness
--Absence of a tail--Defenceless condition of man.
CHAPTER III.
Comparison of the Mental Powers of Man and the Lower Animals.
The difference in mental power between the highest ape and the lowest
savage, immense--Certain instincts in common--The emotions--Curiosity--
Imitation--Attention--Memory--Imagination--Reason--Progressive improvement
--Tools and weapons used by animals--Abstraction, Self-consciousness--
Language--Sense of beauty--Belief in God, spiritual agencies,
superstitions.
CHAPTER IV.
Comparison of the Mental Powers of Man and the Lower Animals--continued.
The moral sense--Fundamental proposition--The qualities of social animals--
Origin of sociability--Struggle between opposed instincts--Man a social
animal--The more enduring social instincts conquer other less persistent
instincts--The social virtues alone regarded by savages--The self-regarding
virtues acquired at a later stage of development--The importance of the
judgment of the members of the same community on conduct--Transmission of
moral tendencies--Summary.
CHAPTER V.
On the Development of the Intellectual and Moral Faculties during Primeval
and Civilised times.
Advancement of the intellectual powers through natural selection--
Importance of imitation--Social and moral faculties--Their development
within the limits of the same tribe--Natural selection as affecting
civilised nations--Evidence that civilised nations were once barbarous.
CHAPTER VI.
On the Affinities and Genealogy of Man.
Position of man in the animal series--The natural system genealogical--
Adaptive characters of slight value--Various small points of resemblance
between man and the Quadrumana--Rank of man in the natural system--
Birthplace and antiquity of man--Absence of fossil connecting-links--Lower
stages in the genealogy of man, as inferred firstly from his affinities and
secondly from his structure--Early androgynous condition of the Vertebrata
--Conclusion.
CHAPTER VII.
On the Races of Man.
The nature and value of specific characters--Application to the races of
man--Arguments in favour of, and opposed to, ranking the so-called races of
man as distinct species--Sub-species--Monogenists and polygenists--
Convergence of character--Numerous points of resemblance in body and mind
between the most distinct races of man--The state of man when he first
spread over the earth--Each race not descended from a single pair--The
extinction of races--The formation of races--The effects of crossing--
Slight influence of the direct action of the conditions of life--Slight or
no influence of natural selection--Sexual selection.
PART II. SEXUAL SELECTION.
CHAPTER VIII.
Principles of Sexual Selection.
Secondary sexual characters--Sexual selection--Manner of action--Excess of
males--Polygamy--The male alone generally modified through sexual
selection--Eagerness of the male--Variability of the male--Choice exerted
by the female--Sexual compared with natural selection--Inheritance at
corresponding periods of life, at corresponding seasons of the year, and as
limited by sex--Relations between the several forms of inheritance--Causes
why one sex and the young are not modified through sexual selection--
Supplement on the proportional numbers of the two sexes throughout the
animal kingdom-- The proportion of the sexes in relation to natural
selection.
CHAPTER IX.
Secondary Sexual Characters in the Lower Classes of the Animal Kingdom.
These characters are absent in the lowest classes--Brilliant colours--
Mollusca--Annelids--Crustacea, secondary sexual characters strongly
developed; dimorphism; colour; characters not acquired before maturity--
Spiders, sexual colours of; stridulation by the males--Myriapoda.
CHAPTER X.
Secondary Sexual Characters of Insects.
Diversified structures possessed by the males for seizing the females--
Differences between the sexes, of which the meaning is not understood--
Difference in size between the sexes--Thysanura--Diptera--Hemiptera--
Homoptera, musical powers possessed by the males alone--Orthoptera, musical
instruments of the males, much diversified in structure; pugnacity;
colours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity
and odours--Coleoptera, colours; furnished with great horns, apparently as
an ornament; battles; stridulating organs generally common to both sexes.
CHAPTER XI.
Insects, continued.--Order Lepidoptera.
(Butterflies and Moths.)
Courtship of Butterflies--Battles--Ticking noise--Colours common to both
sexes, or more brilliant in the males--Examples--Not due to the direct
action of the conditions of life--Colours adapted for protection--Colours
of moths--Display--Perceptive powers of the Lepidoptera--Variability--
Causes of the difference in colour between the males and females--Mimicry,
female butterflies more brilliantly coloured than the males--Bright colours
of caterpillars--Summary and concluding remarks on the secondary sexual
character of insects--Birds and insects compared.
CHAPTER XII.
Secondary Sexual Characters of Fishes, Amphibians, and Reptiles.
Fishes: Courtship and battles of the males--Larger size of the females--
Males, bright colours and ornamental appendages; other strange characters--
Colours and appendages acquired by the males during the breeding-season
alone--Fishes with both sexes brilliantly coloured--Protective colours--The
less conspicuous colours of the female cannot be accounted for on the
principle of protection--Male fishes building nests, and taking charge of
the ova and young. AMPHIBIANS: Differences in structure and colour
between the sexes--Vocal organs. REPTILES: Chelonians--Crocodiles--
Snakes, colours in some cases protective--Lizards, battles of--Ornamental
appendages--Strange differences in structure between the sexes--Colours--
Sexual differences almost as great as with birds.
CHAPTER XIII.
Secondary Sexual Characters of Birds.
Sexual differences--Law of battle--Special weapons--Vocal organs--
Instrumental music--Love-antics and dances--Decorations, permanent and
seasonal--Double and single annual moults--Display of ornaments by the
males.
CHAPTER XIV.
Birds--continued.
Choice exerted by the female--Length of courtship--Unpaired birds--Mental
qualities and taste for the beautiful--Preference or antipathy shewn by the
female for particular males--Variability of birds--Variations sometimes
abrupt--Laws of variation--Formation of ocelli--Gradations of character--
Case of Peacock, Argus pheasant, and Urosticte.
CHAPTER XV.
Birds--continued.
Discussion as to why the males alone of some species, and both sexes of
others are brightly coloured--On sexually-limited inheritance, as applied
to various structures and to brightly-coloured plumage--Nidification in
relation to colour--Loss of nuptial plumage during the winter.
CHAPTER XVI.
Birds--concluded.
The immature plumage in relation to the character of the plumage in both
sexes when adult--Six classes of cases--Sexual differences between the
males of closely-allied or representative species--The female assuming the
characters of the male--Plumage of the young in relation to the summer and
winter plumage of the adults--On the increase of beauty in the birds of the
world--Protective colouring--Conspicuously coloured birds--Novelty
appreciated--Summary of the four chapters on birds.
CHAPTER XVII.
Secondary Sexual Characters of Mammals.
The law of battle--Special weapons, confined to the males--Cause of absence
of weapons in the female--Weapons common to both sexes, yet primarily
acquired by the male--Other uses of such weapons--Their high importance--
Greater size of the male--Means of defence--On the preference shewn by
either sex in the pairing of quadrupeds.
CHAPTER XVIII.
Secondary Sexual Characters of Mammals--continued.
Voice--Remarkable sexual peculiarities in seals--Odour--Development of the
hair--Colour of the hair and skin--Anomalous case of the female being more
ornamented than the male--Colour and ornaments due to sexual selection--
Colour acquired for the sake of protection--Colour, though common to both
sexes, often due to sexual selection--On the disappearance of spots and
stripes in adult quadrupeds--On the colours and ornaments of the
Quadrumana--Summary.
PART III. SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION.
CHAPTER XIX.
Secondary Sexual Characters of Man.
Differences between man and woman--Causes of such differences, and of
certain characters common to both sexes--Law of battle--Differences in
mental powers, and voice--On the influence of beauty in determining the
marriages of mankind--Attention paid by savages to ornaments--Their ideas
of beauty in women--The tendency to exaggerate each natural peculiarity.
CHAPTER XX.
Secondary Sexual Characters of Man--continued.
On the effects of the continued selection of women according to a different
standard of beauty in each race--On the causes which interfere with sexual
selection in civilised and savage nations--Conditions favourable to sexual
selection during primeval times--On the manner of action of sexual
selection with mankind--On the women in savage tribes having some power to
choose their husbands--Absence of hair on the body, and development of the
beard--Colour of the skin--Summary.
CHAPTER XXI.
General Summary and Conclusion.
Main conclusion that man is descended from some lower form--Manner of
development--Genealogy of man--Intellectual and moral faculties--Sexual
selection--Concluding remarks.
SUPPLEMENTAL NOTE.
INDEX.
THE DESCENT OF MAN; AND SELECTION IN RELATION TO SEX.
...
INTRODUCTION.
The nature of the following work will be best understood by a brief account
of how it came to be written. During many years I collected notes on the
origin or descent of man, without any intention of publishing on the
subject, but rather with the determination not to publish, as I thought
that I should thus only add to the prejudices against my views. It seemed
to me sufficient to indicate, in the first edition of my 'Origin of
Species,' that by this work "light would be thrown on the origin of man and
his history;" and this implies that man must be included with other organic
beings in any general conclusion respecting his manner of appearance on
this earth. Now the case wears a wholly different aspect. When a
naturalist like Carl Vogt ventures to say in his address as President of
the National Institution of Geneva (1869), "personne, en Europe au moins,
n'ose plus soutenir la creation independante et de toutes pieces, des
especes," it is manifest that at least a large number of naturalists must
admit that species are the modified descendants of other species; and this
especially holds good with the younger and rising naturalists. The greater
number accept the agency of natural selection; though some urge, whether
with justice the future must decide, that I have greatly overrated its
importance. Of the older and honoured chiefs in natural science, many
unfortunately are still opposed to evolution in every form.
In consequence of the views now adopted by most naturalists, and which will
ultimately, as in every other case, be followed by others who are not
scientific, I have been led to put together my notes, so as to see how far
the general conclusions arrived at in my former works were applicable to
man. This seemed all the more desirable, as I had never deliberately
applied these views to a species taken singly. When we confine our
attention to any one form, we are deprived of the weighty arguments derived
from the nature of the affinities which connect together whole groups of
organisms--their geographical distribution in past and present times, and
their geological succession. The homological structure, embryological
development, and rudimentary organs of a species remain to be considered,
whether it be man or any other animal, to which our attention may be
directed; but these great classes of facts afford, as it appears to me,
ample and conclusive evidence in favour of the principle of gradual
evolution. The strong support derived from the other arguments should,
however, always be kept before the mind.
The sole object of this work is to consider, firstly, whether man, like
every other species, is descended from some pre-existing form; secondly,
the manner of his development; and thirdly, the value of the differences
between the so-called races of man. As I shall confine myself to these
points, it will not be necessary to describe in detail the differences
between the several races--an enormous subject which has been fully
described in many valuable works. The high antiquity of man has recently
been demonstrated by the labours of a host of eminent men, beginning with
M. Boucher de Perthes; and this is the indispensable basis for
understanding his origin. I shall, therefore, take this conclusion for
granted, and may refer my readers to the admirable treatises of Sir Charles
Lyell, Sir John Lubbock, and others. Nor shall I have occasion to do more
than to allude to the amount of difference between man and the
anthropomorphous apes; for Prof. Huxley, in the opinion of most competent
judges, has conclusively shewn that in every visible character man differs
less from the higher apes, than these do from the lower members of the same
order of Primates.
This work contains hardly any original facts in regard to man; but as the
conclusions at which I arrived, after drawing up a rough draft, appeared to
me interesting, I thought that they might interest others. It has often
and confidently been asserted, that man's origin can never be known: but
ignorance more frequently begets confidence than does knowledge: it is
those who know little, and not those who know much, who so positively
assert that this or that problem will never be solved by science. The
conclusion that man is the co-descendant with other species of some
ancient, lower, and extinct form, is not in any degree new. Lamarck long
ago came to this conclusion, which has lately been maintained by several
eminent naturalists and philosophers; for instance, by Wallace, Huxley,
Lyell, Vogt, Lubbock, Buchner, Rolle, etc. (1. As the works of the first-
named authors are so well known, I need not give the titles; but as those
of the latter are less well known in England, I will give them:--'Sechs
Vorlesungen uber die Darwin'sche Theorie:' zweite Auflage, 1868, von Dr L.
Buchner; translated into French under the title 'Conferences sur la Theorie
Darwinienne,' 1869. 'Der Mensch im Lichte der Darwin'sche Lehre,' 1865,
von Dr. F. Rolle. I will not attempt to give references to all the authors
who have taken the same side of the question. Thus G. Canestrini has
published ('Annuario della Soc. d. Nat.,' Modena, 1867, page 81) a very
curious paper on rudimentary characters, as bearing on the origin of man.
Another work has (1869) been published by Dr. Francesco Barrago, bearing in
Italian the title of "Man, made in the image of God, was also made in the
image of the ape."), and especially by Haeckel. This last naturalist,
besides his great work, 'Generelle Morphologie' (1866), has recently (1868,
with a second edition in 1870), published his 'Naturliche
Schopfungsgeschichte,' in which he fully discusses the genealogy of man.
If this work had appeared before my essay had been written, I should
probably never have completed it. Almost all the conclusions at which I
have arrived I find confirmed by this naturalist, whose knowledge on many
points is much fuller than mine. Wherever I have added any fact or view
from Prof. Haeckel's writings, I give his authority in the text; other
statements I leave as they originally stood in my manuscript, occasionally
giving in the foot-notes references to his works, as a confirmation of the
more doubtful or interesting points.
During many years it has seemed to me highly probable that sexual selection
has played an important part in differentiating the races of man; but in my
'Origin of Species' (first edition, page 199) I contented myself by merely
alluding to this belief. When I came to apply this view to man, I found it
indispensable to treat the whole subject in full detail. (2. Prof.
Haeckel was the only author who, at the time when this work first appeared,
had discussed the subject of sexual selection, and had seen its full
importance, since the publication of the 'Origin'; and this he did in a
very able manner in his various works.) Consequently the second part of
the present work, treating of sexual selection, has extended to an
inordinate length, compared with the first part; but this could not be
avoided.
I had intended adding to the present volumes an essay on the expression of
the various emotions by man and the lower animals. My attention was called
to this subject many years ago by Sir Charles Bell's admirable work. This
illustrious anatomist maintains that man is endowed with certain muscles
solely for the sake of expressing his emotions. As this view is obviously
opposed to the belief that man is descended from some other and lower form,
it was necessary for me to consider it. I likewise wished to ascertain how
far the emotions are expressed in the same manner by the different races of
man. But owing to the length of the present work, I have thought it better
to reserve my essay for separate publication.
PART I. THE DESCENT OR ORIGIN OF MAN.
CHAPTER I.
THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM.
Nature of the evidence bearing on the origin of man--Homologous structures
in man and the lower animals--Miscellaneous points of correspondence--
Development--Rudimentary structures, muscles, sense-organs, hair, bones,
reproductive organs, etc.--The bearing of these three great classes of
facts on the origin of man.
He who wishes to decide whether man is the modified descendant of some pre-
existing form, would probably first enquire whether man varies, however
slightly, in bodily structure and in mental faculties; and if so, whether
the variations are transmitted to his offspring in accordance with the laws
which prevail with the lower animals. Again, are the variations the
result, as far as our ignorance permits us to judge, of the same general
causes, and are they governed by the same general laws, as in the case of
other organisms; for instance, by correlation, the inherited effects of use
and disuse, etc.? Is man subject to similar malconformations, the result
of arrested development, of reduplication of parts, etc., and does he
display in any of his anomalies reversion to some former and ancient type
of structure? It might also naturally be enquired whether man, like so
many other animals, has given rise to varieties and sub-races, differing
but slightly from each other, or to races differing so much that they must
be classed as doubtful species? How are such races distributed over the
world; and how, when crossed, do they react on each other in the first and
succeeding generations? And so with many other points.
The enquirer would next come to the important point, whether man tends to
increase at so rapid a rate, as to lead to occasional severe struggles for
existence; and consequently to beneficial variations, whether in body or
mind, being preserved, and injurious ones eliminated. Do the races or
species of men, whichever term may be applied, encroach on and replace one
another, so that some finally become extinct? We shall see that all these
questions, as indeed is obvious in respect to most of them, must be
answered in the affirmative, in the same manner as with the lower animals.
But the several considerations just referred to may be conveniently
deferred for a time: and we will first see how far the bodily structure of
man shews traces, more or less plain, of his descent from some lower form.
In succeeding chapters the mental powers of man, in comparison with those
of the lower animals, will be considered.
THE BODILY STRUCTURE OF MAN.
It is notorious that man is constructed on the same general type or model
as other mammals. All the bones in his skeleton can be compared with
corresponding bones in a monkey, bat, or seal. So it is with his muscles,
nerves, blood-vessels and internal viscera. The brain, the most important
of all the organs, follows the same law, as shewn by Huxley and other
anatomists. Bischoff (1. 'Grosshirnwindungen des Menschen,' 1868, s. 96.
The conclusions of this author, as well as those of Gratiolet and Aeby,
concerning the brain, will be discussed by Prof. Huxley in the Appendix
alluded to in the Preface to this edition.), who is a hostile witness,
admits that every chief fissure and fold in the brain of man has its
analogy in that of the orang; but he adds that at no period of development
do their brains perfectly agree; nor could perfect agreement be expected,
for otherwise their mental powers would have been the same. Vulpian (2.
'Lec. sur la Phys.' 1866, page 890, as quoted by M. Dally, 'L'Ordre des
Primates et le Transformisme,' 1868, page 29.), remarks: "Les differences
reelles qui existent entre l'encephale de l'homme et celui des singes
superieurs, sont bien minimes. Il ne faut pas se faire d'illusions a cet
egard. L'homme est bien plus pres des singes anthropomorphes par les
caracteres anatomiques de son cerveau que ceux-ci ne le sont non seulement
des autres mammiferes, mais meme de certains quadrumanes, des guenons et
des macaques." But it would be superfluous here to give further details on
the correspondence between man and the higher mammals in the structure of
the brain and all other parts of the body.
It may, however, be worth while to specify a few points, not directly or
obviously connected with structure, by which this correspondence or
relationship is well shewn.
Man is liable to receive from the lower animals, and to communicate to
them, certain diseases, as hydrophobia, variola, the glanders, syphilis,
cholera, herpes, etc. (3. Dr. W. Lauder Lindsay has treated this subject
at some length in the 'Journal of Mental Science,' July 1871; and in the
'Edinburgh Veterinary Review,' July 1858.); and this fact proves the close
similarity (4. A Reviewer has criticised ('British Quarterly Review,' Oct.
1st, 1871, page 472) what I have here said with much severity and contempt;
but as I do not use the term identity, I cannot see that I am greatly in
error. There appears to me a strong analogy between the same infection or
contagion producing the same result, or one closely similar, in two
distinct animals, and the testing of two distinct fluids by the same
chemical reagent.) of their tissues and blood, both in minute structure and
composition, far more plainly than does their comparison under the best
microscope, or by the aid of the best chemical analysis. Monkeys are
liable to many of the same non-contagious diseases as we are; thus Rengger
(5. 'Naturgeschichte der Saugethiere von Paraguay,' 1830, s. 50.), who
carefully observed for a long time the Cebus Azarae in its native land,
found it liable to catarrh, with the usual symptoms, and which, when often
recurrent, led to consumption. These monkeys suffered also from apoplexy,
inflammation of the bowels, and cataract in the eye. The younger ones when
shedding their milk-teeth often died from fever. Medicines produced the
same effect on them as on us. Many kinds of monkeys have a strong taste
for tea, coffee, and spiritous liquors: they will also, as I have myself
seen, smoke tobacco with pleasure. (6. The same tastes are common to some
animals much lower in the scale. Mr. A. Nichols informs me that he kept in
Queensland, in Australia, three individuals of the Phaseolarctus cinereus;
and that, without having been taught in any way, they acquired a strong
taste for rum, and for smoking tobacco.) Brehm asserts that the natives of
north-eastern Africa catch the wild baboons by exposing vessels with strong
beer, by which they are made drunk. He has seen some of these animals,
which he kept in confinement, in this state; and he gives a laughable
account of their behaviour and strange grimaces. On the following morning
they were very cross and dismal; they held their aching heads with both
hands, and wore a most pitiable expression: when beer or wine was offered
them, they turned away with disgust, but relished the juice of lemons. (7.
Brehm, 'Thierleben,' B. i. 1864, s. 75, 86. On the Ateles, s. 105. For
other analogous statements, see s. 25, 107.) An American monkey, an
Ateles, after getting drunk on brandy, would never touch it again, and thus
was wiser than many men. These trifling facts prove how similar the nerves
of taste must be in monkeys and man, and how similarly their whole nervous
system is affected.
Man is infested with internal parasites, sometimes causing fatal effects;
and is plagued by external parasites, all of which belong to the same
genera or families as those infesting other mammals, and in the case of
scabies to the same species. (8. Dr. W. Lauder Lindsay, 'Edinburgh Vet.
Review,' July 1858, page 13.) Man is subject, like other mammals, birds,
and even insects (9. With respect to insects see Dr. Laycock, "On a
General Law of Vital Periodicity," 'British Association,' 1842. Dr.
Macculloch, 'Silliman's North American Journal of Science,' vol. XVII. page
305, has seen a dog suffering from tertian ague. Hereafter I shall return
to this subject.), to that mysterious law, which causes certain normal
processes, such as gestation, as well as the maturation and duration of
various diseases, to follow lunar periods. His wounds are repaired by the
same process of healing; and the stumps left after the amputation of his
limbs, especially during an early embryonic period, occasionally possess
some power of regeneration, as in the lowest animals. (10. I have given
the evidence on this head in my 'Variation of Animals and Plants under
Domestication,' vol. ii. page 15, and more could be added.)
The whole process of that most important function, the reproduction of the
species, is strikingly the same in all mammals, from the first act of
courtship by the male (11. Mares e diversis generibus Quadrumanorum sine
dubio dignoscunt feminas humanas a maribus. Primum, credo, odoratu, postea
aspectu. Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus
animalium erat, vir in rebus observandis cautus et sagax, hoc mihi
certissime probavit, et curatores ejusdem loci et alii e ministris
confirmaverunt. Sir Andrew Smith et Brehm notabant idem in Cynocephalo.
Illustrissimus Cuvier etiam narrat multa de hac re, qua ut opinor, nihil
turpius potest indicari inter omnia hominibus et Quadrumanis communia.
Narrat enim Cynocephalum quendam in furorem incidere aspectu feminarum
aliquarem, sed nequaquam accendi tanto furore ab omnibus. Semper eligebat
juniores, et dignoscebat in turba, et advocabat voce gestuque.), to the
birth and nurturing of the young. Monkeys are born in almost as helpless a
condition as our own infants; and in certain genera the young differ fully
as much in appearance from the adults, as do our children from their
full-grown parents. (12. This remark is made with respect to Cynocephalus
and the anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier,
'Histoire Nat. des Mammiferes,' tom. i. 1824.) It has been urged by some
writers, as an important distinction, that with man the young arrive at
maturity at a much later age than with any other animal: but if we look to
the races of mankind which inhabit tropical countries the difference is not
great, for the orang is believed not to be adult till the age of from ten
to fifteen years. (13. Huxley, 'Man's Place in Nature,' 1863, p. 34.)
Man differs from woman in size, bodily strength, hairiness, etc., as well
as in mind, in the same manner as do the two sexes of many mammals. So
that the correspondence in general structure, in the minute structure of
the tissues, in chemical composition and in constitution, between man and
the higher animals, especially the anthropomorphous apes, is extremely
close.
EMBRYONIC DEVELOPMENT.
[Fig. 1. Shows a human embryo, from Ecker, and a dog embryo, from
Bischoff. Labelled in each are:
a. Fore-brain, cerebral hemispheres, etc.
b. Mid-brain, corpora quadrigemina.
c. Hind-brain, cerebellum, medulla oblongata.
d. Eye.
e. Ear.
f. First visceral arch.
g. Second visceral arch.
H. Vertebral columns and muscles in process of development.
i. Anterior extremities.
K. Posterior extremities.
L. Tail or os coccyx.]
Man is developed from an ovule, about the 125th of an inch in diameter,
which differs in no respect from the ovules of other animals. The embryo
itself at a very early period can hardly be distinguished from that of
other members of the vertebrate kingdom. At this period the arteries run
in arch-like branches, as if to carry the blood to branchiae which are not
present in the higher Vertebrata, though the slits on the sides of the neck
still remain (see f, g, fig. 1), marking their former position. At a
somewhat later period, when the extremities are developed, "the feet of
lizards and mammals," as the illustrious Von Baer remarks, "the wings and
feet of birds, no less than the hands and feet of man, all arise from the
same fundamental form." It is, says Prof. Huxley (14. 'Man's Place in
Nature,' 1863, p. 67.), "quite in the later stages of development that the
young human being presents marked differences from the young ape, while the
latter departs as much from the dog in its developments, as the man does.
Startling as this last assertion may appear to be, it is demonstrably
true."
As some of my readers may never have seen a drawing of an embryo, I have
given one of man and another of a dog, at about the same early stage of
development, carefully copied from two works of undoubted accuracy. (15.
The human embryo (upper fig.) is from Ecker, 'Icones Phys.,' 1851-1859,
tab. xxx. fig. 2. This embryo was ten lines in length, so that the drawing
is much magnified. The embryo of the dog is from Bischoff,
'Entwicklungsgeschichte des Hunde-Eies,' 1845, tab. xi. fig. 42B. This
drawing is five times magnified, the embryo being twenty-five days old.
The internal viscera have been omitted, and the uterine appendages in both
drawings removed. I was directed to these figures by Prof. Huxley, from
whose work, 'Man's Place in Nature,' the idea of giving them was taken.
Haeckel has also given analogous drawings in his 'Schopfungsgeschichte.')
After the foregoing statements made by such high authorities, it would be
superfluous on my part to give a number of borrowed details, shewing that
the embryo of man closely resembles that of other mammals. It may,
however, be added, that the human embryo likewise resembles certain low
forms when adult in various points of structure. For instance, the heart
at first exists as a simple pulsating vessel; the excreta are voided
through a cloacal passage; and the os coccyx projects like a true tail,
"extending considerably beyond the rudimentary legs." (16. Prof. Wyman in
'Proceedings of the American Academy of Sciences,' vol. iv. 1860, p. 17.)
In the embryos of all air-breathing vertebrates, certain glands, called the
corpora Wolffiana, correspond with, and act like the kidneys of mature
fishes. (17. Owen, 'Anatomy of Vertebrates,' vol. i. p. 533.) Even at a
later embryonic period, some striking resemblances between man and the
lower animals may be observed. Bischoff says that "the convolutions of the
brain in a human foetus at the end of the seventh month reach about the
same stage of development as in a baboon when adult." (18. 'Die
Grosshirnwindungen des Menschen,' 1868, s. 95.) The great toe, as
Professor Owen remarks (19. 'Anatomy of Vertebrates,' vol. ii. p. 553.),
"which forms the fulcrum when standing or walking, is perhaps the most
characteristic peculiarity in the human structure;" but in an embryo, about
an inch in length, Prof. Wyman (20. 'Proc. Soc. Nat. Hist.' Boston, 1863,
vol. ix. p. 185.) found "that the great toe was shorter than the others;
and, instead of being parallel to them, projected at an angle from the side
of the foot, thus corresponding with the permanent condition of this part
in the quadrumana." I will conclude with a quotation from Huxley (21.
'Man's Place in Nature,' p. 65.) who after asking, does man originate in a
different way from a dog, bird, frog or fish? says, "the reply is not
doubtful for a moment; without question, the mode of origin, and the early
stages of the development of man, are identical with those of the animals
immediately below him in the scale: without a doubt in these respects, he
is far nearer to apes than the apes are to the dog."
RUDIMENTS.
This subject, though not intrinsically more important than the two last,
will for several reasons be treated here more fully. (22. I had written a
rough copy of this chapter before reading a valuable paper, "Caratteri
rudimentali in ordine all' origine dell' uomo" ('Annuario della Soc. d.
Naturalisti,' Modena, 1867, p. 81), by G. Canestrini, to which paper I am
considerably indebted. Haeckel has given admirable discussions on this
whole subject, under the title of Dysteleology, in his 'Generelle
Morphologie' and 'Schopfungsgeschichte.') Not one of the higher animals
can be named which does not bear some part in a rudimentary condition; and
man forms no exception to the rule. Rudimentary organs must be
distinguished from those that are nascent; though in some cases the
distinction is not easy. The former are either absolutely useless, such as
the mammae of male quadrupeds, or the incisor teeth of ruminants which
never cut through the gums; or they are of such slight service to their
present possessors, that we can hardly suppose that they were developed
under the conditions which now exist. Organs in this latter state are not
strictly rudimentary, but they are tending in this direction. Nascent
organs, on the other hand, though not fully developed, are of high service
to their possessors, and are capable of further development. Rudimentary
organs are eminently variable; and this is partly intelligible, as they are
useless, or nearly useless, and consequently are no longer subjected to
natural selection. They often become wholly suppressed. When this occurs,
they are nevertheless liable to occasional reappearance through reversion--
a circumstance well worthy of attention.
The chief agents in causing organs to become rudimentary seem to have been
disuse at that period of life when the organ is chiefly used (and this is
generally during maturity), and also inheritance at a corresponding period
of life. The term "disuse" does not relate merely to the lessened action
of muscles, but includes a diminished flow of blood to a part or organ,
from being subjected to fewer alternations of pressure, or from becoming in
any way less habitually active. Rudiments, however, may occur in one sex
of those parts which are normally present in the other sex; and such
rudiments, as we shall hereafter see, have often originated in a way
distinct from those here referred to. In some cases, organs have been
reduced by means of natural selection, from having become injurious to the
species under changed habits of life. The process of reduction is probably
often aided through the two principles of compensation and economy of
growth; but the later stages of reduction, after disuse has done all that
can fairly be attributed to it, and when the saving to be effected by the
economy of growth would be very small (23. Some good criticisms on this
subject have been given by Messrs. Murie and Mivart, in 'Transact.
Zoological Society,' 1869, vol. vii. p. 92.), are difficult to understand.
The final and complete suppression of a part, already useless and much
reduced in size, in which case neither compensation nor economy can come
into play, is perhaps intelligible by the aid of the hypothesis of
pangenesis. But as the whole subject of rudimentary organs has been
discussed and illustrated in my former works (24. 'Variation of Animals
and Plants under Domestication,' vol. ii pp. 317 and 397. See also 'Origin
of Species,' 5th Edition p. 535.), I need here say no more on this head.
Rudiments of various muscles have been observed in many parts of the human
body (25. For instance, M. Richard ('Annales des Sciences Nat.,' 3rd
series, Zoolog. 1852, tom. xviii. p. 13) describes and figures rudiments of
what he calls the "muscle pedieux de la main," which he says is sometimes
"infiniment petit." Another muscle, called "le tibial posterieur," is
generally quite absent in the hand, but appears from time to time in a more
or less rudimentary condition.); and not a few muscles, which are regularly
present in some of the lower animals can occasionally be detected in man in
a greatly reduced condition. Every one must have noticed the power which
many animals, especially horses, possess of moving or twitching their skin;
and this is effected by the panniculus carnosus. Remnants of this muscle
in an efficient state are found in various parts of our bodies; for
instance, the muscle on the forehead, by which the eyebrows are raised.
The platysma myoides, which is well developed on the neck, belongs to this
system. Prof. Turner, of Edinburgh, has occasionally detected, as he
informs me, muscular fasciculi in five different situations, namely in the
axillae, near the scapulae, etc., all of which must be referred to the
system of the panniculus. He has also shewn (26. Prof. W. Turner,
'Proceedings of the Royal Society of Edinburgh,' 1866-67, p. 65.) that the
musculus sternalis or sternalis brutorum, which is not an extension of the
rectus abdominalis, but is closely allied to the panniculus, occurred in
the proportion of about three per cent. in upwards of 600 bodies: he adds,
that this muscle affords "an excellent illustration of the statement that
occasional and rudimentary structures are especially liable to variation in
arrangement."
Some few persons have the power of contracting the superficial muscles on
their scalps; and these muscles are in a variable and partially rudimentary
condition. M. A. de Candolle has communicated to me a curious instance of
the long-continued persistence or inheritance of this power, as well as of
its unusual development. He knows a family, in which one member, the
present head of the family, could, when a youth, pitch several heavy books
from his head by the movement of the scalp alone; and he won wagers by
performing this feat. His father, uncle, grandfather, and his three
children possess the same power to the same unusual degree. This family
became divided eight generations ago into two branches; so that the head of
the above-mentioned branch is cousin in the seventh degree to the head of
the other branch. This distant cousin resides in another part of France;
and on being asked whether he possessed the same faculty, immediately
exhibited his power. This case offers a good illustration how persistent
may be the transmission of an absolutely useless faculty, probably derived
from our remote semi-human progenitors; since many monkeys have, and
frequently use the power, of largely moving their scalps up and down. (27.
See my 'Expression of the Emotions in Man and Animals,' 1872, p. 144.)
The extrinsic muscles which serve to move the external ear, and the
intrinsic muscles which move the different parts, are in a rudimentary
condition in man, and they all belong to the system of the panniculus; they
are also variable in development, or at least in function. I have seen one
man who could draw the whole ear forwards; other men can draw it upwards;
another who could draw it backwards (28. Canestrini quotes Hyrtl.
('Annuario della Soc. dei Naturalisti,' Modena, 1867, p. 97) to the same
effect.); and from what one of these persons told me, it is probable that
most of us, by often touching our ears, and thus directing our attention
towards them, could recover some power of movement by repeated trials. The
power of erecting and directing the shell of the ears to the various points
of the compass, is no doubt of the highest service to many animals, as they
thus perceive the direction of danger; but I have never heard, on
sufficient evidence, of a man who possessed this power, the one which might
be of use to him. The whole external shell may be considered a rudiment,
together with the various folds and prominences (helix and anti-helix,
tragus and anti-tragus, etc.) which in the lower animals strengthen and
support the ear when erect, without adding much to its weight. Some
authors, however, suppose that the cartilage of the shell serves to
transmit vibrations to the acoustic nerve; but Mr. Toynbee (29. 'The
Diseases of the Ear,' by J. Toynbee, F.R.S., 1860, p. 12. A distinguished
physiologist, Prof. Preyer, informs me that he had lately been
experimenting on the function of the shell of the ear, and has come to
nearly the same conclusion as that given here.), after collecting all the
known evidence on this head, concludes that the external shell is of no
distinct use. The ears of the chimpanzee and orang are curiously like
those of man, and the proper muscles are likewise but very slightly
developed. (30. Prof. A. Macalister, 'Annals and Magazine of Natural
History,' vol. vii. 1871, p. 342.) I am also assured by the keepers in the
Zoological Gardens that these animals never move or erect their ears; so
that they are in an equally rudimentary condition with those of man, as far
as function is concerned. Why these animals, as well as the progenitors of
man, should have lost the power of erecting their ears, we cannot say. It
may be, though I am not satisfied with this view, that owing to their
arboreal habits and great strength they were but little exposed to danger,
and so during a lengthened period moved their ears but little, and thus
gradually lost the power of moving them. This would be a parallel case
with that of those large and heavy birds, which, from ihabiting oceanic
islands, have not been exposed to the attacks of beasts of prey, and have
consequently lost the power of using their wings for flight. The inability
to move the ears in man and several apes is, however, partly compensated by
the freedom with which they can move the head in a horizontal plane, so as
to catch sounds from all directions. It has been asserted that the ear of
man alone possesses a lobule; but "a rudiment of it is found in the
gorilla" (31. Mr. St. George Mivart, 'Elementary Anatomy,' 1873, p. 396.);
and, as I hear from Prof. Preyer, it is not rarely absent in the negro.
[Fig. 2. Human Ear, modelled and drawn by Mr. Woolner. The projecting
point is labelled a.]
The celebrated sculptor, Mr. Woolner, informs me of one little peculiarity
in the external ear, which he has often observed both in men and women, and
of which he perceived the full significance. His attention was first
called to the subject whilst at work on his figure of Puck, to which he had
given pointed ears. He was thus led to examine the ears of various
monkeys, and subsequently more carefully those of man. The peculiarity
consists in a little blunt point, projecting from the inwardly folded
margin, or helix. When present, it is developed at birth, and, according
to Prof. Ludwig Meyer, more frequently in man than in woman. Mr. Woolner
made an exact model of one such case, and sent me the accompanying drawing.
(Fig. 2). These points not only project inwards towards the centre of the
ear, but often a little outwards from its plane, so as to be visible when
the head is viewed from directly in front or behind. They are variable in
size, and somewhat in position, standing either a little higher or lower;
and they sometimes occur on one ear and not on the other. They are not
confined to mankind, for I observed a case in one of the spider-monkeys
(Ateles beelzebuth) in our Zoological Gardens; and Mr. E. Ray Lankester
informs me of another case in a chimpanzee in the gardens at Hamburg. The
helix obviously consists of the extreme margin of the ear folded inwards;
and this folding appears to be in some manner connected with the whole
external ear being permanently pressed backwards. In many monkeys, which
do not stand high in the order, as baboons and some species of macacus (32.
See also some remarks, and the drawings of the ears of the Lemuroidea, in
Messrs. Murie and Mivart's excellent paper in 'Transactions of the
Zoological Society,' vol. vii. 1869, pp. 6 and 90.), the upper portion of
the ear is slightly pointed, and the margin is not at all folded inwards;
but if the margin were to be thus folded, a slight point would necessarily
project inwards towards the centre, and probably a little outwards from the
plane of the ear; and this I believe to be their origin in many cases. On
the other hand, Prof. L. Meyer, in an able paper recently published (33.
'Uber das Darwin'sche Spitzohr,' Archiv fur Path. Anat. und Phys., 1871, p.
485.), maintains that the whole case is one of mere variability; and that
the projections are not real ones, but are due to the internal cartilage on
each side of the points not having been fully developed. I am quite ready
to admit that this is the correct explanation in many instances, as in
those figured by Prof. Meyer, in which there are several minute points, or
the whole margin is sinuous. I have myself seen, through the kindness of
Dr. L. Down, the ear of a microcephalous idiot, on which there is a
projection on the outside of the helix, and not on the inward folded edge,
so that this point can have no relation to a former apex of the ear.
Nevertheless in some cases, my original view, that the points are vestiges
of the tips of formerly erect and pointed ears, still seems to me probable.
I think so from the frequency of their occurrence, and from the general
correspondence in position with that of the tip of a pointed ear. In one
case, of which a photograph has been sent me, the projection is so large,
that supposing, in accordance with Prof. Meyer's view, the ear to be made
perfect by the equal development of the cartilage throughout the whole
extent of the margin, it would have covered fully one-third of the whole
ear. Two cases have been communicated to me, one in North America, and the
other in England, in which the upper margin is not at all folded inwards,
but is pointed, so that it closely resembles the pointed ear of an ordinary
quadruped in outline. In one of these cases, which was that of a young
child, the father compared the ear with the drawing which I have given (34.
'The Expression of the Emotions,' p. 136.) of the ear of a monkey, the
Cynopithecus niger, and says that their outlines are closely similar. If,
in these two cases, the margin had been folded inwards in the normal
manner, an inward projection must have been formed. I may add that in two
other cases the outline still remains somewhat pointed, although the margin
of the upper part of the ear is normally folded inwards--in one of them,
however, very narrowly. [Fig.3. Foetus of an Orang(?). Exact copy of a
photograph, shewing the form of the ear at this early age.] The following
woodcut (No. 3) is an accurate copy of a photograph of the foetus of an
orang (kindly sent me by Dr. Nitsche), in which it may be seen how
different the pointed outline of the ear is at this period from its adult
condition, when it bears a close general resemblance to that of man. It is
evident that the folding over of the tip of such an ear, unless it changed
greatly during its further development, would give rise to a point
projecting inwards. On the whole, it still seems to me probable that the
points in question are in some cases, both in man and apes, vestiges of a
former condition.
The nictitating membrane, or third eyelid, with its accessory muscles and
other structures, is especially well developed in birds, and is of much
functional importance to them, as it can be rapidly drawn across the whole
eye-ball. It is found in some reptiles and amphibians, and in certain
fishes, as in sharks. It is fairly well developed in the two lower
divisions of the mammalian series, namely, in the monotremata and
marsupials, and in some few of the higher mammals, as in the walrus. But
in man, the quadrumana, and most other mammals, it exists, as is admitted
by all anatomists, as a mere rudiment, called the semilunar fold. (35.
Muller's 'Elements of Physiology,' Eng. translat. 1842, vol. ii. p. 1117.
Owen, 'Anatomy of Vertebrates,' vol. iii. p. 260; ibid. on the Walrus,
'Proceedings of the Zoological Society,' November 8, 1854. See also R.
Knox, 'Great Artists and Anatomists,' p. 106. This rudiment apparently is
somewhat larger in Negroes and Australians than in Europeans, see Carl
Vogt, 'Lectures on Man,' Eng. translat. p. 129.)
The sense of smell is of the highest importance to the greater number of
mammals--to some, as the ruminants, in warning them of danger; to others,
as the Carnivora, in finding their prey; to others, again, as the wild
boar, for both purposes combined. But the sense of smell is of extremely
slight service, if any, even to the dark coloured races of men, in whom it
is much more highly developed than in the white and civilised races. (36.
The account given by Humboldt of the power of smell possessed by the
natives of South America is well known, and has been confirmed by others.
M. Houzeau ('Etudes sur les Facultes Mentales,' etc., tom. i. 1872, p. 91)
asserts that he repeatedly made experiments, and proved that Negroes and
Indians could recognise persons in the dark by their odour. Dr. W. Ogle
has made some curious observations on the connection between the power of
smell and the colouring matter of the mucous membrane of the olfactory
region as well as of the skin of the body. I have, therefore, spoken in
the text of the dark-coloured races having a finer sense of smell than the
white races. See his paper, 'Medico-Chirurgical Transactions,' London,
vol. liii. 1870, p. 276.) Nevertheless it does not warn them of danger,
nor guide them to their food; nor does it prevent the Esquimaux from
sleeping in the most fetid atmosphere, nor many savages from eating
half-putrid meat. In Europeans the power differs greatly in different
individuals, as I am assured by an eminent naturalist who possesses this
sense highly developed, and who has attended to the subject. Those who
believe in the principle of gradual evolution, will not readily admit that
the sense of smell in its present state was originally acquired by man, as
he now exists. He inherits the power in an enfeebled and so far
rudimentary condition, from some early progenitor, to whom it was highly
serviceable, and by whom it was continually used. In those animals which
have this sense highly developed, such as dogs and horses, the recollection
of persons and of places is strongly associated with their odour; and we
can thus perhaps understand how it is, as Dr. Maudsley has truly remarked
(37. 'The Physiology and Pathology of Mind,' 2nd ed. 1868, p. 134.), that
the sense of smell in man "is singularly effective in recalling vividly the
ideas and images of forgotten scenes and places."
Man differs conspicuously from all the other primates in being almost
naked. But a few short straggling hairs are found over the greater part of
the body in the man, and fine down on that of the woman. The different
races differ much in hairiness; and in the individuals of the same race the
hairs are highly variable, not only in abundance, but likewise in position:
thus in some Europeans the shoulders are quite naked, whilst in others they
bear thick tufts of hair. (38. Eschricht, Uber die Richtung der Haare am
menschlichen Korper, Muller's 'Archiv fur Anat. und Phys.' 1837, s. 47. I
shall often have to refer to this very curious paper.) There can be little
doubt that the hairs thus scattered over the body are the rudiments of the
uniform hairy coat of the lower animals. This view is rendered all the
more probable, as it is known that fine, short, and pale-coloured hairs on
the limbs and other parts of the body, occasionally become developed into
"thickset, long, and rather coarse dark hairs," when abnormally nourished
near old-standing inflamed surfaces. (39. Paget, 'Lectures on Surgical
Pathology,' 1853, vol. i. p. 71.)
I am informed by Sir James Paget that often several members of a family
have a few hairs in their eyebrows much longer than the others; so that
even this slight peculiarity seems to be inherited. These hairs, too, seem
to have their representatives; for in the chimpanzee, and in certain
species of Macacus, there are scattered hairs of considerable length rising
from the naked skin above the eyes, and corresponding to our eyebrows;
similar long hairs project from the hairy covering of the superciliary
ridges in some baboons.
The fine wool-like hair, or so-called lanugo, with which the human foetus
during the sixth month is thickly covered, offers a more curious case. It
is first developed, during the fifth month, on the eyebrows and face, and
especially round the mouth, where it is much longer than that on the head.
A moustache of this kind was observed by Eschricht (40. Eschricht, ibid.
s. 40, 47.) on a female foetus; but this is not so surprising a
circumstance as it may at first appear, for the two sexes generally
resemble each other in all external characters during an early period of
growth. The direction and arrangement of the hairs on all parts of the
foetal body are the same as in the adult, but are subject to much
variability. The whole surface, including even the forehead and ears, is
thus thickly clothed; but it is a significant fact that the palms of the
hands and the soles of the feet are quite naked, like the inferior surfaces
of all four extremities in most of the lower animals. As this can hardly
be an accidental coincidence, the woolly covering of the foetus probably
represents the first permanent coat of hair in those mammals which are born
hairy. Three or four cases have been recorded of persons born with their
whole bodies and faces thickly covered with fine long hairs; and this
strange condition is strongly inherited, and is correlated with an abnormal
condition of the teeth. (41. See my 'Variation of Animals and Plants
under Domestication,' vol. ii. p. 327. Prof. Alex. Brandt has recently
sent me an additional case of a father and son, born in Russia, with these
peculiarities. I have received drawings of both from Paris.) Prof. Alex.
Brandt informs me that he has compared the hair from the face of a man thus
characterised, aged thirty-five, with the lanugo of a foetus, and finds it
quite similar in texture; therefore, as he remarks, the case may be
attributed to an arrest of development in the hair, together with its
continued growth. Many delicate children, as I have been assured by a
surgeon to a hospital for children, have their backs covered by rather long
silky hairs; and such cases probably come under the same head.
It appears as if the posterior molar or wisdom-teeth were tending to become
rudimentary in the more civilised races of man. These teeth are rather
smaller than the other molars, as is likewise the case with the
corresponding teeth in the chimpanzee and orang; and they have only two
separate fangs. They do not cut through the gums till about the
seventeenth year, and I have been assured that they are much more liable to
decay, and are earlier lost than the other teeth; but this is denied by
some eminent dentists. They are also much more liable to vary, both in
structure and in the period of their development, than the other teeth.
(42. Dr. Webb, 'Teeth in Man and the Anthropoid Apes,' as quoted by Dr. C.
Carter Blake in Anthropological Review, July 1867, p. 299.) In the
Melanian races, on the other hand, the wisdom-teeth are usually furnished
with three separate fangs, and are generally sound; they also differ from
the other molars in size, less than in the Caucasian races. (43. Owen,
'Anatomy of Vertebrates,' vol. iii. pp. 320, 321, and 325.) Prof.
Schaaffhausen accounts for this difference between the races by "the
posterior dental portion of the jaw being always shortened" in those that
are civilised (44. 'On the Primitive Form of the Skull,' Eng. translat.,
in 'Anthropological Review,' Oct. 1868, p. 426), and this shortening may, I
presume, be attributed to civilised men habitually feeding on soft, cooked
food, and thus using their jaws less. I am informed by Mr. Brace that it
is becoming quite a common practice in the United States to remove some of
the molar teeth of children, as the jaw does not grow large enough for the
perfect development of the normal number. (45. Prof. Montegazza writes to
me from Florence, that he has lately been studying the last molar teeth in
the different races of man, and has come to the same conclusion as that
given in my text, viz., that in the higher or civilised races they are on
the road towards atrophy or elimination.)
With respect to the alimentary canal, I have met with an account of only a
single rudiment, namely the vermiform appendage of the caecum. The caecum
is a branch or diverticulum of the intestine, ending in a cul-de-sac, and
is extremely long in many of the lower vegetable-feeding mammals. In the
marsupial koala it is actually more than thrice as long as the whole body.
(46. Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441.) It is
sometimes produced into a long gradually-tapering point, and is sometimes
constricted in parts. It appears as if, in consequence of changed diet or
habits, the caecum had become much shortened in various animals, the
vermiform appendage being left as a rudiment of the shortened part. That
this appendage is a rudiment, we may infer from its small size, and from
the evidence which Prof. Canestrini (47. 'Annuario della Soc. d. Nat.'
Modena, 1867, p. 94.) has collected of its variability in man. It is
occasionally quite absent, or again is largely developed. The passage is
sometimes completely closed for half or two-thirds of its length, with the
terminal part consisting of a flattened solid expansion. In the orang this
appendage is long and convoluted: in man it arises from the end of the
short caecum, and is commonly from four to five inches in length, being
only about the third of an inch in diameter. Not only is it useless, but
it is sometimes the cause of death, of which fact I have lately heard two
instances: this is due to small hard bodies, such as seeds, entering the
passage, and causing inflammation. (48. M. C. Martins ("De l'Unite
Organique," in 'Revue des Deux Mondes,' June 15, 1862, p. 16) and Haeckel
('Generelle Morphologie,' B. ii. s. 278), have both remarked on the
singular fact of this rudiment sometimes causing death.)
In some of the lower Quadrumana, in the Lemuridae and Carnivora, as well as
in many marsupials, there is a passage near the lower end of the humerus,
called the supra-condyloid foramen, through which the great nerve of the
fore limb and often the great artery pass. Now in the humerus of man,
there is generally a trace of this passage, which is sometimes fairly well
developed, being formed by a depending hook-like process of bone, completed
by a band of ligament. Dr. Struthers (49. With respect to inheritance,
see Dr. Struthers in the 'Lancet,' Feb. 15, 1873, and another important
paper, ibid. Jan. 24, 1863, p. 83. Dr. Knox, as I am informed, was the
first anatomist who drew attention to this peculiar structure in man; see
his 'Great Artists and Anatomists,' p. 63. See also an important memoir on
this process by Dr. Gruber, in the 'Bulletin de l'Acad. Imp. de St.
Petersbourg,' tom. xii. 1867, p. 448.), who has closely attended to the
subject, has now shewn that this peculiarity is sometimes inherited, as it
has occurred in a father, and in no less than four out of his seven
children. When present, the great nerve invariably passes through it; and
this clearly indicates that it is the homologue and rudiment of the
supra-condyloid foramen of the lower animals. Prof. Turner estimates, as
he informs me, that it occurs in about one per cent. of recent skeletons.
But if the occasional development of this structure in man is, as seems
probable, due to reversion, it is a return to a very ancient state of
things, because in the higher Quadrumana it is absent.
There is another foramen or perforation in the humerus, occasionally
present in man, which may be called the inter-condyloid. This occurs, but
not constantly, in various anthropoid and other apes (50. Mr. St. George
Mivart, 'Transactions Phil. Soc.' 1867, p. 310.), and likewise in many of
the lower animals. It is remarkable that this perforation seems to have
been present in man much more frequently during ancient times than
recently. Mr. Busk (51. "On the Caves of Gibraltar," 'Transactions of the
International Congress of Prehistoric Archaeology,' Third Session, 1869, p.
159. Prof. Wyman has lately shewn (Fourth Annual Report, Peabody Museum,
1871, p. 20), that this perforation is present in thirty-one per cent. of
some human remains from ancient mounds in the Western United States, and in
Florida. It frequently occurs in the negro.) has collected the following
evidence on this head: Prof. Broca "noticed the perforation in four and a
half per cent. of the arm-bones collected in the 'Cimetiere du Sud,' at
Paris; and in the Grotto of Orrony, the contents of which are referred to
the Bronze period, as many as eight humeri out of thirty-two were
perforated; but this extraordinary proportion, he thinks, might be due to
the cavern having been a sort of 'family vault.' Again, M. Dupont found
thirty per cent. of perforated bones in the caves of the Valley of the
Lesse, belonging to the Reindeer period; whilst M. Leguay, in a sort of
dolmen at Argenteuil, observed twenty-five per cent. to be perforated; and
M. Pruner-Bey found twenty-six per cent. in the same condition in bones
from Vaureal. Nor should it be left unnoticed that M. Pruner-Bey states
that this condition is common in Guanche skeletons." It is an interesting
fact that ancient races, in this and several other cases, more frequently
present structures which resemble those of the lower animals than do the
modern. One chief cause seems to be that the ancient races stand somewhat
nearer in the long line of descent to their remote animal-like progenitors.
In man, the os coccyx, together with certain other vertebrae hereafter to
be described, though functionless as a tail, plainly represent this part in
other vertebrate animals. At an early embryonic period it is free, and
projects beyond the lower extremities; as may be seen in the drawing (Fig.
1.) of a human embryo. Even after birth it has been known, in certain rare
and anomalous cases (52. Quatrefages has lately collected the evidence on
this subject. 'Revue des Cours Scientifiques,' 1867-1868, p. 625. In 1840
Fleischmann exhibited a human foetus bearing a free tail, which, as is not
always the case, included vertebral bodies; and this tail was critically
examined by the many anatomists present at the meeting of naturalists at
Erlangen (see Marshall in Niederlandischen Archiv fur Zoologie, December
1871).), to form a small external rudiment of a tail. The os coccyx is
short, usually including only four vertebrae, all anchylosed together: and
these are in a rudimentary condition, for they consist, with the exception
of the basal one, of the centrum alone. (53. Owen, 'On the Nature of
Limbs,' 1849, p. 114.) They are furnished with some small muscles; one of
which, as I am informed by Prof. Turner, has been expressly described by
Theile as a rudimentary repetition of the extensor of the tail, a muscle
which is so largely developed in many mammals.
The spinal cord in man extends only as far downwards as the last dorsal or
first lumbar vertebra; but a thread-like structure (the filum terminale)
runs down the axis of the sacral part of the spinal canal, and even along
the back of the coccygeal bones. The upper part of this filament, as Prof.
Turner informs me, is undoubtedly homologous with the spinal cord; but the
lower part apparently consists merely of the pia mater, or vascular
investing membrane. Even in this case the os coccyx may be said to possess
a vestige of so important a structure as the spinal cord, though no longer
enclosed within a bony canal. The following fact, for which I am also
indebted to Prof. Turner, shews how closely the os coccyx corresponds with
the true tail in the lower animals: Luschka has recently discovered at the
extremity of the coccygeal bones a very peculiar convoluted body, which is
continuous with the middle sacral artery; and this discovery led Krause and
Meyer to examine the tail of a monkey (Macacus), and of a cat, in both of
which they found a similarly convoluted body, though not at the extremity.
The reproductive system offers various rudimentary structures; but these
differ in one important respect from the foregoing cases. Here we are not
concerned with the vestige of a part which does not belong to the species
in an efficient state, but with a part efficient in the one sex, and
represented in the other by a mere rudiment. Nevertheless, the occurrence
of such rudiments is as difficult to explain, on the belief of the separate
creation of each species, as in the foregoing cases. Hereafter I shall
have to recur to these rudiments, and shall shew that their presence
generally depends merely on inheritance, that is, on parts acquired by one
sex having been partially transmitted to the other. I will in this place
only give some instances of such rudiments. It is well known that in the
males of all mammals, including man, rudimentary mammae exist. These in
several instances have become well developed, and have yielded a copious
supply of milk. Their essential identity in the two sexes is likewise
shewn by their occasional sympathetic enlargement in both during an attack
of the measles. The vesicula prostatica, which has been observed in many
male mammals, is now universally acknowledged to be the homologue of the
female uterus, together with the connected passage. It is impossible to
read Leuckart's able description of this organ, and his reasoning, without
admitting the justness of his conclusion. This is especially clear in the
case of those mammals in which the true female uterus bifurcates, for in
the males of these the vesicula likewise bifurcates. (54. Leuckart, in
Todd's 'Cyclopaedia of Anatomy' 1849-52, vol. iv. p. 1415. In man this
organ is only from three to six lines in length, but, like so many other
rudimentary parts, it is variable in development as well as in other
characters.) Some other rudimentary structures belonging to the
reproductive system might have been here adduced. (55. See, on this
subject, Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 675, 676, 706.)
The bearing of the three great classes of facts now given is unmistakeable.
But it would be superfluous fully to recapitulate the line of argument
given in detail in my 'Origin of Species.' The homological construction of
the whole frame in the members of the same class is intelligible, if we
admit their descent from a common progenitor, together with their
subsequent adaptation to diversified conditions. On any other view, the
similarity of pattern between the hand of a man or monkey, the foot of a
horse, the flipper of a seal, the wing of a bat, etc., is utterly
inexplicable. (56. Prof. Bianconi, in a recently published work,
illustrated by admirable engravings ('La Theorie Darwinienne et la creation
dite independante,' 1874), endeavours to shew that homological structures,
in the above and other cases, can be fully explained on mechanical
principles, in accordance with their uses. No one has shewn so well, how
admirably such structures are adapted for their final purpose; and this
adaptation can, as I believe, be explained through natural selection. In
considering the wing of a bat, he brings forward (p. 218) what appears to
me (to use Auguste Comte's words) a mere metaphysical principle, namely,
the preservation "in its integrity of the mammalian nature of the animal."
In only a few cases does he discuss rudiments, and then only those parts
which are partially rudimentary, such as the little hoofs of the pig and
ox, which do not touch the ground; these he shews clearly to be of service
to the animal. It is unfortunate that he did not consider such cases as
the minute teeth, which never cut through the jaw in the ox, or the mammae
of male quadrupeds, or the wings of certain beetles, existing under the
soldered wing-covers, or the vestiges of the pistil and stamens in various
flowers, and many other such cases. Although I greatly admire Prof.
Bianconi's work, yet the belief now held by most naturalists seems to me
left unshaken, that homological structures are inexplicable on the
principle of mere adaptation.) It is no scientific explanation to assert
that they have all been formed on the same ideal plan. With respect to
development, we can clearly understand, on the principle of variations
supervening at a rather late embryonic period, and being inherited at a
corresponding period, how it is that the embryos of wonderfully different
forms should still retain, more or less perfectly, the structure of their
common progenitor. No other explanation has ever been given of the
marvellous fact that the embryos of a man, dog, seal, bat, reptile, etc.,
can at first hardly be distinguished from each other. In order to
understand the existence of rudimentary organs, we have only to suppose
that a former progenitor possessed the parts in question in a perfect
state, and that under changed habits of life they became greatly reduced,
either from simple disuse, or through the natural selection of those
individuals which were least encumbered with a superfluous part, aided by
the other means previously indicated.
Thus we can understand how it has come to pass that man and all other
vertebrate animals have been constructed on the same general model, why
they pass through the same early stages of development, and why they retain
certain rudiments in common. Consequently we ought frankly to admit their
community of descent: to take any other view, is to admit that our own
structure, and that of all the animals around us, is a mere snare laid to
entrap our judgment. This conclusion is greatly strengthened, if we look
to the members of the whole animal series, and consider the evidence
derived from their affinities or classification, their geographical
distribution and geological succession. It is only our natural prejudice,
and that arrogance which made our forefathers declare that they were
descended from demi-gods, which leads us to demur to this conclusion. But
the time will before long come, when it will be thought wonderful that
naturalists, who were well acquainted with the comparative structure and
development of man, and other mammals, should have believed that each was
the work of a separate act of creation.
CHAPTER II.
ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM.
Variability of body and mind in man--Inheritance--Causes of variability--
Laws of variation the same in man as in the lower animals--Direct action of
the conditions of life--Effects of the increased use and disuse of parts--
Arrested development--Reversion--Correlated variation--Rate of increase--
Checks to increase--Natural selection--Man the most dominant animal in the
world--Importance of his corporeal structure--The causes which have led to
his becoming erect--Consequent changes of structure--Decrease in size of
the canine teeth--Increased size and altered shape of the skull--Nakedness
--Absence of a tail--Defenceless condition of man.
It is manifest that man is now subject to much variability. No two
individuals of the same race are quite alike. We may compare millions of
faces, and each will be distinct. There is an equally great amount of
diversity in the proportions and dimensions of the various parts of the
body; the length of the legs being one of the most variable points. (1.
'Investigations in Military and Anthropological Statistics of American
Soldiers,' by B.A. Gould, 1869, p. 256.) Although in some quarters of the
world an elongated skull, and in other quarters a short skull prevails, yet
there is great diversity of shape even within the limits of the same race,
as with the aborigines of America and South Australia--the latter a race
"probably as pure and homogeneous in blood, customs, and language as any in
existence"--and even with the inhabitants of so confined an area as the
Sandwich Islands. (2. With respect to the "Cranial forms of the American
aborigines," see Dr. Aitken Meigs in 'Proc. Acad. Nat. Sci.' Philadelphia,
May 1868. On the Australians, see Huxley, in Lyell's 'Antiquity of Man,'
1863, p. 87. On the Sandwich Islanders, Prof. J. Wyman, 'Observations on
Crania,' Boston, 1868, p. 18.) An eminent dentist assures me that there is
nearly as much diversity in the teeth as in the features. The chief
arteries so frequently run in abnormal courses, that it has been found
useful for surgical purposes to calculate from 1040 corpses how often each
course prevails. (3. 'Anatomy of the Arteries,' by R. Quain. Preface,
vol. i. 1844.) The muscles are eminently variable: thus those of the foot
were found by Prof. Turner (4. 'Transactions of the Royal Society of
Edinburgh,' vol. xxiv. pp. 175, 189.) not to be strictly alike in any two
out of fifty bodies; and in some the deviations were considerable. He
adds, that the power of performing the appropriate movements must have been
modified in accordance with the several deviations. Mr. J. Wood has
recorded (5. 'Proceedings Royal Society,' 1867, p. 544; also 1868, pp.
483, 524. There is a previous paper, 1866, p. 229.) the occurrence of 295
muscular variations in thirty-six subjects, and in another set of the same
number no less than 558 variations, those occurring on both sides of the
body being only reckoned as one. In the last set, not one body out of the
thirty-six was "found totally wanting in departures from the standard
descriptions of the muscular system given in anatomical text books." A
single body presented the extraordinary number of twenty-five distinct
abnormalities. The same muscle sometimes varies in many ways: thus Prof.
Macalister describes (6. 'Proc. R. Irish Academy,' vol. x. 1868, p. 141.)
no less than twenty distinct variations in the palmaris accessorius.
The famous old anatomist, Wolff (7. 'Act. Acad. St. Petersburg,' 1778,
part ii. p. 217.), insists that the internal viscera are more variable than
the external parts: Nulla particula est quae non aliter et aliter in aliis
se habeat hominibus. He has even written a treatise on the choice of
typical examples of the viscera for representation. A discussion on the
beau-ideal of the liver, lungs, kidneys, etc., as of the human face divine,
sounds strange in our ears.
The variability or diversity of the mental faculties in men of the same
race, not to mention the greater differences between the men of distinct
races, is so notorious that not a word need here be said. So it is with
the lower animals. All who have had charge of menageries admit this fact,
and we see it plainly in our dogs and other domestic animals. Brehm
especially insists that each individual monkey of those which he kept tame
in Africa had its own peculiar disposition and temper: he mentions one
baboon remarkable for its high intelligence; and the keepers in the
Zoological Gardens pointed out to me a monkey, belonging to the New World
division, equally remarkable for intelligence. Rengger, also, insists on
the diversity in the various mental characters of the monkeys of the same
species which he kept in Paraguay; and this diversity, as he adds, is
partly innate, and partly the result of the manner in which they have been
treated or educated. (8. Brehm, 'Thierleben,' B. i. ss. 58, 87. Rengger,
'Saugethiere von Paraguay,' s. 57.)
I have elsewhere (9. 'Variation of Animals and Plants under
Domestication,' vol. ii. chap. xii.) so fully discussed the subject of
Inheritance, that I need here add hardly anything. A greater number of
facts have been collected with respect to the transmission of the most
trifling, as well as of the most important characters in man, than in any
of the lower animals; though the facts are copious enough with respect to
the latter. So in regard to mental qualities, their transmission is
manifest in our dogs, horses, and other domestic animals. Besides special
tastes and habits, general intelligence, courage, bad and good temper,
etc., are certainly transmitted. With man we see similar facts in almost
every family; and we now know, through the admirable labours of Mr. Galton
(10. 'Hereditary Genius: an Inquiry into its Laws and Consequences,'
1869.), that genius which implies a wonderfully complex combination of high
faculties, tends to be inherited; and, on the other hand, it is too certain
that insanity and deteriorated mental powers likewise run in families.
With respect to the causes of variability, we are in all cases very
ignorant; but we can see that in man as in the lower animals, they stand in
some relation to the conditions to which each species has been exposed,
during several generations. Domesticated animals vary more than those in a
state of nature; and this is apparently due to the diversified and changing
nature of the conditions to which they have been subjected. In this
respect the different races of man resemble domesticated animals, and so do
the individuals of the same race, when inhabiting a very wide area, like
that of America. We see the influence of diversified conditions in the
more civilised nations; for the members belonging to different grades of
rank, and following different occupations, present a greater range of
character than do the members of barbarous nations. But the uniformity of
savages has often been exaggerated, and in some cases can hardly be said to
exist. (11. Mr. Bates remarks ('The Naturalist on the Amazons,' 1863,
vol. ii p. 159), with respect to the Indians of the same South American
tribe, "no two of them were at all similar in the shape of the head; one
man had an oval visage with fine features, and another was quite Mongolian
in breadth and prominence of cheek, spread of nostrils, and obliquity of
eyes.") It is, nevertheless, an error to speak of man, even if we look
only to the conditions to which he has been exposed, as "far more
domesticated" (12. Blumenbach, 'Treatises on Anthropology.' Eng.
translat., 1865, p. 205.) than any other animal. Some savage races, such
as the Australians, are not exposed to more diversified conditions than are
many species which have a wide range. In another and much more important
respect, man differs widely from any strictly domesticated animal; for his
breeding has never long been controlled, either by methodical or
unconscious selection. No race or body of men has been so completely
subjugated by other men, as that certain individuals should be preserved,
and thus unconsciously selected, from somehow excelling in utility to their
masters. Nor have certain male and female individuals been intentionally
picked out and matched, except in the well-known case of the Prussian
grenadiers; and in this case man obeyed, as might have been expected, the
law of methodical selection; for it is asserted that many tall men were
reared in the villages inhabited by the grenadiers and their tall wives.
In Sparta, also, a form of selection was followed, for it was enacted that
all children should be examined shortly after birth; the well-formed and
vigorous being preserved, the others left to perish. (13. Mitford's
'History of Greece,' vol. i. p. 282. It appears also from a passage in
Xenophon's 'Memorabilia,' B. ii. 4 (to which my attention has been called
by the Rev. J.N. Hoare), that it was a well recognised principle with the
Greeks, that men ought to select their wives with a view to the health and
vigour of their children. The Grecian poet, Theognis, who lived 550 B.C.,
clearly saw how important selection, if carefully applied, would be for the
improvement of mankind. He saw, likewise, that wealth often checks the
proper action of sexual selection. He thus writes:
"With kine and horses, Kurnus! we proceed
By reasonable rules, and choose a breed
For profit and increase, at any price:
Of a sound stock, without defect or vice.
But, in the daily matches that we make,
The price is everything: for money's sake,
Men marry: women are in marriage given
The churl or ruffian, that in wealth has thriven,
May match his offspring with the proudest race:
Thus everything is mix'd, noble and base!
If then in outward manner, form, and mind,
You find us a degraded, motley kind,
Wonder no more, my friend! the cause is plain,
And to lament the consequence is vain."
(The Works of J. Hookham Frere, vol. ii. 1872, p. 334.))
If we consider all the races of man as forming a single species, his range
is enormous; but some separate races, as the Americans and Polynesians,
have very wide ranges. It is a well-known law that widely-ranging species
are much more variable than species with restricted ranges; and the
variability of man may with more truth be compared with that of widely-
ranging species, than with that of domesticated animals.
Not only does variability appear to be induced in man and the lower animals
by the same general causes, but in both the same parts of the body are
affected in a closely analogous manner. This has been proved in such full
detail by Godron and Quatrefages, that I need here only refer to their
works. (14. Godron, 'De l'Espece,' 1859, tom. ii. livre 3. Quatrefages,
'Unite de l'Espece Humaine,' 1861. Also Lectures on Anthropology, given in
the 'Revue des Cours Scientifiques,' 1866-1868.) Monstrosities, which
graduate into slight variations, are likewise so similar in man and the
lower animals, that the same classification and the same terms can be used
for both, as has been shewn by Isidore Geoffroy St.-Hilaire. (15. 'Hist.
Gen. et Part. des Anomalies de l'Organisation,' in three volumes, tom. i.
1832.) In my work on the variation of domestic animals, I have attempted
to arrange in a rude fashion the laws of variation under the following
heads:--The direct and definite action of changed conditions, as exhibited
by all or nearly all the individuals of the same species, varying in the
same manner under the same circumstances. The effects of the long-
continued use or disuse of parts. The cohesion of homologous parts. The
variability of multiple parts. Compensation of growth; but of this law I
have found no good instance in the case of man. The effects of the
mechanical pressure of one part on another; as of the pelvis on the cranium
of the infant in the womb. Arrests of development, leading to the
diminution or suppression of parts. The reappearance of long-lost
characters through reversion. And lastly, correlated variation. All these
so-called laws apply equally to man and the lower animals; and most of them
even to plants. It would be superfluous here to discuss all of them (16.
I have fully discussed these laws in my 'Variation of Animals and Plants
under Domestication,' vol. ii. chap. xxii. and xxiii. M. J.P. Durand has
lately (1868) published a valuable essay, 'De l'Influence des Milieux,'
etc. He lays much stress, in the case of plants, on the nature of the
soil.); but several are so important, that they must be treated at
considerable length.
THE DIRECT AND DEFINITE ACTION OF CHANGED CONDITIONS.
This is a most perplexing subject. It cannot be denied that changed
conditions produce some, and occasionally a considerable effect, on
organisms of all kinds; and it seems at first probable that if sufficient
time were allowed this would be the invariable result. But I have failed
to obtain clear evidence in favour of this conclusion; and valid reasons
may be urged on the other side, at least as far as the innumerable
structures are concerned, which are adapted for special ends. There can,
however, be no doubt that changed conditions induce an almost indefinite
amount of fluctuating variability, by which the whole organisation is
rendered in some degree plastic.
In the United States, above 1,000,000 soldiers, who served in the late war,
were measured, and the States in which they were born and reared were
recorded. (17. 'Investigations in Military and Anthrop. Statistics,'
etc., 1869, by B.A. Gould, pp. 93, 107, 126, 131, 134.) From this
astonishing number of observations it is proved that local influences of
some kind act directly on stature; and we further learn that "the State
where the physical growth has in great measure taken place, and the State
of birth, which indicates the ancestry, seem to exert a marked influence on
the stature." For instance, it is established, "that residence in the
Western States, during the years of growth, tends to produce increase of
stature." On the other hand, it is certain that with sailors, their life
delays growth, as shewn "by the great difference between the statures of
soldiers and sailors at the ages of seventeen and eighteen years." Mr.
B.A. Gould endeavoured to ascertain the nature of the influences which thus
act on stature; but he arrived only at negative results, namely that they
did not relate to climate, the elevation of the land, soil, nor even "in
any controlling degree" to the abundance or the need of the comforts of
life. This latter conclusion is directly opposed to that arrived at by
Villerme, from the statistics of the height of the conscripts in different
parts of France. When we compare the differences in stature between the
Polynesian chiefs and the lower orders within the same islands, or between
the inhabitants of the fertile volcanic and low barren coral islands of the
same ocean (18. For the Polynesians, see Prichard's 'Physical History of
Mankind,' vol. v. 1847, pp. 145, 283. Also Godron, 'De l'Espece,' tom. ii.
p. 289. There is also a remarkable difference in appearance between the
closely-allied Hindoos inhabiting the Upper Ganges and Bengal; see
Elphinstone's 'History of India,' vol. i. p. 324.) or again between the
Fuegians on the eastern and western shores of their country, where the
means of subsistence are very different, it is scarcely possible to avoid
the conclusion that better food and greater comfort do influence stature.
But the preceding statements shew how difficult it is to arrive at any
precise result. Dr. Beddoe has lately proved that, with the inhabitants of
Britain, residence in towns and certain occupations have a deteriorating
influence on height; and he infers that the result is to a certain extent
inherited, as is likewise the case in the United States. Dr. Beddoe
further believes that wherever a "race attains its maximum of physical
development, it rises highest in energy and moral vigour." (19. 'Memoirs,
Anthropological Society,' vol. iii. 1867-69, pp. 561, 565, 567.)
Whether external conditions produce any other direct effect on man is not
known. It might have been expected that differences of climate would have
had a marked influence, inasmuch as the lungs and kidneys are brought into
activity under a low temperature, and the liver and skin under a high one.
(20. Dr. Brakenridge, 'Theory of Diathesis,' 'Medical Times,' June 19 and
July 17, 1869.) It was formerly thought that the colour of the skin and
the character of the hair were determined by light or heat; and although it
can hardly be denied that some effect is thus produced, almost all
observers now agree that the effect has been very small, even after
exposure during many ages. But this subject will be more properly
discussed when we treat of the different races of mankind. With our
domestic animals there are grounds for believing that cold and damp
directly affect the growth of the hair; but I have not met with any
evidence on this head in the case of man.
EFFECTS OF THE INCREASED USE AND DISUSE OF PARTS.
It is well known that use strengthens the muscles in the individual, and
complete disuse, or the destruction of the proper nerve, weakens them.
When the eye is destroyed, the optic nerve often becomes atrophied. When
an artery is tied, the lateral channels increase not only in diameter, but
in the thickness and strength of their coats. When one kidney ceases to
act from disease, the other increases in size, and does double work. Bones
increase not only in thickness, but in length, from carrying a greater
weight. (21. I have given authorities for these several statements in my
'Variation of Animals and Plants under Domestication,' vol. ii. pp. 297-
300. Dr. Jaeger, "Uber das Langenwachsthum der Knochen," 'Jenaischen
Zeitschrift,' B. v. Heft. i.) Different occupations, habitually followed,
lead to changed proportions in various parts of the body. Thus it was
ascertained by the United States Commission (22. 'Investigations,' etc.,
by B.A. Gould, 1869, p. 288.) that the legs of the sailors employed in the
late war were longer by 0.217 of an inch than those of the soldiers, though
the sailors were on an average shorter men; whilst their arms were shorter
by 1.09 of an inch, and therefore, out of proportion, shorter in relation
to their lesser height. This shortness of the arms is apparently due to
their greater use, and is an unexpected result: but sailors chiefly use
their arms in pulling, and not in supporting weights. With sailors, the
girth of the neck and the depth of the instep are greater, whilst the
circumference of the chest, waist, and hips is less, than in soldiers.
Whether the several foregoing modifications would become hereditary, if the
same habits of life were followed during many generations, is not known,
but it is probable. Rengger (23. 'Saugethiere von Paraguay,' 1830, s. 4.)
attributes the thin legs and thick arms of the Payaguas Indians to
successive generations having passed nearly their whole lives in canoes,
with their lower extremities motionless. Other writers have come to a
similar conclusion in analogous cases. According to Cranz (24. 'History
of Greenland,' Eng. translat., 1767, vol. i. p. 230.), who lived for a long
time with the Esquimaux, "the natives believe that ingenuity and dexterity
in seal-catching (their highest art and virtue) is hereditary; there is
really something in it, for the son of a celebrated seal-catcher will
distinguish himself, though he lost his father in childhood." But in this
case it is mental aptitude, quite as much as bodily structure, which
appears to be inherited. It is asserted that the hands of English
labourers are at birth larger than those of the gentry. (25.
'Intermarriage,' by Alex. Walker, 1838, p. 377.) From the correlation
which exists, at least in some cases (26. 'The Variation of Animals under
Domestication,' vol. i. p. 173.), between the development of the
extremities and of the jaws, it is possible that in those classes which do
not labour much with their hands and feet, the jaws would be reduced in
size from this cause. That they are generally smaller in refined and
civilised men than in hard-working men or savages, is certain. But with
savages, as Mr. Herbert Spencer (27. 'Principles of Biology,' vol. i. p.
455.) has remarked, the greater use of the jaws in chewing coarse, uncooked
food, would act in a direct manner on the masticatory muscles, and on the
bones to which they are attached. In infants, long before birth, the skin
on the soles of the feet is thicker than on any other part of the body;
(28. Paget, 'Lectures on Surgical Pathology,' vol. ii, 1853, p. 209.) and
it can hardly be doubted that this is due to the inherited effects of
pressure during a long series of generations.
It is familiar to every one that watchmakers and engravers are liable to be
short-sighted, whilst men living much out of doors, and especially savages,
are generally long-sighted. (29. It is a singular and unexpected fact
that sailors are inferior to landsmen in their mean distance of distinct
vision. Dr. B.A. Gould ('Sanitary Memoirs of the War of the Rebellion,'
1869, p. 530), has proved this to be the case; and he accounts for it by
the ordinary range of vision in sailors being "restricted to the length of
the vessel and the height of the masts.") Short-sight and long-sight
certainly tend to be inherited. (30. 'The Variation of Animals under
Domestication,' vol. i. p. 8.) The inferiority of Europeans, in comparison
with savages, in eyesight and in the other senses, is no doubt the
accumulated and transmitted effect of lessened use during many generations;
for Rengger (31. 'Saugethiere von Paraguay,' s. 8, 10. I have had good
opportunities for observing the extraordinary power of eyesight in the
Fuegians. See also Lawrence ('Lectures on Physiology,' etc., 1822, p. 404)
on this same subject. M. Giraud-Teulon has recently collected ('Revue des
Cours Scientifiques,' 1870, p. 625) a large and valuable body of evidence
proving that the cause of short-sight, "C'est le travail assidu, de pres.")
states that he has repeatedly observed Europeans, who had been brought up
and spent their whole lives with the wild Indians, who nevertheless did not
equal them in the sharpness of their senses. The same naturalist observes
that the cavities in the skull for the reception of the several sense-
organs are larger in the American aborigines than in Europeans; and this
probably indicates a corresponding difference in the dimensions of the
organs themselves. Blumenbach has also remarked on the large size of the
nasal cavities in the skulls of the American aborigines, and connects this
fact with their remarkably acute power of smell. The Mongolians of the
plains of northern Asia, according to Pallas, have wonderfully perfect
senses; and Prichard believes that the great breadth of their skulls across
the zygomas follows from their highly-developed sense organs. (32.
Prichard, 'Physical History of Mankind,' on the authority of Blumenbach,
vol. i. 1851, p. 311; for the statement by Pallas, vol. iv. 1844, p. 407.)
The Quechua Indians inhabit the lofty plateaux of Peru; and Alcide
d'Orbigny states (33. Quoted by Prichard, 'Researches into the Physical
History of Mankind,' vol. v. p. 463.) that, from continually breathing a
highly rarefied atmosphere, they have acquired chests and lungs of
extraordinary dimensions. The cells, also, of the lungs are larger and
more numerous than in Europeans. These observations have been doubted, but
Mr. D. Forbes carefully measured many Aymaras, an allied race, living at
the height of between 10,000 and 15,000 feet; and he informs me (34. Mr.
Forbes' valuable paper is now published in the 'Journal of the Ethnological
Society of London,' new series, vol. ii. 1870, p.193.) that they differ
conspicuously from the men of all other races seen by him in the
circumference and length of their bodies. In his table of measurements,
the stature of each man is taken at 1000, and the other measurements are
reduced to this standard. It is here seen that the extended arms of the
Aymaras are shorter than those of Europeans, and much shorter than those of
Negroes. The legs are likewise shorter; and they present this remarkable
peculiarity, that in every Aymara measured, the femur is actually shorter
than the tibia. On an average, the length of the femur to that of the
tibia is as 211 to 252; whilst in two Europeans, measured at the same time,
the femora to the tibiae were as 244 to 230; and in three Negroes as 258 to
241. The humerus is likewise shorter relatively to the forearm. This
shortening of that part of the limb which is nearest to the body, appears
to be, as suggested to me by Mr. Forbes, a case of compensation in relation
with the greatly increased length of the trunk. The Aymaras present some
other singular points of structure, for instance, the very small projection
of the heel.
These men are so thoroughly acclimatised to their cold and lofty abode,
that when formerly carried down by the Spaniards to the low eastern plains,
and when now tempted down by high wages to the gold-washings, they suffer a
frightful rate of mortality. Nevertheless Mr. Forbes found a few pure
families which had survived during two generations: and he observed that
they still inherited their characteristic peculiarities. But it was
manifest, even without measurement, that these peculiarities had all
decreased; and on measurement, their bodies were found not to be so much
elongated as those of the men on the high plateau; whilst their femora had
become somewhat lengthened, as had their tibiae, although in a less degree.
The actual measurements may be seen by consulting Mr. Forbes's memoir.
From these observations, there can, I think, be no doubt that residence
during many generations at a great elevation tends, both directly and
indirectly, to induce inherited modifications in the proportions of the
body. (35. Dr. Wilckens ('Landwirthschaft. Wochenblatt,' No. 10, 1869)
has lately published an interesting essay shewing how domestic animals,
which live in mountainous regions, have their frames modified.)
Although man may not have been much modified during the latter stages of
his existence through the increased or decreased use of parts, the facts
now given shew that his liability in this respect has not been lost; and we
positively know that the same law holds good with the lower animals.
Consequently we may infer that when at a remote epoch the progenitors of
man were in a transitional state, and were changing from quadrupeds into
bipeds, natural selection would probably have been greatly aided by the
inherited effects of the increased or diminished use of the different parts
of the body.
ARRESTS OF DEVELOPMENT.
There is a difference between arrested development and arrested growth, for
parts in the former state continue to grow whilst still retaining their
early condition. Various monstrosities come under this head; and some, as
a cleft palate, are known to be occasionally inherited. It will suffice
for our purpose to refer to the arrested brain-development of
microcephalous idiots, as described in Vogt's memoir. (36. 'Memoires sur
les Microcephales,' 1867, pp. 50, 125, 169, 171, 184-198.) Their skulls
are smaller, and the convolutions of the brain are less complex than in
normal men. The frontal sinus, or the projection over the eye-brows, is
largely developed, and the jaws are prognathous to an "effrayant" degree;
so that these idiots somewhat resemble the lower types of mankind. Their
intelligence, and most of their mental faculties, are extremely feeble.
They cannot acquire the power of speech, and are wholly incapable of
prolonged attention, but are much given to imitation. They are strong and
remarkably active, continually gambolling and jumping about, and making
grimaces. They often ascend stairs on all-fours; and are curiously fond of
climbing up furniture or trees. We are thus reminded of the delight shewn
by almost all boys in climbing trees; and this again reminds us how lambs
and kids, originally alpine animals, delight to frisk on any hillock,
however small. Idiots also resemble the lower animals in some other
respects; thus several cases are recorded of their carefully smelling every
mouthful of food before eating it. One idiot is described as often using
his mouth in aid of his hands, whilst hunting for lice. They are often
filthy in their habits, and have no sense of decency; and several cases
have been published of their bodies being remarkably hairy. (37. Prof.
Laycock sums up the character of brute-like idiots by calling them
"theroid;" 'Journal of Mental Science,' July 1863. Dr. Scott ('The Deaf
and Dumb,' 2nd ed. 1870, p. 10) has often observed the imbecile smelling
their food. See, on this same subject, and on the hairiness of idiots, Dr.
Maudsley, 'Body and Mind,' 1870, pp. 46-51. Pinel has also given a
striking case of hairiness in an idiot.)
REVERSION.
Many of the cases to be here given, might have been introduced under the
last heading. When a structure is arrested in its development, but still
continues growing, until it closely resembles a corresponding structure in
some lower and adult member of the same group, it may in one sense be
considered as a case of reversion. The lower members in a group give us
some idea how the common progenitor was probably constructed; and it is
hardly credible that a complex part, arrested at an early phase of
embryonic development, should go on growing so as ultimately to perform its
proper function, unless it had acquired such power during some earlier
state of existence, when the present exceptional or arrested structure was
normal. The simple brain of a microcephalous idiot, in as far as it
resembles that of an ape, may in this sense be said to offer a case of
reversion. (38. In my 'Variation of Animals under Domestication' (vol.
ii. p. 57), I attributed the not very rare cases of supernumerary mammae in
women to reversion. I was led to this as a probable conclusion, by the
additional mammae being generally placed symmetrically on the breast; and
more especially from one case, in which a single efficient mamma occurred
in the inguinal region of a woman, the daughter of another woman with
supernumerary mammae. But I now find (see, for instance, Prof. Preyer,
'Der Kampf um das Dasein,' 1869, s. 45) that mammae erraticae, occur in
other situations, as on the back, in the armpit, and on the thigh; the
mammae in this latter instance having given so much milk that the child was
thus nourished. The probability that the additional mammae are due to
reversion is thus much weakened; nevertheless, it still seems to me
probable, because two pairs are often found symmetrically on the breast;
and of this I myself have received information in several cases. It is
well known that some Lemurs normally have two pairs of mammae on the
breast. Five cases have been recorded of the presence of more than a pair
of mammae (of course rudimentary) in the male sex of mankind; see 'Journal
of Anat. and Physiology,' 1872, p. 56, for a case given by Dr. Handyside,
in which two brothers exhibited this peculiarity; see also a paper by Dr.
Bartels, in 'Reichert's and du Bois-Reymond's Archiv.,' 1872, p. 304. In
one of the cases alluded to by Dr. Bartels, a man bore five mammae, one
being medial and placed above the navel; Meckel von Hemsbach thinks that
this latter case is illustrated by a medial mamma occurring in certain
Cheiroptera. On the whole, we may well doubt if additional mammae would
ever have been developed in both sexes of mankind, had not his early
progenitors been provided with more than a single pair.
In the above work (vol. ii. p. 12), I also attributed, though with much
hesitation, the frequent cases of polydactylism in men and various animals
to reversion. I was partly led to this through Prof. Owen's statement,
that some of the Ichthyopterygia possess more than five digits, and
therefore, as I supposed, had retained a primordial condition; but Prof.
Gegenbaur ('Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), disputes Owen's
conclusion. On the other hand, according to the opinion lately advanced by
Dr. Gunther, on the paddle of Ceratodus, which is provided with articulated
bony rays on both sides of a central chain of bones, there seems no great
difficulty in admitting that six or more digits on one side, or on both
sides, might reappear through reversion. I am informed by Dr. Zouteveen
that there is a case on record of a man having twenty-four fingers and
twenty-four toes! I was chiefly led to the conclusion that the presence of
supernumerary digits might be due to reversion from the fact that such
digits, not only are strongly inherited, but, as I then believed, had the
power of regrowth after amputation, like the normal digits of the lower
vertebrata. But I have explained in the second edition of my Variation
under Domestication why I now place little reliance on the recorded cases
of such regrowth. Nevertheless it deserves notice, inasmuch as arrested
development and reversion are intimately related processes; that various
structures in an embryonic or arrested condition, such as a cleft palate,
bifid uterus, etc., are frequently accompanied by polydactylism. This has
been strongly insisted on by Meckel and Isidore Geoffroy St.-Hilaire. But
at present it is the safest course to give up altogether the idea that
there is any relation between the development of supernumerary digits and
reversion to some lowly organised progenitor of man.) There are other
cases which come more strictly under our present head of reversion.
Certain structures, regularly occurring in the lower members of the group
to which man belongs, occasionally make their appearance in him, though not
found in the normal human embryo; or, if normally present in the human
embryo, they become abnormally developed, although in a manner which is
normal in the lower members of the group. These remarks will be rendered
clearer by the following illustrations.
In various mammals the uterus graduates from a double organ with two
distinct orifices and two passages, as in the marsupials, into a single
organ, which is in no way double except from having a slight internal fold,
as in the higher apes and man. The rodents exhibit a perfect series of
gradations between these two extreme states. In all mammals the uterus is
developed from two simple primitive tubes, the inferior portions of which
form the cornua; and it is in the words of Dr. Farre, "by the coalescence
of the two cornua at their lower extremities that the body of the uterus is
formed in man; while in those animals in which no middle portion or body
exists, the cornua remain ununited. As the development of the uterus
proceeds, the two cornua become gradually shorter, until at length they are
lost, or, as it were, absorbed into the body of the uterus." The angles of
the uterus are still produced into cornua, even in animals as high up in
the scale as the lower apes and lemurs.
Now in women, anomalous cases are not very infrequent, in which the mature
uterus is furnished with cornua, or is partially divided into two organs;
and such cases, according to Owen, repeat "the grade of concentrative
development," attained by certain rodents. Here perhaps we have an
instance of a simple arrest of embryonic development, with subsequent
growth and perfect functional development; for either side of the partially
double uterus is capable of performing the proper office of gestation. In
other and rarer cases, two distinct uterine cavities are formed, each
having its proper orifice and passage. (39. See Dr. A. Farre's well-known
article in the 'Cyclopaedia of Anatomy and Physiology,' vol. v. 1859, p.
642. Owen, 'Anatomy of Vertebrates,' vol. iii. 1868, p. 687. Professor
Turner, in 'Edinburgh Medical Journal,' February, 1865.) No such stage is
passed through during the ordinary development of the embryo; and it is
difficult to believe, though perhaps not impossible, that the two simple,
minute, primitive tubes should know how (if such an expression may be used)
to grow into two distinct uteri, each with a well-constructed orifice and
passage, and each furnished with numerous muscles, nerves, glands and
vessels, if they had not formerly passed through a similar course of
development, as in the case of existing marsupials. No one will pretend
that so perfect a structure as the abnormal double uterus in woman could be
the result of mere chance. But the principle of reversion, by which a
long-lost structure is called back into existence, might serve as the guide
for its full development, even after the lapse of an enormous interval of
time.
Professor Canestrini, after discussing the foregoing and various analogous
cases, arrives at the same conclusion as that just given. He adduces
another instance, in the case of the malar bone (40. 'Annuario della Soc.
dei Naturalisti,' Modena, 1867, p. 83. Prof. Canestrini gives extracts on
this subject from various authorities. Laurillard remarks, that as he has
found a complete similarity in the form, proportions, and connection of the
two malar bones in several human subjects and in certain apes, he cannot
consider this disposition of the parts as simply accidental. Another paper
on this same anomaly has been published by Dr. Saviotti in the 'Gazzetta
delle Cliniche,' Turin, 1871, where he says that traces of the division may
be detected in about two per cent. of adult skulls; he also remarks that it
more frequently occurs in prognathous skulls, not of the Aryan race, than
in others. See also G. Delorenzi on the same subject; 'Tre nuovi casi
d'anomalia dell' osso malare,' Torino, 1872. Also, E. Morselli, 'Sopra una
rara anomalia dell' osso malare,' Modena, 1872. Still more recently Gruber
has written a pamphlet on the division of this bone. I give these
references because a reviewer, without any grounds or scruples, has thrown
doubts on my statements.), which, in some of the Quadrumana and other
mammals, normally consists of two portions. This is its condition in the
human foetus when two months old; and through arrested development, it
sometimes remains thus in man when adult, more especially in the lower
prognathous races. Hence Canestrini concludes that some ancient progenitor
of man must have had this bone normally divided into two portions, which
afterwards became fused together. In man the frontal bone consists of a
single piece, but in the embryo, and in children, and in almost all the
lower mammals, it consists of two pieces separated by a distinct suture.
This suture occasionally persists more or less distinctly in man after
maturity; and more frequently in ancient than in recent crania, especially,
as Canestrini has observed, in those exhumed from the Drift, and belonging
to the brachycephalic type. Here again he comes to the same conclusion as
in the analogous case of the malar bones. In this, and other instances
presently to be given, the cause of ancient races approaching the lower
animals in certain characters more frequently than do the modern races,
appears to be, that the latter stand at a somewhat greater distance in the
long line of descent from their early semi-human progenitors.
Various other anomalies in man, more or less analogous to the foregoing,
have been advanced by different authors, as cases of reversion; but these
seem not a little doubtful, for we have to descend extremely low in the
mammalian series, before we find such structures normally present. (41. A
whole series of cases is given by Isidore Geoffroy St.-Hilaire, 'Hist. des
Anomalies,' tom, iii, p. 437. A reviewer ('Journal of Anatomy and
Physiology,' 1871, p. 366) blames me much for not having discussed the
numerous cases, which have been recorded, of various parts arrested in
their development. He says that, according to my theory, "every transient
condition of an organ, during its development, is not only a means to an
end, but once was an end in itself." This does not seem to me necessarily
to hold good. Why should not variations occur during an early period of
development, having no relation to reversion; yet such variations might be
preserved and accumulated, if in any way serviceable, for instance, in
shortening and simplifying the course of development? And again, why
should not injurious abnormalities, such as atrophied or hypertrophied
parts, which have no relation to a former state of existence, occur at an
early period, as well as during maturity?)
In man, the canine teeth are perfectly efficient instruments for
mastication. But their true canine character, as Owen (42. 'Anatomy of
Vertebrates,' vol. iii. 1868, p. 323.) remarks, "is indicated by the
conical form of the crown, which terminates in an obtuse point, is convex
outward and flat or sub-concave within, at the base of which surface there
is a feeble prominence. The conical form is best expressed in the Melanian
races, especially the Australian. The canine is more deeply implanted, and
by a stronger fang than the incisors." Nevertheless, this tooth no longer
serves man as a special weapon for tearing his enemies or prey; it may,
therefore, as far as its proper function is concerned, be considered as
rudimentary. In every large collection of human skulls some may be found,
as Haeckel (43. 'Generelle Morphologie,' 1866, B. ii. s. clv.) observes,
with the canine teeth projecting considerably beyond the others in the same
manner as in the anthropomorphous apes, but in a less degree. In these
cases, open spaces between the teeth in the one jaw are left for the
reception of the canines of the opposite jaw. An inter-space of this kind
in a Kaffir skull, figured by Wagner, is surprisingly wide. (44. Carl
Vogt's 'Lectures on Man,' Eng. translat., 1864, p. 151.) Considering how
few are the ancient skulls which have been examined, compared to recent
skulls, it is an interesting fact that in at least three cases the canines
project largely; and in the Naulette jaw they are spoken of as enormous.
(45. C. Carter Blake, on a jaw from La Naulette, 'Anthropological Review,'
1867, p. 295. Schaaffhausen, ibid. 1868, p. 426.)
Of the anthropomorphous apes the males alone have their canines fully
developed; but in the female gorilla, and in a less degree in the female
orang, these teeth project considerably beyond the others; therefore the
fact, of which I have been assured, that women sometimes have considerably
projecting canines, is no serious objection to the belief that their
occasional great development in man is a case of reversion to an ape-like
progenitor. He who rejects with scorn the belief that the shape of his own
canines, and their occasional great development in other men, are due to
our early forefathers having been provided with these formidable weapons,
will probably reveal, by sneering, the line of his descent. For though he
no longer intends, nor has the power, to use these teeth as weapons, he
will unconsciously retract his "snarling muscles" (thus named by Sir C.
Bell) (46. The Anatomy of Expression, 1844, pp. 110, 131.), so as to
expose them ready for action, like a dog prepared to fight.
Many muscles are occasionally developed in man, which are proper to the
Quadrumana or other mammals. Professor Vlacovich (47. Quoted by Prof.
Canestrini in the 'Annuario della Soc. dei Naturalisti,' 1867, p. 90.)
examined forty male subjects, and found a muscle, called by him the ischio-
pubic, in nineteen of them; in three others there was a ligament which
represented this muscle; and in the remaining eighteen no trace of it. In
only two out of thirty female subjects was this muscle developed on both
sides, but in three others the rudimentary ligament was present. This
muscle, therefore, appears to be much more common in the male than in the
female sex; and on the belief in the descent of man from some lower form,
the fact is intelligible; for it has been detected in several of the lower
animals, and in all of these it serves exclusively to aid the male in the
act of reproduction.
Mr. J. Wood, in his valuable series of papers (48. These papers deserve
careful study by any one who desires to learn how frequently our muscles
vary, and in varying come to resemble those of the Quadrumana. The
following references relate to the few points touched on in my text:
'Proc. Royal Soc.' vol. xiv. 1865, pp. 379-384; vol. xv. 1866, pp. 241,
242; vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524. I may here add that
Dr. Murie and Mr. St. George Mivart have shewn in their Memoir on the
Lemuroidea ('Transactions, Zoological Society,' vol. vii. 1869, p. 96), how
extraordinarily variable some of the muscles are in these animals, the
lowest members of the Primates. Gradations, also, in the muscles leading
to structures found in animals still lower in the scale, are numerous in
the Lemuroidea.), has minutely described a vast number of muscular
variations in man, which resemble normal structures in the lower animals.
The muscles which closely resemble those regularly present in our nearest
allies, the Quadrumana, are too numerous to be here even specified. In a
single male subject, having a strong bodily frame, and well-formed skull,
no less than seven muscular variations were observed, all of which plainly
represented muscles proper to various kinds of apes. This man, for
instance, had on both sides of his neck a true and powerful "levator
claviculae," such as is found in all kinds of apes, and which is said to
occur in about one out of sixty human subjects. (49. See also Prof.
Macalister in 'Proceedings, Royal Irish Academy,' vol. x. 1868, p. 124.)
Again, this man had "a special abductor of the metatarsal bone of the fifth
digit, such as Professor Huxley and Mr. Flower have shewn to exist
uniformly in the higher and lower apes." I will give only two additional
cases; the acromio-basilar muscle is found in all mammals below man, and
seems to be correlated with a quadrupedal gait, (50. Mr. Champneys in
'Journal of Anatomy and Physiology,' Nov. 1871, p. 178.) and it occurs in
about one out of sixty human subjects. In the lower extremities Mr.
Bradley (51. Ibid. May 1872, p. 421.) found an abductor ossis metatarsi
quinti in both feet of man; this muscle had not up to that time been
recorded in mankind, but is always present in the anthropomorphous apes.
The muscles of the hands and arms--parts which are so eminently
characteristic of man--are extremely liable to vary, so as to resemble the
corresponding muscles in the lower animals. (52. Prof. Macalister (ibid.
p. 121) has tabulated his observations, and finds that muscular
abnormalities are most frequent in the fore-arms, secondly, in the face,
thirdly, in the foot, etc.) Such resemblances are either perfect or
imperfect; yet in the latter case they are manifestly of a transitional
nature. Certain variations are more common in man, and others in woman,
without our being able to assign any reason. Mr. Wood, after describing
numerous variations, makes the following pregnant remark. "Notable
departures from the ordinary type of the muscular structures run in grooves
or directions, which must be taken to indicate some unknown factor, of much
importance to a comprehensive knowledge of general and scientific anatomy."
(53. The Rev. Dr. Haughton, after giving ('Proc. R. Irish Academy,' June
27, 1864, p. 715) a remarkable case of variation in the human flexor
pollicis longus, adds, "This remarkable example shews that man may
sometimes possess the arrangement of tendons of thumb and fingers
characteristic of the macaque; but whether such a case should be regarded
as a macaque passing upwards into a man, or a man passing downwards into a
macaque, or as a congenital freak of nature, I cannot undertake to say."
It is satisfactory to hear so capable an anatomist, and so embittered an
opponent of evolutionism, admitting even the possibility of either of his
first propositions. Prof. Macalister has also described ('Proceedings
Royal Irish Academy,' vol. x. 1864, p. 138) variations in the flexor
pollicis longus, remarkable from their relations to the same muscle in the
Quadrumana.)
That this unknown factor is reversion to a former state of existence may be
admitted as in the highest degree probable. (54. Since the first edition
of this book appeared, Mr. Wood has published another memoir in the
Philosophical Transactions, 1870, p. 83, on the varieties of the muscles of
the human neck, shoulder, and chest. He here shews how extremely variable
these muscles are, and how often and how closely the variations resemble
the normal muscles of the lower animals. He sums up by remarking, "It will
be enough for my purpose if I have succeeded in shewing the more important
forms which, when occurring as varieties in the human subject, tend to
exhibit in a sufficiently marked manner what may be considered as proofs
and examples of the Darwinian principle of reversion, or law of
inheritance, in this department of anatomical science.") It is quite
incredible that a man should through mere accident abnormally resemble
certain apes in no less than seven of his muscles, if there had been no
genetic connection between them. On the other hand, if man is descended
from some ape-like creature, no valid reason can be assigned why certain
muscles should not suddenly reappear after an interval of many thousand
generations, in the same manner as with horses, asses, and mules, dark-
coloured stripes suddenly reappear on the legs, and shoulders, after an
interval of hundreds, or more probably of thousands of generations.
These various cases of reversion are so closely related to those of
rudimentary organs given in the first chapter, that many of them might have
been indifferently introduced either there or here. Thus a human uterus
furnished with cornua may be said to represent, in a rudimentary condition,
the same organ in its normal state in certain mammals. Some parts which
are rudimentary in man, as the os coccyx in both sexes, and the mammae in
the male sex, are always present; whilst others, such as the supracondyloid
foramen, only occasionally appear, and therefore might have been introduced
under the head of reversion. These several reversionary structures, as
well as the strictly rudimentary ones, reveal the descent of man from some
lower form in an unmistakable manner.
CORRELATED VARIATION.
In man, as in the lower animals, many structures are so intimately related,
that when one part varies so does another, without our being able, in most
cases, to assign any reason. We cannot say whether the one part governs
the other, or whether both are governed by some earlier developed part.
Various monstrosities, as I. Geoffroy repeatedly insists, are thus
intimately connected. Homologous structures are particularly liable to
change together, as we see on the opposite sides of the body, and in the
upper and lower extremities. Meckel long ago remarked, that when the
muscles of the arm depart from their proper type, they almost always
imitate those of the leg; and so, conversely, with the muscles of the legs.
The organs of sight and hearing, the teeth and hair, the colour of the skin
and of the hair, colour and constitution, are more or less correlated.
(55. The authorities for these several statements are given in my
'Variation of Animals under Domestication,' vol. ii. pp. 320-335.)
Professor Schaaffhausen first drew attention to the relation apparently
existing between a muscular frame and the strongly-pronounced supra-orbital
ridges, which are so characteristic of the lower races of man.
Besides the variations which can be grouped with more or less probability
under the foregoing heads, there is a large class of variations which may
be provisionally called spontaneous, for to our ignorance they appear to
arise without any exciting cause. It can, however, be shewn that such
variations, whether consisting of slight individual differences, or of
strongly-marked and abrupt deviations of structure, depend much more on the
constitution of the organism than on the nature of the conditions to which
it has been subjected. (56. This whole subject has been discussed in
chap. xxiii. vol. ii. of my 'Variation of Animals and Plants under
Domestication.')
RATE OF INCREASE.
Civilised populations have been known under favourable conditions, as in
the United States, to double their numbers in twenty-five years; and,
according to a calculation, by Euler, this might occur in a little over
twelve years. (57. See the ever memorable 'Essay on the Principle of
Population,' by the Rev. T. Malthus, vol. i. 1826. pp. 6, 517.) At the
former rate, the present population of the United States (thirty millions),
would in 657 years cover the whole terraqueous globe so thickly, that four
men would have to stand on each square yard of surface. The primary or
fundamental check to the continued increase of man is the difficulty of
gaining subsistence, and of living in comfort. We may infer that this is
the case from what we see, for instance, in the United States, where
subsistence is easy, and there is plenty of room. If such means were
suddenly doubled in Great Britain, our number would be quickly doubled.
With civilised nations this primary check acts chiefly by restraining
marriages. The greater death-rate of infants in the poorest classes is
also very important; as well as the greater mortality, from various
diseases, of the inhabitants of crowded and miserable houses, at all ages.
The effects of severe epidemics and wars are soon counterbalanced, and more
than counterbalanced, in nations placed under favourable conditions.
Emigration also comes in aid as a temporary check, but, with the extremely
poor classes, not to any great extent.
There is reason to suspect, as Malthus has remarked, that the reproductive
power is actually less in barbarous, than in civilised races. We know
nothing positively on this head, for with savages no census has been taken;
but from the concurrent testimony of missionaries, and of others who have
long resided with such people, it appears that their families are usually
small, and large ones rare. This may be partly accounted for, as it is
believed, by the women suckling their infants during a long time; but it is
highly probable that savages, who often suffer much hardship, and who do
not obtain so much nutritious food as civilised men, would be actually less
prolific. I have shewn in a former work (58. 'Variation of Animals and
Plants under Domestication,' vol ii. pp. 111-113, 163.), that all our
domesticated quadrupeds and birds, and all our cultivated plants, are more
fertile than the corresponding species in a state of nature. It is no
valid objection to this conclusion that animals suddenly supplied with an
excess of food, or when grown very fat; and that most plants on sudden
removal from very poor to very rich soil, are rendered more or less
sterile. We might, therefore, expect that civilised men, who in one sense
are highly domesticated, would be more prolific than wild men. It is also
probable that the increased fertility of civilised nations would become, as
with our domestic animals, an inherited character: it is at least known
that with mankind a tendency to produce twins runs in families. (59. Mr.
Sedgwick, 'British and Foreign Medico-Chirurgical Review,' July 1863, p.
170.)
Notwithstanding that savages appear to be less prolific than civilised
people, they would no doubt rapidly increase if their numbers were not by
some means rigidly kept down. The Santali, or hill-tribes of India, have
recently afforded a good illustration of this fact; for, as shewn by Mr.
Hunter (60. 'The Annals of Rural Bengal,' by W.W. Hunter, 1868, p. 259.),
they have increased at an extraordinary rate since vaccination has been
introduced, other pestilences mitigated, and war sternly repressed. This
increase, however, would not have been possible had not these rude people
spread into the adjoining districts, and worked for hire. Savages almost
always marry; yet there is some prudential restraint, for they do not
commonly marry at the earliest possible age. The young men are often
required to shew that they can support a wife; and they generally have
first to earn the price with which to purchase her from her parents. With
savages the difficulty of obtaining subsistence occasionally limits their
number in a much more direct manner than with civilised people, for all
tribes periodically suffer from severe famines. At such times savages are
forced to devour much bad food, and their health can hardly fail to be
injured. Many accounts have been published of their protruding stomachs
and emaciated limbs after and during famines. They are then, also,
compelled to wander much, and, as I was assured in Australia, their infants
perish in large numbers. As famines are periodical, depending chiefly on
extreme seasons, all tribes must fluctuate in number. They cannot steadily
and regularly increase, as there is no artificial increase in the supply of
food. Savages, when hard pressed, encroach on each other's territories,
and war is the result; but they are indeed almost always at war with their
neighbours. They are liable to many accidents on land and water in their
search for food; and in some countries they suffer much from the larger
beasts of prey. Even in India, districts have been depopulated by the
ravages of tigers.
Malthus has discussed these several checks, but he does not lay stress
enough on what is probably the most important of all, namely infanticide,
especially of female infants, and the habit of procuring abortion. These
practices now prevail in many quarters of the world; and infanticide seems
formerly to have prevailed, as Mr. M'Lennan (61. 'Primitive Marriage,'
1865.) has shewn, on a still more extensive scale. These practices appear
to have originated in savages recognising the difficulty, or rather the
impossibility of supporting all the infants that are born. Licentiousness
may also be added to the foregoing checks; but this does not follow from
failing means of subsistence; though there is reason to believe that in
some cases (as in Japan) it has been intentionally encouraged as a means of
keeping down the population.
If we look back to an extremely remote epoch, before man had arrived at the
dignity of manhood, he would have been guided more by instinct and less by
reason than are the lowest savages at the present time. Our early semi-
human progenitors would not have practised infanticide or polyandry; for
the instincts of the lower animals are never so perverted (62. A writer in
the 'Spectator' (March 12, 1871, p. 320) comments as follows on this
passage:--"Mr. Darwin finds himself compelled to reintroduce a new doctrine
of the fall of man. He shews that the instincts of the higher animals are
far nobler than the habits of savage races of men, and he finds himself,
therefore, compelled to re-introduce,--in a form of the substantial
orthodoxy of which he appears to be quite unconscious,--and to introduce as
a scientific hypothesis the doctrine that man's gain of KNOWLEDGE was the
cause of a temporary but long-enduring moral deterioration as indicated by
the many foul customs, especially as to marriage, of savage tribes. What
does the Jewish tradition of the moral degeneration of man through his
snatching at a knowledge forbidden him by his highest instinct assert
beyond this?") as to lead them regularly to destroy their own offspring, or
to be quite devoid of jealousy. There would have been no prudential
restraint from marriage, and the sexes would have freely united at an early
age. Hence the progenitors of man would have tended to increase rapidly;
but checks of some kind, either periodical or constant, must have kept down
their numbers, even more severely than with existing savages. What the
precise nature of these checks were, we cannot say, any more than with most
other animals. We know that horses and cattle, which are not extremely
prolific animals, when first turned loose in South America, increased at an
enormous rate. The elephant, the slowest breeder of all known animals,
would in a few thousand years stock the whole world. The increase of every
species of monkey must be checked by some means; but not, as Brehm remarks,
by the attacks of beasts of prey. No one will assume that the actual power
of reproduction in the wild horses and cattle of America, was at first in
any sensible degree increased; or that, as each district became fully
stocked, this same power was diminished. No doubt, in this case, and in
all others, many checks concur, and different checks under different
circumstances; periodical dearths, depending on unfavourable seasons, being
probably the most important of all. So it will have been with the early
progenitors of man.
NATURAL SELECTION.
We have now seen that man is variable in body and mind; and that the
variations are induced, either directly or indirectly, by the same general
causes, and obey the same general laws, as with the lower animals. Man has
spread widely over the face of the earth, and must have been exposed,
during his incessant migrations (63. See some good remarks to this effect
by W. Stanley Jevons, "A Deduction from Darwin's Theory," 'Nature,' 1869,
p. 231.), to the most diversified conditions. The inhabitants of Tierra
del Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and
of the arctic regions in the other, must have passed through many climates,
and changed their habits many times, before they reached their present
homes. (64. Latham, 'Man and his Migrations,' 1851, p. 135.) The early
progenitors of man must also have tended, like all other animals, to have
increased beyond their means of subsistence; they must, therefore,
occasionally have been exposed to a struggle for existence, and
consequently to the rigid law of natural selection. Beneficial variations
of all kinds will thus, either occasionally or habitually, have been
preserved and injurious ones eliminated. I do not refer to strongly-marked
deviations of structure, which occur only at long intervals of time, but to
mere individual differences. We know, for instance, that the muscles of
our hands and feet, which determine our powers of movement, are liable,
like those of the lower animals, (65. Messrs. Murie and Mivart in their
'Anatomy of the Lemuroidea' ('Transact. Zoolog. Soc.' vol. vii. 1869, pp.
96-98) say, "some muscles are so irregular in their distribution that they
cannot be well classed in any of the above groups." These muscles differ
even on the opposite sides of the same individual.) to incessant
variability. If then the progenitors of man inhabiting any district,
especially one undergoing some change in its conditions, were divided into
two equal bodies, the one half which included all the individuals best
adapted by their powers of movement for gaining subsistence, or for
defending themselves, would on an average survive in greater numbers, and
procreate more offspring than the other and less well endowed half.
Man in the rudest state in which he now exists is the most dominant animal
that has ever appeared on this earth. He has spread more widely than any
other highly organised form: and all others have yielded before him. He
manifestly owes this immense superiority to his intellectual faculties, to
his social habits, which lead him to aid and defend his fellows, and to his
corporeal structure. The supreme importance of these characters has been
proved by the final arbitrament of the battle for life. Through his powers
of intellect, articulate language has been evolved; and on this his
wonderful advancement has mainly depended. As Mr. Chauncey Wright remarks
(66. Limits of Natural Selection, 'North American Review,' Oct. 1870, p.
295.): "a psychological analysis of the faculty of language shews, that
even the smallest proficiency in it might require more brain power than the
greatest proficiency in any other direction." He has invented and is able
to use various weapons, tools, traps, etc., with which he defends himself,
kills or catches prey, and otherwise obtains food. He has made rafts or
canoes for fishing or crossing over to neighbouring fertile islands. He
has discovered the art of making fire, by which hard and stringy roots can
be rendered digestible, and poisonous roots or herbs innocuous. This
discovery of fire, probably the greatest ever made by man, excepting
language, dates from before the dawn of history. These several inventions,
by which man in the rudest state has become so pre-eminent, are the direct
results of the development of his powers of observation, memory, curiosity,
imagination, and reason. I cannot, therefore, understand how it is that
Mr. Wallace (67. 'Quarterly Review,' April 1869, p. 392. This subject is
more fully discussed in Mr. Wallace's 'Contributions to the Theory of
Natural Selection,' 1870, in which all the essays referred to in this work
are re-published. The 'Essay on Man,' has been ably criticised by Prof.
Claparede, one of the most distinguished zoologists in Europe, in an
article published in the 'Bibliotheque Universelle,' June 1870. The remark
quoted in my text will surprise every one who has read Mr. Wallace's
celebrated paper on 'The Origin of Human Races Deduced from the Theory of
Natural Selection,' originally published in the 'Anthropological Review,'
May 1864, p. clviii. I cannot here resist quoting a most just remark by
Sir J. Lubbock ('Prehistoric Times,' 1865, p. 479) in reference to this
paper, namely, that Mr. Wallace, "with characteristic unselfishness,
ascribes it (i.e. the idea of natural selection) unreservedly to Mr.
Darwin, although, as is well known, he struck out the idea independently,
and published it, though not with the same elaboration, at the same time.")
maintains, that "natural selection could only have endowed the savage with
a brain a little superior to that of an ape."
Although the intellectual powers and social habits of man are of paramount
importance to him, we must not underrate the importance of his bodily
structure, to which subject the remainder of this chapter will be devoted;
the development of the intellectual and social or moral faculties being
discussed in a later chapter.
Even to hammer with precision is no easy matter, as every one who has tried
to learn carpentry will admit. To throw a stone with as true an aim as a
Fuegian in defending himself, or in killing birds, requires the most
consummate perfection in the correlated action of the muscles of the hand,
arm, and shoulder, and, further, a fine sense of touch. In throwing a
stone or spear, and in many other actions, a man must stand firmly on his
feet; and this again demands the perfect co-adaptation of numerous muscles.
To chip a flint into the rudest tool, or to form a barbed spear or hook
from a bone, demands the use of a perfect hand; for, as a most capable
judge, Mr. Schoolcraft (68. Quoted by Mr. Lawson Tait in his 'Law of
Natural Selection,' 'Dublin Quarterly Journal of Medical Science,' Feb.
1869. Dr. Keller is likewise quoted to the same effect.), remarks, the
shaping fragments of stone into knives, lances, or arrow-heads, shews
"extraordinary ability and long practice." This is to a great extent
proved by the fact that primeval men practised a division of labour; each
man did not manufacture his own flint tools or rude pottery, but certain
individuals appear to have devoted themselves to such work, no doubt
receiving in exchange the produce of the chase. Archaeologists are
convinced that an enormous interval of time elapsed before our ancestors
thought of grinding chipped flints into smooth tools. One can hardly
doubt, that a man-like animal who possessed a hand and arm sufficiently
perfect to throw a stone with precision, or to form a flint into a rude
tool, could, with sufficient practice, as far as mechanical skill alone is
concerned, make almost anything which a civilised man can make. The
structure of the hand in this respect may be compared with that of the
vocal organs, which in the apes are used for uttering various signal-cries,
or, as in one genus, musical cadences; but in man the closely similar vocal
organs have become adapted through the inherited effects of use for the
utterance of articulate language.
Turning now to the nearest allies of men, and therefore to the best
representatives of our early progenitors, we find that the hands of the
Quadrumana are constructed on the same general pattern as our own, but are
far less perfectly adapted for diversified uses. Their hands do not serve
for locomotion so well as the feet of a dog; as may be seen in such monkeys
as the chimpanzee and orang, which walk on the outer margins of the palms,
or on the knuckles. (69. Owen, 'Anatomy of Vertebrates,' vol. iii. p.
71.) Their hands, however, are admirably adapted for climbing trees.
Monkeys seize thin branches or ropes, with the thumb on one side and the
fingers and palm on the other, in the same manner as we do. They can thus
also lift rather large objects, such as the neck of a bottle, to their
mouths. Baboons turn over stones, and scratch up roots with their hands.
They seize nuts, insects, or other small objects with the thumb in
opposition to the fingers, and no doubt they thus extract eggs and young
from the nests of birds. American monkeys beat the wild oranges on the
branches until the rind is cracked, and then tear it off with the fingers
of the two hands. In a wild state they break open hard fruits with stones.
Other monkeys open mussel-shells with the two thumbs. With their fingers
they pull out thorns and burs, and hunt for each other's parasites. They
roll down stones, or throw them at their enemies: nevertheless, they are
clumsy in these various actions, and, as I have myself seen, are quite
unable to throw a stone with precision.
It seems to me far from true that because "objects are grasped clumsily" by
monkeys, "a much less specialised organ of prehension" would have served
them (70. 'Quarterly Review,' April 1869, p. 392.) equally well with their
present hands. On the contrary, I see no reason to doubt that more
perfectly constructed hands would have been an advantage to them, provided
that they were not thus rendered less fitted for climbing trees. We may
suspect that a hand as perfect as that of man would have been
disadvantageous for climbing; for the most arboreal monkeys in the world,
namely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are
either thumbless, or their toes partially cohere, so that their limbs are
converted into mere grasping hooks. (71. In Hylobates syndactylus, as the
name expresses, two of the toes regularly cohere; and this, as Mr. Blyth
informs me, is occasionally the case with the toes of H. agilis, lar, and
leuciscus. Colobus is strictly arboreal and extraordinarily active (Brehm,
'Thierleben,' B. i. s. 50), but whether a better climber than the species
of the allied genera, I do not know. It deserves notice that the feet of
the sloths, the most arboreal animals in the world, are wonderfully hook-
like.
As soon as some ancient member in the great series of the Primates came to
be less arboreal, owing to a change in its manner of procuring subsistence,
or to some change in the surrounding conditions, its habitual manner of
progression would have been modified: and thus it would have been rendered
more strictly quadrupedal or bipedal. Baboons frequent hilly and rocky
districts, and only from necessity climb high trees (72. Brehm,
'Thierleben,' B. i. s. 80.); and they have acquired almost the gait of a
dog. Man alone has become a biped; and we can, I think, partly see how he
has come to assume his erect attitude, which forms one of his most
conspicuous characters. Man could not have attained his present dominant
position in the world without the use of his hands, which are so admirably
adapted to act in obedience to his will. Sir C. Bell (73. 'The Hand,'
etc., 'Bridgewater Treatise,' 1833, p. 38.) insists that "the hand supplies
all instruments, and by its correspondence with the intellect gives him
universal dominion." But the hands and arms could hardly have become
perfect enough to have manufactured weapons, or to have hurled stones and
spears with a true aim, as long as they were habitually used for locomotion
and for supporting the whole weight of the body, or, as before remarked, so
long as they were especially fitted for climbing trees. Such rough
treatment would also have blunted the sense of touch, on which their
delicate use largely depends. From these causes alone it would have been
an advantage to man to become a biped; but for many actions it is
indispensable that the arms and whole upper part of the body should be
free; and he must for this end stand firmly on his feet. To gain this
great advantage, the feet have been rendered flat; and the great toe has
been peculiarly modified, though this has entailed the almost complete loss
of its power of prehension. It accords with the principle of the division
of physiological labour, prevailing throughout the animal kingdom, that as
the hands became perfected for prehension, the feet should have become
perfected for support and locomotion. With some savages, however, the foot
has not altogether lost its prehensile power, as shewn by their manner of
climbing trees, and of using them in other ways. (74. Haeckel has an
excellent discussion on the steps by which man became a biped: 'Naturliche
Schopfungsgeschicte,' 1868, s. 507. Dr. Buchner ('Conferences sur la
Theorie Darwinienne,' 1869, p. 135) has given good cases of the use of the
foot as a prehensile organ by man; and has also written on the manner of
progression of the higher apes, to which I allude in the following
paragraph: see also Owen ('Anatomy of Vertebrates,' vol. iii. p. 71) on
this latter subject.
If it be an advantage to man to stand firmly on his feet and to have his
hands and arms free, of which, from his pre-eminent success in the battle
of life there can be no doubt, then I can see no reason why it should not
have been advantageous to the progenitors of man to have become more and
more erect or bipedal. They would thus have been better able to defend
themselves with stones or clubs, to attack their prey, or otherwise to
obtain food. The best built individuals would in the long run have
succeeded best, and have survived in larger numbers. If the gorilla and a
few allied forms had become extinct, it might have been argued, with great
force and apparent truth, that an animal could not have been gradually
converted from a quadruped into a biped, as all the individuals in an
intermediate condition would have been miserably ill-fitted for
progression. But we know (and this is well worthy of reflection) that the
anthropomorphous apes are now actually in an intermediate condition; and no
one doubts that they are on the whole well adapted for their conditions of
life. Thus the gorilla runs with a sidelong shambling gait, but more
commonly progresses by resting on its bent hands. The long-armed apes
occasionally use their arms like crutches, swinging their bodies forward
between them, and some kinds of Hylobates, without having been taught, can
walk or run upright with tolerable quickness; yet they move awkwardly, and
much less securely than man. We see, in short, in existing monkeys a
manner of progression intermediate between that of a quadruped and a biped;
but, as an unprejudiced judge (75. Prof. Broca, La Constitution des
Vertebres caudales; 'La Revue d'Anthropologie,' 1872, p. 26, (separate
copy).) insists, the anthropomorphous apes approach in structure more
nearly to the bipedal than to the quadrupedal type.
As the progenitors of man became more and more erect, with their hands and
arms more and more modified for prehension and other purposes, with their
feet and legs at the same time transformed for firm support and
progression, endless other changes of structure would have become
necessary. The pelvis would have to be broadened, the spine peculiarly
curved, and the head fixed in an altered position, all which changes have
been attained by man. Prof. Schaaffhausen (76. 'On the Primitive Form of
the Skull,' translated in 'Anthropological Review,' Oct. 1868, p. 428.
Owen ('Anatomy of Vertebrates,' vol. ii. 1866, p. 551) on the mastoid
processes in the higher apes.) maintains that "the powerful mastoid
processes of the human skull are the result of his erect position;" and
these processes are absent in the orang, chimpanzee, etc., and are smaller
in the gorilla than in man. Various other structures, which appear
connected with man's erect position, might here have been added. It is
very difficult to decide how far these correlated modifications are the
result of natural selection, and how far of the inherited effects of the
increased use of certain parts, or of the action of one part on another.
No doubt these means of change often co-operate: thus when certain
muscles, and the crests of bone to which they are attached, become enlarged
by habitual use, this shews that certain actions are habitually performed
and must be serviceable. Hence the individuals which performed them best,
would tend to survive in greater numbers.
The free use of the arms and hands, partly the cause and partly the result
of man's erect position, appears to have led in an indirect manner to other
modifications of structure. The early male forefathers of man were, as
previously stated, probably furnished with great canine teeth; but as they
gradually acquired the habit of using stones, clubs, or other weapons, for
fighting with their enemies or rivals, they would use their jaws and teeth
less and less. In this case, the jaws, together with the teeth, would
become reduced in size, as we may feel almost sure from innumerable
analogous cases. In a future chapter we shall meet with a closely parallel
case, in the reduction or complete disappearance of the canine teeth in
male ruminants, apparently in relation with the development of their horns;
and in horses, in relation to their habit of fighting with their incisor
teeth and hoofs.
In the adult male anthropomorphous apes, as Rutimeyer (77. 'Die Grenzen
der Thierwelt, eine Betrachtung zu Darwin's Lehre,' 1868, s. 51.), and
others, have insisted, it is the effect on the skull of the great
development of the jaw-muscles that causes it to differ so greatly in many
respects from that of man, and has given to these animals "a truly
frightful physiognomy." Therefore, as the jaws and teeth in man's
progenitors gradually become reduced in size, the adult skull would have
come to resemble more and more that of existing man. As we shall hereafter
see, a great reduction of the canine teeth in the males would almost
certainly affect the teeth of the females through inheritance.
As the various mental faculties gradually developed themselves the brain
would almost certainly become larger. No one, I presume, doubts that the
large proportion which the size of man's brain bears to his body, compared
to the same proportion in the gorilla or orang, is closely connected with
his higher mental powers. We meet with closely analogous facts with
insects, for in ants the cerebral ganglia are of extraordinary dimensions,
and in all the Hymenoptera these ganglia are many times larger than in the
less intelligent orders, such as beetles. (78. Dujardin, 'Annales des
Sciences Nat.' 3rd series, Zoolog., tom. xiv. 1850, p. 203. See also Mr.
Lowne, 'Anatomy and Phys. of the Musca vomitoria,' 1870, p. 14. My son,
Mr. F. Darwin, dissected for me the cerebral ganglia of the Formica rufa.)
On the other hand, no one supposes that the intellect of any two animals or
of any two men can be accurately gauged by the cubic contents of their
skulls. It is certain that there may be extraordinary mental activity with
an extremely small absolute mass of nervous matter: thus the wonderfully
diversified instincts, mental powers, and affections of ants are notorious,
yet their cerebral ganglia are not so large as the quarter of a small pin's
head. Under this point of view, the brain of an ant is one of the most
marvellous atoms of matter in the world, perhaps more so than the brain of
a man.
The belief that there exists in man some close relation between the size of
the brain and the development of the intellectual faculties is supported by
the comparison of the skulls of savage and civilised races, of ancient and
modern people, and by the analogy of the whole vertebrate series. Dr. J.
Barnard Davis has proved (79. 'Philosophical Transactions,' 1869, p.
513.), by many careful measurements, that the mean internal capacity of the
skull in Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics
87.1; and in Australians only 81.9 cubic inches. Professor Broca (80.
'Les Selections,' M. P. Broca, 'Revue d'Anthropologies,' 1873; see also, as
quoted in C. Vogt's 'Lectures on Man,' Engl. translat., 1864, pp. 88, 90.
Prichard, 'Physical History of Mankind,' vol. i. 1838, p. 305.) found that
the nineteenth century skulls from graves in Paris were larger than those
from vaults of the twelfth century, in the proportion of 1484 to 1426; and
that the increased size, as ascertained by measurements, was exclusively in
the frontal part of the skull--the seat of the intellectual faculties.
Prichard is persuaded that the present inhabitants of Britain have "much
more capacious brain-cases" than the ancient inhabitants. Nevertheless, it
must be admitted that some skulls of very high antiquity, such as the
famous one of Neanderthal, are well developed and capacious. (81. In the
interesting article just referred to, Prof. Broca has well remarked, that
in civilised nations, the average capacity of the skull must be lowered by
the preservation of a considerable number of individuals, weak in mind and
body, who would have been promptly eliminated in the savage state. On the
other hand, with savages, the average includes only the more capable
individuals, who have been able to survive under extremely hard conditions
of life. Broca thus explains the otherwise inexplicable fact, that the
mean capacity of the skull of the ancient Troglodytes of Lozere is greater
than that of modern Frenchmen.) With respect to the lower animals, M.E.
Lartet (82. 'Comptes-rendus des Sciences,' etc., June 1, 1868.), by
comparing the crania of tertiary and recent mammals belonging to the same
groups, has come to the remarkable conclusion that the brain is generally
larger and the convolutions are more complex in the more recent forms. On
the other hand, I have shewn (83. The 'Variation of Animals and Plants
under Domestication,' vol. i. pp. 124-129.) that the brains of domestic
rabbits are considerably reduced in bulk, in comparison with those of the
wild rabbit or hare; and this may be attributed to their having been
closely confined during many generations, so that they have exerted their
intellect, instincts, senses and voluntary movements but little.
The gradually increasing weight of the brain and skull in man must have
influenced the development of the supporting spinal column, more especially
whilst he was becoming erect. As this change of position was being brought
about, the internal pressure of the brain will also have influenced the
form of the skull; for many facts shew how easily the skull is thus
affected. Ethnologists believe that it is modified by the kind of cradle
in which infants sleep. Habitual spasms of the muscles, and a cicatrix
from a severe burn, have permanently modified the facial bones. In young
persons whose heads have become fixed either sideways or backwards, owing
to disease, one of the two eyes has changed its position, and the shape of
the skull has been altered apparently by the pressure of the brain in a new
direction. (84. Schaaffhausen gives from Blumenbach and Busch, the cases
of the spasms and cicatrix, in 'Anthropological Review,' Oct. 1868, p. 420.
Dr. Jarrold ('Anthropologia,' 1808, pp. 115, 116) adduces from Camper and
from his own observations, cases of the modification of the skull from the
head being fixed in an unnatural position. He believes that in certain
trades, such as that of a shoemaker, where the head is habitually held
forward, the forehead becomes more rounded and prominent.) I have shewn
that with long-eared rabbits even so trifling a cause as the lopping
forward of one ear drags forward almost every bone of the skull on that
side; so that the bones on the opposite side no longer strictly correspond.
Lastly, if any animal were to increase or diminish much in general size,
without any change in its mental powers, or if the mental powers were to be
much increased or diminished, without any great change in the size of the
body, the shape of the skull would almost certainly be altered. I infer
this from my observations on domestic rabbits, some kinds of which have
become very much larger than the wild animal, whilst others have retained
nearly the same size, but in both cases the brain has been much reduced
relatively to the size of the body. Now I was at first much surprised on
finding that in all these rabbits the skull had become elongated or
dolichocephalic; for instance, of two skulls of nearly equal breadth, the
one from a wild rabbit and the other from a large domestic kind, the former
was 3.15 and the latter 4.3 inches in length. (85. 'Variation of Animals
and Plants under Domestication,' vol. i. p. 117, on the elongation of the
skull; p. 119, on the effect of the lopping of one ear.) One of the most
marked distinctions in different races of men is that the skull in some is
elongated, and in others rounded; and here the explanation suggested by the
case of the rabbits may hold good; for Welcker finds that short "men
incline more to brachycephaly, and tall men to dolichocephaly" (86. Quoted
by Schaaffhausen, in 'Anthropological Review,' Oct. 1868, p. 419.); and
tall men may be compared with the larger and longer-bodied rabbits, all of
which have elongated skulls or are dolichocephalic.
From these several facts we can understand, to a certain extent, the means
by which the great size and more or less rounded form of the skull have
been acquired by man; and these are characters eminently distinctive of him
in comparison with the lower animals.
Another most conspicuous difference between man and the lower animals is
the nakedness of his skin. Whales and porpoises (Cetacea), dugongs
(Sirenia) and the hippopotamus are naked; and this may be advantageous to
them for gliding through the water; nor would it be injurious to them from
the loss of warmth, as the species, which inhabit the colder regions, are
protected by a thick layer of blubber, serving the same purpose as the fur
of seals and otters. Elephants and rhinoceroses are almost hairless; and
as certain extinct species, which formerly lived under an Arctic climate,
were covered with long wool or hair, it would almost appear as if the
existing species of both genera had lost their hairy covering from exposure
to heat. This appears the more probable, as the elephants in India which
live on elevated and cool districts are more hairy (87. Owen, 'Anatomy of
Vertebrates,' vol. iii. p. 619.) than those on the lowlands. May we then
infer that man became divested of hair from having aboriginally inhabited
some tropical land? That the hair is chiefly retained in the male sex on
the chest and face, and in both sexes at the junction of all four limbs
with the trunk, favours this inference--on the assumption that the hair was
lost before man became erect; for the parts which now retain most hair
would then have been most protected from the heat of the sun. The crown of
the head, however, offers a curious exception, for at all times it must
have been one of the most exposed parts, yet it is thickly clothed with
hair. The fact, however, that the other members of the order of Primates,
to which man belongs, although inhabiting various hot regions, are well
clothed with hair, generally thickest on the upper surface (88. Isidore
Geoffroy St.-Hilaire remarks ('Histoire Nat. Generale,' tom. ii. 1859, pp.
215-217) on the head of man being covered with long hair; also on the upper
surfaces of monkeys and of other mammals being more thickly clothed than
the lower surfaces. This has likewise been observed by various authors.
Prof. P. Gervais ('Histoire Nat. des Mammiferes,' tom. i. 1854, p. 28),
however, states that in the Gorilla the hair is thinner on the back, where
it is partly rubbed off, than on the lower surface.), is opposed to the
supposition that man became naked through the action of the sun. Mr. Belt
believes (89. The 'Naturalist in Nicaragua,' 1874, p. 209. As some
confirmation of Mr. Belt's view, I may quote the following passage from Sir
W. Denison ('Varieties of Vice-Regal Life,' vol. i. 1870, p. 440): "It is
said to be a practice with the Australians, when the vermin get
troublesome, to singe themselves.") that within the tropics it is an
advantage to man to be destitute of hair, as he is thus enabled to free
himself of the multitude of ticks (acari) and other parasites, with which
he is often infested, and which sometimes cause ulceration. But whether
this evil is of sufficient magnitude to have led to the denudation of his
body through natural selection, may be doubted, since none of the many
quadrupeds inhabiting the tropics have, as far as I know, acquired any
specialised means of relief. The view which seems to me the most probable
is that man, or rather primarily woman, became divested of hair for
ornamental purposes, as we shall see under Sexual Selection; and, according
to this belief, it is not surprising that man should differ so greatly in
hairiness from all other Primates, for characters, gained through sexual
selection, often differ to an extraordinary degree in closely related
forms.
According to a popular impression, the absence of a tail is eminently
distinctive of man; but as those apes which come nearest to him are
destitute of this organ, its disappearance does not relate exclusively to
man. The tail often differs remarkably in length within the same genus:
thus in some species of Macacus it is longer than the whole body, and is
formed of twenty-four vertebrae; in others it consists of a scarcely
visible stump, containing only three or four vertebrae. In some kinds of
baboons there are twenty-five, whilst in the mandrill there are ten very
small stunted caudal vertebrae, or, according to Cuvier (90. Mr. St.
George Mivart, 'Proc. Zoolog. Soc.' 1865, pp. 562, 583. Dr. J.E. Gray,
'Cat. Brit. Mus.: 'Skeletons.' Owen, 'Anatomy of Vertebrates,' vol. ii.
p. 517. Isidore Geoffroy, 'Hist. Nat. Gen.' tom. ii. p. 244.), sometimes
only five. The tail, whether it be long or short, almost always tapers
towards the end; and this, I presume, results from the atrophy of the
terminal muscles, together with their arteries and nerves, through disuse,
leading to the atrophy of the terminal bones. But no explanation can at
present be given of the great diversity which often occurs in its length.
Here, however, we are more specially concerned with the complete external
disappearance of the tail. Professor Broca has recently shewn (91. 'Revue
d'Anthropologie,' 1872; 'La Constitution des vertebres caudales.') that the
tail in all quadrupeds consists of two portions, generally separated
abruptly from each other; the basal portion consists of vertebrae, more or
less perfectly channelled and furnished with apophyses like ordinary
vertebrae; whereas those of the terminal portion are not channelled, are
almost smooth, and scarcely resemble true vertebrae. A tail, though not
externally visible, is really present in man and the anthropomorphous apes,
and is constructed on exactly the same pattern in both. In the terminal
portion the vertabrae, constituting the os coccyx, are quite rudimentary,
being much reduced in size and number. In the basal portion, the vertebrae
are likewise few, are united firmly together, and are arrested in
development; but they have been rendered much broader and flatter than the
corresponding vertebrae in the tails of other animals: they constitute
what Broca calls the accessory sacral vertebrae. These are of functional
importance by supporting certain internal parts and in other ways; and
their modification is directly connected with the erect or semi-erect
attitude of man and the anthropomorphous apes. This conclusion is the more
trustworthy, as Broca formerly held a different view, which he has now
abandoned. The modification, therefore, of the basal caudal vertebrae in
man and the higher apes may have been effected, directly or indirectly,
through natural selection.
But what are we to say about the rudimentary and variable vertebrae of the
terminal portion of the tail, forming the os coccyx? A notion which has
often been, and will no doubt again be ridiculed, namely, that friction has
had something to do with the disappearance of the external portion of the
tail, is not so ridiculous as it at first appears. Dr. Anderson (92.
'Proceedings Zoological Society,' 1872, p. 210.) states that the extremely
short tail of Macacus brunneus is formed of eleven vertebrae, including the
imbedded basal ones. The extremity is tendinous and contains no vertebrae;
this is succeeded by five rudimentary ones, so minute that together they
are only one line and a half in length, and these are permanently bent to
one side in the shape of a hook. The free part of the tail, only a little
above an inch in length, includes only four more small vertebrae. This
short tail is carried erect; but about a quarter of its total length is
doubled on to itself to the left; and this terminal part, which includes
the hook-like portion, serves "to fill up the interspace between the upper
divergent portion of the callosities;" so that the animal sits on it, and
thus renders it rough and callous. Dr. Anderson thus sums up his
observations: "These facts seem to me to have only one explanation; this
tail, from its short size, is in the monkey's way when it sits down, and
frequently becomes placed under the animal while it is in this attitude;
and from the circumstance that it does not extend beyond the extremity of
the ischial tuberosities, it seems as if the tail originally had been bent
round by the will of the animal, into the interspace between the
callosities, to escape being pressed between them and the ground, and that
in time the curvature became permanent, fitting in of itself when the organ
happens to be sat upon." Under these circumstances it is not surprising
that the surface of the tail should have been roughened and rendered
callous, and Dr. Murie (93. 'Proceedings Zoological Society,' 1872, p.
786.), who carefully observed this species in the Zoological Gardens, as
well as three other closely allied forms with slightly longer tails, says
that when the animal sits down, the tail "is necessarily thrust to one side
of the buttocks; and whether long or short its root is consequently liable
to be rubbed or chafed." As we now have evidence that mutilations
occasionally produce an inherited effect (94. I allude to Dr. Brown-
Sequard's observations on the transmitted effect of an operation causing
epilepsy in guinea-pigs, and likewise more recently on the analogous
effects of cutting the sympathetic nerve in the neck. I shall hereafter
have occasion to refer to Mr. Salvin's interesting case of the apparently
inherited effects of mot-mots biting off the barbs of their own tail-
feathers. See also on the general subject 'Variation of Animals and Plants
under Domestication,' vol. ii. pp. 22-24.), it is not very improbable that
in short-tailed monkeys, the projecting part of the tail, being
functionally useless, should after many generations have become rudimentary
and distorted, from being continually rubbed and chafed. We see the
projecting part in this condition in the Macacus brunneus, and absolutely
aborted in the M. ecaudatus and in several of the higher apes. Finally,
then, as far as we can judge, the tail has disappeared in man and the
anthropomorphous apes, owing to the terminal portion having been injured by
friction during a long lapse of time; the basal and embedded portion having
been reduced and modified, so as to become suitable to the erect or semi-
erect position.
I have now endeavoured to shew that some of the most distinctive characters
of man have in all probability been acquired, either directly, or more
commonly indirectly, through natural selection. We should bear in mind
that modifications in structure or constitution which do not serve to adapt
an organism to its habits of life, to the food which it consumes, or
passively to the surrounding conditions, cannot have been thus acquired.
We must not, however, be too confident in deciding what modifications are
of service to each being: we should remember how little we know about the
use of many parts, or what changes in the blood or tissues may serve to fit
an organism for a new climate or new kinds of food. Nor must we forget the
principle of correlation, by which, as Isidore Geoffroy has shewn in the
case of man, many strange deviations of structure are tied together.
Independently of correlation, a change in one part often leads, through the
increased or decreased use of other parts, to other changes of a quite
unexpected nature. It is also well to reflect on such facts, as the
wonderful growth of galls on plants caused by the poison of an insect, and
on the remarkable changes of colour in the plumage of parrots when fed on
certain fishes, or inoculated with the poison of toads (95. The 'Variation
of Animals and Plants under Domestication,' vol. ii. pp. 280, 282.); for we
can thus see that the fluids of the system, if altered for some special
purpose, might induce other changes. We should especially bear in mind
that modifications acquired and continually used during past ages for some
useful purpose, would probably become firmly fixed, and might be long
inherited.
Thus a large yet undefined extension may safely be given to the direct and
indirect results of natural selection; but I now admit, after reading the
essay by Nageli on plants, and the remarks by various authors with respect
to animals, more especially those recently made by Professor Broca, that in
the earlier editions of my 'Origin of Species' I perhaps attributed too
much to the action of natural selection or the survival of the fittest. I
have altered the fifth edition of the 'Origin' so as to confine my remarks
to adaptive changes of structure; but I am convinced, from the light gained
during even the last few years, that very many structures which now appear
to us useless, will hereafter be proved to be useful, and will therefore
come within the range of natural selection. Nevertheless, I did not
formerly consider sufficiently the existence of structures, which, as far
as we can at present judge, are neither beneficial nor injurious; and this
I believe to be one of the greatest oversights as yet detected in my work.
I may be permitted to say, as some excuse, that I had two distinct objects
in view; firstly, to shew that species had not been separately created, and
secondly, that natural selection had been the chief agent of change, though
largely aided by the inherited effects of habit, and slightly by the direct
action of the surrounding conditions. I was not, however, able to annul
the influence of my former belief, then almost universal, that each species
had been purposely created; and this led to my tacit assumption that every
detail of structure, excepting rudiments, was of some special, though
unrecognised, service. Any one with this assumption in his mind would
naturally extend too far the action of natural selection, either during
past or present times. Some of those who admit the principle of evolution,
but reject natural selection, seem to forget, when criticising my book,
that I had the above two objects in view; hence if I have erred in giving
to natural selection great power, which I am very far from admitting, or in
having exaggerated its power, which is in itself probable, I have at least,
as I hope, done good service in aiding to overthrow the dogma of separate
creations.
It is, as I can now see, probable that all organic beings, including man,
possess peculiarities of structure, which neither are now, nor were
formerly of any service to them, and which, therefore, are of no
physiological importance. We know not what produces the numberless slight
differences between the individuals of each species, for reversion only
carries the problem a few steps backwards, but each peculiarity must have
had its efficient cause. If these causes, whatever they may be, were to
act more uniformly and energetically during a lengthened period (and
against this no reason can be assigned), the result would probably be not a
mere slight individual difference, but a well-marked and constant
modification, though one of no physiological importance. Changed
structures, which are in no way beneficial, cannot be kept uniform through
natural selection, though the injurious will be thus eliminated.
Uniformity of character would, however, naturally follow from the assumed
uniformity of the exciting causes, and likewise from the free intercrossing
of many individuals. During successive periods, the same organism might in
this manner acquire successive modifications, which would be transmitted in
a nearly uniform state as long as the exciting causes remained the same and
there was free intercrossing. With respect to the exciting causes we can
only say, as when speaking of so-called spontaneous variations, that they
relate much more closely to the constitution of the varying organism, than
to the nature of the conditions to which it has been subjected.
CONCLUSION.
In this chapter we have seen that as man at the present day is liable, like
every other animal, to multiform individual differences or slight
variations, so no doubt were the early progenitors of man; the variations
being formerly induced by the same general causes, and governed by the same
general and complex laws as at present. As all animals tend to multiply
beyond their means of subsistence, so it must have been with the
progenitors of man; and this would inevitably lead to a struggle for
existence and to natural selection. The latter process would be greatly
aided by the inherited effects of the increased use of parts, and these two
processes would incessantly react on each other. It appears, also, as we
shall hereafter see, that various unimportant characters have been acquired
by man through sexual selection. An unexplained residuum of change must be
left to the assumed uniform action of those unknown agencies, which
occasionally induce strongly marked and abrupt deviations of structure in
our domestic productions.
Judging from the habits of savages and of the greater number of the
Quadrumana, primeval men, and even their ape-like progenitors, probably
lived in society. With strictly social animals, natural selection
sometimes acts on the individual, through the preservation of variations
which are beneficial to the community. A community which includes a large
number of well-endowed individuals increases in number, and is victorious
over other less favoured ones; even although each separate member gains no
advantage over the others of the same community. Associated insects have
thus acquired many remarkable structures, which are of little or no service
to the individual, such as the pollen-collecting apparatus, or the sting of
the worker-bee, or the great jaws of soldier-ants. With the higher social
animals, I am not aware that any structure has been modified solely for the
good of the community, though some are of secondary service to it. For
instance, the horns of ruminants and the great canine teeth of baboons
appear to have been acquired by the males as weapons for sexual strife, but
they are used in defence of the herd or troop. In regard to certain mental
powers the case, as we shall see in the fifth chapter, is wholly different;
for these faculties have been chiefly, or even exclusively, gained for the
benefit of the community, and the individuals thereof have at the same time
gained an advantage indirectly.
It has often been objected to such views as the foregoing, that man is one
of the most helpless and defenceless creatures in the world; and that
during his early and less well-developed condition, he would have been
still more helpless. The Duke of Argyll, for instance, insists (96.
'Primeval Man,' 1869, p. 66.) that "the human frame has diverged from the
structure of brutes, in the direction of greater physical helplessness and
weakness. That is to say, it is a divergence which of all others it is
most impossible to ascribe to mere natural selection." He adduces the
naked and unprotected state of the body, the absence of great teeth or
claws for defence, the small strength and speed of man, and his slight
power of discovering food or of avoiding danger by smell. To these
deficiencies there might be added one still more serious, namely, that he
cannot climb quickly, and so escape from enemies. The loss of hair would
not have been a great injury to the inhabitants of a warm country. For we
know that the unclothed Fuegians can exist under a wretched climate. When
we compare the defenceless state of man with that of apes, we must remember
that the great canine teeth with which the latter are provided, are
possessed in their full development by the males alone, and are chiefly
used by them for fighting with their rivals; yet the females, which are not
thus provided, manage to survive.
In regard to bodily size or strength, we do not know whether man is
descended from some small species, like the chimpanzee, or from one as
powerful as the gorilla; and, therefore, we cannot say whether man has
become larger and stronger, or smaller and weaker, than his ancestors. We
should, however, bear in mind that an animal possessing great size,
strength, and ferocity, and which, like the gorilla, could defend itself
from all enemies, would not perhaps have become social: and this would
most effectually have checked the acquirement of the higher mental
qualities, such as sympathy and the love of his fellows. Hence it might
have been an immense advantage to man to have sprung from some
comparatively weak creature.
The small strength and speed of man, his want of natural weapons, etc., are
more than counterbalanced, firstly, by his intellectual powers, through
which he has formed for himself weapons, tools, etc., though still
remaining in a barbarous state, and, secondly, by his social qualities
which lead him to give and receive aid from his fellow-men. No country in
the world abounds in a greater degree with dangerous beasts than Southern
Africa; no country presents more fearful physical hardships than the Arctic
regions; yet one of the puniest of races, that of the Bushmen, maintains
itself in Southern Africa, as do the dwarfed Esquimaux in the Arctic
regions. The ancestors of man were, no doubt, inferior in intellect, and
probably in social disposition, to the lowest existing savages; but it is
quite conceivable that they might have existed, or even flourished, if
they had advanced in intellect, whilst gradually losing their brute-like
powers, such as that of climbing trees, etc. But these ancestors would not
have been exposed to any special danger, even if far more helpless and
defenceless than any existing savages, had they inhabited some warm
continent or large island, such as Australia, New Guinea, or Borneo, which
is now the home of the orang. And natural selection arising from the
competition of tribe with tribe, in some such large area as one of these,
together with the inherited effects of habit, would, under favourable
conditions, have sufficed to raise man to his present high position in the
organic scale.
CHAPTER III.
COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS.
The difference in mental power between the highest ape and the lowest
savage, immense--Certain instincts in common--The emotions--Curiosity--
Imitation--Attention--Memory--Imagination--Reason--Progressive improvement
--Tools and weapons used by animals--Abstraction, Self-consciousness--
Language--Sense of beauty--Belief in God, spiritual agencies,
superstitions.
We have seen in the last two chapters that man bears in his bodily
structure clear traces of his descent from some lower form; but it may be
urged that, as man differs so greatly in his mental power from all other
animals, there must be some error in this conclusion. No doubt the
difference in this respect is enormous, even if we compare the mind of one
of the lowest savages, who has no words to express any number higher than
four, and who uses hardly any abstract terms for common objects or for the
affections (1. See the evidence on those points, as given by Lubbock,
'Prehistoric Times,' p. 354, etc.), with that of the most highly organised
ape. The difference would, no doubt, still remain immense, even if one of
the higher apes had been improved or civilised as much as a dog has been in
comparison with its parent-form, the wolf or jackal. The Fuegians rank
amongst the lowest barbarians; but I was continually struck with surprise
how closely the three natives on board H.M.S. "Beagle," who had lived some
years in England, and could talk a little English, resembled us in
disposition and in most of our mental faculties. If no organic being
excepting man had possessed any mental power, or if his powers had been of
a wholly different nature from those of the lower animals, then we should
never have been able to convince ourselves that our high faculties had been
gradually developed. But it can be shewn that there is no fundamental
difference of this kind. We must also admit that there is a much wider
interval in mental power between one of the lowest fishes, as a lamprey or
lancelet, and one of the higher apes, than between an ape and man; yet this
interval is filled up by numberless gradations.
Nor is the difference slight in moral disposition between a barbarian, such
as the man described by the old navigator Byron, who dashed his child on
the rocks for dropping a basket of sea-urchins, and a Howard or Clarkson;
and in intellect, between a savage who uses hardly any abstract terms, and
a Newton or Shakspeare. Differences of this kind between the highest men
of the highest races and the lowest savages, are connected by the finest
gradations. Therefore it is possible that they might pass and be developed
into each other.
My object in this chapter is to shew that there is no fundamental
difference between man and the higher mammals in their mental faculties.
Each division of the subject might have been extended into a separate
essay, but must here be treated briefly. As no classification of the
mental powers has been universally accepted, I shall arrange my remarks in
the order most convenient for my purpose; and will select those facts which
have struck me most, with the hope that they may produce some effect on the
reader.
With respect to animals very low in the scale, I shall give some additional
facts under Sexual Selection, shewing that their mental powers are much
higher than might have been expected. The variability of the faculties in
the individuals of the same species is an important point for us, and some
few illustrations will here be given. But it would be superfluous to enter
into many details on this head, for I have found on frequent enquiry, that
it is the unanimous opinion of all those who have long attended to animals
of many kinds, including birds, that the individuals differ greatly in
every mental characteristic. In what manner the mental powers were first
developed in the lowest organisms, is as hopeless an enquiry as how life
itself first originated. These are problems for the distant future, if
they are ever to be solved by man.
As man possesses the same senses as the lower animals, his fundamental
intuitions must be the same. Man has also some few instincts in common, as
that of self-preservation, sexual love, the love of the mother for her new-
born offspring, the desire possessed by the latter to suck, and so forth.
But man, perhaps, has somewhat fewer instincts than those possessed by the
animals which come next to him in the series. The orang in the Eastern
islands, and the chimpanzee in Africa, build platforms on which they sleep;
and, as both species follow the same habit, it might be argued that this
was due to instinct, but we cannot feel sure that it is not the result of
both animals having similar wants, and possessing similar powers of
reasoning. These apes, as we may assume, avoid the many poisonous fruits
of the tropics, and man has no such knowledge: but as our domestic
animals, when taken to foreign lands, and when first turned out in the
spring, often eat poisonous herbs, which they afterwards avoid, we cannot
feel sure that the apes do not learn from their own experience or from that
of their parents what fruits to select. It is, however, certain, as we
shall presently see, that apes have an instinctive dread of serpents, and
probably of other dangerous animals.
The fewness and the comparative simplicity of the instincts in the higher
animals are remarkable in contrast with those of the lower animals. Cuvier
maintained that instinct and intelligence stand in an inverse ratio to each
other; and some have thought that the intellectual faculties of the higher
animals have been gradually developed from their instincts. But Pouchet,
in an interesting essay (2. 'L'Instinct chez les Insectes,' 'Revue des
Deux Mondes,' Feb. 1870, p. 690.), has shewn that no such inverse ratio
really exists. Those insects which possess the most wonderful instincts
are certainly the most intelligent. In the vertebrate series, the least
intelligent members, namely fishes and amphibians, do not possess complex
instincts; and amongst mammals the animal most remarkable for its
instincts, namely the beaver, is highly intelligent, as will be admitted by
every one who has read Mr. Morgan's excellent work. (3. 'The American
Beaver and His Works,' 1868.)
Although the first dawnings of intelligence, according to Mr. Herbert
Spencer (4. 'The Principles of Psychology,' 2nd edit., 1870, pp. 418-
443.), have been developed through the multiplication and co-ordination of
reflex actions, and although many of the simpler instincts graduate into
reflex actions, and can hardly be distinguished from them, as in the case
of young animals sucking, yet the more complex instincts seem to have
originated independently of intelligence. I am, however, very far from
wishing to deny that instinctive actions may lose their fixed and untaught
character, and be replaced by others performed by the aid of the free will.
On the other hand, some intelligent actions, after being performed during
several generations, become converted into instincts and are inherited, as
when birds on oceanic islands learn to avoid man. These actions may then
be said to be degraded in character, for they are no longer performed
through reason or from experience. But the greater number of the more
complex instincts appear to have been gained in a wholly different manner,
through the natural selection of variations of simpler instinctive actions.
Such variations appear to arise from the same unknown causes acting on the
cerebral organisation, which induce slight variations or individual
differences in other parts of the body; and these variations, owing to our
ignorance, are often said to arise spontaneously. We can, I think, come to
no other conclusion with respect to the origin of the more complex
instincts, when we reflect on the marvellous instincts of sterile worker-
ants and bees, which leave no offspring to inherit the effects of
experience and of modified habits.
Although, as we learn from the above-mentioned insects and the beaver, a
high degree of intelligence is certainly compatible with complex instincts,
and although actions, at first learnt voluntarily can soon through habit be
performed with the quickness and certainty of a reflex action, yet it is
not improbable that there is a certain amount of interference between the
development of free intelligence and of instinct,--which latter implies
some inherited modification of the brain. Little is known about the
functions of the brain, but we can perceive that as the intellectual powers
become highly developed, the various parts of the brain must be connected
by very intricate channels of the freest intercommunication; and as a
consequence each separate part would perhaps tend to be less well fitted to
answer to particular sensations or associations in a definite and
inherited--that is instinctive--manner. There seems even to exist some
relation between a low degree of intelligence and a strong tendency to the
formation of fixed, though not inherited habits; for as a sagacious
physician remarked to me, persons who are slightly imbecile tend to act in
everything by routine or habit; and they are rendered much happier if this
is encouraged.
I have thought this digression worth giving, because we may easily
underrate the mental powers of the higher animals, and especially of man,
when we compare their actions founded on the memory of past events, on
foresight, reason, and imagination, with exactly similar actions
instinctively performed by the lower animals; in this latter case the
capacity of performing such actions has been gained, step by step, through
the variability of the mental organs and natural selection, without any
conscious intelligence on the part of the animal during each successive
generation. No doubt, as Mr. Wallace has argued (5. 'Contributions to the
Theory of Natural Selection,' 1870, p. 212.), much of the intelligent work
done by man is due to imitation and not to reason; but there is this great
difference between his actions and many of those performed by the lower
animals, namely, that man cannot, on his first trial, make, for instance, a
stone hatchet or a canoe, through his power of imitation. He has to learn
his work by practice; a beaver, on the other hand, can make its dam or
canal, and a bird its nest, as well, or nearly as well, and a spider its
wonderful web, quite as well (6. For the evidence on this head, see Mr. J.
Traherne Moggridge's most interesting work, 'Harvesting Ants and Trap-Door
Spiders,' 1873, pp. 126, 128.), the first time it tries as when old and
experienced.
To return to our immediate subject: the lower animals, like man,
manifestly feel pleasure and pain, happiness and misery. Happiness is
never better exhibited than by young animals, such as puppies, kittens,
lambs, etc., when playing together, like our own children. Even insects
play together, as has been described by that excellent observer, P. Huber
(7. 'Recherches sur les Moeurs des Fourmis,' 1810, p. 173.), who saw ants
chasing and pretending to bite each other, like so many puppies.
The fact that the lower animals are excited by the same emotions as
ourselves is so well established, that it will not be necessary to weary
the reader by many details. Terror acts in the same manner on them as on
us, causing the muscles to tremble, the heart to palpitate, the sphincters
to be relaxed, and the hair to stand on end. Suspicion, the offspring of
fear, is eminently characteristic of most wild animals. It is, I think,
impossible to read the account given by Sir E. Tennent, of the behaviour of
the female elephants, used as decoys, without admitting that they
intentionally practise deceit, and well know what they are about. Courage
and timidity are extremely variable qualities in the individuals of the
same species, as is plainly seen in our dogs. Some dogs and horses are
ill-tempered, and easily turn sulky; others are good-tempered; and these
qualities are certainly inherited. Every one knows how liable animals are
to furious rage, and how plainly they shew it. Many, and probably true,
anecdotes have been published on the long-delayed and artful revenge of
various animals. The accurate Rengger, and Brehm (8. All the following
statements, given on the authority of these two naturalists, are taken from
Rengger's 'Naturgesch. der Saugethiere von Paraguay,' 1830, s. 41-57, and
from Brehm's 'Thierleben,' B. i. s. 10-87.) state that the American and
African monkeys which they kept tame, certainly revenged themselves. Sir
Andrew Smith, a zoologist whose scrupulous accuracy was known to many
persons, told me the following story of which he was himself an eye-
witness; at the Cape of Good Hope an officer had often plagued a certain
baboon, and the animal, seeing him approaching one Sunday for parade,
poured water into a hole and hastily made some thick mud, which he
skilfully dashed over the officer as he passed by, to the amusement of many
bystanders. For long afterwards the baboon rejoiced and triumphed whenever
he saw his victim.
The love of a dog for his master is notorious; as an old writer quaintly
says (9. Quoted by Dr. Lauder Lindsay, in his 'Physiology of Mind in the
Lower Animals,' 'Journal of Mental Science,' April 1871, p. 38.), "A dog is
the only thing on this earth that luvs you more than he luvs himself."
In the agony of death a dog has been known to caress his master, and every
one has heard of the dog suffering under vivisection, who licked the hand
of the operator; this man, unless the operation was fully justified by an
increase of our knowledge, or unless he had a heart of stone, must have
felt remorse to the last hour of his life.
As Whewell (10. 'Bridgewater Treatise,' p. 263.) has well asked, "who that
reads the touching instances of maternal affection, related so often of the
women of all nations, and of the females of all animals, can doubt that the
principle of action is the same in the two cases?" We see maternal
affection exhibited in the most trifling details; thus Rengger observed an
American monkey (a Cebus) carefully driving away the flies which plagued
her infant; and Duvaucel saw a Hylobates washing the faces of her young
ones in a stream. So intense is the grief of female monkeys for the loss
of their young, that it invariably caused the death of certain kinds kept
under confinement by Brehm in N. Africa. Orphan monkeys were always
adopted and carefully guarded by the other monkeys, both males and females.
One female baboon had so capacious a heart that she not only adopted young
monkeys of other species, but stole young dogs and cats, which she
continually carried about. Her kindness, however, did not go so far as to
share her food with her adopted offspring, at which Brehm was surprised, as
his monkeys always divided everything quite fairly with their own young
ones. An adopted kitten scratched this affectionate baboon, who certainly
had a fine intellect, for she was much astonished at being scratched, and
immediately examined the kitten's feet, and without more ado bit off the
claws. (11. A critic, without any grounds ('Quarterly Review,' July 1871,
p. 72), disputes the possibility of this act as described by Brehm, for the
sake of discrediting my work. Therefore I tried, and found that I could
readily seize with my own teeth the sharp little claws of a kitten nearly
five weeks old.) In the Zoological Gardens, I heard from the keeper that
an old baboon (C. chacma) had adopted a Rhesus monkey; but when a young
drill and mandrill were placed in the cage, she seemed to perceive that
these monkeys, though distinct species, were her nearer relatives, for she
at once rejected the Rhesus and adopted both of them. The young Rhesus, as
I saw, was greatly discontented at being thus rejected, and it would, like
a naughty child, annoy and attack the young drill and mandrill whenever it
could do so with safety; this conduct exciting great indignation in the old
baboon. Monkeys will also, according to Brehm, defend their master when
attacked by any one, as well as dogs to whom they are attached, from the
attacks of other dogs. But we here trench on the subjects of sympathy and
fidelity, to which I shall recur. Some of Brehm's monkeys took much
delight in teasing a certain old dog whom they disliked, as well as other
animals, in various ingenious ways.
Most of the more complex emotions are common to the higher animals and
ourselves. Every one has seen how jealous a dog is of his master's
affection, if lavished on any other creature; and I have observed the same
fact with monkeys. This shews that animals not only love, but have desire
to be loved. Animals manifestly feel emulation. They love approbation or
praise; and a dog carrying a basket for his master exhibits in a high
degree self-complacency or pride. There can, I think, be no doubt that a
dog feels shame, as distinct from fear, and something very like modesty
when begging too often for food. A great dog scorns the snarling of a
little dog, and this may be called magnanimity. Several observers have
stated that monkeys certainly dislike being laughed at; and they sometimes
invent imaginary offences. In the Zoological Gardens I saw a baboon who
always got into a furious rage when his keeper took out a letter or book
and read it aloud to him; and his rage was so violent that, as I witnessed
on one occasion, he bit his own leg till the blood flowed. Dogs shew what
may be fairly called a sense of humour, as distinct from mere play; if a
bit of stick or other such object be thrown to one, he will often carry it
away for a short distance; and then squatting down with it on the ground
close before him, will wait until his master comes quite close to take it
away. The dog will then seize it and rush away in triumph, repeating the
same manoeuvre, and evidently enjoying the practical joke.
We will now turn to the more intellectual emotions and faculties, which are
very important, as forming the basis for the development of the higher
mental powers. Animals manifestly enjoy excitement, and suffer from ennui,
as may be seen with dogs, and, according to Rengger, with monkeys. All
animals feel WONDER, and many exhibit CURIOSITY. They sometimes suffer
from this latter quality, as when the hunter plays antics and thus attracts
them; I have witnessed this with deer, and so it is with the wary chamois,
and with some kinds of wild-ducks. Brehm gives a curious account of the
instinctive dread, which his monkeys exhibited, for snakes; but their
curiosity was so great that they could not desist from occasionally
satiating their horror in a most human fashion, by lifting up the lid of
the box in which the snakes were kept. I was so much surprised at his
account, that I took a stuffed and coiled-up snake into the monkey-house at
the Zoological Gardens, and the excitement thus caused was one of the most
curious spectacles which I ever beheld. Three species of Cercopithecus
were the most alarmed; they dashed about their cages, and uttered sharp
signal cries of danger, which were understood by the other monkeys. A few
young monkeys and one old Anubis baboon alone took no notice of the snake.
I then placed the stuffed specimen on the ground in one of the larger
compartments. After a time all the monkeys collected round it in a large
circle, and staring intently, presented a most ludicrous appearance. They
became extremely nervous; so that when a wooden ball, with which they were
familiar as a plaything, was accidentally moved in the straw, under which
it was partly hidden, they all instantly started away. These monkeys
behaved very differently when a dead fish, a mouse (12. I have given a
short account of their behaviour on this occasion in my 'Expression of the
Emotions in Man and Animals,' p. 43.), a living turtle, and other new
objects were placed in their cages; for though at first frightened, they
soon approached, handled and examined them. I then placed a live snake in
a paper bag, with the mouth loosely closed, in one of the larger
compartments. One of the monkeys immediately approached, cautiously opened
the bag a little, peeped in, and instantly dashed away. Then I witnessed
what Brehm has described, for monkey after monkey, with head raised high
and turned on one side, could not resist taking a momentary peep into the
upright bag, at the dreadful object lying quietly at the bottom. It would
almost appear as if monkeys had some notion of zoological affinities, for
those kept by Brehm exhibited a strange, though mistaken, instinctive dread
of innocent lizards and frogs. An orang, also, has been known to be much
alarmed at the first sight of a turtle. (13. W.C.L. Martin, 'Natural
History of Mammalia,' 1841, p. 405.)
The principle of IMITATION is strong in man, and especially, as I have
myself observed, with savages. In certain morbid states of the brain this
tendency is exaggerated to an extraordinary degree: some hemiplegic
patients and others, at the commencement of inflammatory softening of the
brain, unconsciously imitate every word which is uttered, whether in their
own or in a foreign language, and every gesture or action which is
performed near them. (14. Dr. Bateman, 'On Aphasia,' 1870, p. 110.)
Desor (15. Quoted by Vogt, 'Memoire sur les Microcephales,' 1867, p. 168.)
has remarked that no animal voluntarily imitates an action performed by
man, until in the ascending scale we come to monkeys, which are well known
to be ridiculous mockers. Animals, however, sometimes imitate each other's
actions: thus two species of wolves, which had been reared by dogs,
learned to bark, as does sometimes the jackal (16. The 'Variation of
Animals and Plants under Domestication,' vol. i. p. 27.), but whether this
can be called voluntary imitation is another question. Birds imitate the
songs of their parents, and sometimes of other birds; and parrots are
notorious imitators of any sound which they often hear. Dureau de la Malle
gives an account (17. 'Annales des Sciences Nat.' (1st Series), tom. xxii.
p. 397.) of a dog reared by a cat, who learnt to imitate the well-known
action of a cat licking her paws, and thus washing her ears and face; this
was also witnessed by the celebrated naturalist Audouin. I have received
several confirmatory accounts; in one of these, a dog had not been suckled
by a cat, but had been brought up with one, together with kittens, and had
thus acquired the above habit, which he ever afterwards practised during
his life of thirteen years. Dureau de la Malle's dog likewise learnt from
the kittens to play with a ball by rolling it about with his fore paws, and
springing on it. A correspondent assures me that a cat in his house used
to put her paws into jugs of milk having too narrow a mouth for her head.
A kitten of this cat soon learned the same trick, and practised it ever
afterwards, whenever there was an opportunity.
The parents of many animals, trusting to the principle of imitation in
their young, and more especially to their instinctive or inherited
tendencies, may be said to educate them. We see this when a cat brings a
live mouse to her kittens; and Dureau de la Malle has given a curious
account (in the paper above quoted) of his observations on hawks which
taught their young dexterity, as well as judgment of distances, by first
dropping through the air dead mice and sparrows, which the young generally
failed to catch, and then bringing them live birds and letting them loose.
Hardly any faculty is more important for the intellectual progress of man
than ATTENTION. Animals clearly manifest this power, as when a cat watches
by a hole and prepares to spring on its prey. Wild animals sometimes
become so absorbed when thus engaged, that they may be easily approached.
Mr. Bartlett has given me a curious proof how variable this faculty is in
monkeys. A man who trains monkeys to act in plays, used to purchase common
kinds from the Zoological Society at the price of five pounds for each; but
he offered to give double the price, if he might keep three or four of them
for a few days, in order to select one. When asked how he could possibly
learn so soon, whether a particular monkey would turn out a good actor, he
answered that it all depended on their power of attention. If when he was
talking and explaining anything to a monkey, its attention was easily
distracted, as by a fly on the wall or other trifling object, the case was
hopeless. If he tried by punishment to make an inattentive monkey act, it
turned sulky. On the other hand, a monkey which carefully attended to him
could always be trained.
It is almost superfluous to state that animals have excellent MEMORIES for
persons and places. A baboon at the Cape of Good Hope, as I have been
informed by Sir Andrew Smith, recognised him with joy after an absence of
nine months. I had a dog who was savage and averse to all strangers, and I
purposely tried his memory after an absence of five years and two days. I
went near the stable where he lived, and shouted to him in my old manner;
he shewed no joy, but instantly followed me out walking, and obeyed me,
exactly as if I had parted with him only half an hour before. A train of
old associations, dormant during five years, had thus been instantaneously
awakened in his mind. Even ants, as P. Huber (18. 'Les Moeurs des
Fourmis,' 1810, p. 150.) has clearly shewn, recognised their fellow-ants
belonging to the same community after a separation of four months. Animals
can certainly by some means judge of the intervals of time between
recurrent events.
The IMAGINATION is one of the highest prerogatives of man. By this faculty
he unites former images and ideas, independently of the will, and thus
creates brilliant and novel results. A poet, as Jean Paul Richter remarks
(19. Quoted in Dr. Maudsley's 'Physiology and Pathology of Mind,' 1868,
pp. 19, 220.), "who must reflect whether he shall make a character say yes
or no--to the devil with him; he is only a stupid corpse." Dreaming gives
us the best notion of this power; as Jean Paul again says, "The dream is an
involuntary art of poetry." The value of the products of our imagination
depends of course on the number, accuracy, and clearness of our
impressions, on our judgment and taste in selecting or rejecting the
involuntary combinations, and to a certain extent on our power of
voluntarily combining them. As dogs, cats, horses, and probably all the
higher animals, even birds (20. Dr. Jerdon, 'Birds of India,' vol. i.
1862, p. xxi. Houzeau says that his parokeets and canary-birds dreamt:
'Etudes sur les Facultes Mentales des Animaux,' tom. ii. p. 136.) have
vivid dreams, and this is shewn by their movements and the sounds uttered,
we must admit that they possess some power of imagination. There must be
something special, which causes dogs to howl in the night, and especially
during moonlight, in that remarkable and melancholy manner called baying.
All dogs do not do so; and, according to Houzeau (21. ibid. 1872, tom. ii.
p. 181.), they do not then look at the moon, but at some fixed point near
the horizon. Houzeau thinks that their imaginations are disturbed by the
vague outlines of the surrounding objects, and conjure up before them
fantastic images: if this be so, their feelings may almost be called
superstitious.
Of all the faculties of the human mind, it will, I presume, be admitted
that REASON stands at the summit. Only a few persons now dispute that
animals possess some power of reasoning. Animals may constantly be seen to
pause, deliberate, and resolve. It is a significant fact, that the more
the habits of any particular animal are studied by a naturalist, the more
he attributes to reason and the less to unlearnt instincts. (22. Mr. L.H.
Morgan's work on 'The American Beaver,' 1868, offers a good illustration of
this remark. I cannot help thinking, however, that he goes too far in
underrating the power of instinct.) In future chapters we shall see that
some animals extremely low in the scale apparently display a certain amount
of reason. No doubt it is often difficult to distinguish between the power
of reason and that of instinct. For instance, Dr. Hayes, in his work on
'The Open Polar Sea,' repeatedly remarks that his dogs, instead of
continuing to draw the sledges in a compact body, diverged and separated
when they came to thin ice, so that their weight might be more evenly
distributed. This was often the first warning which the travellers
received that the ice was becoming thin and dangerous. Now, did the dogs
act thus from the experience of each individual, or from the example of the
older and wiser dogs, or from an inherited habit, that is from instinct?
This instinct, may possibly have arisen since the time, long ago, when dogs
were first employed by the natives in drawing their sledges; or the Arctic
wolves, the parent-stock of the Esquimaux dog, may have acquired an
instinct impelling them not to attack their prey in a close pack, when on
thin ice.
We can only judge by the circumstances under which actions are performed,
whether they are due to instinct, or to reason, or to the mere association
of ideas: this latter principle, however, is intimately connected with
reason. A curious case has been given by Prof. Mobius (23. 'Die
Bewegungen der Thiere,' etc., 1873, p. 11.), of a pike, separated by a
plate of glass from an adjoining aquarium stocked with fish, and who often
dashed himself with such violence against the glass in trying to catch the
other fishes, that he was sometimes completely stunned. The pike went on
thus for three months, but at last learnt caution, and ceased to do so.
The plate of glass was then removed, but the pike would not attack these
particular fishes, though he would devour others which were afterwards
introduced; so strongly was the idea of a violent shock associated in his
feeble mind with the attempt on his former neighbours. If a savage, who
had never seen a large plate-glass window, were to dash himself even once
against it, he would for a long time afterwards associate a shock with a
window-frame; but very differently from the pike, he would probably reflect
on the nature of the impediment, and be cautious under analogous
circumstances. Now with monkeys, as we shall presently see, a painful or
merely a disagreeable impression, from an action once performed, is
sometimes sufficient to prevent the animal from repeating it. If we
attribute this difference between the monkey and the pike solely to the
association of ideas being so much stronger and more persistent in the one
than the other, though the pike often received much the more severe injury,
can we maintain in the case of man that a similar difference implies the
possession of a fundamentally different mind?
Houzeau relates (24. 'Etudes sur les Facultes Mentales des Animaux,' 1872,
tom. ii. p. 265.) that, whilst crossing a wide and arid plain in Texas, his
two dogs suffered greatly from thirst, and that between thirty and forty
times they rushed down the hollows to search for water. These hollows were
not valleys, and there were no trees in them, or any other difference in
the vegetation, and as they were absolutely dry there could have been no
smell of damp earth. The dogs behaved as if they knew that a dip in the
ground offered them the best chance of finding water, and Houzeau has often
witnessed the same behaviour in other animals.
I have seen, as I daresay have others, that when a small object is thrown
on the ground beyond the reach of one of the elephants in the Zoological
Gardens, he blows through his trunk on the ground beyond the object, so
that the current reflected on all sides may drive the object within his
reach. Again a well-known ethnologist, Mr. Westropp, informs me that he
observed in Vienna a bear deliberately making with his paw a current in
some water, which was close to the bars of his cage, so as to draw a piece
of floating bread within his reach. These actions of the elephant and bear
can hardly be attributed to instinct or inherited habit, as they would be
of little use to an animal in a state of nature. Now, what is the
difference between such actions, when performed by an uncultivated man, and
by one of the higher animals?
The savage and the dog have often found water at a low level, and the
coincidence under such circumstances has become associated in their minds.
A cultivated man would perhaps make some general proposition on the
subject; but from all that we know of savages it is extremely doubtful
whether they would do so, and a dog certainly would not. But a savage, as
well as a dog, would search in the same way, though frequently
disappointed; and in both it seems to be equally an act of reason, whether
or not any general proposition on the subject is consciously placed before
the mind. (25. Prof. Huxley has analysed with admirable clearness the
mental steps by which a man, as well as a dog, arrives at a conclusion in a
case analogous to that given in my text. See his article, 'Mr. Darwin's
Critics,' in the 'Contemporary Review,' Nov. 1871, p. 462, and in his
'Critiques and Essays,' 1873, p. 279.) The same would apply to the
elephant and the bear making currents in the air or water. The savage
would certainly neither know nor care by what law the desired movements
were effected; yet his act would be guided by a rude process of reasoning,
as surely as would a philosopher in his longest chain of deductions. There
would no doubt be this difference between him and one of the higher
animals, that he would take notice of much slighter circumstances and
conditions, and would observe any connection between them after much less
experience, and this would be of paramount importance. I kept a daily
record of the actions of one of my infants, and when he was about eleven
months old, and before he could speak a single word, I was continually
struck with the greater quickness, with which all sorts of objects and
sounds were associated together in his mind, compared with that of the most
intelligent dogs I ever knew. But the higher animals differ in exactly the
same way in this power of association from those low in the scale, such as
the pike, as well as in that of drawing inferences and of observation.
The promptings of reason, after very short experience, are well shewn by
the following actions of American monkeys, which stand low in their order.
Rengger, a most careful observer, states that when he first gave eggs to
his monkeys in Paraguay, they smashed them, and thus lost much of their
contents; afterwards they gently hit one end against some hard body, and
picked off the bits of shell with their fingers. After cutting themselves
only ONCE with any sharp tool, they would not touch it again, or would
handle it with the greatest caution. Lumps of sugar were often given them
wrapped up in paper; and Rengger sometimes put a live wasp in the paper, so
that in hastily unfolding it they got stung; after this had ONCE happened,
they always first held the packet to their ears to detect any movement
within. (26. Mr. Belt, in his most interesting work, 'The Naturalist in
Nicaragua,' 1874, (p. 119,) likewise describes various actions of a tamed
Cebus, which, I think, clearly shew that this animal possessed some
reasoning power.)
The following cases relate to dogs. Mr. Colquhoun (27. 'The Moor and the
Loch,' p. 45. Col. Hutchinson on 'Dog Breaking,' 1850, p. 46.) winged two
wild-ducks, which fell on the further side of a stream; his retriever tried
to bring over both at once, but could not succeed; she then, though never
before known to ruffle a feather, deliberately killed one, brought over the
other, and returned for the dead bird. Col. Hutchinson relates that two
partridges were shot at once, one being killed, the other wounded; the
latter ran away, and was caught by the retriever, who on her return came
across the dead bird; "she stopped, evidently greatly puzzled, and after
one or two trials, finding she could not take it up without permitting the
escape of the winged bird, she considered a moment, then deliberately
murdered it by giving it a severe crunch, and afterwards brought away both
together. This was the only known instance of her ever having wilfully
injured any game." Here we have reason though not quite perfect, for the
retriever might have brought the wounded bird first and then returned for
the dead one, as in the case of the two wild-ducks. I give the above
cases, as resting on the evidence of two independent witnesses, and because
in both instances the retrievers, after deliberation, broke through a habit
which is inherited by them (that of not killing the game retrieved), and
because they shew how strong their reasoning faculty must have been to
overcome a fixed habit.
I will conclude by quoting a remark by the illustrious Humboldt. (28.
'Personal Narrative,' Eng. translat., vol. iii. p. 106.) "The muleteers in
S. America say, 'I will not give you the mule whose step is easiest, but la
mas racional,--the one that reasons best'"; and; as, he adds, "this popular
expression, dictated by long experience, combats the system of animated
machines, better perhaps than all the arguments of speculative philosophy."
Nevertheless some writers even yet deny that the higher animals possess a
trace of reason; and they endeavour to explain away, by what appears to be
mere verbiage, (29. I am glad to find that so acute a reasoner as Mr.
Leslie Stephen ('Darwinism and Divinity, Essays on Free Thinking,' 1873, p.
80), in speaking of the supposed impassable barrier between the minds of
man and the lower animals, says, "The distinctions, indeed, which have been
drawn, seem to us to rest upon no better foundation than a great many other
metaphysical distinctions; that is, the assumption that because you can
give two things different names, they must therefore have different
natures. It is difficult to understand how anybody who has ever kept a
dog, or seen an elephant, can have any doubt as to an animal's power of
performing the essential processes of reasoning.") all such facts as those
above given.
It has, I think, now been shewn that man and the higher animals, especially
the Primates, have some few instincts in common. All have the same senses,
intuitions, and sensations,--similar passions, affections, and emotions,
even the more complex ones, such as jealousy, suspicion, emulation,
gratitude, and magnanimity; they practise deceit and are revengeful; they
are sometimes susceptible to ridicule, and even have a sense of humour;
they feel wonder and curiosity; they possess the same faculties of
imitation, attention, deliberation, choice, memory, imagination, the
association of ideas, and reason, though in very different degrees. The
individuals of the same species graduate in intellect from absolute
imbecility to high excellence. They are also liable to insanity, though
far less often than in the case of man. (30. See 'Madness in Animals,' by
Dr. W. Lauder Lindsay, in 'Journal of Mental Science,' July 1871.)
Nevertheless, many authors have insisted that man is divided by an
insuperable barrier from all the lower animals in his mental faculties. I
formerly made a collection of above a score of such aphorisms, but they are
almost worthless, as their wide difference and number prove the difficulty,
if not the impossibility, of the attempt. It has been asserted that man
alone is capable of progressive improvement; that he alone makes use of
tools or fire, domesticates other animals, or possesses property; that no
animal has the power of abstraction, or of forming general concepts, is
self-conscious and comprehends itself; that no animal employs language;
that man alone has a sense of beauty, is liable to caprice, has the feeling
of gratitude, mystery, etc.; believes in God, or is endowed with a
conscience. I will hazard a few remarks on the more important and
interesting of these points.
Archbishop Sumner formerly maintained (31. Quoted by Sir C. Lyell,
'Antiquity of Man,' p. 497.) that man alone is capable of progressive
improvement. That he is capable of incomparably greater and more rapid
improvement than is any other animal, admits of no dispute; and this is
mainly due to his power of speaking and handing down his acquired
knowledge. With animals, looking first to the individual, every one who
has had any experience in setting traps, knows that young animals can he
caught much more easily than old ones; and they can be much more easily
approached by an enemy. Even with respect to old animals, it is impossible
to catch many in the same place and in the same kind of trap, or to destroy
them by the same kind of poison; yet it is improbable that all should have
partaken of the poison, and impossible that all should have been caught in
a trap. They must learn caution by seeing their brethren caught or
poisoned. In North America, where the fur-bearing animals have long been
pursued, they exhibit, according to the unanimous testimony of all
observers, an almost incredible amount of sagacity, caution and cunning;
but trapping has been there so long carried on, that inheritance may
possibly have come into play. I have received several accounts that when
telegraphs are first set up in any district, many birds kill themselves by
flying against the wires, but that in the course of a very few years they
learn to avoid this danger, by seeing, as it would appear, their comrades
killed. (32. For additional evidence, with details, see M. Houzeau,
'Etudes sur les Facultes Mentales des Animaux,' tom. ii. 1872, p. 147.)
If we look to successive generations, or to the race, there is no doubt
that birds and other animals gradually both acquire and lose caution in
relation to man or other enemies (33. See, with respect to birds on
oceanic islands, my 'Journal of Researches during the Voyage of the
"Beagle,"' 1845, p. 398. 'Origin of Species,' 5th ed. p. 260.); and this
caution is certainly in chief part an inherited habit or instinct, but in
part the result of individual experience. A good observer, Leroy (34.
'Lettres Phil. sur l'Intelligence des Animaux,' nouvelle edit., 1802, p.
86.), states, that in districts where foxes are much hunted, the young, on
first leaving their burrows, are incontestably much more wary than the old
ones in districts where they are not much disturbed.
Our domestic dogs are descended from wolves and jackals (35. See the
evidence on this head in chap. i. vol. i., 'On the Variation of Animals and
Plants under Domestication.'), and though they may not have gained in
cunning, and may have lost in wariness and suspicion, yet they have
progressed in certain moral qualities, such as in affection, trust-
worthiness, temper, and probably in general intelligence. The common rat
has conquered and beaten several other species throughout Europe, in parts
of North America, New Zealand, and recently in Formosa, as well as on the
mainland of China. Mr. Swinhoe (36. 'Proceedings Zoological Society,'
1864, p. 186.), who describes these two latter cases, attributes the
victory of the common rat over the large Mus coninga to its superior
cunning; and this latter quality may probably be attributed to the habitual
exercise of all its faculties in avoiding extirpation by man, as well as to
nearly all the less cunning or weak-minded rats having been continuously
destroyed by him. It is, however, possible that the success of the common
rat may be due to its having possessed greater cunning than its fellow-
species, before it became associated with man. To maintain, independently
of any direct evidence, that no animal during the course of ages has
progressed in intellect or other mental faculties, is to beg the question
of the evolution of species. We have seen that, according to Lartet,
existing mammals belonging to several orders have larger brains than their
ancient tertiary prototypes.
It has often been said that no animal uses any tool; but the chimpanzee in
a state of nature cracks a native fruit, somewhat like a walnut, with a
stone. (37. Savage and Wyman in 'Boston Journal of Natural History,' vol.
iv. 1843-44, p. 383.) Rengger (38. 'Saugethiere von Paraguay,' 1830, s.
51-56.) easily taught an American monkey thus to break open hard palm-nuts;
and afterwards of its own accord, it used stones to open other kinds of
nuts, as well as boxes. It thus also removed the soft rind of fruit that
had a disagreeable flavour. Another monkey was taught to open the lid of a
large box with a stick, and afterwards it used the stick as a lever to move
heavy bodies; and I have myself seen a young orang put a stick into a
crevice, slip his hand to the other end, and use it in the proper manner as
a lever. The tamed elephants in India are well known to break off branches
of trees and use them to drive away the flies; and this same act has been
observed in an elephant in a state of nature. (39. The Indian Field,
March 4, 1871.) I have seen a young orang, when she thought she was going
to be whipped, cover and protect herself with a blanket or straw. In these
several cases stones and sticks were employed as implements; but they are
likewise used as weapons. Brehm (40. 'Thierleben,' B. i. s. 79, 82.)
states, on the authority of the well-known traveller Schimper, that in
Abyssinia when the baboons belonging to one species (C. gelada) descend in
troops from the mountains to plunder the fields, they sometimes encounter
troops of another species (C. hamadryas), and then a fight ensues. The
Geladas roll down great stones, which the Hamadryas try to avoid, and then
both species, making a great uproar, rush furiously against each other.
Brehm, when accompanying the Duke of Coburg-Gotha, aided in an attack with
fire-arms on a troop of baboons in the pass of Mensa in Abyssinia. The
baboons in return rolled so many stones down the mountain, some as large as
a man's head, that the attackers had to beat a hasty retreat; and the pass
was actually closed for a time against the caravan. It deserves notice
that these baboons thus acted in concert. Mr. Wallace (41. 'The Malay
Archipelago,' vol. i. 1869, p. 87.) on three occasions saw female orangs,
accompanied by their young, "breaking off branches and the great spiny
fruit of the Durian tree, with every appearance of rage; causing such a
shower of missiles as effectually kept us from approaching too near the
tree." As I have repeatedly seen, a chimpanzee will throw any object at
hand at a person who offends him; and the before-mentioned baboon at the
Cape of Good Hope prepared mud for the purpose.
In the Zoological Gardens, a monkey, which had weak teeth, used to break
open nuts with a stone; and I was assured by the keepers that after using
the stone, he hid it in the straw, and would not let any other monkey touch
it. Here, then, we have the idea of property; but this idea is common to
every dog with a bone, and to most or all birds with their nests.
The Duke of Argyll (42. 'Primeval Man,' 1869, pp. 145, 147.) remarks, that
the fashioning of an implement for a special purpose is absolutely peculiar
to man; and he considers that this forms an immeasurable gulf between him
and the brutes. This is no doubt a very important distinction; but there
appears to me much truth in Sir J. Lubbock's suggestion (43. 'Prehistoric
Times,' 1865, p. 473, etc.), that when primeval man first used flint-stones
for any purpose, he would have accidentally splintered them, and would then
have used the sharp fragments. From this step it would be a small one to
break the flints on purpose, and not a very wide step to fashion them
rudely. This latter advance, however, may have taken long ages, if we may
judge by the immense interval of time which elapsed before the men of the
neolithic period took to grinding and polishing their stone tools. In
breaking the flints, as Sir J. Lubbock likewise remarks, sparks would have
been emitted, and in grinding them heat would have been evolved: thus the
two usual methods of "obtaining fire may have originated." The nature of
fire would have been known in the many volcanic regions where lava
occasionally flows through forests. The anthropomorphous apes, guided
probably by instinct, build for themselves temporary platforms; but as many
instincts are largely controlled by reason, the simpler ones, such as this
of building a platform, might readily pass into a voluntary and conscious
act. The orang is known to cover itself at night with the leaves of the
Pandanus; and Brehm states that one of his baboons used to protect itself
from the heat of the sun by throwing a straw-mat over its head. In these
several habits, we probably see the first steps towards some of the simpler
arts, such as rude architecture and dress, as they arose amongst the early
progenitors of man.
ABSTRACTION, GENERAL CONCEPTIONS, SELF-CONSCIOUSNESS, MENTAL INDIVIDUALITY.
It would be very difficult for any one with even much more knowledge than I
possess, to determine how far animals exhibit any traces of these high
mental powers. This difficulty arises from the impossibility of judging
what passes through the mind of an animal; and again, the fact that writers
differ to a great extent in the meaning which they attribute to the above
terms, causes a further difficulty. If one may judge from various articles
which have been published lately, the greatest stress seems to be laid on
the supposed entire absence in animals of the power of abstraction, or of
forming general concepts. But when a dog sees another dog at a distance,
it is often clear that he perceives that it is a dog in the abstract; for
when he gets nearer his whole manner suddenly changes, if the other dog be
a friend. A recent writer remarks, that in all such cases it is a pure
assumption to assert that the mental act is not essentially of the same
nature in the animal as in man. If either refers what he perceives with
his senses to a mental concept, then so do both. (44. Mr. Hookham, in a
letter to Prof. Max Muller, in the 'Birmingham News,' May 1873.) When I
say to my terrier, in an eager voice (and I have made the trial many
times), "Hi, hi, where is it?" she at once takes it as a sign that
something is to be hunted, and generally first looks quickly all around,
and then rushes into the nearest thicket, to scent for any game, but
finding nothing, she looks up into any neighbouring tree for a squirrel.
Now do not these actions clearly shew that she had in her mind a general
idea or concept that some animal is to be discovered and hunted?
It may be freely admitted that no animal is self-conscious, if by this term
it is implied, that he reflects on such points, as whence he comes or
whither he will go, or what is life and death, and so forth. But how can
we feel sure that an old dog with an excellent memory and some power of
imagination, as shewn by his dreams, never reflects on his past pleasures
or pains in the chase? And this would be a form of self-consciousness. On
the other hand, as Buchner (45. 'Conferences sur la Theorie Darwinienne,'
French translat. 1869, p. 132.) has remarked, how little can the hard-
worked wife of a degraded Australian savage, who uses very few abstract
words, and cannot count above four, exert her self-consciousness, or
reflect on the nature of her own existence. It is generally admitted, that
the higher animals possess memory, attention, association, and even some
imagination and reason. If these powers, which differ much in different
animals, are capable of improvement, there seems no great improbability in
more complex faculties, such as the higher forms of abstraction, and self-
consciousness, etc., having been evolved through the development and
combination of the simpler ones. It has been urged against the views here
maintained that it is impossible to say at what point in the ascending
scale animals become capable of abstraction, etc.; but who can say at what
age this occurs in our young children? We see at least that such powers
are developed in children by imperceptible degrees.
That animals retain their mental individuality is unquestionable. When my
voice awakened a train of old associations in the mind of the before-
mentioned dog, he must have retained his mental individuality, although
every atom of his brain had probably undergone change more than once during
the interval of five years. This dog might have brought forward the
argument lately advanced to crush all evolutionists, and said, "I abide
amid all mental moods and all material changes...The teaching that atoms
leave their impressions as legacies to other atoms falling into the places
they have vacated is contradictory of the utterance of consciousness, and
is therefore false; but it is the teaching necessitated by evolutionism,
consequently the hypothesis is a false one." (46. The Rev. Dr. J. M'Cann,
'Anti-Darwinism,' 1869, p. 13.)
LANGUAGE.
This faculty has justly been considered as one of the chief distinctions
between man and the lower animals. But man, as a highly competent judge,
Archbishop Whately remarks, "is not the only animal that can make use of
language to express what is passing in his mind, and can understand, more
or less, what is so expressed by another." (47. Quoted in
'Anthropological Review,' 1864, p. 158.) In Paraguay the Cebus azarae when
excited utters at least six distinct sounds, which excite in other monkeys
similar emotions. (48. Rengger, ibid. s. 45.) The movements of the
features and gestures of monkeys are understood by us, and they partly
understand ours, as Rengger and others declare. It is a more remarkable
fact that the dog, since being domesticated, has learnt to bark (49. See
my 'Variation of Animals and Plants under Domestication,' vol. i. p. 27.)
in at least four or five distinct tones. Although barking is a new art, no
doubt the wild parent-species of the dog expressed their feelings by cries
of various kinds. With the domesticated dog we have the bark of eagerness,
as in the chase; that of anger, as well as growling; the yelp or howl of
despair, as when shut up; the baying at night; the bark of joy, as when
starting on a walk with his master; and the very distinct one of demand or
supplication, as when wishing for a door or window to be opened. According
to Houzeau, who paid particular attention to the subject, the domestic fowl
utters at least a dozen significant sounds. (50. 'Facultes Mentales des
Animaux,' tom. ii. 1872, p. 346-349.)
The habitual use of articulate language is, however, peculiar to man; but
he uses, in common with the lower animals, inarticulate cries to express
his meaning, aided by gestures and the movements of the muscles of the
face. (51. See a discussion on this subject in Mr. E.B. Tylor's very
interesting work, 'Researches into the Early History of Mankind,' 1865,
chaps. ii. to iv.) This especially holds good with the more simple and
vivid feelings, which are but little connected with our higher
intelligence. Our cries of pain, fear, surprise, anger, together with
their appropriate actions, and the murmur of a mother to her beloved child
are more expressive than any words. That which distinguishes man from the
lower animals is not the understanding of articulate sounds, for, as every
one knows, dogs understand many words and sentences. In this respect they
are at the same stage of development as infants, between the ages of ten
and twelve months, who understand many words and short sentences, but
cannot yet utter a single word. It is not the mere articulation which is
our distinguishing character, for parrots and other birds possess this
power. Nor is it the mere capacity of connecting definite sounds with
definite ideas; for it is certain that some parrots, which have been taught
to speak, connect unerringly words with things, and persons with events.
(52. I have received several detailed accounts to this effect. Admiral
Sir B.J. Sulivan, whom I know to be a careful observer, assures me that an
African parrot, long kept in his father's house, invariably called certain
persons of the household, as well as visitors, by their names. He said
"good morning" to every one at breakfast, and "good night" to each as they
left the room at night, and never reversed these salutations. To Sir B.J.
Sulivan's father, he used to add to the " good morning" a short sentence,
which was never once repeated after his father's death. He scolded
violently a strange dog which came into the room through the open window;
and he scolded another parrot (saying "you naughty polly") which had got
out of its cage, and was eating apples on the kitchen table. See also, to
the same effect, Houzeau on parrots, 'Facultes Mentales,' tom. ii. p. 309.
Dr. A. Moschkau informs me that he knew a starling which never made a
mistake in saying in German "good morning" to persons arriving, and "good
bye, old fellow," to those departing. I could add several other such
cases.) The lower animals differ from man solely in his almost infinitely
larger power of associating together the most diversified sounds and ideas;
and this obviously depends on the high development of his mental powers.
As Horne Tooke, one of the founders of the noble science of philology,
observes, language is an art, like brewing or baking; but writing would
have been a better simile. It certainly is not a true instinct, for every
language has to be learnt. It differs, however, widely from all ordinary
arts, for man has an instinctive tendency to speak, as we see in the babble
of our young children; whilst no child has an instinctive tendency to brew,
bake, or write. Moreover, no philologist now supposes that any language
has been deliberately invented; it has been slowly and unconsciously
developed by many steps. (53. See some good remarks on this head by Prof.
Whitney, in his 'Oriental and Linguistic Studies,' 1873, p. 354. He
observes that the desire of communication between man is the living force,
which, in the development of language, "works both consciously and
unconsciously; consciously as regards the immediate end to be attained;
unconsciously as regards the further consequences of the act.") The sounds
uttered by birds offer in several respects the nearest analogy to language,
for all the members of the same species utter the same instinctive cries
expressive of their emotions; and all the kinds which sing, exert their
power instinctively; but the actual song, and even the call-notes, are
learnt from their parents or foster-parents. These sounds, as Daines
Barrington (54. Hon. Daines Barrington in 'Philosoph. Transactions,' 1773,
p. 262. See also Dureau de la Malle, in 'Ann. des. Sc. Nat.' 3rd series,
Zoolog., tom. x. p. 119.) has proved, "are no more innate than language is
in man." The first attempts to sing "may be compared to the imperfect
endeavour in a child to babble." The young males continue practising, or
as the bird-catchers say, "recording," for ten or eleven months. Their
first essays shew hardly a rudiment of the future song; but as they grow
older we can perceive what they are aiming at; and at last they are said
"to sing their song round." Nestlings which have learnt the song of a
distinct species, as with the canary-birds educated in the Tyrol, teach and
transmit their new song to their offspring. The slight natural differences
of song in the same species inhabiting different districts may be
appositely compared, as Barrington remarks, "to provincial dialects"; and
the songs of allied, though distinct species may be compared with the
languages of distinct races of man. I have given the foregoing details to
shew that an instinctive tendency to acquire an art is not peculiar to man.
With respect to the origin of articulate language, after having read on the
one side the highly interesting works of Mr. Hensleigh Wedgwood, the Rev.
F. Farrar, and Prof. Schleicher (55. 'On the Origin of Language,' by H.
Wedgwood, 1866. 'Chapters on Language,' by the Rev. F.W. Farrar, 1865.
These works are most interesting. See also 'De la Phys. et de Parole,' par
Albert Lemoine, 1865, p. 190. The work on this subject, by the late Prof.
Aug. Schleicher, has been translated by Dr. Bikkers into English, under the
title of 'Darwinism tested by the Science of Language,' 1869.), and the
celebrated lectures of Prof. Max Muller on the other side, I cannot doubt
that language owes its origin to the imitation and modification of various
natural sounds, the voices of other animals, and man's own instinctive
cries, aided by signs and gestures. When we treat of sexual selection we
shall see that primeval man, or rather some early progenitor of man,
probably first used his voice in producing true musical cadences, that is
in singing, as do some of the gibbon-apes at the present day; and we may
conclude from a widely-spread analogy, that this power would have been
especially exerted during the courtship of the sexes,--would have expressed
various emotions, such as love, jealousy, triumph,--and would have served
as a challenge to rivals. It is, therefore, probable that the imitation of
musical cries by articulate sounds may have given rise to words expressive
of various complex emotions. The strong tendency in our nearest allies,
the monkeys, in microcephalous idiots (56. Vogt, 'Memoire sur les
Microcephales,' 1867, p. 169. With respect to savages, I have given some
facts in my 'Journal of Researches,' etc., 1845, p. 206.), and in the
barbarous races of mankind, to imitate whatever they hear deserves notice,
as bearing on the subject of imitation. Since monkeys certainly understand
much that is said to them by man, and when wild, utter signal-cries of
danger to their fellows (57. See clear evidence on this head in the two
works so often quoted, by Brehm and Rengger.); and since fowls give
distinct warnings for danger on the ground, or in the sky from hawks (both,
as well as a third cry, intelligible to dogs) (58. Houzeau gives a very
curious account of his observations on this subject in his 'Facultes
Mentales des Animaux,' tom. ii. p. 348.), may not some unusually wise ape-
like animal have imitated the growl of a beast of prey, and thus told his
fellow-monkeys the nature of the expected danger? This would have been a
first step in the formation of a language.
As the voice was used more and more, the vocal organs would have been
strengthened and perfected through the principle of the inherited effects
of use; and this would have reacted on the power of speech. But the
relation between the continued use of language and the development of the
brain, has no doubt been far more important. The mental powers in some
early progenitor of man must have been more highly developed than in any
existing ape, before even the most imperfect form of speech could have come
into use; but we may confidently believe that the continued use and
advancement of this power would have reacted on the mind itself, by
enabling and encouraging it to carry on long trains of thought. A complex
train of thought can no more be carried on without the aid of words,
whether spoken or silent, than a long calculation without the use of
figures or algebra. It appears, also, that even an ordinary train of
thought almost requires, or is greatly facilitated by some form of
language, for the dumb, deaf, and blind girl, Laura Bridgman, was observed
to use her fingers whilst dreaming. (59. See remarks on this head by Dr.
Maudsley, 'The Physiology and Pathology of Mind,' 2nd ed., 1868, p. 199.)
Nevertheless, a long succession of vivid and connected ideas may pass
through the mind without the aid of any form of language, as we may infer
from the movements of dogs during their dreams. We have, also, seen that
animals are able to reason to a certain extent, manifestly without the aid
of language. The intimate connection between the brain, as it is now
developed in us, and the faculty of speech, is well shewn by those curious
cases of brain-disease in which speech is specially affected, as when the
power to remember substantives is lost, whilst other words can be correctly
used, or where substantives of a certain class, or all except the initial
letters of substantives and proper names are forgotten. (60. Many curious
cases have been recorded. See, for instance, Dr. Bateman 'On Aphasia,'
1870, pp. 27, 31, 53, 100, etc. Also, 'Inquiries Concerning the
Intellectual Powers,' by Dr. Abercrombie, 1838, p. 150.) There is no more
improbability in the continued use of the mental and vocal organs leading
to inherited changes in their structure and functions, than in the case of
hand-writing, which depends partly on the form of the hand and partly on
the disposition of the mind; and handwriting is certainly inherited. (61.
'The Variation of Animals and Plants under Domestication,' vol. ii. p. 6.'
Several writers, more especially Prof. Max Muller (62. Lectures on 'Mr.
Darwin's Philosophy of Language,' 1873.), have lately insisted that the use
of language implies the power of forming general concepts; and that as no
animals are supposed to possess this power, an impassable barrier is formed
between them and man. (63. The judgment of a distinguished philologist,
such as Prof. Whitney, will have far more weight on this point than
anything that I can say. He remarks ('Oriental and Linguistic Studies,'
1873, p. 297), in speaking of Bleek's views: "Because on the grand scale
language is the necessary auxiliary of thought, indispensable to the
development of the power of thinking, to the distinctness and variety and
complexity of cognitions to the full mastery of consciousness; therefore he
would fain make thought absolutely impossible without speech, identifying
the faculty with its instrument. He might just as reasonably assert that
the human hand cannot act without a tool. With such a doctrine to start
from, he cannot stop short of Max Muller's worst paradoxes, that an infant
(in fans, not speaking) is not a human being, and that deaf-mutes do not
become possessed of reason until they learn to twist their fingers into
imitation of spoken words." Max Muller gives in italics ('Lectures on Mr.
Darwin's Philosophy of Language,' 1873, third lecture) this aphorism:
"There is no thought without words, as little as there are words without
thought." What a strange definition must here be given to the word
thought!) With respect to animals, I have already endeavoured to shew that
they have this power, at least in a rude and incipient degree. As far as
concerns infants of from ten to eleven months old, and deaf-mutes, it seems
to me incredible, that they should be able to connect certain sounds with
certain general ideas as quickly as they do, unless such ideas were already
formed in their minds. The same remark may be extended to the more
intelligent animals; as Mr. Leslie Stephen observes (64. 'Essays on Free
Thinking,' etc., 1873, p. 82.), "A dog frames a general concept of cats or
sheep, and knows the corresponding words as well as a philosopher. And the
capacity to understand is as good a proof of vocal intelligence, though in
an inferior degree, as the capacity to speak."
Why the organs now used for speech should have been originally perfected
for this purpose, rather than any other organs, it is not difficult to see.
Ants have considerable powers of intercommunication by means of their
antennae, as shewn by Huber, who devotes a whole chapter to their language.
We might have used our fingers as efficient instruments, for a person with
practice can report to a deaf man every word of a speech rapidly delivered
at a public meeting; but the loss of our hands, whilst thus employed, would
have been a serious inconvenience. As all the higher mammals possess vocal
organs, constructed on the same general plan as ours, and used as a means
of communication, it was obviously probable that these same organs would be
still further developed if the power of communication had to be improved;
and this has been effected by the aid of adjoining and well adapted parts,
namely the tongue and lips. (65. See some good remarks to this effect by
Dr. Maudsley, 'The Physiology and Pathology of Mind,' 1868, p. 199.) The
fact of the higher apes not using their vocal organs for speech, no doubt
depends on their intelligence not having been sufficiently advanced. The
possession by them of organs, which with long-continued practice might have
been used for speech, although not thus used, is paralleled by the case of
many birds which possess organs fitted for singing, though they never sing.
Thus, the nightingale and crow have vocal organs similarly constructed,
these being used by the former for diversified song, and by the latter only
for croaking. (66. Macgillivray, 'Hist. of British Birds,' vol. ii. 1839,
p. 29. An excellent observer, Mr. Blackwall, remarks that the magpie
learns to pronounce single words, and even short sentences, more readily
than almost any other British bird; yet, as he adds, after long and closely
investigating its habits, he has never known it, in a state of nature,
display any unusual capacity for imitation. 'Researches in Zoology,' 1834,
p. 158.) If it be asked why apes have not had their intellects developed
to the same degree as that of man, general causes only can be assigned in
answer, and it is unreasonable to expect any thing more definite,
considering our ignorance with respect to the successive stages of
development through which each creature has passed.
The formation of different languages and of distinct species, and the
proofs that both have been developed through a gradual process, are
curiously parallel. (67. See the very interesting parallelism between the
development of species and languages, given by Sir C. Lyell in 'The
Geological Evidences of the Antiquity of Man,' 1863, chap. xxiii.) But we
can trace the formation of many words further back than that of species,
for we can perceive how they actually arose from the imitation of various
sounds. We find in distinct languages striking homologies due to community
of descent, and analogies due to a similar process of formation. The
manner in which certain letters or sounds change when others change is very
like correlated growth. We have in both cases the reduplication of parts,
the effects of long-continued use, and so forth. The frequent presence of
rudiments, both in languages and in species, is still more remarkable. The
letter m in the word am, means I; so that in the expression I am, a
superfluous and useless rudiment has been retained. In the spelling also
of words, letters often remain as the rudiments of ancient forms of
pronunciation. Languages, like organic beings, can be classed in groups
under groups; and they can be classed either naturally according to
descent, or artificially by other characters. Dominant languages and
dialects spread widely, and lead to the gradual extinction of other
tongues. A language, like a species, when once extinct, never, as Sir C.
Lyell remarks, reappears. The same language never has two birth-places.
Distinct languages may be crossed or blended together. (68. See remarks
to this effect by the Rev. F.W. Farrar, in an interesting article, entitled
'Philology and Darwinism,' in 'Nature,' March 24th, 1870, p. 528.) We see
variability in every tongue, and new words are continually cropping up; but
as there is a limit to the powers of the memory, single words, like whole
languages, gradually become extinct. As Max Muller (69. 'Nature,' January
6th, 1870, p. 257.) has well remarked:--"A struggle for life is constantly
going on amongst the words and grammatical forms in each language. The
better, the shorter, the easier forms are constantly gaining the upper
hand, and they owe their success to their own inherent virtue." To these
more important causes of the survival of certain words, mere novelty and
fashion may be added; for there is in the mind of man a strong love for
slight changes in all things. The survival or preservation of certain
favoured words in the struggle for existence is natural selection.
The perfectly regular and wonderfully complex construction of the languages
of many barbarous nations has often been advanced as a proof, either of the
divine origin of these languages, or of the high art and former
civilisation of their founders. Thus F. von Schlegel writes: "In those
languages which appear to be at the lowest grade of intellectual culture,
we frequently observe a very high and elaborate degree of art in their
grammatical structure. This is especially the case with the Basque and the
Lapponian, and many of the American languages." (70. Quoted by C.S. Wake,
'Chapters on Man,' 1868, p. 101.) But it is assuredly an error to speak of
any language as an art, in the sense of its having been elaborately and
methodically formed. Philologists now admit that conjugations,
declensions, etc., originally existed as distinct words, since joined
together; and as such words express the most obvious relations between
objects and persons, it is not surprising that they should have been used
by the men of most races during the earliest ages. With respect to
perfection, the following illustration will best shew how easily we may
err: a Crinoid sometimes consists of no less than 150,000 pieces of shell
(71. Buckland, 'Bridgewater Treatise,' p. 411.), all arranged with perfect
symmetry in radiating lines; but a naturalist does not consider an animal
of this kind as more perfect than a bilateral one with comparatively few
parts, and with none of these parts alike, excepting on the opposite sides
of the body. He justly considers the differentiation and specialisation of
organs as the test of perfection. So with languages: the most symmetrical
and complex ought not to be ranked above irregular, abbreviated, and
bastardised languages, which have borrowed expressive words and useful
forms of construction from various conquering, conquered, or immigrant
races.
From these few and imperfect remarks I conclude that the extremely complex
and regular construction of many barbarous languages, is no proof that they
owe their origin to a special act of creation. (72. See some good remarks
on the simplification of languages, by Sir J. Lubbock, 'Origin of
Civilisation,' 1870, p. 278.) Nor, as we have seen, does the faculty of
articulate speech in itself offer any insuperable objection to the belief
that man has been developed from some lower form.
SENSE OF BEAUTY.
This sense has been declared to be peculiar to man. I refer here only to
the pleasure given by certain colours, forms, and sounds, and which may
fairly be called a sense of the beautiful; with cultivated men such
sensations are, however, intimately associated with complex ideas and
trains of thought. When we behold a male bird elaborately displaying his
graceful plumes or splendid colours before the female, whilst other birds,
not thus decorated, make no such display, it is impossible to doubt that
she admires the beauty of her male partner. As women everywhere deck
themselves with these plumes, the beauty of such ornaments cannot be
disputed. As we shall see later, the nests of humming-birds, and the
playing passages of bower-birds are tastefully ornamented with gaily-
coloured objects; and this shews that they must receive some kind of
pleasure from the sight of such things. With the great majority of
animals, however, the taste for the beautiful is confined, as far as we can
judge, to the attractions of the opposite sex. The sweet strains poured
forth by many male birds during the season of love, are certainly admired
by the females, of which fact evidence will hereafter be given. If female
birds had been incapable of appreciating the beautiful colours, the
ornaments, and voices of their male partners, all the labour and anxiety
exhibited by the latter in displaying their charms before the females would
have been thrown away; and this it is impossible to admit. Why certain
bright colours should excite pleasure cannot, I presume, be explained, any
more than why certain flavours and scents are agreeable; but habit has
something to do with the result, for that which is at first unpleasant to
our senses, ultimately becomes pleasant, and habits are inherited. With
respect to sounds, Helmholtz has explained to a certain extent on
physiological principles, why harmonies and certain cadences are agreeable.
But besides this, sounds frequently recurring at irregular intervals are
highly disagreeable, as every one will admit who has listened at night to
the irregular flapping of a rope on board ship. The same principle seems
to come into play with vision, as the eye prefers symmetry or figures with
some regular recurrence. Patterns of this kind are employed by even the
lowest savages as ornaments; and they have been developed through sexual
selection for the adornment of some male animals. Whether we can or not
give any reason for the pleasure thus derived from vision and hearing, yet
man and many of the lower animals are alike pleased by the same colours,
graceful shading and forms, and the same sounds.
The taste for the beautiful, at least as far as female beauty is concerned,
is not of a special nature in the human mind; for it differs widely in the
different races of man, and is not quite the same even in the different
nations of the same race. Judging from the hideous ornaments, and the
equally hideous music admired by most savages, it might be urged that their
aesthetic faculty was not so highly developed as in certain animals, for
instance, as in birds. Obviously no animal would be capable of admiring
such scenes as the heavens at night, a beautiful landscape, or refined
music; but such high tastes are acquired through culture, and depend on
complex associations; they are not enjoyed by barbarians or by uneducated
persons.
Many of the faculties, which have been of inestimable service to man for
his progressive advancement, such as the powers of the imagination, wonder,
curiosity, an undefined sense of beauty, a tendency to imitation, and the
love of excitement or novelty, could hardly fail to lead to capricious
changes of customs and fashions. I have alluded to this point, because a
recent writer (73. 'The Spectator,' Dec. 4th, 1869, p. 1430.) has oddly
fixed on Caprice "as one of the most remarkable and typical differences
between savages and brutes." But not only can we partially understand how
it is that man is from various conflicting influences rendered capricious,
but that the lower animals are, as we shall hereafter see, likewise
capricious in their affections, aversions, and sense of beauty. There is
also reason to suspect that they love novelty, for its own sake.
BELIEF IN GOD--RELIGION.
There is no evidence that man was aboriginally endowed with the ennobling
belief in the existence of an Omnipotent God. On the contrary there is
ample evidence, derived not from hasty travellers, but from men who have
long resided with savages, that numerous races have existed, and still
exist, who have no idea of one or more gods, and who have no words in their
languages to express such an idea. (74. See an excellent article on this
subject by the Rev. F.W. Farrar, in the 'Anthropological Review,' Aug.
1864, p. ccxvii. For further facts see Sir J. Lubbock, 'Prehistoric
Times,' 2nd edit., 1869, p. 564; and especially the chapters on Religion in
his 'Origin of Civilisation,' 1870.) The question is of course wholly
distinct from that higher one, whether there exists a Creator and Ruler of
the universe; and this has been answered in the affirmative by some of the
highest intellects that have ever existed.
If, however, we include under the term "religion" the belief in unseen or
spiritual agencies, the case is wholly different; for this belief seems to
be universal with the less civilised races. Nor is it difficult to
comprehend how it arose. As soon as the important faculties of the
imagination, wonder, and curiosity, together with some power of reasoning,
had become partially developed, man would naturally crave to understand
what was passing around him, and would have vaguely speculated on his own
existence. As Mr. M'Lennan (75. 'The Worship of Animals and Plants,' in
the 'Fortnightly Review,' Oct. 1, 1869, p. 422.) has remarked, "Some
explanation of the phenomena of life, a man must feign for himself, and to
judge from the universality of it, the simplest hypothesis, and the first
to occur to men, seems to have been that natural phenomena are ascribable
to the presence in animals, plants, and things, and in the forces of
nature, of such spirits prompting to action as men are conscious they
themselves possess." It is also probable, as Mr. Tylor has shewn, that
dreams may have first given rise to the notion of spirits; for savages do
not readily distinguish between subjective and objective impressions. When
a savage dreams, the figures which appear before him are believed to have
come from a distance, and to stand over him; or "the soul of the dreamer
goes out on its travels, and comes home with a remembrance of what it has
seen." (76. Tylor, 'Early History of Mankind,' 1865, p. 6. See also the
three striking chapters on the 'Development of Religion,' in Lubbock's
'Origin of Civilisation,' 1870. In a like manner Mr. Herbert Spencer, in
his ingenious essay in the 'Fortnightly Review' (May 1st, 1870, p. 535),
accounts for the earliest forms of religious belief throughout the world,
by man being led through dreams, shadows, and other causes, to look at
himself as a double essence, corporeal and spiritual. As the spiritual
being is supposed to exist after death and to be powerful, it is
propitiated by various gifts and ceremonies, and its aid invoked. He then
further shews that names or nicknames given from some animal or other
object, to the early progenitors or founders of a tribe, are supposed after
a long interval to represent the real progenitor of the tribe; and such
animal or object is then naturally believed still to exist as a spirit, is
held sacred, and worshipped as a god. Nevertheless I cannot but suspect
that there is a still earlier and ruder stage, when anything which
manifests power or movement is thought to be endowed with some form of
life, and with mental faculties analogous to our own.) But until the
faculties of imagination, curiosity, reason, etc., had been fairly well
developed in the mind of man, his dreams would not have led him to believe
in spirits, any more than in the case of a dog.
The tendency in savages to imagine that natural objects and agencies are
animated by spiritual or living essences, is perhaps illustrated by a
little fact which I once noticed: my dog, a full-grown and very sensible
animal, was lying on the lawn during a hot and still day; but at a little
distance a slight breeze occasionally moved an open parasol, which would
have been wholly disregarded by the dog, had any one stood near it. As it
was, every time that the parasol slightly moved, the dog growled fiercely
and barked. He must, I think, have reasoned to himself in a rapid and
unconscious manner, that movement without any apparent cause indicated the
presence of some strange living agent, and that no stranger had a right to
be on his territory.
The belief in spiritual agencies would easily pass into the belief in the
existence of one or more gods. For savages would naturally attribute to
spirits the same passions, the same love of vengeance or simplest form of
justice, and the same affections which they themselves feel. The Fuegians
appear to be in this respect in an intermediate condition, for when the
surgeon on board the "Beagle" shot some young ducklings as specimens, York
Minster declared in the most solemn manner, "Oh, Mr. Bynoe, much rain, much
snow, blow much"; and this was evidently a retributive punishment for
wasting human food. So again he related how, when his brother killed a
"wild man," storms long raged, much rain and snow fell. Yet we could never
discover that the Fuegians believed in what we should call a God, or
practised any religious rites; and Jemmy Button, with justifiable pride,
stoutly maintained that there was no devil in his land. This latter
assertion is the more remarkable, as with savages the belief in bad spirits
is far more common than that in good ones.
The feeling of religious devotion is a highly complex one, consisting of
love, complete submission to an exalted and mysterious superior, a strong
sense of dependence (77. See an able article on the 'Physical Elements of
Religion,' by Mr. L. Owen Pike, in 'Anthropological Review,' April 1870, p.
lxiii.), fear, reverence, gratitude, hope for the future, and perhaps other
elements. No being could experience so complex an emotion until advanced
in his intellectual and moral faculties to at least a moderately high
level. Nevertheless, we see some distant approach to this state of mind in
the deep love of a dog for his master, associated with complete submission,
some fear, and perhaps other feelings. The behaviour of a dog when
returning to his master after an absence, and, as I may add, of a monkey to
his beloved keeper, is widely different from that towards their fellows.
In the latter case the transports of joy appear to be somewhat less, and
the sense of equality is shewn in every action. Professor Braubach goes so
far as to maintain that a dog looks on his master as on a god. (78.
'Religion, Moral, etc., der Darwin'schen Art-Lehre,' 1869, s. 53. It is
said (Dr. W. Lauder Lindsay, 'Journal of Mental Science,' 1871, p. 43),
that Bacon long ago, and the poet Burns, held the same notion.)
The same high mental faculties which first led man to believe in unseen
spiritual agencies, then in fetishism, polytheism, and ultimately in
monotheism, would infallibly lead him, as long as his reasoning powers
remained poorly developed, to various strange superstitions and customs.
Many of these are terrible to think of--such as the sacrifice of human
beings to a blood-loving god; the trial of innocent persons by the ordeal
of poison or fire; witchcraft, etc.--yet it is well occasionally to reflect
on these superstitions, for they shew us what an infinite debt of gratitude
we owe to the improvement of our reason, to science, and to our accumulated
knowledge. As Sir J. Lubbock (79. 'Prehistoric Times,' 2nd edit., p. 571.
In this work (p. 571) there will be found an excellent account of the many
strange and capricious customs of savages.) has well observed, "it is not
too much to say that the horrible dread of unknown evil hangs like a thick
cloud over savage life, and embitters every pleasure." These miserable and
indirect consequences of our highest faculties may be compared with the
incidental and occasional mistakes of the instincts of the lower animals.
CHAPTER IV.
COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS--continued.
The moral sense--Fundamental proposition--The qualities of social animals--
Origin of sociability--Struggle between opposed instincts--Man a social
animal--The more enduring social instincts conquer other less persistent
instincts--The social virtues alone regarded by savages--The self-regarding
virtues acquired at a later stage of development--The importance of the
judgment of the members of the same community on conduct--Transmission of
moral tendencies--Summary.
I fully subscribe to the judgment of those writers (1. See, for instance,
on this subject, Quatrefages, 'Unite de l'Espece Humaine,' 1861, p. 21,
etc.) who maintain that of all the differences between man and the lower
animals, the moral sense or conscience is by far the most important. This
sense, as Mackintosh (2. 'Dissertation an Ethical Philosophy,' 1837, p.
231, etc.) remarks, "has a rightful supremacy over every other principle of
human action"; it is summed up in that short but imperious word "ought," so
full of high significance. It is the most noble of all the attributes of
man, leading him without a moment's hesitation to risk his life for that of
a fellow-creature; or after due deliberation, impelled simply by the deep
feeling of right or duty, to sacrifice it in some great cause. Immanuel
Kant exclaims, "Duty! Wondrous thought, that workest neither by fond
insinuation, flattery, nor by any threat, but merely by holding up thy
naked law in the soul, and so extorting for thyself always reverence, if
not always obedience; before whom all appetites are dumb, however secretly
they rebel; whence thy original?" (3. 'Metaphysics of Ethics,' translated
by J.W. Semple, Edinburgh, 1836, p. 136.)
This great question has been discussed by many writers (4. Mr. Bain gives
a list ('Mental and Moral Science,' 1868, pp. 543-725) of twenty-six
British authors who have written on this subject, and whose names are
familiar to every reader; to these, Mr. Bain's own name, and those of Mr.
Lecky, Mr. Shadworth Hodgson, Sir J. Lubbock, and others, might be added.)
of consummate ability; and my sole excuse for touching on it, is the
impossibility of here passing it over; and because, as far as I know, no
one has approached it exclusively from the side of natural history. The
investigation possesses, also, some independent interest, as an attempt to
see how far the study of the lower animals throws light on one of the
highest psychical faculties of man.
The following proposition seems to me in a high degree probable--namely,
that any animal whatever, endowed with well-marked social instincts (5.
Sir B. Brodie, after observing that man is a social animal ('Psychological
Enquiries,' 1854, p. 192), asks the pregnant question, "ought not this to
settle the disputed question as to the existence of a moral sense?"
Similar ideas have probably occurred to many persons, as they did long ago
to Marcus Aurelius. Mr. J.S. Mill speaks, in his celebrated work,
'Utilitarianism,' (1864, pp. 45, 46), of the social feelings as a "powerful
natural sentiment," and as "the natural basis of sentiment for utilitarian
morality." Again he says, "Like the other acquired capacities above
referred to, the moral faculty, if not a part of our nature, is a natural
out-growth from it; capable, like them, in a certain small degree of
springing up spontaneously." But in opposition to all this, he also
remarks, "if, as in my own belief, the moral feelings are not innate, but
acquired, they are not for that reason less natural." It is with
hesitation that I venture to differ at all from so profound a thinker, but
it can hardly be disputed that the social feelings are instinctive or
innate in the lower animals; and why should they not be so in man? Mr.
Bain (see, for instance, 'The Emotions and the Will,' 1865, p. 481) and
others believe that the moral sense is acquired by each individual during
his lifetime. On the general theory of evolution this is at least
extremely improbable. The ignoring of all transmitted mental qualities
will, as it seems to me, be hereafter judged as a most serious blemish in
the works of Mr. Mill.), the parental and filial affections being here
included, would inevitably acquire a moral sense or conscience, as soon as
its intellectual powers had become as well, or nearly as well developed, as
in man. For, FIRSTLY, the social instincts lead an animal to take pleasure
in the society of its fellows, to feel a certain amount of sympathy with
them, and to perform various services for them. The services may be of a
definite and evidently instinctive nature; or there may be only a wish and
readiness, as with most of the higher social animals, to aid their fellows
in certain general ways. But these feelings and services are by no means
extended to all the individuals of the same species, only to those of the
same association. SECONDLY, as soon as the mental faculties had become
highly developed, images of all past actions and motives would be
incessantly passing through the brain of each individual: and that feeling
of dissatisfaction, or even misery, which invariably results, as we shall
hereafter see, from any unsatisfied instinct, would arise, as often as it
was perceived that the enduring and always present social instinct had
yielded to some other instinct, at the time stronger, but neither enduring
in its nature, nor leaving behind it a very vivid impression. It is clear
that many instinctive desires, such as that of hunger, are in their nature
of short duration; and after being satisfied, are not readily or vividly
recalled. THIRDLY, after the power of language had been acquired, and the
wishes of the community could be expressed, the common opinion how each
member ought to act for the public good, would naturally become in a
paramount degree the guide to action. But it should be borne in mind that
however great weight we may attribute to public opinion, our regard for the
approbation and disapprobation of our fellows depends on sympathy, which,
as we shall see, forms an essential part of the social instinct, and is
indeed its foundation-stone. LASTLY, habit in the individual would
ultimately play a very important part in guiding the conduct of each
member; for the social instinct, together with sympathy, is, like any other
instinct, greatly strengthened by habit, and so consequently would be
obedience to the wishes and judgment of the community. These several
subordinate propositions must now be discussed, and some of them at
considerable length.
It may be well first to premise that I do not wish to maintain that any
strictly social animal, if its intellectual faculties were to become as
active and as highly developed as in man, would acquire exactly the same
moral sense as ours. In the same manner as various animals have some sense
of beauty, though they admire widely-different objects, so they might have
a sense of right and wrong, though led by it to follow widely different
lines of conduct. If, for instance, to take an extreme case, men were
reared under precisely the same conditions as hive-bees, there can hardly
be a doubt that our unmarried females would, like the worker-bees, think it
a sacred duty to kill their brothers, and mothers would strive to kill
their fertile daughters; and no one would think of interfering. (6. Mr.
H. Sidgwick remarks, in an able discussion on this subject (the 'Academy,'
June 15, 1872, p. 231), "a superior bee, we may feel sure, would aspire to
a milder solution of the population question." Judging, however, from the
habits of many or most savages, man solves the problem by female
infanticide, polyandry and promiscuous intercourse; therefore it may well
be doubted whether it would be by a milder method. Miss Cobbe, in
commenting ('Darwinism in Morals,' 'Theological Review,' April 1872, pp.
188-191) on the same illustration, says, the PRINCIPLES of social duty
would be thus reversed; and by this, I presume, she means that the
fulfilment of a social duty would tend to the injury of individuals; but
she overlooks the fact, which she would doubtless admit, that the instincts
of the bee have been acquired for the good of the community. She goes so
far as to say that if the theory of ethics advocated in this chapter were
ever generally accepted, "I cannot but believe that in the hour of their
triumph would be sounded the knell of the virtue of mankind!" It is to be
hoped that the belief in the permanence of virtue on this earth is not held
by many persons on so weak a tenure.) Nevertheless, the bee, or any other
social animal, would gain in our supposed case, as it appears to me, some
feeling of right or wrong, or a conscience. For each individual would have
an inward sense of possessing certain stronger or more enduring instincts,
and others less strong or enduring; so that there would often be a struggle
as to which impulse should be followed; and satisfaction, dissatisfaction,
or even misery would be felt, as past impressions were compared during
their incessant passage through the mind. In this case an inward monitor
would tell the animal that it would have been better to have followed the
one impulse rather than the other. The one course ought to have been
followed, and the other ought not; the one would have been right and the
other wrong; but to these terms I shall recur.
SOCIABILITY.
Animals of many kinds are social; we find even distinct species living
together; for example, some American monkeys; and united flocks of rooks,
jackdaws, and starlings. Man shews the same feeling in his strong love for
the dog, which the dog returns with interest. Every one must have noticed
how miserable horses, dogs, sheep, etc., are when separated from their
companions, and what strong mutual affection the two former kinds, at
least, shew on their reunion. It is curious to speculate on the feelings
of a dog, who will rest peacefully for hours in a room with his master or
any of the family, without the least notice being taken of him; but if left
for a short time by himself, barks or howls dismally. We will confine our
attention to the higher social animals; and pass over insects, although
some of these are social, and aid one another in many important ways. The
most common mutual service in the higher animals is to warn one another of
danger by means of the united senses of all. Every sportsman knows, as Dr.
Jaeger remarks (7. 'Die Darwin'sche Theorie,' s. 101.), how difficult it
is to approach animals in a herd or troop. Wild horses and cattle do not,
I believe, make any danger-signal; but the attitude of any one of them who
first discovers an enemy, warns the others. Rabbits stamp loudly on the
ground with their hind-feet as a signal: sheep and chamois do the same
with their forefeet, uttering likewise a whistle. Many birds, and some
mammals, post sentinels, which in the case of seals are said (8. Mr. R.
Brown in 'Proc. Zoolog. Soc.' 1868, p. 409.) generally to be the females.
The leader of a troop of monkeys acts as the sentinel, and utters cries
expressive both of danger and of safety. (9. Brehm, 'Thierleben,' B. i.
1864, s. 52, 79. For the case of the monkeys extracting thorns from each
other, see s. 54. With respect to the Hamadryas turning over stones, the
fact is given (s. 76), on the evidence of Alvarez, whose observations Brehm
thinks quite trustworthy. For the cases of the old male baboons attacking
the dogs, see s. 79; and with respect to the eagle, s. 56.) Social animals
perform many little services for each other: horses nibble, and cows lick
each other, on any spot which itches: monkeys search each other for
external parasites; and Brehm states that after a troop of the
Cercopithecus griseo-viridis has rushed through a thorny brake, each monkey
stretches itself on a branch, and another monkey sitting by,
"conscientiously" examines its fur, and extracts every thorn or burr.
Animals also render more important services to one another: thus wolves
and some other beasts of prey hunt in packs, and aid one another in
attacking their victims. Pelicans fish in concert. The Hamadryas baboons
turn over stones to find insects, etc.; and when they come to a large one,
as many as can stand round, turn it over together and share the booty.
Social animals mutually defend each other. Bull bisons in N. America, when
there is danger, drive the cows and calves into the middle of the herd,
whilst they defend the outside. I shall also in a future chapter give an
account of two young wild bulls at Chillingham attacking an old one in
concert, and of two stallions together trying to drive away a third
stallion from a troop of mares. In Abyssinia, Brehm encountered a great
troop of baboons who were crossing a valley: some had already ascended the
opposite mountain, and some were still in the valley; the latter were
attacked by the dogs, but the old males immediately hurried down from the
rocks, and with mouths widely opened, roared so fearfully, that the dogs
quickly drew back. They were again encouraged to the attack; but by this
time all the baboons had reascended the heights, excepting a young one,
about six months old, who, loudly calling for aid, climbed on a block of
rock, and was surrounded. Now one of the largest males, a true hero, came
down again from the mountain, slowly went to the young one, coaxed him, and
triumphantly led him away--the dogs being too much astonished to make an
attack. I cannot resist giving another scene which was witnessed by this
same naturalist; an eagle seized a young Cercopithecus, which, by clinging
to a branch, was not at once carried off; it cried loudly for assistance,
upon which the other members of the troop, with much uproar, rushed to the
rescue, surrounded the eagle, and pulled out so many feathers, that he no
longer thought of his prey, but only how to escape. This eagle, as Brehm
remarks, assuredly would never again attack a single monkey of a troop.
(10. Mr. Belt gives the case of a spider-monkey (Ateles) in Nicaragua,
which was heard screaming for nearly two hours in the forest, and was found
with an eagle perched close by it. The bird apparently feared to attack as
long as it remained face to face; and Mr. Belt believes, from what he has
seen of the habits of these monkeys, that they protect themselves from
eagles by keeping two or three together. 'The Naturalist in Nicaragua,'
1874, p. 118.)
It is certain that associated animals have a feeling of love for each
other, which is not felt by non-social adult animals. How far in most
cases they actually sympathise in the pains and pleasures of others, is
more doubtful, especially with respect to pleasures. Mr. Buxton, however,
who had excellent means of observation (11. 'Annals and Magazine of
Natural History,' November 1868, p. 382.), states that his macaws, which
lived free in Norfolk, took "an extravagant interest" in a pair with a
nest; and whenever the female left it, she was surrounded by a troop
"screaming horrible acclamations in her honour." It is often difficult to
judge whether animals have any feeling for the sufferings of others of
their kind. Who can say what cows feel, when they surround and stare
intently on a dying or dead companion; apparently, however, as Houzeau
remarks, they feel no pity. That animals sometimes are far from feeling
any sympathy is too certain; for they will expel a wounded animal from the
herd, or gore or worry it to death. This is almost the blackest fact in
natural history, unless, indeed, the explanation which has been suggested
is true, that their instinct or reason leads them to expel an injured
companion, lest beasts of prey, including man, should be tempted to follow
the troop. In this case their conduct is not much worse than that of the
North American Indians, who leave their feeble comrades to perish on the
plains; or the Fijians, who, when their parents get old, or fall ill, bury
them alive. (12. Sir J. Lubbock, 'Prehistoric Times,' 2nd ed., p. 446.)
Many animals, however, certainly sympathise with each other's distress or
danger. This is the case even with birds. Captain Stansbury (13. As
quoted by Mr. L.H. Morgan, 'The American Beaver,' 1868, p. 272. Capt.
Stansbury also gives an interesting account of the manner in which a very
young pelican, carried away by a strong stream, was guided and encouraged
in its attempts to reach the shore by half a dozen old birds.) found on a
salt lake in Utah an old and completely blind pelican, which was very fat,
and must have been well fed for a long time by his companions. Mr. Blyth,
as he informs me, saw Indian crows feeding two or three of their companions
which were blind; and I have heard of an analogous case with the domestic
cock. We may, if we choose, call these actions instinctive; but such cases
are much too rare for the development of any special instinct. (14. As
Mr. Bain states, "effective aid to a sufferer springs from sympathy
proper:" 'Mental and Moral Science,' 1868, p. 245.) I have myself seen a
dog, who never passed a cat who lay sick in a basket, and was a great
friend of his, without giving her a few licks with his tongue, the surest
sign of kind feeling in a dog.
It must be called sympathy that leads a courageous dog to fly at any one
who strikes his master, as he certainly will. I saw a person pretending to
beat a lady, who had a very timid little dog on her lap, and the trial had
never been made before; the little creature instantly jumped away, but
after the pretended beating was over, it was really pathetic to see how
perseveringly he tried to lick his mistress's face, and comfort her. Brehm
(15. 'Thierleben,' B. i. s. 85.) states that when a baboon in confinement
was pursued to be punished, the others tried to protect him. It must have
been sympathy in the cases above given which led the baboons and
Cercopitheci to defend their young comrades from the dogs and the eagle. I
will give only one other instance of sympathetic and heroic conduct, in the
case of a little American monkey. Several years ago a keeper at the
Zoological Gardens shewed me some deep and scarcely healed wounds on the
nape of his own neck, inflicted on him, whilst kneeling on the floor, by a
fierce baboon. The little American monkey, who was a warm friend of this
keeper, lived in the same large compartment, and was dreadfully afraid of
the great baboon. Nevertheless, as soon as he saw his friend in peril, he
rushed to the rescue, and by screams and bites so distracted the baboon
that the man was able to escape, after, as the surgeon thought, running
great risk of his life.
Besides love and sympathy, animals exhibit other qualities connected with
the social instincts, which in us would be called moral; and I agree with
Agassiz (16. 'De l'Espece et de la Classe,' 1869, p. 97.) that dogs
possess something very like a conscience.
Dogs possess some power of self-command, and this does not appear to be
wholly the result of fear. As Braubach (17. 'Die Darwin'sche Art-Lehre,'
1869, s. 54.) remarks, they will refrain from stealing food in the absence
of their master. They have long been accepted as the very type of fidelity
and obedience. But the elephant is likewise very faithful to his driver or
keeper, and probably considers him as the leader of the herd. Dr. Hooker
informs me that an elephant, which he was riding in India, became so deeply
bogged that he remained stuck fast until the next day, when he was
extricated by men with ropes. Under such circumstances elephants will
seize with their trunks any object, dead or alive, to place under their
knees, to prevent their sinking deeper in the mud; and the driver was
dreadfully afraid lest the animal should have seized Dr. Hooker and crushed
him to death. But the driver himself, as Dr. Hooker was assured, ran no
risk. This forbearance under an emergency so dreadful for a heavy animal,
is a wonderful proof of noble fidelity. (18. See also Hooker's 'Himalayan
Journals,' vol. ii. 1854, p. 333.)
All animals living in a body, which defend themselves or attack their
enemies in concert, must indeed be in some degree faithful to one another;
and those that follow a leader must be in some degree obedient. When the
baboons in Abyssinia (19. Brehm, 'Thierleben,' B. i. s. 76.) plunder a
garden, they silently follow their leader; and if an imprudent young animal
makes a noise, he receives a slap from the others to teach him silence and
obedience. Mr. Galton, who has had excellent opportunities for observing
the half-wild cattle in S. Africa, says (20. See his extremely interesting
paper on 'Gregariousness in Cattle, and in Man,' 'Macmillan's Magazine,'
Feb. 1871, p. 353.), that they cannot endure even a momentary separation
from the herd. They are essentially slavish, and accept the common
determination, seeking no better lot than to be led by any one ox who has
enough self-reliance to accept the position. The men who break in these
animals for harness, watch assiduously for those who, by grazing apart,
shew a self-reliant disposition, and these they train as fore-oxen. Mr.
Galton adds that such animals are rare and valuable; and if many were born
they would soon be eliminated, as lions are always on the look-out for the
individuals which wander from the herd.
With respect to the impulse which leads certain animals to associate
together, and to aid one another in many ways, we may infer that in most
cases they are impelled by the same sense of satisfaction or pleasure which
they experience in performing other instinctive actions; or by the same
sense of dissatisfaction as when other instinctive actions are checked. We
see this in innumerable instances, and it is illustrated in a striking
manner by the acquired instincts of our domesticated animals; thus a young
shepherd-dog delights in driving and running round a flock of sheep, but
not in worrying them; a young fox-hound delights in hunting a fox, whilst
some other kinds of dogs, as I have witnessed, utterly disregard foxes.
What a strong feeling of inward satisfaction must impel a bird, so full of
activity, to brood day after day over her eggs. Migratory birds are quite
miserable if stopped from migrating; perhaps they enjoy starting on their
long flight; but it is hard to believe that the poor pinioned goose,
described by Audubon, which started on foot at the proper time for its
journey of probably more than a thousand miles, could have felt any joy in
doing so. Some instincts are determined solely by painful feelings, as by
fear, which leads to self-preservation, and is in some cases directed
towards special enemies. No one, I presume, can analyse the sensations of
pleasure or pain. In many instances, however, it is probable that
instincts are persistently followed from the mere force of inheritance,
without the stimulus of either pleasure or pain. A young pointer, when it
first scents game, apparently cannot help pointing. A squirrel in a cage
who pats the nuts which it cannot eat, as if to bury them in the ground,
can hardly be thought to act thus, either from pleasure or pain. Hence the
common assumption that men must be impelled to every action by experiencing
some pleasure or pain may be erroneous. Although a habit may be blindly
and implicitly followed, independently of any pleasure or pain felt at the
moment, yet if it be forcibly and abruptly checked, a vague sense of
dissatisfaction is generally experienced.
It has often been assumed that animals were in the first place rendered
social, and that they feel as a consequence uncomfortable when separated
from each other, and comfortable whilst together; but it is a more probable
view that these sensations were first developed, in order that those
animals which would profit by living in society, should be induced to live
together, in the same manner as the sense of hunger and the pleasure of
eating were, no doubt, first acquired in order to induce animals to eat.
The feeling of pleasure from society is probably an extension of the
parental or filial affections, since the social instinct seems to be
developed by the young remaining for a long time with their parents; and
this extension may be attributed in part to habit, but chiefly to natural
selection. With those animals which were benefited by living in close
association, the individuals which took the greatest pleasure in society
would best escape various dangers, whilst those that cared least for their
comrades, and lived solitary, would perish in greater numbers. With
respect to the origin of the parental and filial affections, which
apparently lie at the base of the social instincts, we know not the steps
by which they have been gained; but we may infer that it has been to a
large extent through natural selection. So it has almost certainly been
with the unusual and opposite feeling of hatred between the nearest
relations, as with the worker-bees which kill their brother drones, and
with the queen-bees which kill their daughter-queens; the desire to destroy
their nearest relations having been in this case of service to the
community. Parental affection, or some feeling which replaces it, has been
developed in certain animals extremely low in the scale, for example, in
star-fishes and spiders. It is also occasionally present in a few members
alone in a whole group of animals, as in the genus Forficula, or earwigs.
The all-important emotion of sympathy is distinct from that of love. A
mother may passionately love her sleeping and passive infant, but she can
hardly at such times be said to feel sympathy for it. The love of a man
for his dog is distinct from sympathy, and so is that of a dog for his
master. Adam Smith formerly argued, as has Mr. Bain recently, that the
basis of sympathy lies in our strong retentiveness of former states of pain
or pleasure. Hence, "the sight of another person enduring hunger, cold,
fatigue, revives in us some recollection of these states, which are painful
even in idea." We are thus impelled to relieve the sufferings of another,
in order that our own painful feelings may be at the same time relieved.
In like manner we are led to participate in the pleasures of others. (21.
See the first and striking chapter in Adam Smith's 'Theory of Moral
Sentiments.' Also 'Mr. Bain's Mental and Moral Science,' 1868, pp. 244,
and 275-282. Mr. Bain states, that, "sympathy is, indirectly, a source of
pleasure to the sympathiser"; and he accounts for this through reciprocity.
He remarks that "the person benefited, or others in his stead, may make up,
by sympathy and good offices returned, for all the sacrifice." But if, as
appears to be the case, sympathy is strictly an instinct, its exercise
would give direct pleasure, in the same manner as the exercise, as before
remarked, of almost every other instinct.) But I cannot see how this view
explains the fact that sympathy is excited, in an immeasurably stronger
degree, by a beloved, than by an indifferent person. The mere sight of
suffering, independently of love, would suffice to call up in us vivid
recollections and associations. The explanation may lie in the fact that,
with all animals, sympathy is directed solely towards the members of the
same community, and therefore towards known, and more or less beloved
members, but not to all the individuals of the same species. This fact is
not more surprising than that the fears of many animals should be directed
against special enemies. Species which are not social, such as lions and
tigers, no doubt feel sympathy for the suffering of their own young, but
not for that of any other animal. With mankind, selfishness, experience,
and imitation, probably add, as Mr. Bain has shewn, to the power of
sympathy; for we are led by the hope of receiving good in return to perform
acts of sympathetic kindness to others; and sympathy is much strengthened
by habit. In however complex a manner this feeling may have originated, as
it is one of high importance to all those animals which aid and defend one
another, it will have been increased through natural selection; for those
communities, which included the greatest number of the most sympathetic
members, would flourish best, and rear the greatest number of offspring.
It is, however, impossible to decide in many cases whether certain social
instincts have been acquired through natural selection, or are the indirect
result of other instincts and faculties, such as sympathy, reason,
experience, and a tendency to imitation; or again, whether they are simply
the result of long-continued habit. So remarkable an instinct as the
placing sentinels to warn the community of danger, can hardly have been the
indirect result of any of these faculties; it must, therefore, have been
directly acquired. On the other hand, the habit followed by the males of
some social animals of defending the community, and of attacking their
enemies or their prey in concert, may perhaps have originated from mutual
sympathy; but courage, and in most cases strength, must have been
previously acquired, probably through natural selection.
Of the various instincts and habits, some are much stronger than others;
that is, some either give more pleasure in their performance, and more
distress in their prevention, than others; or, which is probably quite as
important, they are, through inheritance, more persistently followed,
without exciting any special feeling of pleasure or pain. We are ourselves
conscious that some habits are much more difficult to cure or change than
others. Hence a struggle may often be observed in animals between
different instincts, or between an instinct and some habitual disposition;
as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues
again, or returns ashamed to his master; or as between the love of a female
dog for her young puppies and for her master,--for she may be seen to slink
away to them, as if half ashamed of not accompanying her master. But the
most curious instance known to me of one instinct getting the better of
another, is the migratory instinct conquering the maternal instinct. The
former is wonderfully strong; a confined bird will at the proper season
beat her breast against the wires of her cage, until it is bare and bloody.
It causes young salmon to leap out of the fresh water, in which they could
continue to exist, and thus unintentionally to commit suicide. Every one
knows how strong the maternal instinct is, leading even timid birds to face
great danger, though with hesitation, and in opposition to the instinct of
self-preservation. Nevertheless, the migratory instinct is so powerful,
that late in the autumn swallows, house-martins, and swifts frequently
desert their tender young, leaving them to perish miserably in their nests.
(22. This fact, the Rev. L. Jenyns states (see his edition of 'White's
Nat. Hist. of Selborne,' 1853, p. 204) was first recorded by the
illustrious Jenner, in 'Phil. Transact.' 1824, and has since been confirmed
by several observers, especially by Mr. Blackwall. This latter careful
observer examined, late in the autumn, during two years, thirty-six nests;
he found that twelve contained young dead birds, five contained eggs on the
point of being hatched, and three, eggs not nearly hatched. Many birds,
not yet old enough for a prolonged flight, are likewise deserted and left
behind. See Blackwall, 'Researches in Zoology,' 1834, pp. 108, 118. For
some additional evidence, although this is not wanted, see Leroy, 'Lettres
Phil.' 1802, p. 217. For Swifts, Gould's 'Introduction to the Birds of
Great Britain,' 1823, p. 5. Similar cases have been observed in Canada by
Mr. Adams; 'Pop. Science Review,' July 1873, p. 283.)
We can perceive that an instinctive impulse, if it be in any way more
beneficial to a species than some other or opposed instinct, would be
rendered the more potent of the two through natural selection; for the
individuals which had it most strongly developed would survive in larger
numbers. Whether this is the case with the migratory in comparison with
the maternal instinct, may be doubted. The great persistence, or steady
action of the former at certain seasons of the year during the whole day,
may give it for a time paramount force.
MAN A SOCIAL ANIMAL.
Every one will admit that man is a social being. We see this in his
dislike of solitude, and in his wish for society beyond that of his own
family. Solitary confinement is one of the severest punishments which can
be inflicted. Some authors suppose that man primevally lived in single
families; but at the present day, though single families, or only two or
three together, roam the solitudes of some savage lands, they always, as
far as I can discover, hold friendly relations with other families
inhabiting the same district. Such families occasionally meet in council,
and unite for their common defence. It is no argument against savage man
being a social animal, that the tribes inhabiting adjacent districts are
almost always at war with each other; for the social instincts never extend
to all the individuals of the same species. Judging from the analogy of
the majority of the Quadrumana, it is probable that the early ape-like
progenitors of man were likewise social; but this is not of much importance
for us. Although man, as he now exists, has few special instincts, having
lost any which his early progenitors may have possessed, this is no reason
why he should not have retained from an extremely remote period some degree
of instinctive love and sympathy for his fellows. We are indeed all
conscious that we do possess such sympathetic feelings (23. Hume remarks
('An Enquiry Concerning the Principles of Morals,' edit. of 1751, p. 132),
"There seems a necessity for confessing that the happiness and misery of
others are not spectacles altogether indifferent to us, but that the view
of the former...communicates a secret joy; the appearance of the latter...
throws a melancholy damp over the imagination."); but our consciousness
does not tell us whether they are instinctive, having originated long ago
in the same manner as with the lower animals, or whether they have been
acquired by each of us during our early years. As man is a social animal,
it is almost certain that he would inherit a tendency to be faithful to his
comrades, and obedient to the leader of his tribe; for these qualities are
common to most social animals. He would consequently possess some capacity
for self-command. He would from an inherited tendency be willing to
defend, in concert with others, his fellow-men; and would be ready to aid
them in any way, which did not too greatly interfere with his own welfare
or his own strong desires.
The social animals which stand at the bottom of the scale are guided almost
exclusively, and those which stand higher in the scale are largely guided,
by special instincts in the aid which they give to the members of the same
community; but they are likewise in part impelled by mutual love and
sympathy, assisted apparently by some amount of reason. Although man, as
just remarked, has no special instincts to tell him how to aid his fellow-
men, he still has the impulse, and with his improved intellectual faculties
would naturally be much guided in this respect by reason and experience.
Instinctive sympathy would also cause him to value highly the approbation
of his fellows; for, as Mr. Bain has clearly shewn (24. 'Mental and Moral
Science,' 1868, p. 254.), the love of praise and the strong feeling of
glory, and the still stronger horror of scorn and infamy, "are due to the
workings of sympathy." Consequently man would be influenced in the highest
degree by the wishes, approbation, and blame of his fellow-men, as
expressed by their gestures and language. Thus the social instincts, which
must have been acquired by man in a very rude state, and probably even by
his early ape-like progenitors, still give the impulse to some of his best
actions; but his actions are in a higher degree determined by the expressed
wishes and judgment of his fellow-men, and unfortunately very often by his
own strong selfish desires. But as love, sympathy and self-command become
strengthened by habit, and as the power of reasoning becomes clearer, so
that man can value justly the judgments of his fellows, he will feel
himself impelled, apart from any transitory pleasure or pain, to certain
lines of conduct. He might then declare--not that any barbarian or
uncultivated man could thus think--I am the supreme judge of my own
conduct, and in the words of Kant, I will not in my own person violate the
dignity of humanity.
THE MORE ENDURING SOCIAL INSTINCTS CONQUER THE LESS PERSISTENT INSTINCTS.
We have not, however, as yet considered the main point, on which, from our
present point of view, the whole question of the moral sense turns. Why
should a man feel that he ought to obey one instinctive desire rather than
another? Why is he bitterly regretful, if he has yielded to a strong sense
of self-preservation, and has not risked his life to save that of a fellow-
creature? or why does he regret having stolen food from hunger?
It is evident in the first place, that with mankind the instinctive
impulses have different degrees of strength; a savage will risk his own
life to save that of a member of the same community, but will be wholly
indifferent about a stranger: a young and timid mother urged by the
maternal instinct will, without a moment's hesitation, run the greatest
danger for her own infant, but not for a mere fellow-creature.
Nevertheless many a civilised man, or even boy, who never before risked his
life for another, but full of courage and sympathy, has disregarded the
instinct of self-preservation, and plunged at once into a torrent to save a
drowning man, though a stranger. In this case man is impelled by the same
instinctive motive, which made the heroic little American monkey, formerly
described, save his keeper, by attacking the great and dreaded baboon.
Such actions as the above appear to be the simple result of the greater
strength of the social or maternal instincts rather than that of any other
instinct or motive; for they are performed too instantaneously for
reflection, or for pleasure or pain to be felt at the time; though, if
prevented by any cause, distress or even misery might be felt. In a timid
man, on the other hand, the instinct of self-preservation might be so
strong, that he would be unable to force himself to run any such risk,
perhaps not even for his own child.
I am aware that some persons maintain that actions performed impulsively,
as in the above cases, do not come under the dominion of the moral sense,
and cannot be called moral. They confine this term to actions done
deliberately, after a victory over opposing desires, or when prompted by
some exalted motive. But it appears scarcely possible to draw any clear
line of distinction of this kind. (25. I refer here to the distinction
between what has been called MATERIAL and FORMAL morality. I am glad to
find that Professor Huxley ('Critiques and Addresses,' 1873, p. 287) takes
the same view on this subject as I do. Mr. Leslie Stephen remarks ('Essays
on Freethinking and Plain Speaking,' 1873, p. 83), "the metaphysical
distinction, between material and formal morality is as irrelevant as other
such distinctions.") As far as exalted motives are concerned, many
instances have been recorded of savages, destitute of any feeling of
general benevolence towards mankind, and not guided by any religious
motive, who have deliberately sacrificed their lives as prisoners(26. I
have given one such case, namely of three Patagonian Indians who preferred
being shot, one after the other, to betraying the plans of their companions
in war ('Journal of Researches,' 1845, p. 103).), rather than betray their
comrades; and surely their conduct ought to be considered as moral. As far
as deliberation, and the victory over opposing motives are concerned,
animals may be seen doubting between opposed instincts, in rescuing their
offspring or comrades from danger; yet their actions, though done for the
good of others, are not called moral. Moreover, anything performed very
often by us, will at last be done without deliberation or hesitation, and
can then hardly be distinguished from an instinct; yet surely no one will
pretend that such an action ceases to be moral. On the contrary, we all
feel that an act cannot be considered as perfect, or as performed in the
most noble manner, unless it be done impulsively, without deliberation or
effort, in the same manner as by a man in whom the requisite qualities are
innate. He who is forced to overcome his fear or want of sympathy before
he acts, deserves, however, in one way higher credit than the man whose
innate disposition leads him to a good act without effort. As we cannot
distinguish between motives, we rank all actions of a certain class as
moral, if performed by a moral being. A moral being is one who is capable
of comparing his past and future actions or motives, and of approving or
disapproving of them. We have no reason to suppose that any of the lower
animals have this capacity; therefore, when a Newfoundland dog drags a
child out of the water, or a monkey faces danger to rescue its comrade, or
takes charge of an orphan monkey, we do not call its conduct moral. But in
the case of man, who alone can with certainty be ranked as a moral being,
actions of a certain class are called moral, whether performed
deliberately, after a struggle with opposing motives, or impulsively
through instinct, or from the effects of slowly-gained habit.
But to return to our more immediate subject. Although some instincts are
more powerful than others, and thus lead to corresponding actions, yet it
is untenable, that in man the social instincts (including the love of
praise and fear of blame) possess greater strength, or have, through long
habit, acquired greater strength than the instincts of self-preservation,
hunger, lust, vengeance, etc. Why then does man regret, even though trying
to banish such regret, that he has followed the one natural impulse rather
than the other; and why does he further feel that he ought to regret his
conduct? Man in this respect differs profoundly from the lower animals.
Nevertheless we can, I think, see with some degree of clearness the reason
of this difference.
Man, from the activity of his mental faculties, cannot avoid reflection:
past impressions and images are incessantly and clearly passing through his
mind. Now with those animals which live permanently in a body, the social
instincts are ever present and persistent. Such animals are always ready
to utter the danger-signal, to defend the community, and to give aid to
their fellows in accordance with their habits; they feel at all times,
without the stimulus of any special passion or desire, some degree of love
and sympathy for them; they are unhappy if long separated from them, and
always happy to be again in their company. So it is with ourselves. Even
when we are quite alone, how often do we think with pleasure or pain of
what others think of us,--of their imagined approbation or disapprobation;
and this all follows from sympathy, a fundamental element of the social
instincts. A man who possessed no trace of such instincts would be an
unnatural monster. On the other hand, the desire to satisfy hunger, or any
passion such as vengeance, is in its nature temporary, and can for a time
be fully satisfied. Nor is it easy, perhaps hardly possible, to call up
with complete vividness the feeling, for instance, of hunger; nor indeed,
as has often been remarked, of any suffering. The instinct of self-
preservation is not felt except in the presence of danger; and many a
coward has thought himself brave until he has met his enemy face to face.
The wish for another man's property is perhaps as persistent a desire as
any that can be named; but even in this case the satisfaction of actual
possession is generally a weaker feeling than the desire: many a thief, if
not a habitual one, after success has wondered why he stole some article.
(27. Enmity or hatred seems also to be a highly persistent feeling, perhaps
more so than any other that can be named. Envy is defined as hatred of
another for some excellence or success; and Bacon insists (Essay ix.), "Of
all other affections envy is the most importune and continual." Dogs are
very apt to hate both strange men and strange dogs, especially if they live
near at hand, but do not belong to the same family, tribe, or clan; this
feeling would thus seem to be innate, and is certainly a most persistent
one. It seems to be the complement and converse of the true social
instinct. From what we hear of savages, it would appear that something of
the same kind holds good with them. If this be so, it would be a small
step in any one to transfer such feelings to any member of the same tribe
if he had done him an injury and had become his enemy. Nor is it probable
that the primitive conscience would reproach a man for injuring his enemy;
rather it would reproach him, if he had not revenged himself. To do good
in return for evil, to love your enemy, is a height of morality to which it
may be doubted whether the social instincts would, by themselves, have ever
led us. It is necessary that these instincts, together with sympathy,
should have been highly cultivated and extended by the aid of reason,
instruction, and the love or fear of God, before any such golden rule would
ever be thought of and obeyed.)
A man cannot prevent past impressions often repassing through his mind; he
will thus be driven to make a comparison between the impressions of past
hunger, vengeance satisfied, or danger shunned at other men's cost, with
the almost ever-present instinct of sympathy, and with his early knowledge
of what others consider as praiseworthy or blameable. This knowledge
cannot be banished from his mind, and from instinctive sympathy is esteemed
of great moment. He will then feel as if he had been baulked in following
a present instinct or habit, and this with all animals causes
dissatisfaction, or even misery.
The above case of the swallow affords an illustration, though of a reversed
nature, of a temporary though for the time strongly persistent instinct
conquering another instinct, which is usually dominant over all others. At
the proper season these birds seem all day long to be impressed with the
desire to migrate; their habits change; they become restless, are noisy and
congregate in flocks. Whilst the mother-bird is feeding, or brooding over
her nestlings, the maternal instinct is probably stronger than the
migratory; but the instinct which is the more persistent gains the victory,
and at last, at a moment when her young ones are not in sight, she takes
flight and deserts them. When arrived at the end of her long journey, and
the migratory instinct has ceased to act, what an agony of remorse the bird
would feel, if, from being endowed with great mental activity, she could
not prevent the image constantly passing through her mind, of her young
ones perishing in the bleak north from cold and hunger.
At the moment of action, man will no doubt be apt to follow the stronger
impulse; and though this may occasionally prompt him to the noblest deeds,
it will more commonly lead him to gratify his own desires at the expense of
other men. But after their gratification when past and weaker impressions
are judged by the ever-enduring social instinct, and by his deep regard for
the good opinion of his fellows, retribution will surely come. He will
then feel remorse, repentance, regret, or shame; this latter feeling,
however, relates almost exclusively to the judgment of others. He will
consequently resolve more or less firmly to act differently for the future;
and this is conscience; for conscience looks backwards, and serves as a
guide for the future.
The nature and strength of the feelings which we call regret, shame,
repentance or remorse, depend apparently not only on the strength of the
violated instinct, but partly on the strength of the temptation, and often
still more on the judgment of our fellows. How far each man values the
appreciation of others, depends on the strength of his innate or acquired
feeling of sympathy; and on his own capacity for reasoning out the remote
consequences of his acts. Another element is most important, although not
necessary, the reverence or fear of the Gods, or Spirits believed in by
each man: and this applies especially in cases of remorse. Several
critics have objected that though some slight regret or repentance may be
explained by the view advocated in this chapter, it is impossible thus to
account for the soul-shaking feeling of remorse. But I can see little
force in this objection. My critics do not define what they mean by
remorse, and I can find no definition implying more than an overwhelming
sense of repentance. Remorse seems to bear the same relation to
repentance, as rage does to anger, or agony to pain. It is far from
strange that an instinct so strong and so generally admired, as maternal
love, should, if disobeyed, lead to the deepest misery, as soon as the
impression of the past cause of disobedience is weakened. Even when an
action is opposed to no special instinct, merely to know that our friends
and equals despise us for it is enough to cause great misery. Who can
doubt that the refusal to fight a duel through fear has caused many men an
agony of shame? Many a Hindoo, it is said, has been stirred to the bottom
of his soul by having partaken of unclean food. Here is another case of
what must, I think, be called remorse. Dr. Landor acted as a magistrate in
West Australia, and relates (28. 'Insanity in Relation to Law,' Ontario,
United States, 1871, p. 1.), that a native on his farm, after losing one of
his wives from disease, came and said that, "he was going to a distant
tribe to spear a woman, to satisfy his sense of duty to his wife. I told
him that if he did so, I would send him to prison for life. He remained
about the farm for some months, but got exceedingly thin, and complained
that he could not rest or eat, that his wife's spirit was haunting him,
because he had not taken a life for hers. I was inexorable, and assured
him that nothing should save him if he did." Nevertheless the man
disappeared for more than a year, and then returned in high condition; and
his other wife told Dr. Landor that her husband had taken the life of a
woman belonging to a distant tribe; but it was impossible to obtain legal
evidence of the act. The breach of a rule held sacred by the tribe, will
thus, as it seems, give rise to the deepest feelings,--and this quite apart
from the social instincts, excepting in so far as the rule is grounded on
the judgment of the community. How so many strange superstitions have
arisen throughout the world we know not; nor can we tell how some real and
great crimes, such as incest, have come to be held in an abhorrence (which
is not however quite universal) by the lowest savages. It is even doubtful
whether in some tribes incest would be looked on with greater horror, than
would the marriage of a man with a woman bearing the same name, though not
a relation. "To violate this law is a crime which the Australians hold in
the greatest abhorrence, in this agreeing exactly with certain tribes of
North America. When the question is put in either district, is it worse to
kill a girl of a foreign tribe, or to marry a girl of one's own, an answer
just opposite to ours would be given without hesitation." (29. E.B.
Tylor, in 'Contemporary Review,' April 1873, p. 707.) We may, therefore,
reject the belief, lately insisted on by some writers, that the abhorrence
of incest is due to our possessing a special God-implanted conscience. On
the whole it is intelligible, that a man urged by so powerful a sentiment
as remorse, though arising as above explained, should be led to act in a
manner, which he has been taught to believe serves as an expiation, such as
delivering himself up to justice.
Man prompted by his conscience, will through long habit acquire such
perfect self-command, that his desires and passions will at last yield
instantly and without a struggle to his social sympathies and instincts,
including his feeling for the judgment of his fellows. The still hungry,
or the still revengeful man will not think of stealing food, or of wreaking
his vengeance. It is possible, or as we shall hereafter see, even
probable, that the habit of self-command may, like other habits, be
inherited. Thus at last man comes to feel, through acquired and perhaps
inherited habit, that it is best for him to obey his more persistent
impulses. The imperious word "ought" seems merely to imply the
consciousness of the existence of a rule of conduct, however it may have
originated. Formerly it must have been often vehemently urged that an
insulted gentleman OUGHT to fight a duel. We even say that a pointer OUGHT
to point, and a retriever to retrieve game. If they fail to do so, they
fail in their duty and act wrongly.
If any desire or instinct leading to an action opposed to the good of
others still appears, when recalled to mind, as strong as, or stronger
than, the social instinct, a man will feel no keen regret at having
followed it; but he will be conscious that if his conduct were known to his
fellows, it would meet with their disapprobation; and few are so destitute
of sympathy as not to feel discomfort when this is realised. If he has no
such sympathy, and if his desires leading to bad actions are at the time
strong, and when recalled are not over-mastered by the persistent social
instincts, and the judgment of others, then he is essentially a bad man
(30. Dr. Prosper Despine, in his Psychologie Naturelle, 1868 (tom. i. p.
243; tom. ii. p. 169) gives many curious cases of the worst criminals, who
apparently have been entirely destitute of conscience.); and the sole
restraining motive left is the fear of punishment, and the conviction that
in the long run it would be best for his own selfish interests to regard
the good of others rather than his own.
It is obvious that every one may with an easy conscience gratify his own
desires, if they do not interfere with his social instincts, that is with
the good of others; but in order to be quite free from self-reproach, or at
least of anxiety, it is almost necessary for him to avoid the
disapprobation, whether reasonable or not, of his fellow-men. Nor must he
break through the fixed habits of his life, especially if these are
supported by reason; for if he does, he will assuredly feel
dissatisfaction. He must likewise avoid the reprobation of the one God or
gods in whom, according to his knowledge or superstition, he may believe;
but in this case the additional fear of divine punishment often supervenes.
THE STRICTLY SOCIAL VIRTUES AT FIRST ALONE REGARDED.
The above view of the origin and nature of the moral sense, which tells us
what we ought to do, and of the conscience which reproves us if we disobey
it, accords well with what we see of the early and undeveloped condition of
this faculty in mankind. The virtues which must be practised, at least
generally, by rude men, so that they may associate in a body, are those
which are still recognised as the most important. But they are practised
almost exclusively in relation to the men of the same tribe; and their
opposites are not regarded as crimes in relation to the men of other
tribes. No tribe could hold together if murder, robbery, treachery, etc.,
were common; consequently such crimes within the limits of the same tribe
"are branded with everlasting infamy" (31. See an able article in the
'North British Review,' 1867, p. 395. See also Mr. W. Bagehot's articles
on the Importance of Obedience and Coherence to Primitive Man, in the
'Fortnightly Review,' 1867, p. 529, and 1868, p. 457, etc.); but excite no
such sentiment beyond these limits. A North-American Indian is well
pleased with himself, and is honoured by others, when he scalps a man of
another tribe; and a Dyak cuts off the head of an unoffending person, and
dries it as a trophy. The murder of infants has prevailed on the largest
scale throughout the world (32. The fullest account which I have met with
is by Dr. Gerland, in his 'Ueber den Aussterben der Naturvolker,' 1868; but
I shall have to recur to the subject of infanticide in a future chapter.),
and has met with no reproach; but infanticide, especially of females, has
been thought to be good for the tribe, or at least not injurious. Suicide
during former times was not generally considered as a crime (33. See the
very interesting discussion on suicide in Lecky's 'History of European
Morals,' vol. i. 1869, p. 223. With respect to savages, Mr. Winwood Reade
informs me that the negroes of West Africa often commit suicide. It is
well known how common it was amongst the miserable aborigines of South
America after the Spanish conquest. For New Zealand, see the voyage of the
"Novara," and for the Aleutian Islands, Muller, as quoted by Houzeau, 'Les
Facultes Mentales,' etc., tom. ii. p. 136.), but rather, from the courage
displayed, as an honourable act; and it is still practised by some semi-
civilised and savage nations without reproach, for it does not obviously
concern others of the tribe. It has been recorded that an Indian Thug
conscientiously regretted that he had not robbed and strangled as many
travellers as did his father before him. In a rude state of civilisation
the robbery of strangers is, indeed, generally considered as honourable.
Slavery, although in some ways beneficial during ancient times (34. See
Mr. Bagehot, 'Physics and Politics,' 1872, p. 72.), is a great crime; yet
it was not so regarded until quite recently, even by the most civilised
nations. And this was especially the case, because the slaves belonged in
general to a race different from that of their masters. As barbarians do
not regard the opinion of their women, wives are commonly treated like
slaves. Most savages are utterly indifferent to the sufferings of
strangers, or even delight in witnessing them. It is well known that the
women and children of the North-American Indians aided in torturing their
enemies. Some savages take a horrid pleasure in cruelty to animals (35.
See, for instance, Mr. Hamilton's account of the Kaffirs, 'Anthropological
Review,' 1870, p. xv.), and humanity is an unknown virtue. Nevertheless,
besides the family affections, kindness is common, especially during
sickness, between the members of the same tribe, and is sometimes extended
beyond these limits. Mungo Park's touching account of the kindness of the
negro women of the interior to him is well known. Many instances could be
given of the noble fidelity of savages towards each other, but not to
strangers; common experience justifies the maxim of the Spaniard, "Never,
never trust an Indian." There cannot be fidelity without truth; and this
fundamental virtue is not rare between the members of the same tribe: thus
Mungo Park heard the negro women teaching their young children to love the
truth. This, again, is one of the virtues which becomes so deeply rooted
in the mind, that it is sometimes practised by savages, even at a high
cost, towards strangers; but to lie to your enemy has rarely been thought a
sin, as the history of modern diplomacy too plainly shews. As soon as a
tribe has a recognised leader, disobedience becomes a crime, and even
abject submission is looked at as a sacred virtue.
As during rude times no man can be useful or faithful to his tribe without
courage, this quality has universally been placed in the highest rank; and
although in civilised countries a good yet timid man may be far more useful
to the community than a brave one, we cannot help instinctively honouring
the latter above a coward, however benevolent. Prudence, on the other
hand, which does not concern the welfare of others, though a very useful
virtue, has never been highly esteemed. As no man can practise the virtues
necessary for the welfare of his tribe without self-sacrifice, self-
command, and the power of endurance, these qualities have been at all times
highly and most justly valued. The American savage voluntarily submits to
the most horrid tortures without a groan, to prove and strengthen his
fortitude and courage; and we cannot help admiring him, or even an Indian
Fakir, who, from a foolish religious motive, swings suspended by a hook
buried in his flesh.
The other so-called self-regarding virtues, which do not obviously, though
they may really, affect the welfare of the tribe, have never been esteemed
by savages, though now highly appreciated by civilised nations. The
greatest intemperance is no reproach with savages. Utter licentiousness,
and unnatural crimes, prevail to an astounding extent. (36. Mr. M'Lennan
has given ('Primitive Marriage,' 1865, p. 176) a good collection of facts
on this head.) As soon, however, as marriage, whether polygamous, or
monogamous, becomes common, jealousy will lead to the inculcation of female
virtue; and this, being honoured, will tend to spread to the unmarried
females. How slowly it spreads to the male sex, we see at the present day.
Chastity eminently requires self-command; therefore it has been honoured
from a very early period in the moral history of civilised man. As a
consequence of this, the senseless practice of celibacy has been ranked
from a remote period as a virtue. (38. Lecky, 'History of European
Morals,' vol. i. 1869, p. 109.) The hatred of indecency, which appears to
us so natural as to be thought innate, and which is so valuable an aid to
chastity, is a modern virtue, appertaining exclusively, as Sir G. Staunton
remarks (38. 'Embassy to China,' vol. ii. p. 348.), to civilised life.
This is shewn by the ancient religious rites of various nations, by the
drawings on the walls of Pompeii, and by the practices of many savages.
We have now seen that actions are regarded by savages, and were probably so
regarded by primeval man, as good or bad, solely as they obviously affect
the welfare of the tribe,--not that of the species, nor that of an
individual member of the tribe. This conclusion agrees well with the
belief that the so-called moral sense is aboriginally derived from the
social instincts, for both relate at first exclusively to the community.
The chief causes of the low morality of savages, as judged by our standard,
are, firstly, the confinement of sympathy to the same tribe. Secondly,
powers of reasoning insufficient to recognise the bearing of many virtues,
especially of the self-regarding virtues, on the general welfare of the
tribe. Savages, for instance, fail to trace the multiplied evils
consequent on a want of temperance, chastity, etc. And, thirdly, weak
power of self-command; for this power has not been strengthened through
long-continued, perhaps inherited, habit, instruction and religion.
I have entered into the above details on the immorality of savages (39.
See on this subject copious evidence in Chap. vii. of Sir J. Lubbock,
'Origin of Civilisation,' 1870.), because some authors have recently taken
a high view of their moral nature, or have attributed most of their crimes
to mistaken benevolence. (40. For instance Lecky, 'History of European
Morals,' vol. i. p. 124.) These authors appear to rest their conclusion on
savages possessing those virtues which are serviceable, or even necessary,
for the existence of the family and of the tribe,--qualities which they
undoubtedly do possess, and often in a high degree.
CONCLUDING REMARKS.
It was assumed formerly by philosophers of the derivative (41. This term
is used in an able article in the 'Westminster Review,' Oct. 1869, p. 498.
For the "Greatest happiness principle," see J.S. Mill, 'Utilitarianism,' p.
17.) school of morals that the foundation of morality lay in a form of
Selfishness; but more recently the "Greatest happiness principle" has been
brought prominently forward. It is, however, more correct to speak of the
latter principle as the standard, and not as the motive of conduct.
Nevertheless, all the authors whose works I have consulted, with a few
exceptions (42. Mill recognises ('System of Logic,' vol. ii. p. 422) in
the clearest manner, that actions may be performed through habit without
the anticipation of pleasure. Mr. H. Sidgwick also, in his Essay on
Pleasure and Desire ('The Contemporary Review,' April 1872, p. 671),
remarks: "To sum up, in contravention of the doctrine that our conscious
active impulses are always directed towards the production of agreeable
sensations in ourselves, I would maintain that we find everywhere in
consciousness extra-regarding impulse, directed towards something that is
not pleasure; that in many cases the impulse is so far incompatible with
the self-regarding that the two do not easily co-exist in the same moment
of consciousness." A dim feeling that our impulses do not by any means
always arise from any contemporaneous or anticipated pleasure, has, I
cannot but think, been one chief cause of the acceptance of the intuitive
theory of morality, and of the rejection of the utilitarian or "Greatest
happiness" theory. With respect to the latter theory the standard and the
motive of conduct have no doubt often been confused, but they are really in
some degree blended.), write as if there must be a distinct motive for
every action, and that this must be associated with some pleasure or
displeasure. But man seems often to act impulsively, that is from instinct
or long habit, without any consciousness of pleasure, in the same manner as
does probably a bee or ant, when it blindly follows its instincts. Under
circumstances of extreme peril, as during a fire, when a man endeavours to
save a fellow-creature without a moment's hesitation, he can hardly feel
pleasure; and still less has he time to reflect on the dissatisfaction
which he might subsequently experience if he did not make the attempt.
Should he afterwards reflect over his own conduct, he would feel that there
lies within him an impulsive power widely different from a search after
pleasure or happiness; and this seems to be the deeply planted social
instinct.
In the case of the lower animals it seems much more appropriate to speak of
their social instincts, as having been developed for the general good
rather than for the general happiness of the species. The term, general
good, may be defined as the rearing of the greatest number of individuals
in full vigour and health, with all their faculties perfect, under the
conditions to which they are subjected. As the social instincts both of
man and the lower animals have no doubt been developed by nearly the same
steps, it would be advisable, if found practicable, to use the same
definition in both cases, and to take as the standard of morality, the
general good or welfare of the community, rather than the general
happiness; but this definition would perhaps require some limitation on
account of political ethics.
When a man risks his life to save that of a fellow-creature, it seems also
more correct to say that he acts for the general good, rather than for the
general happiness of mankind. No doubt the welfare and the happiness of
the individual usually coincide; and a contented, happy tribe will flourish
better than one that is discontented and unhappy. We have seen that even
at an early period in the history of man, the expressed wishes of the
community will have naturally influenced to a large extent the conduct of
each member; and as all wish for happiness, the "greatest happiness
principle" will have become a most important secondary guide and object;
the social instinct, however, together with sympathy (which leads to our
regarding the approbation and disapprobation of others), having served as
the primary impulse and guide. Thus the reproach is removed of laying the
foundation of the noblest part of our nature in the base principle of
selfishness; unless, indeed, the satisfaction which every animal feels,
when it follows its proper instincts, and the dissatisfaction felt when
prevented, be called selfish.
The wishes and opinions of the members of the same community, expressed at
first orally, but later by writing also, either form the sole guides of our
conduct, or greatly reinforce the social instincts; such opinions, however,
have sometimes a tendency directly opposed to these instincts. This latter
fact is well exemplified by the LAW OF HONOUR, that is, the law of the
opinion of our equals, and not of all our countrymen. The breach of this
law, even when the breach is known to be strictly accordant with true
morality, has caused many a man more agony than a real crime. We recognise
the same influence in the burning sense of shame which most of us have
felt, even after the interval of years, when calling to mind some
accidental breach of a trifling, though fixed, rule of etiquette. The
judgment of the community will generally be guided by some rude experience
of what is best in the long run for all the members; but this judgment will
not rarely err from ignorance and weak powers of reasoning. Hence the
strangest customs and superstitions, in complete opposition to the true
welfare and happiness of mankind, have become all-powerful throughout the
world. We see this in the horror felt by a Hindoo who breaks his caste,
and in many other such cases. It would be difficult to distinguish between
the remorse felt by a Hindoo who has yielded to the temptation of eating
unclean food, from that felt after committing a theft; but the former would
probably be the more severe.
How so many absurd rules of conduct, as well as so many absurd religious
beliefs, have originated, we do not know; nor how it is that they have
become, in all quarters of the world, so deeply impressed on the mind of
men; but it is worthy of remark that a belief constantly inculcated during
the early years of life, whilst the brain is impressible, appears to
acquire almost the nature of an instinct; and the very essence of an
instinct is that it is followed independently of reason. Neither can we
say why certain admirable virtues, such as the love of truth, are much more
highly appreciated by some savage tribes than by others (43. Good
instances are given by Mr. Wallace in 'Scientific Opinion,' Sept. 15, 1869;
and more fully in his 'Contributions to the Theory of Natural Selection,'
1870, p. 353.); nor, again, why similar differences prevail even amongst
highly civilised nations. Knowing how firmly fixed many strange customs
and superstitions have become, we need feel no surprise that the self-
regarding virtues, supported as they are by reason, should now appear to us
so natural as to be thought innate, although they were not valued by man in
his early condition.
Not withstanding many sources of doubt, man can generally and readily
distinguish between the higher and lower moral rules. The higher are
founded on the social instincts, and relate to the welfare of others. They
are supported by the approbation of our fellow-men and by reason. The
lower rules, though some of them when implying self-sacrifice hardly
deserve to be called lower, relate chiefly to self, and arise from public
opinion, matured by experience and cultivation; for they are not practised
by rude tribes.
As man advances in civilisation, and small tribes are united into larger
communities, the simplest reason would tell each individual that he ought
to extend his social instincts and sympathies to all the members of the
same nation, though personally unknown to him. This point being once
reached, there is only an artificial barrier to prevent his sympathies
extending to the men of all nations and races. If, indeed, such men are
separated from him by great differences in appearance or habits, experience
unfortunately shews us how long it is, before we look at them as our
fellow-creatures. Sympathy beyond the confines of man, that is, humanity
to the lower animals, seems to be one of the latest moral acquisitions. It
is apparently unfelt by savages, except towards their pets. How little the
old Romans knew of it is shewn by their abhorrent gladiatorial exhibitions.
The very idea of humanity, as far as I could observe, was new to most of
the Gauchos of the Pampas. This virtue, one of the noblest with which man
is endowed, seems to arise incidentally from our sympathies becoming more
tender and more widely diffused, until they are extended to all sentient
beings. As soon as this virtue is honoured and practised by some few men,
it spreads through instruction and example to the young, and eventually
becomes incorporated in public opinion.
The highest possible stage in moral culture is when we recognise that we
ought to control our thoughts, and "not even in inmost thought to think
again the sins that made the past so pleasant to us." (44. Tennyson,
Idylls of the King, p. 244.) Whatever makes any bad action familiar to the
mind, renders its performance by so much the easier. As Marcus Aurelius
long ago said, "Such as are thy habitual thoughts, such also will be the
character of thy mind; for the soul is dyed by the thoughts." (45. 'The
Thoughts of the Emperor M. Aurelius Antoninus,' English translation, 2nd
edit., 1869. p. 112. Marcus Aurelius ws born A.D. 121.)
Our great philosopher, Herbert Spencer, has recently explained his views on
the moral sense. He says (46. Letter to Mr. Mill in Bain's 'Mental and
Moral Science,' 1868, p. 722.), "I believe that the experiences of utility
organised and consolidated through all past generations of the human race,
have been producing corresponding modifications, which, by continued
transmission and accumulation, have become in us certain faculties of moral
intuition--certain emotions responding to right and wrong conduct, which
have no apparent basis in the individual experiences of utility." There is
not the least inherent improbability, as it seems to me, in virtuous
tendencies being more or less strongly inherited; for, not to mention the
various dispositions and habits transmitted by many of our domestic animals
to their offspring, I have heard of authentic cases in which a desire to
steal and a tendency to lie appeared to run in families of the upper ranks;
and as stealing is a rare crime in the wealthy classes, we can hardly
account by accidental coincidence for the tendency occurring in two or
three members of the same family. If bad tendencies are transmitted, it is
probable that good ones are likewise transmitted. That the state of the
body by affecting the brain, has great influence on the moral tendencies is
known to most of those who have suffered from chronic derangements of the
digestion or liver. The same fact is likewise shewn by the "perversion or
destruction of the moral sense being often one of the earliest symptoms of
mental derangement" (47. Maudsley, 'Body and Mind,' 1870, p. 60.); and
insanity is notoriously often inherited. Except through the principle of
the transmission of moral tendencies, we cannot understand the differences
believed to exist in this respect between the various races of mankind.
Even the partial transmission of virtuous tendencies would be an immense
assistance to the primary impulse derived directly and indirectly from the
social instincts. Admitting for a moment that virtuous tendencies are
inherited, it appears probable, at least in such cases as chastity,
temperance, humanity to animals, etc., that they become first impressed on
the mental organization through habit, instruction and example, continued
during several generations in the same family, and in a quite subordinate
degree, or not at all, by the individuals possessing such virtues having
succeeded best in the struggle for life. My chief source of doubt with
respect to any such inheritance, is that senseless customs, superstitions,
and tastes, such as the horror of a Hindoo for unclean food, ought on the
same principle to be transmitted. I have not met with any evidence in
support of the transmission of superstitious customs or senseless habits,
although in itself it is perhaps not less probable than that animals should
acquire inherited tastes for certain kinds of food or fear of certain foes.
Finally the social instincts, which no doubt were acquired by man as by the
lower animals for the good of the community, will from the first have given
to him some wish to aid his fellows, some feeling of sympathy, and have
compelled him to regard their approbation and disapprobation. Such
impulses will have served him at a very early period as a rude rule of
right and wrong. But as man gradually advanced in intellectual power, and
was enabled to trace the more remote consequences of his actions; as he
acquired sufficient knowledge to reject baneful customs and superstitions;
as he regarded more and more, not only the welfare, but the happiness of
his fellow-men; as from habit, following on beneficial experience,
instruction and example, his sympathies became more tender and widely
diffused, extending to men of all races, to the imbecile, maimed, and other
useless members of society, and finally to the lower animals,--so would the
standard of his morality rise higher and higher. And it is admitted by
moralists of the derivative school and by some intuitionists, that the
standard of morality has risen since an early period in the history of man.
(48. A writer in the 'North British Review' (July 1869, p. 531), well
capable of forming a sound judgment, expresses himself strongly in favour
of this conclusion. Mr. Lecky ('History of Morals,' vol. i. p. 143) seems
to a certain extent to coincide therein.)
As a struggle may sometimes be seen going on between the various instincts
of the lower animals, it is not surprising that there should be a struggle
in man between his social instincts, with their derived virtues, and his
lower, though momentarily stronger impulses or desires. This, as Mr.
Galton (49. See his remarkable work on 'Hereditary Genius,' 1869, p. 349.
The Duke of Argyll ('Primeval Man,' 1869, p. 188) has some good remarks on
the contest in man's nature between right and wrong.) has remarked, is all
the less surprising, as man has emerged from a state of barbarism within a
comparatively recent period. After having yielded to some temptation we
feel a sense of dissatisfaction, shame, repentance, or remorse, analogous
to the feelings caused by other powerful instincts or desires, when left
unsatisfied or baulked. We compare the weakened impression of a past
temptation with the ever present social instincts, or with habits, gained
in early youth and strengthened during our whole lives, until they have
become almost as strong as instincts. If with the temptation still before
us we do not yield, it is because either the social instinct or some custom
is at the moment predominant, or because we have learnt that it will appear
to us hereafter the stronger, when compared with the weakened impression of
the temptation, and we realise that its violation would cause us suffering.
Looking to future generations, there is no cause to fear that the social
instincts will grow weaker, and we may expect that virtuous habits will
grow stronger, becoming perhaps fixed by inheritance. In this case the
struggle between our higher and lower impulses will be less severe, and
virtue will be triumphant.
SUMMARY OF THE LAST TWO CHAPTERS.
There can be no doubt that the difference between the mind of the lowest
man and that of the highest animal is immense. An anthropomorphous ape, if
he could take a dispassionate view of his own case, would admit that though
he could form an artful plan to plunder a garden--though he could use
stones for fighting or for breaking open nuts, yet that the thought of
fashioning a stone into a tool was quite beyond his scope. Still less, as
he would admit, could he follow out a train of metaphysical reasoning, or
solve a mathematical problem, or reflect on God, or admire a grand natural
scene. Some apes, however, would probably declare that they could and did
admire the beauty of the coloured skin and fur of their partners in
marriage. They would admit, that though they could make other apes
understand by cries some of their perceptions and simpler wants, the notion
of expressing definite ideas by definite sounds had never crossed their
minds. They might insist that they were ready to aid their fellow-apes of
the same troop in many ways, to risk their lives for them, and to take
charge of their orphans; but they would be forced to acknowledge that
disinterested love for all living creatures, the most noble attribute of
man, was quite beyond their comprehension.
Nevertheless the difference in mind between man and the higher animals,
great as it is, certainly is one of degree and not of kind. We have seen
that the senses and intuitions, the various emotions and faculties, such as
love, memory, attention, curiosity, imitation, reason, etc., of which man
boasts, may be found in an incipient, or even sometimes in a well-developed
condition, in the lower animals. They are also capable of some inherited
improvement, as we see in the domestic dog compared with the wolf or
jackal. If it could be proved that certain high mental powers, such as the
formation of general concepts, self-consciousness, etc., were absolutely
peculiar to man, which seems extremely doubtful, it is not improbable that
these qualities are merely the incidental results of other highly-advanced
intellectual faculties; and these again mainly the result of the continued
use of a perfect language. At what age does the new-born infant possess
the power of abstraction, or become self-conscious, and reflect on its own
existence? We cannot answer; nor can we answer in regard to the ascending
organic scale. The half-art, half-instinct of language still bears the
stamp of its gradual evolution. The ennobling belief in God is not
universal with man; and the belief in spiritual agencies naturally follows
from other mental powers. The moral sense perhaps affords the best and
highest distinction between man and the lower animals; but I need say
nothing on this head, as I have so lately endeavoured to shew that the
social instincts,--the prime principle of man's moral constitution (50.
'The Thoughts of Marcus Aurelius,' etc., p. 139.)--with the aid of active
intellectual powers and the effects of habit, naturally lead to the golden
rule, "As ye would that men should do to you, do ye to them likewise;" and
this lies at the foundation of morality.
In the next chapter I shall make some few remarks on the probable steps and
means by which the several mental and moral faculties of man have been
gradually evolved. That such evolution is at least possible, ought not to
be denied, for we daily see these faculties developing in every infant; and
we may trace a perfect gradation from the mind of an utter idiot, lower
than that of an animal low in the scale, to the mind of a Newton.
CHAPTER V.
ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL
AND CIVILISED TIMES.
Advancement of the intellectual powers through natural selection--
Importance of imitation--Social and moral faculties--Their development
within the limits of the same tribe--Natural selection as affecting
civilised nations--Evidence that civilised nations were once barbarous.
The subjects to be discussed in this chapter are of the highest interest,
but are treated by me in an imperfect and fragmentary manner. Mr. Wallace,
in an admirable paper before referred to (1. Anthropological Review, May
1864, p. clviii.), argues that man, after he had partially acquired those
intellectual and moral faculties which distinguish him from the lower
animals, would have been but little liable to bodily modifications through
natural selection or any other means. For man is enabled through his
mental faculties "to keep with an unchanged body in harmony with the
changing universe." He has great power of adapting his habits to new
conditions of life. He invents weapons, tools, and various stratagems to
procure food and to defend himself. When he migrates into a colder climate
he uses clothes, builds sheds, and makes fires; and by the aid of fire
cooks food otherwise indigestible. He aids his fellow-men in many ways,
and anticipates future events. Even at a remote period he practised some
division of labour.
The lower animals, on the other hand, must have their bodily structure
modified in order to survive under greatly changed conditions. They must
be rendered stronger, or acquire more effective teeth or claws, for defence
against new enemies; or they must be reduced in size, so as to escape
detection and danger. When they migrate into a colder climate, they must
become clothed with thicker fur, or have their constitutions altered. If
they fail to be thus modified, they will cease to exist.
The case, however, is widely different, as Mr. Wallace has with justice
insisted, in relation to the intellectual and moral faculties of man.
These faculties are variable; and we have every reason to believe that the
variations tend to be inherited. Therefore, if they were formerly of high
importance to primeval man and to his ape-like progenitors, they would have
been perfected or advanced through natural selection. Of the high
importance of the intellectual faculties there can be no doubt, for man
mainly owes to them his predominant position in the world. We can see,
that in the rudest state of society, the individuals who were the most
sagacious, who invented and used the best weapons or traps, and who were
best able to defend themselves, would rear the greatest number of
offspring. The tribes, which included the largest number of men thus
endowed, would increase in number and supplant other tribes. Numbers
depend primarily on the means of subsistence, and this depends partly on
the physical nature of the country, but in a much higher degree on the arts
which are there practised. As a tribe increases and is victorious, it is
often still further increased by the absorption of other tribes. (2.
After a time the members or tribes which are absorbed into another tribe
assume, as Sir Henry Maine remarks ('Ancient Law,' 1861, p. 131), that they
are the co-descendants of the same ancestors.) The stature and strength of
the men of a tribe are likewise of some importance for its success, and
these depend in part on the nature and amount of the food which can be
obtained. In Europe the men of the Bronze period were supplanted by a race
more powerful, and, judging from their sword-handles, with larger hands (3.
Morlot, 'Soc. Vaud. Sc. Nat.' 1860, p. 294.); but their success was
probably still more due to their superiority in the arts.
All that we know about savages, or may infer from their traditions and from
old monuments, the history of which is quite forgotten by the present
inhabitants, shew that from the remotest times successful tribes have
supplanted other tribes. Relics of extinct or forgotten tribes have been
discovered throughout the civilised regions of the earth, on the wild
plains of America, and on the isolated islands in the Pacific Ocean. At
the present day civilised nations are everywhere supplanting barbarous
nations, excepting where the climate opposes a deadly barrier; and they
succeed mainly, though not exclusively, through their arts, which are the
products of the intellect. It is, therefore, highly probable that with
mankind the intellectual faculties have been mainly and gradually perfected
through natural selection; and this conclusion is sufficient for our
purpose. Undoubtedly it would be interesting to trace the development of
each separate faculty from the state in which it exists in the lower
animals to that in which it exists in man; but neither my ability nor
knowledge permits the attempt.
It deserves notice that, as soon as the progenitors of man became social
(and this probably occurred at a very early period), the principle of
imitation, and reason, and experience would have increased, and much
modified the intellectual powers in a way, of which we see only traces in
the lower animals. Apes are much given to imitation, as are the lowest
savages; and the simple fact previously referred to, that after a time no
animal can be caught in the same place by the same sort of trap, shews that
animals learn by experience, and imitate the caution of others. Now, if
some one man in a tribe, more sagacious than the others, invented a new
snare or weapon, or other means of attack or defence, the plainest self-
interest, without the assistance of much reasoning power, would prompt the
other members to imitate him; and all would thus profit. The habitual
practice of each new art must likewise in some slight degree strengthen the
intellect. If the new invention were an important one, the tribe would
increase in number, spread, and supplant other tribes. In a tribe thus
rendered more numerous there would always be a rather greater chance of the
birth of other superior and inventive members. If such men left children
to inherit their mental superiority, the chance of the birth of still more
ingenious members would be somewhat better, and in a very small tribe
decidedly better. Even if they left no children, the tribe would still
include their blood-relations; and it has been ascertained by
agriculturists (4. I have given instances in my Variation of Animals under
Domestication, vol. ii. p. 196.) that by preserving and breeding from the
family of an animal, which when slaughtered was found to be valuable, the
desired character has been obtained.
Turning now to the social and moral faculties. In order that primeval men,
or the ape-like progenitors of man, should become social, they must have
acquired the same instinctive feelings, which impel other animals to live
in a body; and they no doubt exhibited the same general disposition. They
would have felt uneasy when separated from their comrades, for whom they
would have felt some degree of love; they would have warned each other of
danger, and have given mutual aid in attack or defence. All this implies
some degree of sympathy, fidelity, and courage. Such social qualities, the
paramount importance of which to the lower animals is disputed by no one,
were no doubt acquired by the progenitors of man in a similar manner,
namely, through natural selection, aided by inherited habit. When two
tribes of primeval man, living in the same country, came into competition,
if (other circumstances being equal) the one tribe included a great number
of courageous, sympathetic and faithful members, who were always ready to
warn each other of danger, to aid and defend each other, this tribe would
succeed better and conquer the other. Let it be borne in mind how all-
important in the never-ceasing wars of savages, fidelity and courage must
be. The advantage which disciplined soldiers have over undisciplined
hordes follows chiefly from the confidence which each man feels in his
comrades. Obedience, as Mr. Bagehot has well shewn (5. See a remarkable
series of articles on 'Physics and Politics,' in the 'Fortnightly Review,'
Nov. 1867; April 1, 1868; July 1, 1869, since separately published.), is of
the highest value, for any form of government is better than none. Selfish
and contentious people will not cohere, and without coherence nothing can
be effected. A tribe rich in the above qualities would spread and be
victorious over other tribes: but in the course of time it would, judging
from all past history, be in its turn overcome by some other tribe still
more highly endowed. Thus the social and moral qualities would tend slowly
to advance and be diffused throughout the world.
But it may be asked, how within the limits of the same tribe did a large
number of members first become endowed with these social and moral
qualities, and how was the standard of excellence raised? It is extremely
doubtful whether the offspring of the more sympathetic and benevolent
parents, or of those who were the most faithful to their comrades, would be
reared in greater numbers than the children of selfish and treacherous
parents belonging to the same tribe. He who was ready to sacrifice his
life, as many a savage has been, rather than betray his comrades, would
often leave no offspring to inherit his noble nature. The bravest men, who
were always willing to come to the front in war, and who freely risked
their lives for others, would on an average perish in larger numbers than
other men. Therefore, it hardly seems probable, that the number of men
gifted with such virtues, or that the standard of their excellence, could
be increased through natural selection, that is, by the survival of the
fittest; for we are not here speaking of one tribe being victorious over
another.
Although the circumstances, leading to an increase in the number of those
thus endowed within the same tribe, are too complex to be clearly followed
out, we can trace some of the probable steps. In the first place, as the
reasoning powers and foresight of the members became improved, each man
would soon learn that if he aided his fellow-men, he would commonly receive
aid in return. From this low motive he might acquire the habit of aiding
his fellows; and the habit of performing benevolent actions certainly
strengthens the feeling of sympathy which gives the first impulse to
benevolent actions. Habits, moreover, followed during many generations
probably tend to be inherited.
But another and much more powerful stimulus to the development of the
social virtues, is afforded by the praise and the blame of our fellow-men.
To the instinct of sympathy, as we have already seen, it is primarily due,
that we habitually bestow both praise and blame on others, whilst we love
the former and dread the latter when applied to ourselves; and this
instinct no doubt was originally acquired, like all the other social
instincts, through natural selection. At how early a period the
progenitors of man in the course of their development, became capable of
feeling and being impelled by, the praise or blame of their fellow-
creatures, we cannot of course say. But it appears that even dogs
appreciate encouragement, praise, and blame. The rudest savages feel the
sentiment of glory, as they clearly shew by preserving the trophies of
their prowess, by their habit of excessive boasting, and even by the
extreme care which they take of their personal appearance and decorations;
for unless they regarded the opinion of their comrades, such habits would
be senseless.
They certainly feel shame at the breach of some of their lesser rules, and
apparently remorse, as shewn by the case of the Australian who grew thin
and could not rest from having delayed to murder some other woman, so as to
propitiate his dead wife's spirit. Though I have not met with any other
recorded case, it is scarcely credible that a savage, who will sacrifice
his life rather than betray his tribe, or one who will deliver himself up
as a prisoner rather than break his parole (6. Mr. Wallace gives cases in
his 'Contributions to the Theory of Natural Selection,' 1870, p. 354.),
would not feel remorse in his inmost soul, if he had failed in a duty,
which he held sacred.
We may therefore conclude that primeval man, at a very remote period, was
influenced by the praise and blame of his fellows. It is obvious, that the
members of the same tribe would approve of conduct which appeared to them
to be for the general good, and would reprobate that which appeared evil.
To do good unto others--to do unto others as ye would they should do unto
you--is the foundation-stone of morality. It is, therefore, hardly
possible to exaggerate the importance during rude times of the love of
praise and the dread of blame. A man who was not impelled by any deep,
instinctive feeling, to sacrifice his life for the good of others, yet was
roused to such actions by a sense of glory, would by his example excite the
same wish for glory in other men, and would strengthen by exercise the
noble feeling of admiration. He might thus do far more good to his tribe
than by begetting offspring with a tendency to inherit his own high
character.
With increased experience and reason, man perceives the more remote
consequences of his actions, and the self-regarding virtues, such as
temperance, chastity, etc., which during early times are, as we have before
seen, utterly disregarded, come to be highly esteemed or even held sacred.
I need not, however, repeat what I have said on this head in the fourth
chapter. Ultimately our moral sense or conscience becomes a highly complex
sentiment--originating in the social instincts, largely guided by the
approbation of our fellow-men, ruled by reason, self-interest, and in later
times by deep religious feelings, and confirmed by instruction and habit.
It must not be forgotten that although a high standard of morality gives
but a slight or no advantage to each individual man and his children over
the other men of the same tribe, yet that an increase in the number of
well-endowed men and an advancement in the standard of morality will
certainly give an immense advantage to one tribe over another. A tribe
including many members who, from possessing in a high degree the spirit of
patriotism, fidelity, obedience, courage, and sympathy, were always ready
to aid one another, and to sacrifice themselves for the common good, would
be victorious over most other tribes; and this would be natural selection.
At all times throughout the world tribes have supplanted other tribes; and
as morality is one important element in their success, the standard of
morality and the number of well-endowed men will thus everywhere tend to
rise and increase.
It is, however, very difficult to form any judgment why one particular
tribe and not another has been successful and has risen in the scale of
civilisation. Many savages are in the same condition as when first
discovered several centuries ago. As Mr. Bagehot has remarked, we are apt
to look at progress as normal in human society; but history refutes this.
The ancients did not even entertain the idea, nor do the Oriental nations
at the present day. According to another high authority, Sir Henry Maine
(7. 'Ancient Law,' 1861, p. 22. For Mr. Bagehot's remarks, 'Fortnightly
Review,' April 1, 1868, p. 452.), "the greatest part of mankind has never
shewn a particle of desire that its civil institutions should be improved."
Progress seems to depend on many concurrent favourable conditions, far too
complex to be followed out. But it has often been remarked, that a cool
climate, from leading to industry and to the various arts, has been highly
favourable thereto. The Esquimaux, pressed by hard necessity, have
succeeded in many ingenious inventions, but their climate has been too
severe for continued progress. Nomadic habits, whether over wide plains,
or through the dense forests of the tropics, or along the shores of the
sea, have in every case been highly detrimental. Whilst observing the
barbarous inhabitants of Tierra del Fuego, it struck me that the possession
of some property, a fixed abode, and the union of many families under a
chief, were the indispensable requisites for civilisation. Such habits
almost necessitate the cultivation of the ground; and the first steps in
cultivation would probably result, as I have elsewhere shewn (8. 'The
Variation of Animals and Plants under Domestication,' vol. i. p. 309.),
from some such accident as the seeds of a fruit-tree falling on a heap of
refuse, and producing an unusually fine variety. The problem, however, of
the first advance of savages towards civilisation is at present much too
difficult to be solved.
NATURAL SELECTION AS AFFECTING CIVILISED NATIONS.
I have hitherto only considered the advancement of man from a semi-human
condition to that of the modern savage. But some remarks on the action of
natural selection on civilised nations may be worth adding. This subject
has been ably discussed by Mr. W.R. Greg (9. 'Fraser's Magazine,' Sept.
1868, p. 353. This article seems to have struck many persons, and has
given rise to two remarkable essays and a rejoinder in the 'Spectator,'
Oct. 3rd and 17th, 1868. It has also been discussed in the 'Quarterly
Journal of Science,' 1869, p. 152, and by Mr. Lawson Tait in the 'Dublin
Quarterly Journal of Medical Science,' Feb. 1869, and by Mr. E. Ray
Lankester in his 'Comparative Longevity,' 1870, p. 128. Similar views
appeared previously in the 'Australasian,' July 13, 1867. I have borrowed
ideas from several of these writers.), and previously by Mr. Wallace and
Mr. Galton. (10. For Mr. Wallace, see 'Anthropological Review,' as before
cited. Mr. Galton in 'Macmillan's Magazine,' Aug. 1865, p. 318; also his
great work, 'Hereditary Genius,' 1870.) Most of my remarks are taken from
these three authors. With savages, the weak in body or mind are soon
eliminated; and those that survive commonly exhibit a vigorous state of
health. We civilised men, on the other hand, do our utmost to check the
process of elimination; we build asylums for the imbecile, the maimed, and
the sick; we institute poor-laws; and our medical men exert their utmost
skill to save the life of every one to the last moment. There is reason to
believe that vaccination has preserved thousands, who from a weak
constitution would formerly have succumbed to small-pox. Thus the weak
members of civilised societies propagate their kind. No one who has
attended to the breeding of domestic animals will doubt that this must be
highly injurious to the race of man. It is surprising how soon a want of
care, or care wrongly directed, leads to the degeneration of a domestic
race; but excepting in the case of man himself, hardly any one is so
ignorant as to allow his worst animals to breed.
The aid which we feel impelled to give to the helpless is mainly an
incidental result of the instinct of sympathy, which was originally
acquired as part of the social instincts, but subsequently rendered, in the
manner previously indicated, more tender and more widely diffused. Nor
could we check our sympathy, even at the urging of hard reason, without
deterioration in the noblest part of our nature. The surgeon may harden
himself whilst performing an operation, for he knows that he is acting for
the good of his patient; but if we were intentionally to neglect the weak
and helpless, it could only be for a contingent benefit, with an
overwhelming present evil. We must therefore bear the undoubtedly bad
effects of the weak surviving and propagating their kind; but there appears
to be at least one check in steady action, namely that the weaker and
inferior members of society do not marry so freely as the sound; and this
check might be indefinitely increased by the weak in body or mind
refraining from marriage, though this is more to be hoped for than
expected.
In every country in which a large standing army is kept up, the finest
young men are taken by the conscription or are enlisted. They are thus
exposed to early death during war, are often tempted into vice, and are
prevented from marrying during the prime of life. On the other hand the
shorter and feebler men, with poor constitutions, are left at home, and
consequently have a much better chance of marrying and propagating their
kind. (11. Prof. H. Fick ('Einfluss der Naturwissenschaft auf das Recht,'
June 1872) has some good remarks on this head, and on other such points.)
Man accumulates property and bequeaths it to his children, so that the
children of the rich have an advantage over the poor in the race for
success, independently of bodily or mental superiority. On the other hand,
the children of parents who are short-lived, and are therefore on an
average deficient in health and vigour, come into their property sooner
than other children, and will be likely to marry earlier, and leave a
larger number of offspring to inherit their inferior constitutions. But
the inheritance of property by itself is very far from an evil; for without
the accumulation of capital the arts could not progress; and it is chiefly
through their power that the civilised races have extended, and are now
everywhere extending their range, so as to take the place of the lower
races. Nor does the moderate accumulation of wealth interfere with the
process of selection. When a poor man becomes moderately rich, his
children enter trades or professions in which there is struggle enough, so
that the able in body and mind succeed best. The presence of a body of
well-instructed men, who have not to labour for their daily bread, is
important to a degree which cannot be over-estimated; as all high
intellectual work is carried on by them, and on such work, material
progress of all kinds mainly depends, not to mention other and higher
advantages. No doubt wealth when very great tends to convert men into
useless drones, but their number is never large; and some degree of
elimination here occurs, for we daily see rich men, who happen to be fools
or profligate, squandering away their wealth.
Primogeniture with entailed estates is a more direct evil, though it may
formerly have been a great advantage by the creation of a dominant class,
and any government is better than none. Most eldest sons, though they may
be weak in body or mind, marry, whilst the younger sons, however superior
in these respects, do not so generally marry. Nor can worthless eldest
sons with entailed estates squander their wealth. But here, as elsewhere,
the relations of civilised life are so complex that some compensatory
checks intervene. The men who are rich through primogeniture are able to
select generation after generation the more beautiful and charming women;
and these must generally be healthy in body and active in mind. The evil
consequences, such as they may be, of the continued preservation of the
same line of descent, without any selection, are checked by men of rank
always wishing to increase their wealth and power; and this they effect by
marrying heiresses. But the daughters of parents who have produced single
children, are themselves, as Mr. Galton (12. 'Hereditary Genius,' 1870, pp.
132-140.) has shewn, apt to be sterile; and thus noble families are
continually cut off in the direct line, and their wealth flows into some
side channel; but unfortunately this channel is not determined by
superiority of any kind.
Although civilisation thus checks in many ways the action of natural
selection, it apparently favours the better development of the body, by
means of good food and the freedom from occasional hardships. This may be
inferred from civilised men having been found, wherever compared, to be
physically stronger than savages. (13. Quatrefages, 'Revue des Cours
Scientifiques,' 1867-68, p. 659.) They appear also to have equal powers of
endurance, as has been proved in many adventurous expeditions. Even the
great luxury of the rich can be but little detrimental; for the expectation
of life of our aristocracy, at all ages and of both sexes, is very little
inferior to that of healthy English lives in the lower classes. (14.
See the fifth and sixth columns, compiled from good authorities, in the
table given in Mr. E.R. Lankester's 'Comparative Longevity,' 1870, p. 115.)
We will now look to the intellectual faculties. If in each grade of
society the members were divided into two equal bodies, the one including
the intellectually superior and the other the inferior, there can be little
doubt that the former would succeed best in all occupations, and rear a
greater number of children. Even in the lowest walks of life, skill and
ability must be of some advantage; though in many occupations, owing to the
great division of labour, a very small one. Hence in civilised nations
there will be some tendency to an increase both in the number and in the
standard of the intellectually able. But I do not wish to assert that this
tendency may not be more than counterbalanced in other ways, as by the
multiplication of the reckless and improvident; but even to such as these,
ability must be some advantage.
It has often been objected to views like the foregoing, that the most
eminent men who have ever lived have left no offspring to inherit their
great intellect. Mr. Galton says, "I regret I am unable to solve the
simple question whether, and how far, men and women who are prodigies of
genius are infertile. I have, however, shewn that men of eminence are by
no means so." (15. 'Hereditary Genius,' 1870, p. 330.) Great lawgivers,
the founders of beneficent religions, great philosophers and discoverers in
science, aid the progress of mankind in a far higher degree by their works
than by leaving a numerous progeny. In the case of corporeal structures,
it is the selection of the slightly better-endowed and the elimination of
the slightly less well-endowed individuals, and not the preservation of
strongly-marked and rare anomalies, that leads to the advancement of a
species. (16. 'Origin of Species' (fifth edition, 1869), p. 104.) So it
will be with the intellectual faculties, since the somewhat abler men in
each grade of society succeed rather better than the less able, and
consequently increase in number, if not otherwise prevented. When in any
nation the standard of intellect and the number of intellectual men have
increased, we may expect from the law of the deviation from an average,
that prodigies of genius will, as shewn by Mr. Galton, appear somewhat more
frequently than before.
In regard to the moral qualities, some elimination of the worst
dispositions is always in progress even in the most civilised nations.
Malefactors are executed, or imprisoned for long periods, so that they
cannot freely transmit their bad qualities. Melancholic and insane persons
are confined, or commit suicide. Violent and quarrelsome men often come to
a bloody end. The restless who will not follow any steady occupation--and
this relic of barbarism is a great check to civilisation (17. 'Hereditary
Genius,' 1870, p. 347.)--emigrate to newly-settled countries; where they
prove useful pioneers. Intemperance is so highly destructive, that the
expectation of life of the intemperate, at the age of thirty for instance,
is only 13.8 years; whilst for the rural labourers of England at the same
age it is 40.59 years. (18. E. Ray Lankester, 'Comparative Longevity,'
1870, p. 115. The table of the intemperate is from Neison's 'Vital
Statistics.' In regard to profligacy, see Dr. Farr, 'Influence of Marriage
on Mortality,' 'Nat. Assoc. for the Promotion of Social Science,' 1858.)
Profligate women bear few children, and profligate men rarely marry; both
suffer from disease. In the breeding of domestic animals, the elimination
of those individuals, though few in number, which are in any marked manner
inferior, is by no means an unimportant element towards success. This
especially holds good with injurious characters which tend to reappear
through reversion, such as blackness in sheep; and with mankind some of the
worst dispositions, which occasionally without any assignable cause make
their appearance in families, may perhaps be reversions to a savage state,
from which we are not removed by very many generations. This view seems
indeed recognised in the common expression that such men are the black
sheep of the family.
With civilised nations, as far as an advanced standard of morality, and an
increased number of fairly good men are concerned, natural selection
apparently effects but little; though the fundamental social instincts were
originally thus gained. But I have already said enough, whilst treating of
the lower races, on the causes which lead to the advance of morality,
namely, the approbation of our fellow-men--the strengthening of our
sympathies by habit--example and imitation--reason--experience, and even
self-interest--instruction during youth, and religious feelings.
A most important obstacle in civilised countries to an increase in the
number of men of a superior class has been strongly insisted on by Mr. Greg
and Mr. Galton (19. 'Fraser's Magazine,' Sept. 1868, p. 353. 'Macmillan's
Magazine,' Aug. 1865, p. 318. The Rev. F.W. Farrar ('Fraser's Magazine,'
Aug. 1870, p. 264) takes a different view.), namely, the fact that the very
poor and reckless, who are often degraded by vice, almost invariably marry
early, whilst the careful and frugal, who are generally otherwise virtuous,
marry late in life, so that they may be able to support themselves and
their children in comfort. Those who marry early produce within a given
period not only a greater number of generations, but, as shewn by Dr.
Duncan (20. 'On the Laws of the Fertility of Women,' in 'Transactions of
the Royal Society,' Edinburgh, vol. xxiv. p. 287; now published separately
under the title of 'Fecundity, Fertility, and Sterility,' 1871. See, also,
Mr. Galton, 'Hereditary Genius,' pp. 352-357, for observations to the above
effect.), they produce many more children. The children, moreover, that
are borne by mothers during the prime of life are heavier and larger, and
therefore probably more vigorous, than those born at other periods. Thus
the reckless, degraded, and often vicious members of society, tend to
increase at a quicker rate than the provident and generally virtuous
members. Or as Mr. Greg puts the case: "The careless, squalid, unaspiring
Irishman multiplies like rabbits: the frugal, foreseeing, self-respecting,
ambitious Scot, stern in his morality, spiritual in his faith, sagacious
and disciplined in his intelligence, passes his best years in struggle and
in celibacy, marries late, and leaves few behind him. Given a land
originally peopled by a thousand Saxons and a thousand Celts--and in a
dozen generations five-sixths of the population would be Celts, but five-
sixths of the property, of the power, of the intellect, would belong to the
one-sixth of Saxons that remained. In the eternal 'struggle for
existence,' it would be the inferior and LESS favoured race that had
prevailed--and prevailed by virtue not of its good qualities but of its
faults."
There are, however, some checks to this downward tendency. We have seen
that the intemperate suffer from a high rate of mortality, and the
extremely profligate leave few offspring. The poorest classes crowd into
towns, and it has been proved by Dr. Stark from the statistics of ten years
in Scotland (21. 'Tenth Annual Report of Births, Deaths, etc., in
Scotland,' 1867, p. xxix.), that at all ages the death-rate is higher in
towns than in rural districts, "and during the first five years of life the
town death-rate is almost exactly double that of the rural districts." As
these returns include both the rich and the poor, no doubt more than twice
the number of births would be requisite to keep up the number of the very
poor inhabitants in the towns, relatively to those in the country. With
women, marriage at too early an age is highly injurious; for it has been
found in France that, "Twice as many wives under twenty die in the year, as
died out of the same number of the unmarried." The mortality, also, of
husbands under twenty is "excessively high" (22. These quotations are
taken from our highest authority on such questions, namely, Dr. Farr, in
his paper 'On the Influence of Marriage on the Mortality of the French
People,' read before the Nat. Assoc. for the Promotion of Social Science,
1858.), but what the cause of this may be, seems doubtful. Lastly, if the
men who prudently delay marrying until they can bring up their families in
comfort, were to select, as they often do, women in the prime of life, the
rate of increase in the better class would be only slightly lessened.
It was established from an enormous body of statistics, taken during 1853,
that the unmarried men throughout France, between the ages of twenty and
eighty, die in a much larger proportion than the married: for instance,
out of every 1000 unmarried men, between the ages of twenty and thirty,
11.3 annually died, whilst of the married, only 6.5 died. (23. Dr. Farr,
ibid. The quotations given below are extracted from the same striking
paper.) A similar law was proved to hold good, during the years 1863 and
1864, with the entire population above the age of twenty in Scotland: for
instance, out of every 1000 unmarried men, between the ages of twenty and
thirty, 14.97 annually died, whilst of the married only 7.24 died, that is
less than half. (24. I have taken the mean of the quinquennial means,
given in 'The Tenth Annual Report of Births, Deaths, etc., in Scotland,'
1867. The quotation from Dr. Stark is copied from an article in the 'Daily
News,' Oct. 17, 1868, which Dr. Farr considers very carefully written.)
Dr. Stark remarks on this, "Bachelorhood is more destructive to life than
the most unwholesome trades, or than residence in an unwholesome house or
district where there has never been the most distant attempt at sanitary
improvement." He considers that the lessened mortality is the direct
result of "marriage, and the more regular domestic habits which attend that
state." He admits, however, that the intemperate, profligate, and criminal
classes, whose duration of life is low, do not commonly marry; and it must
likewise be admitted that men with a weak constitution, ill health, or any
great infirmity in body or mind, will often not wish to marry, or will be
rejected. Dr. Stark seems to have come to the conclusion that marriage in
itself is a main cause of prolonged life, from finding that aged married
men still have a considerable advantage in this respect over the unmarried
of the same advanced age; but every one must have known instances of men,
who with weak health during youth did not marry, and yet have survived to
old age, though remaining weak, and therefore always with a lessened chance
of life or of marrying. There is another remarkable circumstance which
seems to support Dr. Stark's conclusion, namely, that widows and widowers
in France suffer in comparison with the married a very heavy rate of
mortality; but Dr. Farr attributes this to the poverty and evil habits
consequent on the disruption of the family, and to grief. On the whole we
may conclude with Dr. Farr that the lesser mortality of married than of
unmarried men, which seems to be a general law, "is mainly due to the
constant elimination of imperfect types, and to the skilful selection of
the finest individuals out of each successive generation;" the selection
relating only to the marriage state, and acting on all corporeal,
intellectual, and moral qualities. (25. Dr. Duncan remarks ('Fecundity,
Fertility, etc.' 1871, p. 334) on this subject: "At every age the healthy
and beautiful go over from the unmarried side to the married, leaving the
unmarried columns crowded with the sickly and unfortunate.") We may,
therefore, infer that sound and good men who out of prudence remain for a
time unmarried, do not suffer a high rate of mortality.
If the various checks specified in the two last paragraphs, and perhaps
others as yet unknown, do not prevent the reckless, the vicious and
otherwise inferior members of society from increasing at a quicker rate
than the better class of men, the nation will retrograde, as has too often
occurred in the history of the world. We must remember that progress is no
invariable rule. It is very difficult to say why one civilised nation
rises, becomes more powerful, and spreads more widely, than another; or why
the same nation progresses more quickly at one time than at another. We
can only say that it depends on an increase in the actual number of the
population, on the number of men endowed with high intellectual and moral
faculties, as well as on their standard of excellence. Corporeal structure
appears to have little influence, except so far as vigour of body leads to
vigour of mind.
It has been urged by several writers that as high intellectual powers are
advantageous to a nation, the old Greeks, who stood some grades higher in
intellect than any race that has ever existed (26. See the ingenious and
original argument on this subject by Mr. Galton, 'Hereditary Genius,' pp.
340-342.), ought, if the power of natural selection were real, to have
risen still higher in the scale, increased in number, and stocked the whole
of Europe. Here we have the tacit assumption, so often made with respect
to corporeal structures, that there is some innate tendency towards
continued development in mind and body. But development of all kinds
depends on many concurrent favourable circumstances. Natural selection
acts only tentatively. Individuals and races may have acquired certain
indisputable advantages, and yet have perished from failing in other
characters. The Greeks may have retrograded from a want of coherence
between the many small states, from the small size of their whole country,
from the practice of slavery, or from extreme sensuality; for they did not
succumb until "they were enervated and corrupt to the very core." (27.
Mr. Greg, 'Fraser's Magazine,' Sept. 1868, p. 357.) The western nations of
Europe, who now so immeasurably surpass their former savage progenitors,
and stand at the summit of civilisation, owe little or none of their
superiority to direct inheritance from the old Greeks, though they owe much
to the written works of that wonderful people.
Who can positively say why the Spanish nation, so dominant at one time, has
been distanced in the race. The awakening of the nations of Europe from
the dark ages is a still more perplexing problem. At that early period, as
Mr. Galton has remarked, almost all the men of a gentle nature, those given
to meditation or culture of the mind, had no refuge except in the bosom of
a Church which demanded celibacy (28. 'Hereditary Genius,' 1870, pp. 357-
359. The Rev. F.W. Farrar ('Fraser's Magazine,' Aug. 1870, p. 257)
advances arguments on the other side. Sir C. Lyell had already
('Principles of Geology,' vol. ii. 1868, p. 489), in a striking passage
called attention to the evil influence of the Holy Inquisition in having,
through selection, lowered the general standard of intelligence in
Europe.); and this could hardly fail to have had a deteriorating influence
on each successive generation. During this same period the Holy
Inquisition selected with extreme care the freest and boldest men in order
to burn or imprison them. In Spain alone some of the best men--those who
doubted and questioned, and without doubting there can be no progress--were
eliminated during three centuries at the rate of a thousand a year. The
evil which the Catholic Church has thus effected is incalculable, though no
doubt counterbalanced to a certain, perhaps to a large, extent in other
ways; nevertheless, Europe has progressed at an unparalleled rate.
The remarkable success of the English as colonists, compared to other
European nations, has been ascribed to their "daring and persistent
energy"; a result which is well illustrated by comparing the progress of
the Canadians of English and French extraction; but who can say how the
English gained their energy? There is apparently much truth in the belief
that the wonderful progress of the United States, as well as the character
of the people, are the results of natural selection; for the more
energetic, restless, and courageous men from all parts of Europe have
emigrated during the last ten or twelve generations to that great country,
and have there succeeded best. (29. Mr. Galton, 'Macmillan's Magazine,'
August 1865, p. 325. See also, 'Nature,' 'On Darwinism and National Life,'
Dec. 1869, p. 184.) Looking to the distant future, I do not think that the
Rev. Mr. Zincke takes an exaggerated view when he says (30. 'Last Winter
in the United States,' 1868, p. 29.): "All other series of events--as that
which resulted in the culture of mind in Greece, and that which resulted in
the empire of Rome--only appear to have purpose and value when viewed in
connection with, or rather as subsidiary to...the great stream of Anglo-
Saxon emigration to the west." Obscure as is the problem of the advance of
civilisation, we can at least see that a nation which produced during a
lengthened period the greatest number of highly intellectual, energetic,
brave, patriotic, and benevolent men, would generally prevail over less
favoured nations.
Natural selection follows from the struggle for existence; and this from a
rapid rate of increase. It is impossible not to regret bitterly, but
whether wisely is another question, the rate at which man tends to
increase; for this leads in barbarous tribes to infanticide and many other
evils, and in civilised nations to abject poverty, celibacy, and to the
late marriages of the prudent. But as man suffers from the same physical
evils as the lower animals, he has no right to expect an immunity from the
evils consequent on the struggle for existence. Had he not been subjected
during primeval times to natural selection, assuredly he would never have
attained to his present rank. Since we see in many parts of the world
enormous areas of the most fertile land capable of supporting numerous
happy homes, but peopled only by a few wandering savages, it might be
argued that the struggle for existence had not been sufficiently severe to
force man upwards to his highest standard. Judging from all that we know
of man and the lower animals, there has always been sufficient variability
in their intellectual and moral faculties, for a steady advance through
natural selection. No doubt such advance demands many favourable
concurrent circumstances; but it may well be doubted whether the most
favourable would have sufficed, had not the rate of increase been rapid,
and the consequent struggle for existence extremely severe. It even
appears from what we see, for instance, in parts of S. America, that a
people which may be called civilised, such as the Spanish settlers, is
liable to become indolent and to retrograde, when the conditions of life
are very easy. With highly civilised nations continued progress depends in
a subordinate degree on natural selection; for such nations do not supplant
and exterminate one another as do savage tribes. Nevertheless the more
intelligent members within the same community will succeed better in the
long run than the inferior, and leave a more numerous progeny, and this is
a form of natural selection. The more efficient causes of progress seem to
consist of a good education during youth whilst the brain is impressible,
and of a high standard of excellence, inculcated by the ablest and best
men, embodied in the laws, customs and traditions of the nation, and
enforced by public opinion. It should, however, be borne in mind, that the
enforcement of public opinion depends on our appreciation of the
approbation and disapprobation of others; and this appreciation is founded
on our sympathy, which it can hardly be doubted was originally developed
through natural selection as one of the most important elements of the
social instincts. (31. I am much indebted to Mr. John Morley for some
good criticisms on this subject: see, also Broca, 'Les Selections,' 'Revue
d'Anthropologie,' 1872.)
ON THE EVIDENCE THAT ALL CIVILISED NATIONS WERE ONCE BARBAROUS.
The present subject has been treated in so full and admirable a manner by
Sir J. Lubbock (32. 'On the Origin of Civilisation,' 'Proceedings of the
Ethnological Society,' Nov. 26, 1867.), Mr. Tylor, Mr. M'Lennan, and
others, that I need here give only the briefest summary of their results.
The arguments recently advanced by the Duke of Argyll (33. 'Primeval Man,'
1869.) and formerly by Archbishop Whately, in favour of the belief that man
came into the world as a civilised being, and that all savages have since
undergone degradation, seem to me weak in comparison with those advanced on
the other side. Many nations, no doubt, have fallen away in civilisation,
and some may have lapsed into utter barbarism, though on this latter head I
have met with no evidence. The Fuegians were probably compelled by other
conquering hordes to settle in their inhospitable country, and they may
have become in consequence somewhat more degraded; but it would be
difficult to prove that they have fallen much below the Botocudos, who
inhabit the finest parts of Brazil.
The evidence that all civilised nations are the descendants of barbarians,
consists, on the one side, of clear traces of their former low condition in
still-existing customs, beliefs, language, etc.; and on the other side, of
proofs that savages are independently able to raise themselves a few steps
in the scale of civilisation, and have actually thus risen. The evidence
on the first head is extremely curious, but cannot be here given: I refer
to such cases as that of the art of enumeration, which, as Mr. Tylor
clearly shews by reference to the words still used in some places,
originated in counting the fingers, first of one hand and then of the
other, and lastly of the toes. We have traces of this in our own decimal
system, and in the Roman numerals, where, after the V, which is supposed to
be an abbreviated picture of a human hand, we pass on to VI, etc., when the
other hand no doubt was used. So again, "when we speak of three-score and
ten, we are counting by the vigesimal system, each score thus ideally made,
standing for 20--for 'one man' as a Mexican or Carib would put it." (34.
'Royal Institution of Great Britain,' March 15, 1867. Also, 'Researches
into the Early History of Mankind,' 1865.) According to a large and
increasing school of philologists, every language bears the marks of its
slow and gradual evolution. So it is with the art of writing, for letters
are rudiments of pictorial representations. It is hardly possible to read
Mr. M'Lennan's work (35. 'Primitive Marriage,' 1865. See, likewise, an
excellent article, evidently by the same author, in the 'North British
Review,' July 1869. Also, Mr. L.H. Morgan, 'A Conjectural Solution of the
Origin of the Class, System of Relationship,' in 'Proc. American Acad. of
Sciences,' vol. vii. Feb. 1868. Prof. Schaaffhausen ('Anthropolog.
Review,' Oct. 1869, p. 373) remarks on "the vestiges of human sacrifices
found both in Homer and the Old Testament.") and not admit that almost all
civilised nations still retain traces of such rude habits as the forcible
capture of wives. What ancient nation, as the same author asks, can be
named that was originally monogamous? The primitive idea of justice, as
shewn by the law of battle and other customs of which vestiges still
remain, was likewise most rude. Many existing superstitions are the
remnants of former false religious beliefs. The highest form of religion--
the grand idea of God hating sin and loving righteousness--was unknown
during primeval times.
Turning to the other kind of evidence: Sir J. Lubbock has shewn that some
savages have recently improved a little in some of their simpler arts.
From the extremely curious account which he gives of the weapons, tools,
and arts, in use amongst savages in various parts of the world, it cannot
be doubted that these have nearly all been independent discoveries,
excepting perhaps the art of making fire. (36. Sir J. Lubbock,
'Prehistoric Times,' 2nd edit. 1869, chaps. xv. and xvi. et passim. See
also the excellent 9th Chapter in Tylor's 'Early History of Mankind,' 2nd
edit., 1870.) The Australian boomerang is a good instance of one such
independent discovery. The Tahitians when first visited had advanced in
many respects beyond the inhabitants of most of the other Polynesian
islands. There are no just grounds for the belief that the high culture of
the native Peruvians and Mexicans was derived from abroad (37. Dr. F.
Muller has made some good remarks to this effect in the 'Reise der Novara:
Anthropolog. Theil,' Abtheil. iii. 1868, s. 127.); many native plants were
there cultivated, and a few native animals domesticated. We should bear in
mind that, judging from the small influence of most missionaries, a
wandering crew from some semi-civilised land, if washed to the shores of
America, would not have produced any marked effect on the natives, unless
they had already become somewhat advanced. Looking to a very remote period
in the history of the world, we find, to use Sir J. Lubbock's well-known
terms, a paleolithic and neolithic period; and no one will pretend that the
art of grinding rough flint tools was a borrowed one. In all parts of
Europe, as far east as Greece, in Palestine, India, Japan, New Zealand, and
Africa, including Egypt, flint tools have been discovered in abundance; and
of their use the existing inhabitants retain no tradition. There is also
indirect evidence of their former use by the Chinese and ancient Jews.
Hence there can hardly be a doubt that the inhabitants of these countries,
which include nearly the whole civilised world, were once in a barbarous
condition. To believe that man was aboriginally civilised and then
suffered utter degradation in so many regions, is to take a pitiably low
view of human nature. It is apparently a truer and more cheerful view that
progress has been much more general than retrogression; that man has risen,
though by slow and interrupted steps, from a lowly condition to the highest
standard as yet attained by him in knowledge, morals and religion.
CHAPTER VI.
ON THE AFFINITIES AND GENEALOGY OF MAN.
Position of man in the animal series--The natural system genealogical--
Adaptive characters of slight value--Various small points of resemblance
between man and the Quadrumana--Rank of man in the natural system--
Birthplace and antiquity of man--Absence of fossil connecting links--Lower
stages in the genealogy of man, as inferred, firstly from his affinities
and secondly from his structure--Early androgynous condition of the
Vertebrata--Conclusion.
Even if it be granted that the difference between man and his nearest
allies is as great in corporeal structure as some naturalists maintain, and
although we must grant that the difference between them is immense in
mental power, yet the facts given in the earlier chapters appear to
declare, in the plainest manner, that man is descended from some lower
form, notwithstanding that connecting-links have not hitherto been
discovered.
Man is liable to numerous, slight, and diversified variations, which are
induced by the same general causes, are governed and transmitted in
accordance with the same general laws, as in the lower animals. Man has
multiplied so rapidly, that he has necessarily been exposed to struggle for
existence, and consequently to natural selection. He has given rise to
many races, some of which differ so much from each other, that they have
often been ranked by naturalists as distinct species. His body is
constructed on the same homological plan as that of other mammals. He
passes through the same phases of embryological development. He retains
many rudimentary and useless structures, which no doubt were once
serviceable. Characters occasionally make their re-appearance in him,
which we have reason to believe were possessed by his early progenitors.
If the origin of man had been wholly different from that of all other
animals, these various appearances would be mere empty deceptions; but such
an admission is incredible. These appearances, on the other hand, are
intelligible, at least to a large extent, if man is the co-descendant with
other mammals of some unknown and lower form.
Some naturalists, from being deeply impressed with the mental and spiritual
powers of man, have divided the whole organic world into three kingdoms,
the Human, the Animal, and the Vegetable, thus giving to man a separate
kingdom. (1. Isidore Geoffroy St.-Hilaire gives a detailed account of the
position assigned to man by various naturalists in their classifications:
'Hist. Nat. Gen.' tom. ii. 1859, pp. 170-189.) Spiritual powers cannot be
compared or classed by the naturalist: but he may endeavour to shew, as I
have done, that the mental faculties of man and the lower animals do not
differ in kind, although immensely in degree. A difference in degree,
however great, does not justify us in placing man in a distinct kingdom, as
will perhaps be best illustrated by comparing the mental powers of two
insects, namely, a coccus or scale-insect and an ant, which undoubtedly
belong to the same class. The difference is here greater than, though of a
somewhat different kind from, that between man and the highest mammal. The
female coccus, whilst young, attaches itself by its proboscis to a plant;
sucks the sap, but never moves again; is fertilised and lays eggs; and this
is its whole history. On the other hand, to describe the habits and mental
powers of worker-ants, would require, as Pierre Huber has shewn, a large
volume; I may, however, briefly specify a few points. Ants certainly
communicate information to each other, and several unite for the same work,
or for games of play. They recognise their fellow-ants after months of
absence, and feel sympathy for each other. They build great edifices, keep
them clean, close the doors in the evening, and post sentries. They make
roads as well as tunnels under rivers, and temporary bridges over them, by
clinging together. They collect food for the community, and when an
object, too large for entrance, is brought to the nest, they enlarge the
door, and afterwards build it up again. They store up seeds, of which they
prevent the germination, and which, if damp, are brought up to the surface
to dry. They keep aphides and other insects as milch-cows. They go out to
battle in regular bands, and freely sacrifice their lives for the common
weal. They emigrate according to a preconcerted plan. They capture
slaves. They move the eggs of their aphides, as well as their own eggs and
cocoons, into warm parts of the nest, in order that they may be quickly
hatched; and endless similar facts could be given. (2. Some of the most
interesting facts ever published on the habits of ants are given by Mr.
Belt, in his 'Naturalist in Nicaragua,' 1874. See also Mr. Moggridge's
admirable work, 'Harvesting Ants,' etc., 1873, also 'L'Instinct chez les
Insectes,' by M. George Pouchet, 'Revue des Deux Mondes,' Feb. 1870, p.
682.) On the whole, the difference in mental power between an ant and a
coccus is immense; yet no one has ever dreamed of placing these insects in
distinct classes, much less in distinct kingdoms. No doubt the difference
is bridged over by other insects; and this is not the case with man and the
higher apes. But we have every reason to believe that the breaks in the
series are simply the results of many forms having become extinct.
Professor Owen, relying chiefly on the structure of the brain, has divided
the mammalian series into four sub-classes. One of these he devotes to
man; in another he places both the marsupials and the Monotremata; so that
he makes man as distinct from all other mammals as are these two latter
groups conjoined. This view has not been accepted, as far as I am aware,
by any naturalist capable of forming an independent judgment, and therefore
need not here be further considered.
We can understand why a classification founded on any single character or
organ--even an organ so wonderfully complex and important as the brain--or
on the high development of the mental faculties, is almost sure to prove
unsatisfactory. This principle has indeed been tried with hymenopterous
insects; but when thus classed by their habits or instincts, the
arrangement proved thoroughly artificial. (3. Westwood, 'Modern
Classification of Insects,' vol. ii. 1840, p. 87.) Classifications may, of
course, be based on any character whatever, as on size, colour, or the
element inhabited; but naturalists have long felt a profound conviction
that there is a natural system. This system, it is now generally admitted,
must be, as far as possible, genealogical in arrangement,--that is, the co-
descendants of the same form must be kept together in one group, apart from
the co-descendants of any other form; but if the parent-forms are related,
so will be their descendants, and the two groups together will form a
larger group. The amount of difference between the several groups--that is
the amount of modification which each has undergone--is expressed by such
terms as genera, families, orders, and classes. As we have no record of
the lines of descent, the pedigree can be discovered only by observing the
degrees of resemblance between the beings which are to be classed. For
this object numerous points of resemblance are of much more importance than
the amount of similarity or dissimilarity in a few points. If two
languages were found to resemble each other in a multitude of words and
points of construction, they would be universally recognised as having
sprung from a common source, notwithstanding that they differed greatly in
some few words or points of construction. But with organic beings the
points of resemblance must not consist of adaptations to similar habits of
life: two animals may, for instance, have had their whole frames modified
for living in the water, and yet they will not be brought any nearer to
each other in the natural system. Hence we can see how it is that
resemblances in several unimportant structures, in useless and rudimentary
organs, or not now functionally active, or in an embryological condition,
are by far the most serviceable for classification; for they can hardly be
due to adaptations within a late period; and thus they reveal the old lines
of descent or of true affinity.
We can further see why a great amount of modification in some one character
ought not to lead us to separate widely any two organisms. A part which
already differs much from the same part in other allied forms has already,
according to the theory of evolution, varied much; consequently it would
(as long as the organism remained exposed to the same exciting conditions)
be liable to further variations of the same kind; and these, if beneficial,
would be preserved, and thus be continually augmented. In many cases the
continued development of a part, for instance, of the beak of a bird, or of
the teeth of a mammal, would not aid the species in gaining its food, or
for any other object; but with man we can see no definite limit to the
continued development of the brain and mental faculties, as far as
advantage is concerned. Therefore in determining the position of man in
the natural or genealogical system, the extreme development of his brain
ought not to outweigh a multitude of resemblances in other less important
or quite unimportant points.
The greater number of naturalists who have taken into consideration the
whole structure of man, including his mental faculties, have followed
Blumenbach and Cuvier, and have placed man in a separate Order, under the
title of the Bimana, and therefore on an equality with the orders of the
Quadrumana, Carnivora, etc. Recently many of our best naturalists have
recurred to the view first propounded by Linnaeus, so remarkable for his
sagacity, and have placed man in the same Order with the Quadrumana, under
the title of the Primates. The justice of this conclusion will be
admitted: for in the first place, we must bear in mind the comparative
insignificance for classification of the great development of the brain in
man, and that the strongly-marked differences between the skulls of man and
the Quadrumana (lately insisted upon by Bischoff, Aeby, and others)
apparently follow from their differently developed brains. In the second
place, we must remember that nearly all the other and more important
differences between man and the Quadrumana are manifestly adaptive in their
nature, and relate chiefly to the erect position of man; such as the
structure of his hand, foot, and pelvis, the curvature of his spine, and
the position of his head. The family of Seals offers a good illustration
of the small importance of adaptive characters for classification. These
animals differ from all other Carnivora in the form of their bodies and in
the structure of their limbs, far more than does man from the higher apes;
yet in most systems, from that of Cuvier to the most recent one by Mr.
Flower (4. 'Proceedings Zoological Society,' 1863, p. 4.), seals are
ranked as a mere family in the Order of the Carnivora. If man had not been
his own classifier, he would never have thought of founding a separate
order for his own reception.
It would be beyond my limits, and quite beyond my knowledge, even to name
the innumerable points of structure in which man agrees with the other
Primates. Our great anatomist and philosopher, Prof. Huxley, has fully
discussed this subject (5. 'Evidence as to Man's Place in Nature,' 1863,
p. 70, et passim.), and concludes that man in all parts of his organization
differs less from the higher apes, than these do from the lower members of
the same group. Consequently there "is no justification for placing man in
a distinct order."
In an early part of this work I brought forward various facts, shewing how
closely man agrees in constitution with the higher mammals; and this
agreement must depend on our close similarity in minute structure and
chemical composition. I gave, as instances, our liability to the same
diseases, and to the attacks of allied parasites; our tastes in common for
the same stimulants, and the similar effects produced by them, as well as
by various drugs, and other such facts.
As small unimportant points of resemblance between man and the Quadrumana
are not commonly noticed in systematic works, and as, when numerous, they
clearly reveal our relationship, I will specify a few such points. The
relative position of our features is manifestly the same; and the various
emotions are displayed by nearly similar movements of the muscles and skin,
chiefly above the eyebrows and round the mouth. Some few expressions are,
indeed, almost the same, as in the weeping of certain kinds of monkeys and
in the laughing noise made by others, during which the corners of the mouth
are drawn backwards, and the lower eyelids wrinkled. The external ears are
curiously alike. In man the nose is much more prominent than in most
monkeys; but we may trace the commencement of an aquiline curvature in the
nose of the Hoolock Gibbon; and this in the Semnopithecus nasica is carried
to a ridiculous extreme.
The faces of many monkeys are ornamented with beards, whiskers, or
moustaches. The hair on the head grows to a great length in some species
of Semnopithecus (6. Isidore Geoffroy St.-Hilaire, 'Hist. Nat. Gen.' tom.
ii. 1859, p. 217.); and in the Bonnet monkey (Macacus radiatus) it radiates
from a point on the crown, with a parting down the middle. It is commonly
said that the forehead gives to man his noble and intellectual appearance;
but the thick hair on the head of the Bonnet monkey terminates downwards
abruptly, and is succeeded by hair so short and fine that at a little
distance the forehead, with the exception of the eyebrows, appears quite
naked. It has been erroneously asserted that eyebrows are not present in
any monkey. In the species just named the degree of nakedness of the
forehead differs in different individuals; and Eschricht states (7. 'Uber
die Richtung der Haare,' etc., Muller's 'Archiv fur Anat. und Phys.' 1837,
s. 51.) that in our children the limit between the hairy scalp and the
naked forehead is sometimes not well defined; so that here we seem to have
a trifling case of reversion to a progenitor, in whom the forehead had not
as yet become quite naked.
It is well known that the hair on our arms tends to converge from above and
below to a point at the elbow. This curious arrangement, so unlike that in
most of the lower mammals, is common to the gorilla, chimpanzee, orang,
some species of Hylobates, and even to some few American monkeys. But in
Hylobates agilis the hair on the fore-arm is directed downwards or towards
the wrist in the ordinary manner; and in H. lar it is nearly erect, with
only a very slight forward inclination; so that in this latter species it
is in a transitional state. It can hardly be doubted that with most
mammals the thickness of the hair on the back and its direction, is adapted
to throw off the rain; even the transverse hairs on the fore-legs of a dog
may serve for this end when he is coiled up asleep. Mr. Wallace, who has
carefully studied the habits of the orang, remarks that the convergence of
the hair towards the elbow on the arms of the orang may be explained as
serving to throw off the rain, for this animal during rainy weather sits
with its arms bent, and with the hands clasped round a branch or over its
head. According to Livingstone, the gorilla also "sits in pelting rain
with his hands over his head." (8. Quoted by Reade, 'The African Sketch
Book,' vol i. 1873, p. 152.) If the above explanation is correct, as seems
probable, the direction of the hair on our own arms offers a curious record
of our former state; for no one supposes that it is now of any use in
throwing off the rain; nor, in our present erect condition, is it properly
directed for this purpose.
It would, however, be rash to trust too much to the principle of adaptation
in regard to the direction of the hair in man or his early progenitors; for
it is impossible to study the figures given by Eschricht of the arrangement
of the hair on the human foetus (this being the same as in the adult) and
not agree with this excellent observer that other and more complex causes
have intervened. The points of convergence seem to stand in some relation
to those points in the embryo which are last closed in during development.
There appears, also, to exist some relation between the arrangement of the
hair on the limbs, and the course of the medullary arteries. (9. On the
hair in Hylobates, see 'Natural History of Mammals,' by C.L. Martin, 1841,
p. 415. Also, Isidore Geoffroy on the American monkeys and other kinds,
'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243. Eschricht, ibid. s. 46, 55,
61. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 619. Wallace,
'Contributions to the Theory of Natural Selection,' 1870, p. 344.)
It must not be supposed that the resemblances between man and certain apes
in the above and in many other points--such as in having a naked forehead,
long tresses on the head, etc.,--are all necessarily the result of unbroken
inheritance from a common progenitor, or of subsequent reversion. Many of
these resemblances are more probably due to analogous variation, which
follows, as I have elsewhere attempted to shew (10. 'Origin of Species,'
5th edit. 1869, p.194. 'The Variation of Animals and Plants under
Domestication,' vol. ii. 1868, p. 348.), from co-descended organisms having
a similar constitution, and having been acted on by like causes inducing
similar modifications. With respect to the similar direction of the hair
on the fore-arms of man and certain monkeys, as this character is common to
almost all the anthropomorphous apes, it may probably be attributed to
inheritance; but this is not certain, as some very distinct American
monkeys are thus characterised.
Although, as we have now seen, man has no just right to form a separate
Order for his own reception, he may perhaps claim a distinct Sub-order or
Family. Prof. Huxley, in his last work (11. 'An Introduction to the
Classification of Animals,' 1869, p. 99.), divides the primates into three
Sub-orders; namely, the Anthropidae with man alone, the Simiadae including
monkeys of all kinds, and the Lemuridae with the diversified genera of
lemurs. As far as differences in certain important points of structure are
concerned, man may no doubt rightly claim the rank of a Sub-order; and this
rank is too low, if we look chiefly to his mental faculties. Nevertheless,
from a genealogical point of view it appears that this rank is too high,
and that man ought to form merely a Family, or possibly even only a Sub-
family. If we imagine three lines of descent proceeding from a common
stock, it is quite conceivable that two of them might after the lapse of
ages be so slightly changed as still to remain as species of the same
genus, whilst the third line might become so greatly modified as to deserve
to rank as a distinct Sub-family, Family, or even Order. But in this case
it is almost certain that the third line would still retain through
inheritance numerous small points of resemblance with the other two. Here,
then, would occur the difficulty, at present insoluble, how much weight we
ought to assign in our classifications to strongly-marked differences in
some few points,--that is, to the amount of modification undergone; and how
much to close resemblance in numerous unimportant points, as indicating the
lines of descent or genealogy. To attach much weight to the few but strong
differences is the most obvious and perhaps the safest course, though it
appears more correct to pay great attention to the many small resemblances,
as giving a truly natural classification.
In forming a judgment on this head with reference to man, we must glance at
the classification of the Simiadae. This family is divided by almost all
naturalists into the Catarrhine group, or Old World monkeys, all of which
are characterised (as their name expresses) by the peculiar structure of
their nostrils, and by having four premolars in each jaw; and into the
Platyrrhine group or New World monkeys (including two very distinct sub-
groups), all of which are characterised by differently constructed
nostrils, and by having six premolars in each jaw. Some other small
differences might be mentioned. Now man unquestionably belongs in his
dentition, in the structure of his nostrils, and some other respects, to
the Catarrhine or Old World division; nor does he resemble the Platyrrhines
more closely than the Catarrhines in any characters, excepting in a few of
not much importance and apparently of an adaptive nature. It is therefore
against all probability that some New World species should have formerly
varied and produced a man-like creature, with all the distinctive
characters proper to the Old World division; losing at the same time all
its own distinctive characters. There can, consequently, hardly be a doubt
that man is an off-shoot from the Old World Simian stem; and that under a
genealogical point of view he must be classed with the Catarrhine division.
(12. This is nearly the same classification as that provisionally adopted
by Mr. St. George Mivart, ('Transactions, Philosophical Society," 1867, p.
300), who, after separating the Lemuridae, divides the remainder of the
Primates into the Hominidae, the Simiadae which answer to the Catarrhines,
the Cebidae, and the Hapalidae,--these two latter groups answering to the
Platyrrhines. Mr. Mivart still abides by the same view; see 'Nature,'
1871, p. 481.)
The anthropomorphous apes, namely the gorilla, chimpanzee, orang, and
hylobates, are by most naturalists separated from the other Old World
monkeys, as a distinct sub-group. I am aware that Gratiolet, relying on
the structure of the brain, does not admit the existence of this sub-group,
and no doubt it is a broken one. Thus the orang, as Mr. St. G. Mivart
remarks, "is one of the most peculiar and aberrant forms to be found in the
Order." (13. 'Transactions, Zoolog. Soc.' vol. vi. 1867, p. 214.) The
remaining non-anthropomorphous Old World monkeys, are again divided by some
naturalists into two or three smaller sub-groups; the genus Semnopithecus,
with its peculiar sacculated stomach, being the type of one sub-group. But
it appears from M. Gaudry's wonderful discoveries in Attica, that during
the Miocene period a form existed there, which connected Semnopithecus and
Macacus; and this probably illustrates the manner in which the other and
higher groups were once blended together.
If the anthropomorphous apes be admitted to form a natural sub-group, then
as man agrees with them, not only in all those characters which he
possesses in common with the whole Catarrhine group, but in other peculiar
characters, such as the absence of a tail and of callosities, and in
general appearance, we may infer that some ancient member of the
anthropomorphous sub-group gave birth to man. It is not probable that,
through the law of analogous variation, a member of one of the other lower
sub-groups should have given rise to a man-like creature, resembling the
higher anthropomorphous apes in so many respects. No doubt man, in
comparison with most of his allies, has undergone an extraordinary amount
of modification, chiefly in consequence of the great development of his
brain and his erect position; nevertheless, we should bear in mind that he
"is but one of several exceptional forms of Primates." (14. Mr. St. G.
Mivart, 'Transactions of the Philosophical Society,' 1867, p. 410.)
Every naturalist, who believes in the principle of evolution, will grant
that the two main divisions of the Simiadae, namely the Catarrhine and
Platyrrhine monkeys, with their sub-groups, have all proceeded from some
one extremely ancient progenitor. The early descendants of this
progenitor, before they had diverged to any considerable extent from each
other, would still have formed a single natural group; but some of the
species or incipient genera would have already begun to indicate by their
diverging characters the future distinctive marks of the Catarrhine and
Platyrrhine divisions. Hence the members of this supposed ancient group
would not have been so uniform in their dentition, or in the structure of
their nostrils, as are the existing Catarrhine monkeys in one way and the
Platyrrhines in another way, but would have resembled in this respect the
allied Lemuridae, which differ greatly from each other in the form of their
muzzles (15. Messrs. Murie and Mivart on the Lemuroidea, 'Transactions,
Zoological Society,' vol. vii, 1869, p. 5.), and to an extraordinary degree
in their dentition.
The Catarrhine and Platyrrhine monkeys agree in a multitude of characters,
as is shewn by their unquestionably belonging to one and the same Order.
The many characters which they possess in common can hardly have been
independently acquired by so many distinct species; so that these
characters must have been inherited. But a naturalist would undoubtedly
have ranked as an ape or a monkey, an ancient form which possessed many
characters common to the Catarrhine and Platyrrhine monkeys, other
characters in an intermediate condition, and some few, perhaps, distinct
from those now found in either group. And as man from a genealogical point
of view belongs to the Catarrhine or Old World stock, we must conclude,
however much the conclusion may revolt our pride, that our early
progenitors would have been properly thus designated. (16. Haeckel has
come to this same conclusion. See 'Uber die Entstehung des
Menschengeschlechts,' in Virchow's 'Sammlung. gemein. wissen. Vortrage,'
1868, s. 61. Also his 'Naturliche Schopfungsgeschicte,' 1868, in which he
gives in detail his views on the genealogy of man.) But we must not fall
into the error of supposing that the early progenitor of the whole Simian
stock, including man, was identical with, or even closely resembled, any
existing ape or monkey.
ON THE BIRTHPLACE AND ANTIQUITY OF MAN.
We are naturally led to enquire, where was the birthplace of man at that
stage of descent when our progenitors diverged from the Catarrhine stock?
The fact that they belonged to this stock clearly shews that they inhabited
the Old World; but not Australia nor any oceanic island, as we may infer
from the laws of geographical distribution. In each great region of the
world the living mammals are closely related to the extinct species of the
same region. It is therefore probable that Africa was formerly inhabited
by extinct apes closely allied to the gorilla and chimpanzee; and as these
two species are now man's nearest allies, it is somewhat more probable that
our early progenitors lived on the African continent than elsewhere. But
it is useless to speculate on this subject; for two or three
anthropomorphous apes, one the Dryopithecus (17. Dr. C. Forsyth Major,
'Sur les Singes fossiles trouves en Italie:' 'Soc. Ital. des Sc. Nat.' tom.
xv. 1872.) of Lartet, nearly as large as a man, and closely allied to
Hylobates, existed in Europe during the Miocene age; and since so remote a
period the earth has certainly undergone many great revolutions, and there
has been ample time for migration on the largest scale.
At the period and place, whenever and wherever it was, when man first lost
his hairy covering, he probably inhabited a hot country; a circumstance
favourable for the frugiferous diet on which, judging from analogy, he
subsisted. We are far from knowing how long ago it was when man first
diverged from the Catarrhine stock; but it may have occurred at an epoch as
remote as the Eocene period; for that the higher apes had diverged from the
lower apes as early as the Upper Miocene period is shewn by the existence
of the Dryopithecus. We are also quite ignorant at how rapid a rate
organisms, whether high or low in the scale, may be modified under
favourable circumstances; we know, however, that some have retained the
same form during an enormous lapse of time. From what we see going on
under domestication, we learn that some of the co-descendants of the same
species may be not at all, some a little, and some greatly changed, all
within the same period. Thus it may have been with man, who has undergone
a great amount of modification in certain characters in comparison with the
higher apes.
The great break in the organic chain between man and his nearest allies,
which cannot be bridged over by any extinct or living species, has often
been advanced as a grave objection to the belief that man is descended from
some lower form; but this objection will not appear of much weight to those
who, from general reasons, believe in the general principle of evolution.
Breaks often occur in all parts of the series, some being wide, sharp and
defined, others less so in various degrees; as between the orang and its
nearest allies--between the Tarsius and the other Lemuridae--between the
elephant, and in a more striking manner between the Ornithorhynchus or
Echidna, and all other mammals. But these breaks depend merely on the
number of related forms which have become extinct. At some future period,
not very distant as measured by centuries, the civilised races of man will
almost certainly exterminate, and replace, the savage races throughout the
world. At the same time the anthropomorphous apes, as Professor
Schaaffhausen has remarked (18. 'Anthropological Review,' April 1867, p.
236.), will no doubt be exterminated. The break between man and his
nearest allies will then be wider, for it will intervene between man in a
more civilised state, as we may hope, even than the Caucasian, and some ape
as low as a baboon, instead of as now between the negro or Australian and
the gorilla.
With respect to the absence of fossil remains, serving to connect man with
his ape-like progenitors, no one will lay much stress on this fact who
reads Sir C. Lyell's discussion (19. 'Elements of Geology,' 1865, pp. 583-
585. 'Antiquity of Man,' 1863, p. 145.), where he shews that in all the
vertebrate classes the discovery of fossil remains has been a very slow and
fortuitous process. Nor should it be forgotten that those regions which
are the most likely to afford remains connecting man with some extinct ape-
like creature, have not as yet been searched by geologists.
LOWER STAGES IN THE GENEALOGY OF MAN.
We have seen that man appears to have diverged from the Catarrhine or Old
World division of the Simiadae, after these had diverged from the New World
division. We will now endeavour to follow the remote traces of his
genealogy, trusting principally to the mutual affinities between the
various classes and orders, with some slight reference to the periods, as
far as ascertained, of their successive appearance on the earth. The
Lemuridae stand below and near to the Simiadae, and constitute a very
distinct family of the primates, or, according to Haeckel and others, a
distinct Order. This group is diversified and broken to an extraordinary
degree, and includes many aberrant forms. It has, therefore, probably
suffered much extinction. Most of the remnants survive on islands, such as
Madagascar and the Malayan archipelago, where they have not been exposed to
so severe a competition as they would have been on well-stocked continents.
This group likewise presents many gradations, leading, as Huxley remarks
(20. 'Man's Place in Nature,' p. 105.), "insensibly from the crown and
summit of the animal creation down to creatures from which there is but a
step, as it seems, to the lowest, smallest, and least intelligent of the
placental mammalia." From these various considerations it is probable that
the Simiadae were originally developed from the progenitors of the existing
Lemuridae; and these in their turn from forms standing very low in the
mammalian series.
The Marsupials stand in many important characters below the placental
mammals. They appeared at an earlier geological period, and their range
was formerly much more extensive than at present. Hence the Placentata are
generally supposed to have been derived from the Implacentata or
Marsupials; not, however, from forms closely resembling the existing
Marsupials, but from their early progenitors. The Monotremata are plainly
allied to the Marsupials, forming a third and still lower division in the
great mammalian series. They are represented at the present day solely by
the Ornithorhynchus and Echidna; and these two forms may be safely
considered as relics of a much larger group, representatives of which have
been preserved in Australia through some favourable concurrence of
circumstances. The Monotremata are eminently interesting, as leading in
several important points of structure towards the class of reptiles.
In attempting to trace the genealogy of the Mammalia, and therefore of man,
lower down in the series, we become involved in greater and greater
obscurity; but as a most capable judge, Mr. Parker, has remarked, we have
good reason to believe, that no true bird or reptile intervenes in the
direct line of descent. He who wishes to see what ingenuity and knowledge
can effect, may consult Prof. Haeckel's works. (21. Elaborate tables are
given in his 'Generelle Morphologie' (B. ii. s. cliii. and s. 425); and
with more especial reference to man in his 'Naturliche
Schopfungsgeschichte,' 1868. Prof. Huxley, in reviewing this latter work
('The Academy,' 1869, p. 42) says, that he considers the phylum or lines of
descent of the Vertebrata to be admirably discussed by Haeckel, although he
differs on some points. He expresses, also, his high estimate of the
general tenor and spirit of the whole work.) I will content myself with a
few general remarks. Every evolutionist will admit that the five great
vertebrate classes, namely, mammals, birds, reptiles, amphibians, and
fishes, are descended from some one prototype; for they have much in
common, especially during their embryonic state. As the class of fishes is
the most lowly organised, and appeared before the others, we may conclude
that all the members of the vertebrate kingdom are derived from some
fishlike animal. The belief that animals so distinct as a monkey, an
elephant, a humming-bird, a snake, a frog, and a fish, etc., could all have
sprung from the same parents, will appear monstrous to those who have not
attended to the recent progress of natural history. For this belief
implies the former existence of links binding closely together all these
forms, now so utterly unlike.
Nevertheless, it is certain that groups of animals have existed, or do now
exist, which serve to connect several of the great vertebrate classes more
or less closely. We have seen that the Ornithorhynchus graduates towards
reptiles; and Prof. Huxley has discovered, and is confirmed by Mr. Cope and
others, that the Dinosaurians are in many important characters intermediate
between certain reptiles and certain birds--the birds referred to being the
ostrich-tribe (itself evidently a widely-diffused remnant of a larger
group) and the Archeopteryx, that strange Secondary bird, with a long
lizard-like tail. Again, according to Prof. Owen (22. 'Palaeontology'
1860, p. 199.), the Ichthyosaurians--great sea-lizards furnished with
paddles--present many affinities with fishes, or rather, according to
Huxley, with amphibians; a class which, including in its highest division
frogs and toads, is plainly allied to the Ganoid fishes. These latter
fishes swarmed during the earlier geological periods, and were constructed
on what is called a generalised type, that is, they presented diversified
affinities with other groups of organisms. The Lepidosiren is also so
closely allied to amphibians and fishes, that naturalists long disputed in
which of these two classes to rank it; it, and also some few Ganoid fishes,
have been preserved from utter extinction by inhabiting rivers, which are
harbours of refuge, and are related to the great waters of the ocean in the
same way that islands are to continents.
Lastly, one single member of the immense and diversified class of fishes,
namely, the lancelet or amphioxus, is so different from all other fishes,
that Haeckel maintains that it ought to form a distinct class in the
vertebrate kingdom. This fish is remarkable for its negative characters;
it can hardly be said to possess a brain, vertebral column, or heart, etc.;
so that it was classed by the older naturalists amongst the worms. Many
years ago Prof. Goodsir perceived that the lancelet presented some
affinities with the Ascidians, which are invertebrate, hermaphrodite,
marine creatures permanently attached to a support. They hardly appear
like animals, and consist of a simple, tough, leathery sack, with two small
projecting orifices. They belong to the Mulluscoida of Huxley--a lower
division of the great kingdom of the Mollusca; but they have recently been
placed by some naturalists amongst the Vermes or worms. Their larvae
somewhat resemble tadpoles in shape (23. At the Falkland Islands I had the
satisfaction of seeing, in April, 1833, and therefore some years before any
other naturalist, the locomotive larvae of a compound Ascidian, closely
allied to Synoicum, but apparently generically distinct from it. The tail
was about five times as long as the oblong head, and terminated in a very
fine filament. It was, as sketched by me under a simple microscope,
plainly divided by transverse opaque partitions, which I presume represent
the great cells figured by Kovalevsky. At an early stage of development
the tail was closely coiled round the head of the larva.), and have the
power of swimming freely about. Mr. Kovalevsky (24. 'Memoires de l'Acad.
des Sciences de St. Petersbourg,' tom. x. No. 15, 1866.) has lately
observed that the larvae of Ascidians are related to the Vertebrata, in
their manner of development, in the relative position of the nervous
system, and in possessing a structure closely like the chorda dorsalis of
vertebrate animals; and in this he has been since confirmed by Prof.
Kupffer. M. Kovalevsky writes to me from Naples, that he has now carried
these observations yet further, and should his results be well established,
the whole will form a discovery of the very greatest value. Thus, if we
may rely on embryology, ever the safest guide in classification, it seems
that we have at last gained a clue to the source whence the Vertebrata were
derived. (25. But I am bound to add that some competent judges dispute
this conclusion; for instance, M. Giard, in a series of papers in the
'Archives de Zoologie Experimentale,' for 1872. Nevertheless, this
naturalist remarks, p. 281, "L'organisation de la larve ascidienne en
dehors de toute hypothese et de toute theorie, nous montre comment la
nature peut produire la disposition fondamentale du type vertebre
(l'existence d'une corde dorsale) chez un invertebre par la seule condition
vitale de l'adaptation, et cette simple possibilite du passage supprime
l'abime entre les deux sous-regnes, encore bien qu'en ignore par ou le
passage s'est fait en realite.") We should then be justified in believing
that at an extremely remote period a group of animals existed, resembling
in many respects the larvae of our present Ascidians, which diverged into
two great branches--the one retrograding in development and producing the
present class of Ascidians, the other rising to the crown and summit of the
animal kingdom by giving birth to the Vertebrata.
We have thus far endeavoured rudely to trace the genealogy of the
Vertebrata by the aid of their mutual affinities. We will now look to man
as he exists; and we shall, I think, be able partially to restore the
structure of our early progenitors, during successive periods, but not in
due order of time. This, can be effected by means of the rudiments which
man still retains, by the characters which occasionally make their
appearance in him through reversion, and by the aid of the principles of
morphology and embryology. The various facts, to which I shall here
allude, have been given in the previous chapters.
The early progenitors of man must have been once covered with hair, both
sexes having beards; their ears were probably pointed, and capable of
movement; and their bodies were provided with a tail, having the proper
muscles. Their limbs and bodies were also acted on by many muscles which
now only occasionally reappear, but are normally present in the Quadrumana.
At this or some earlier period, the great artery and nerve of the humerus
ran through a supra-condyloid foramen. The intestine gave forth a much
larger diverticulum or caecum than that now existing. The foot was then
prehensile, judging from the condition of the great toe in the foetus; and
our progenitors, no doubt, were arboreal in their habits, and frequented
some warm, forest-clad land. The males had great canine teeth, which
served them as formidable weapons. At a much earlier period the uterus was
double; the excreta were voided through a cloaca; and the eye was protected
by a third eyelid or nictitating membrane. At a still earlier period the
progenitors of man must have been aquatic in their habits; for morphology
plainly tells us that our lungs consist of a modified swim-bladder, which
once served as a float. The clefts on the neck in the embryo of man shew
where the branchiae once existed. In the lunar or weekly recurrent periods
of some of our functions we apparently still retain traces of our
primordial birthplace, a shore washed by the tides. At about this same
early period the true kidneys were replaced by the corpora wolffiana. The
heart existed as a simple pulsating vessel; and the chorda dorsalis took
the place of a vertebral column. These early ancestors of man, thus seen
in the dim recesses of time, must have been as simply, or even still more
simply organised than the lancelet or amphioxus.
There is one other point deserving a fuller notice. It has long been known
that in the vertebrate kingdom one sex bears rudiments of various accessory
parts, appertaining to the reproductive system, which properly belong to
the opposite sex; and it has now been ascertained that at a very early
embryonic period both sexes possess true male and female glands. Hence
some remote progenitor of the whole vertebrate kingdom appears to have been
hermaphrodite or androgynous. (26. This is the conclusion of Prof.
Gegenbaur, one of the highest authorities in comparative anatomy: see
'Grundzuge der vergleich. Anat.' 1870, s. 876. The result has been arrived
at chiefly from the study of the Amphibia; but it appears from the
researches of Waldeyer (as quoted in 'Journal of Anat. and Phys.' 1869, p.
161), that the sexual organs of even "the higher vertebrata are, in their
early condition, hermaphrodite." Similar views have long been held by some
authors, though until recently without a firm basis.) But here we
encounter a singular difficulty. In the mammalian class the males possess
rudiments of a uterus with the adjacent passage, in their vesiculae
prostaticae; they bear also rudiments of mammae, and some male Marsupials
have traces of a marsupial sack. (27. The male Thylacinus offers the best
instance. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 771.) Other
analogous facts could be added. Are we, then, to suppose that some
extremely ancient mammal continued androgynous, after it had acquired the
chief distinctions of its class, and therefore after it had diverged from
the lower classes of the vertebrate kingdom? This seems very improbable,
for we have to look to fishes, the lowest of all the classes, to find any
still existent androgynous forms. (28. Hermaphroditism has been observed
in several species of Serranus, as well as in some other fishes, where it
is either normal and symmetrical, or abnormal and unilateral. Dr.
Zouteveen has given me references on this subject, more especially to a
paper by Prof. Halbertsma, in the 'Transact. of the Dutch Acad. of
Sciences,' vol. xvi. Dr. Gunther doubts the fact, but it has now been
recorded by too many good observers to be any longer disputed. Dr. M.
Lessona writes to me, that he has verified the observations made by
Cavolini on Serranus. Prof. Ercolani has recently shewn ('Accad. delle
Scienze,' Bologna, Dec. 28, 1871) that eels are androgynous.) That various
accessory parts, proper to each sex, are found in a rudimentary condition
in the opposite sex, may be explained by such organs having been gradually
acquired by the one sex, and then transmitted in a more or less imperfect
state to the other. When we treat of sexual selection, we shall meet with
innumerable instances of this form of transmission,--as in the case of the
spurs, plumes, and brilliant colours, acquired for battle or ornament by
male birds, and inherited by the females in an imperfect or rudimentary
condition.
The possession by male mammals of functionally imperfect mammary organs is,
in some respects, especially curious. The Monotremata have the proper
milk-secreting glands with orifices, but no nipples; and as these animals
stand at the very base of the mammalian series, it is probable that the
progenitors of the class also had milk-secreting glands, but no nipples.
This conclusion is supported by what is known of their manner of
development; for Professor Turner informs me, on the authority of Kolliker
and Langer, that in the embryo the mammary glands can be distinctly traced
before the nipples are in the least visible; and the development of
successive parts in the individual generally represents and accords with
the development of successive beings in the same line of descent. The
Marsupials differ from the Monotremata by possessing nipples; so that
probably these organs were first acquired by the Marsupials, after they had
diverged from, and risen above, the Monotremata, and were then transmitted
to the placental mammals. (29. Prof. Gegenbaur has shewn ('Jenaische
Zeitschrift,' Bd. vii. p. 212) that two distinct types of nipples prevail
throughout the several mammalian orders, but that it is quite intelligible
how both could have been derived from the nipples of the Marsupials, and
the latter from those of the Monotremata. See, also, a memoir by Dr. Max
Huss, on the mammary glands, ibid. B. viii. p. 176.) No one will suppose
that the marsupials still remained androgynous, after they had
approximately acquired their present structure. How then are we to account
for male mammals possessing mammae? It is possible that they were first
developed in the females and then transferred to the males, but from what
follows this is hardly probable.
It may be suggested, as another view, that long after the progenitors of
the whole mammalian class had ceased to be androgynous, both sexes yielded
milk, and thus nourished their young; and in the case of the Marsupials,
that both sexes carried their young in marsupial sacks. This will not
appear altogether improbable, if we reflect that the males of existing
syngnathous fishes receive the eggs of the females in their abdominal
pouches, hatch them, and afterwards, as some believe, nourish the young
(30. Mr. Lockwood believes (as quoted in 'Quart. Journal of Science,'
April 1868, p. 269), from what he has observed of the development of
Hippocampus, that the walls of the abdominal pouch of the male in some way
afford nourishment. On male fishes hatching the ova in their mouths, see a
very interesting paper by Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.'
Sept. 15, 1857; also Prof. Turner, in 'Journal of Anatomy and Physiology,'
Nov. 1, 1866, p. 78. Dr. Gunther has likewise described similar cases.);--
that certain other male fishes hatch the eggs within their mouths or
branchial cavities;--that certain male toads take the chaplets of eggs from
the females, and wind them round their own thighs, keeping them there until
the tadpoles are born;--that certain male birds undertake the whole duty of
incubation, and that male pigeons, as well as the females, feed their
nestlings with a secretion from their crops. But the above suggestion
first occurred to me from mammary glands of male mammals being so much more
perfectly developed than the rudiments of the other accessory reproductive
parts, which are found in the one sex though proper to the other. The
mammary glands and nipples, as they exist in male mammals, can indeed
hardly be called rudimentary; they are merely not fully developed, and not
functionally active. They are sympathetically affected under the influence
of certain diseases, like the same organs in the female. They often
secrete a few drops of milk at birth and at puberty: this latter fact
occurred in the curious case, before referred to, where a young man
possessed two pairs of mammae. In man and some other male mammals these
organs have been known occasionally to become so well developed during
maturity as to yield a fair supply of milk. Now if we suppose that during
a former prolonged period male mammals aided the females in nursing their
offspring (31. Mlle. C. Royer has suggested a similar view in her 'Origine
de l'homme,' etc., 1870.), and that afterwards from some cause (as from the
production of a smaller number of young) the males ceased to give this aid,
disuse of the organs during maturity would lead to their becoming inactive;
and from two well-known principles of inheritance, this state of inactivity
would probably be transmitted to the males at the corresponding age of
maturity. But at an earlier age these organs would be left unaffected, so
that they would be almost equally well developed in the young of both
sexes.
CONCLUSION.
Von Baer has defined advancement or progress in the organic scale better
than any one else, as resting on the amount of differentiation and
specialisation of the several parts of a being,--when arrived at maturity,
as I should be inclined to add. Now as organisms have become slowly
adapted to diversified lines of life by means of natural selection, their
parts will have become more and more differentiated and specialised for
various functions from the advantage gained by the division of
physiological labour. The same part appears often to have been modified
first for one purpose, and then long afterwards for some other and quite
distinct purpose; and thus all the parts are rendered more and more
complex. But each organism still retains the general type of structure of
the progenitor from which it was aboriginally derived. In accordance with
this view it seems, if we turn to geological evidence, that organisation on
the whole has advanced throughout the world by slow and interrupted steps.
In the great kingdom of the Vertebrata it has culminated in man. It must
not, however, be supposed that groups of organic beings are always
supplanted, and disappear as soon as they have given birth to other and
more perfect groups. The latter, though victorious over their
predecessors, may not have become better adapted for all places in the
economy of nature. Some old forms appear to have survived from inhabiting
protected sites, where they have not been exposed to very severe
competition; and these often aid us in constructing our genealogies, by
giving us a fair idea of former and lost populations. But we must not fall
into the error of looking at the existing members of any lowly-organised
group as perfect representatives of their ancient predecessors.
The most ancient progenitors in the kingdom of the Vertebrata, at which we
are able to obtain an obscure glance, apparently consisted of a group of
marine animals (32. The inhabitants of the seashore must be greatly
affected by the tides; animals living either about the MEAN high-water
mark, or about the MEAN low-water mark, pass through a complete cycle of
tidal changes in a fortnight. Consequently, their food supply will undergo
marked changes week by week. The vital functions of such animals, living
under these conditions for many generations, can hardly fail to run their
course in regular weekly periods. Now it is a mysterious fact that in the
higher and now terrestrial Vertebrata, as well as in other classes, many
normal and abnormal processes have one or more whole weeks as their
periods; this would be rendered intelligible if the Vertebrata are
descended from an animal allied to the existing tidal Ascidians. Many
instances of such periodic processes might be given, as the gestation of
mammals, the duration of fevers, etc. The hatching of eggs affords also a
good example, for, according to Mr. Bartlett ('Land and Water,' Jan. 7,
1871), the eggs of the pigeon are hatched in two weeks; those of the fowl
in three; those of the duck in four; those of the goose in five; and those
of the ostrich in seven weeks. As far as we can judge, a recurrent period,
if approximately of the right duration for any process or function, would
not, when once gained, be liable to change; consequently it might be thus
transmitted through almost any number of generations. But if the function
changed, the period would have to change, and would be apt to change almost
abruptly by a whole week. This conclusion, if sound, is highly remarkable;
for the period of gestation in each mammal, and the hatching of each bird's
eggs, and many other vital processes, thus betray to us the primordial
birthplace of these animals.), resembling the larvae of existing Ascidians.
These animals probably gave rise to a group of fishes, as lowly organised
as the lancelet; and from these the Ganoids, and other fishes like the
Lepidosiren, must have been developed. From such fish a very small advance
would carry us on to the Amphibians. We have seen that birds and reptiles
were once intimately connected together; and the Monotremata now connect
mammals with reptiles in a slight degree. But no one can at present say by
what line of descent the three higher and related classes, namely, mammals,
birds, and reptiles, were derived from the two lower vertebrate classes,
namely, amphibians and fishes. In the class of mammals the steps are not
difficult to conceive which led from the ancient Monotremata to the ancient
Marsupials; and from these to the early progenitors of the placental
mammals. We may thus ascend to the Lemuridae; and the interval is not very
wide from these to the Simiadae. The Simiadae then branched off into two
great stems, the New World and Old World monkeys; and from the latter, at a
remote period, Man, the wonder and glory of the Universe, proceeded.
Thus we have given to man a pedigree of prodigious length, but not, it may
be said, of noble quality. The world, it has often been remarked, appears
as if it had long been preparing for the advent of man: and this, in one
sense is strictly true, for he owes his birth to a long line of
progenitors. If any single link in this chain had never existed, man would
not have been exactly what he now is. Unless we wilfully close our eyes,
we may, with our present knowledge, approximately recognise our parentage;
nor need we feel ashamed of it. The most humble organism is something much
higher than the inorganic dust under our feet; and no one with an unbiassed
mind can study any living creature, however humble, without being struck
with enthusiasm at its marvellous structure and properties.
CHAPTER VII.
ON THE RACES OF MAN.
The nature and value of specific characters--Application to the races of
man--Arguments in favour of, and opposed to, ranking the so-called races of
man as district species--Sub-species--Monogenists and polygenists--
Convergence of character--Numerous points of resemblance in body and mind
between the most distinct races of man--The state of man when he first
spread over the earth--Each race not descended from a single pair--The
extinction of races--The formation of races--The effects of crossing--
Slight influence of the direct action of the conditions of life--Slight or
no influence of natural selection--Sexual selection.
It is not my intention here to describe the several so-called races of men;
but I am about to enquire what is the value of the differences between them
under a classificatory point of view, and how they have originated. In
determining whether two or more allied forms ought to be ranked as species
or varieties, naturalists are practically guided by the following
considerations; namely, the amount of difference between them, and whether
such differences relate to few or many points of structure, and whether
they are of physiological importance; but more especially whether they are
constant. Constancy of character is what is chiefly valued and sought for
by naturalists. Whenever it can be shewn, or rendered probable, that the
forms in question have remained distinct for a long period, this becomes an
argument of much weight in favour of treating them as species. Even a
slight degree of sterility between any two forms when first crossed, or in
their offspring, is generally considered as a decisive test of their
specific distinctness; and their continued persistence without blending
within the same area, is usually accepted as sufficient evidence, either of
some degree of mutual sterility, or in the case of animals of some mutual
repugnance to pairing.
Independently of fusion from intercrossing, the complete absence, in a
well-investigated region, of varieties linking together any two closely-
allied forms, is probably the most important of all the criterions of their
specific distinctness; and this is a somewhat different consideration from
mere constancy of character, for two forms may be highly variable and yet
not yield intermediate varieties. Geographical distribution is often
brought into play unconsciously and sometimes consciously; so that forms
living in two widely separated areas, in which most of the other
inhabitants are specifically distinct, are themselves usually looked at as
distinct; but in truth this affords no aid in distinguishing geographical
races from so-called good or true species.
Now let us apply these generally-admitted principles to the races of man,
viewing him in the same spirit as a naturalist would any other animal. In
regard to the amount of difference between the races, we must make some
allowance for our nice powers of discrimination gained by the long habit of
observing ourselves. In India, as Elphinstone remarks, although a newly-
arrived European cannot at first distinguish the various native races, yet
they soon appear to him extremely dissimilar (1. 'History of India,' 1841,
vol. i. p. 323. Father Ripa makes exactly the same remark with respect to
the Chinese.); and the Hindoo cannot at first perceive any difference
between the several European nations. Even the most distinct races of man
are much more like each other in form than would at first be supposed;
certain negro tribes must be excepted, whilst others, as Dr. Rohlfs writes
to me, and as I have myself seen, have Caucasian features. This general
similarity is well shewn by the French photographs in the Collection
Anthropologique du Museum de Paris of the men belonging to various races,
the greater number of which might pass for Europeans, as many persons to
whom I have shewn them have remarked. Nevertheless, these men, if seen
alive, would undoubtedly appear very distinct, so that we are clearly much
influenced in our judgment by the mere colour of the skin and hair, by
slight differences in the features, and by expression.
There is, however, no doubt that the various races, when carefully compared
and measured, differ much from each other,--as in the texture of the hair,
the relative proportions of all parts of the body (2. A vast number of
measurements of Whites, Blacks, and Indians, are given in the
'Investigations in the Military and Anthropolog. Statistics of American
Soldiers,' by B.A. Gould, 1869, pp. 298-358; 'On the capacity of the
lungs,' p. 471. See also the numerous and valuable tables, by Dr.
Weisbach, from the observations of Dr. Scherzer and Dr. Schwarz, in the
'Reise der Novara: Anthropolog. Theil,' 1867.), the capacity of the lungs,
the form and capacity of the skull, and even in the convolutions of the
brain. (3. See, for instance, Mr. Marshall's account of the brain of a
Bushwoman, in 'Philosophical Transactions,' 1864, p. 519.) But it would be
an endless task to specify the numerous points of difference. The races
differ also in constitution, in acclimatisation and in liability to certain
diseases. Their mental characteristics are likewise very distinct; chiefly
as it would appear in their emotional, but partly in their intellectual
faculties. Every one who has had the opportunity of comparison, must have
been struck with the contrast between the taciturn, even morose, aborigines
of S. America and the light-hearted, talkative negroes. There is a nearly
similar contrast between the Malays and the Papuans (4. Wallace, 'The
Malay Archipelago,' vol. ii. 1869, p. 178.), who live under the same
physical conditions, and are separated from each other only by a narrow
space of sea.
We will first consider the arguments which may be advanced in favour of
classing the races of man as distinct species, and then the arguments on
the other side. If a naturalist, who had never before seen a Negro,
Hottentot, Australian, or Mongolian, were to compare them, he would at once
perceive that they differed in a multitude of characters, some of slight
and some of considerable importance. On enquiry he would find that they
were adapted to live under widely different climates, and that they
differed somewhat in bodily constitution and mental disposition. If he
were then told that hundreds of similar specimens could be brought from the
same countries, he would assuredly declare that they were as good species
as many to which he had been in the habit of affixing specific names. This
conclusion would be greatly strengthened as soon as he had ascertained that
these forms had all retained the same character for many centuries; and
that negroes, apparently identical with existing negroes, had lived at
least 4000 years ago. (5. With respect to the figures in the famous
Egyptian caves of Abou-Simbel, M. Pouchet says ('The Plurality of the Human
Races,' Eng. translat., 1864, p. 50), that he was far from finding
recognisable representations of the dozen or more nations which some
authors believe that they can recognise. Even some of the most strongly-
marked races cannot be identified with that degree of unanimity which might
have been expected from what has been written on the subject. Thus Messrs.
Nott and Gliddon ('Types of Mankind,' p. 148), state that Rameses II., or
the Great, has features superbly European; whereas Knox, another firm
believer in the specific distinctness of the races of man ('Races of Man,'
1850, p. 201), speaking of young Memnon (the same as Rameses II., as I am
informed by Mr. Birch), insists in the strongest manner that he is
identical in character with the Jews of Antwerp. Again, when I looked at
the statue of Amunoph III., I agreed with two officers of the
establishment, both competent judges, that he had a strongly-marked negro
type of features; but Messrs. Nott and Gliddon (ibid. p. 146, fig. 53),
describe him as a hybrid, but not of "negro intermixture.") He would also
hear, on the authority of an excellent observer, Dr. Lund (6. As quoted by
Nott and Gliddon, 'Types of Mankind,' 1854, p. 439. They give also
corroborative evidence; but C. Vogt thinks that the subject requires
further investigation.), that the human skulls found in the caves of
Brazil, entombed with many extinct mammals, belonged to the same type as
that now prevailing throughout the American Continent.
Our naturalist would then perhaps turn to geographical distribution, and he
would probably declare that those forms must be distinct species, which
differ not only in appearance, but are fitted for hot, as well as damp or
dry countries, and for the Artic regions. He might appeal to the fact that
no species in the group next to man--namely, the Quadrumana, can resist a
low temperature, or any considerable change of climate; and that the
species which come nearest to man have never been reared to maturity, even
under the temperate climate of Europe. He would be deeply impressed with
the fact, first noticed by Agassiz (7. 'Diversity of Origin of the Human
Races,' in the 'Christian Examiner,' July 1850.), that the different races
of man are distributed over the world in the same zoological provinces, as
those inhabited by undoubtedly distinct species and genera of mammals.
This is manifestly the case with the Australian, Mongolian, and Negro races
of man; in a less well-marked manner with the Hottentots; but plainly with
the Papuans and Malays, who are separated, as Mr. Wallace has shewn, by
nearly the same line which divides the great Malayan and Australian
zoological provinces. The Aborigines of America range throughout the
Continent; and this at first appears opposed to the above rule, for most of
the productions of the Southern and Northern halves differ widely: yet
some few living forms, as the opossum, range from the one into the other,
as did formerly some of the gigantic Edentata. The Esquimaux, like other
Arctic animals, extend round the whole polar regions. It should be
observed that the amount of difference between the mammals of the several
zoological provinces does not correspond with the degree of separation
between the latter; so that it can hardly be considered as an anomaly that
the Negro differs more, and the American much less from the other races of
man, than do the mammals of the African and American continents from the
mammals of the other provinces. Man, it may be added, does not appear to
have aboriginally inhabited any oceanic island; and in this respect, he
resembles the other members of his class.
In determining whether the supposed varieties of the same kind of domestic
animal should be ranked as such, or as specifically distinct, that is,
whether any of them are descended from distinct wild species, every
naturalist would lay much stress on the fact of their external parasites
being specifically distinct. All the more stress would be laid on this
fact, as it would be an exceptional one; for I am informed by Mr. Denny
that the most different kinds of dogs, fowls, and pigeons, in England, are
infested by the same species of Pediculi or lice. Now Mr. A. Murray has
carefully examined the Pediculi collected in different countries from the
different races of man (8. 'Transactions of the Royal Society of
Edinburgh,' vol. xxii, 1861, p. 567.); and he finds that they differ, not
only in colour, but in the structure of their claws and limbs. In every
case in which many specimens were obtained the differences were constant.
The surgeon of a whaling ship in the Pacific assured me that when the
Pediculi, with which some Sandwich Islanders on board swarmed, strayed on
to the bodies of the English sailors, they died in the course of three or
four days. These Pediculi were darker coloured, and appeared different
from those proper to the natives of Chiloe in South America, of which he
gave me specimens. These, again, appeared larger and much softer than
European lice. Mr. Murray procured four kinds from Africa, namely, from
the Negroes of the Eastern and Western coasts, from the Hottentots and
Kaffirs; two kinds from the natives of Australia; two from North and two
from South America. In these latter cases it may be presumed that the
Pediculi came from natives inhabiting different districts. With insects
slight structural differences, if constant, are generally esteemed of
specific value: and the fact of the races of man being infested by
parasites, which appear to be specifically distinct, might fairly be urged
as an argument that the races themselves ought to be classed as distinct
species.
Our supposed naturalist having proceeded thus far in his investigation,
would next enquire whether the races of men, when crossed, were in any
degree sterile. He might consult the work (9. 'On the Phenomena of
Hybridity in the Genus Homo,' Eng. translat., 1864.) of Professor Broca, a
cautious and philosophical observer, and in this he would find good
evidence that some races were quite fertile together, but evidence of an
opposite nature in regard to other races. Thus it has been asserted that
the native women of Australia and Tasmania rarely produce children to
European men; the evidence, however, on this head has now been shewn to be
almost valueless. The half-castes are killed by the pure blacks: and an
account has lately been published of eleven half-caste youths murdered and
burnt at the same time, whose remains were found by the police. (10. See
the interesting letter by Mr. T.A. Murray, in the 'Anthropological Review,'
April 1868, p. liii. In this letter Count Strzelecki's statement that
Australian women who have borne children to a white man, are afterwards
sterile with their own race, is disproved. M. A. de Quatrefages has also
collected (Revue des Cours Scientifiques, March, 1869, p. 239), much
evidence that Australians and Europeans are not sterile when crossed.)
Again, it has often been said that when mulattoes intermarry, they produce
few children; on the other hand, Dr. Bachman, of Charleston (11. 'An
Examination of Prof. Agassiz's Sketch of the Nat. Provinces of the Animal
World,' Charleston, 1855, p. 44.), positively asserts that he has known
mulatto families which have intermarried for several generations, and have
continued on an average as fertile as either pure whites or pure blacks.
Enquiries formerly made by Sir C. Lyell on this subject led him, as he
informs me, to the same conclusion. (12. Dr. Rohlfs writes to me that he
found the mixed races in the Great Sahara, derived from Arabs, Berbers, and
Negroes of three tribes, extraordinarily fertile. On the other hand, Mr.
Winwood Reade informs me that the Negroes on the Gold Coast, though
admiring white men and mulattoes, have a maxim that mulattoes should not
intermarry, as the children are few and sickly. This belief, as Mr. Reade
remarks, deserves attention, as white men have visited and resided on the
Gold Coast for four hundred years, so that the natives have had ample time
to gain knowledge through experience.) In the United States the census for
the year 1854 included, according to Dr. Bachman, 405,751 mulattoes; and
this number, considering all the circumstances of the case, seems small;
but it may partly be accounted for by the degraded and anomalous position
of the class, and by the profligacy of the women. A certain amount of
absorption of mulattoes into negroes must always be in progress; and this
would lead to an apparent diminution of the former. The inferior vitality
of mulattoes is spoken of in a trustworthy work (13. 'Military and
Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p.
319.) as a well-known phenomenon; and this, although a different
consideration from their lessened fertility, may perhaps be advanced as a
proof of the specific distinctness of the parent races. No doubt both
animal and vegetable hybrids, when produced from extremely distinct
species, are liable to premature death; but the parents of mulattoes cannot
be put under the category of extremely distinct species. The common Mule,
so notorious for long life and vigour, and yet so sterile, shews how little
necessary connection there is in hybrids between lessened fertility and
vitality; other analogous cases could be cited.
Even if it should hereafter be proved that all the races of men were
perfectly fertile together, he who was inclined from other reasons to rank
them as distinct species, might with justice argue that fertility and
sterility are not safe criterions of specific distinctness. We know that
these qualities are easily affected by changed conditions of life, or by
close inter-breeding, and that they are governed by highly complex laws,
for instance, that of the unequal fertility of converse crosses between the
same two species. With forms which must be ranked as undoubted species, a
perfect series exists from those which are absolutely sterile when crossed,
to those which are almost or completely fertile. The degrees of sterility
do not coincide strictly with the degrees of difference between the parents
in external structure or habits of life. Man in many respects may be
compared with those animals which have long been domesticated, and a large
body of evidence can be advanced in favour of the Pallasian doctrine (14.
The 'Variation of Animals and Plants under Domestication,' vol. ii. p. 109.
I may here remind the reader that the sterility of species when crossed is
not a specially-acquired quality, but, like the incapacity of certain trees
to be grafted together, is incidental on other acquired differences. The
nature of these differences is unknown, but they relate more especially to
the reproductive system, and much less so to external structure or to
ordinary differences in constitution. One important element in the
sterility of crossed species apparently lies in one or both having been
long habituated to fixed conditions; for we know that changed conditions
have a special influence on the reproductive system, and we have good
reason to believe (as before remarked) that the fluctuating conditions of
domestication tend to eliminate that sterility which is so general with
species, in a natural state, when crossed. It has elsewhere been shewn by
me (ibid. vol. ii. p. 185, and 'Origin of Species,' 5th edit. p. 317), that
the sterility of crossed species has not been acquired through natural
selection: we can see that when two forms have already been rendered very
sterile, it is scarcely possible that their sterility should be augmented
by the preservation or survival of the more and more sterile individuals;
for, as the sterility increases, fewer and fewer offspring will be produced
from which to breed, and at last only single individuals will be produced
at the rarest intervals. But there is even a higher grade of sterility
than this. Both Gartner and Kolreuter have proved that in genera of
plants, including many species, a series can be formed from species which,
when crossed, yield fewer and fewer seeds, to species which never produce a
single seed, but yet are affected by the pollen of the other species, as
shewn by the swelling of the germen. It is here manifestly impossible to
select the more sterile individuals, which have already ceased to yield
seeds; so that the acme of sterility, when the germen alone is affected,
cannot have been gained through selection. This acme, and no doubt the
other grades of sterility, are the incidental results of certain unknown
differences in the constitution of the reproductive system of the species
which are crossed.), that domestication tends to eliminate the sterility
which is so general a result of the crossing of species in a state of
nature. From these several considerations, it may be justly urged that the
perfect fertility of the intercrossed races of man, if established, would
not absolutely preclude us from ranking them as distinct species.
Independently of fertility, the characters presented by the offspring from
a cross have been thought to indicate whether or not the parent-forms ought
to be ranked as species or varieties; but after carefully studying the
evidence, I have come to the conclusion that no general rules of this kind
can be trusted. The ordinary result of a cross is the production of a
blended or intermediate form; but in certain cases some of the offspring
take closely after one parent-form, and some after the other. This is
especially apt to occur when the parents differ in characters which first
appeared as sudden variations or monstrosities. (15. 'The Variation of
Animals,' etc., vol. ii. p. 92.) I refer to this point, because Dr. Rohlfs
informs me that he has frequently seen in Africa the offspring of negroes
crossed with members of other races, either completely black or completely
white, or rarely piebald. On the other hand, it is notorious that in
America mulattoes commonly present an intermediate appearance.
We have now seen that a naturalist might feel himself fully justified in
ranking the races of man as distinct species; for he has found that they
are distinguished by many differences in structure and constitution, some
being of importance. These differences have, also, remained nearly
constant for very long periods of time. Our naturalist will have been in
some degree influenced by the enormous range of man, which is a great
anomaly in the class of mammals, if mankind be viewed as a single species.
He will have been struck with the distribution of the several so-called
races, which accords with that of other undoubtedly distinct species of
mammals. Finally, he might urge that the mutual fertility of all the races
has not as yet been fully proved, and even if proved would not be an
absolute proof of their specific identity.
On the other side of the question, if our supposed naturalist were to
enquire whether the forms of man keep distinct like ordinary species, when
mingled together in large numbers in the same country, he would immediately
discover that this was by no means the case. In Brazil he would behold an
immense mongrel population of Negroes and Portuguese; in Chiloe, and other
parts of South America, he would behold the whole population consisting of
Indians and Spaniards blended in various degrees. (16. M. de Quatrefages
has given ('Anthropological Review,' Jan. 1869, p. 22), an interesting
account of the success and energy of the Paulistas in Brazil, who are a
much crossed race of Portuguese and Indians, with a mixture of the blood of
other races.) In many parts of the same continent he would meet with the
most complex crosses between Negroes, Indians, and Europeans; and judging
from the vegetable kingdom, such triple crosses afford the severest test of
the mutual fertility of the parent forms. In one island of the Pacific he
would find a small population of mingled Polynesian and English blood; and
in the Fiji Archipelago a population of Polynesian and Negritos crossed in
all degrees. Many analogous cases could be added; for instance, in Africa.
Hence the races of man are not sufficiently distinct to inhabit the same
country without fusion; and the absence of fusion affords the usual and
best test of specific distinctness.
Our naturalist would likewise be much disturbed as soon as he perceived
that the distinctive characters of all the races were highly variable.
This fact strikes every one on first beholding the negro slaves in Brazil,
who have been imported from all parts of Africa. The same remark holds
good with the Polynesians, and with many other races. It may be doubted
whether any character can be named which is distinctive of a race and is
constant. Savages, even within the limits of the same tribe, are not
nearly so uniform in character, as has been often asserted. Hottentot
women offer certain peculiarities, more strongly marked than those
occurring in any other race, but these are known not to be of constant
occurrence. In the several American tribes, colour and hairiness differ
considerably; as does colour to a certain degree, and the shape of the
features greatly, in the Negroes of Africa. The shape of the skull varies
much in some races (17. For instance, with the aborigines of America and
Australia, Prof. Huxley says ('Transact. Internat. Congress of Prehist.
Arch.' 1868, p. 105), that the skulls of many South Germans and Swiss are
"as short and as broad as those of the Tartars," etc.); and so it is with
every other character. Now all naturalists have learnt by dearly bought
experience, how rash it is to attempt to define species by the aid of
inconstant characters.
But the most weighty of all the arguments against treating the races of man
as distinct species, is that they graduate into each other, independently
in many cases, as far as we can judge, of their having intercrossed. Man
has been studied more carefully than any other animal, and yet there is the
greatest possible diversity amongst capable judges whether he should be
classed as a single species or race, or as two (Virey), as three
(Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven
(Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent),
sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-
three, according to Burke. (18. See a good discussion on this subject in
Waitz, 'Introduction to Anthropology,' Eng. translat., 1863, pp. 198-208,
227. I have taken some of the above statements from H. Tuttle's 'Origin
and Antiquity of Physical Man,' Boston, 1866, p. 35.) This diversity of
judgment does not prove that the races ought not to be ranked as species,
but it shews that they graduate into each other, and that it is hardly
possible to discover clear distinctive characters between them.
Every naturalist who has had the misfortune to undertake the description of
a group of highly varying organisms, has encountered cases (I speak after
experience) precisely like that of man; and if of a cautious disposition,
he will end by uniting all the forms which graduate into each other, under
a single species; for he will say to himself that he has no right to give
names to objects which he cannot define. Cases of this kind occur in the
Order which includes man, namely in certain genera of monkeys; whilst in
other genera, as in Cercopithecus, most of the species can be determined
with certainty. In the American genus Cebus, the various forms are ranked
by some naturalists as species, by others as mere geographical races. Now
if numerous specimens of Cebus were collected from all parts of South
America, and those forms which at present appear to be specifically
distinct, were found to graduate into each other by close steps, they would
usually be ranked as mere varieties or races; and this course has been
followed by most naturalists with respect to the races of man.
Nevertheless, it must be confessed that there are forms, at least in the
vegetable kingdom (19. Prof. Nageli has carefully described several
striking cases in his 'Botanische Mittheilungen,' B. ii. 1866, ss. 294-369.
Prof. Asa Gray has made analogous remarks on some intermediate forms in the
Compositae of N. America.), which we cannot avoid naming as species, but
which are connected together by numberless gradations, independently of
intercrossing.
Some naturalists have lately employed the term "sub-species" to designate
forms which possess many of the characteristics of true species, but which
hardly deserve so high a rank. Now if we reflect on the weighty arguments
above given, for raising the races of man to the dignity of species, and
the insuperable difficulties on the other side in defining them, it seems
that the term "sub-species" might here be used with propriety. But from
long habit the term "race" will perhaps always be employed. The choice of
terms is only so far important in that it is desirable to use, as far as
possible, the same terms for the same degrees of difference. Unfortunately
this can rarely be done: for the larger genera generally include closely-
allied forms, which can be distinguished only with much difficulty, whilst
the smaller genera within the same family include forms that are perfectly
distinct; yet all must be ranked equally as species. So again, species
within the same large genus by no means resemble each other to the same
degree: on the contrary, some of them can generally be arranged in little
groups round other species, like satellites round planets. (20. 'Origin
of Species,' 5th edit. p. 68.)
The question whether mankind consists of one or several species has of late
years been much discussed by anthropologists, who are divided into the two
schools of monogenists and polygenists. Those who do not admit the
principle of evolution, must look at species as separate creations, or in
some manner as distinct entities; and they must decide what forms of man
they will consider as species by the analogy of the method commonly pursued
in ranking other organic beings as species. But it is a hopeless endeavour
to decide this point, until some definition of the term "species" is
generally accepted; and the definition must not include an indeterminate
element such as an act of creation. We might as well attempt without any
definition to decide whether a certain number of houses should be called a
village, town, or city. We have a practical illustration of the difficulty
in the never-ending doubts whether many closely-allied mammals, birds,
insects, and plants, which represent each other respectively in North
America and Europe, should be ranked as species or geographical races; and
the like holds true of the productions of many islands situated at some
little distance from the nearest continent.
Those naturalists, on the other hand, who admit the principle of evolution,
and this is now admitted by the majority of rising men, will feel no doubt
that all the races of man are descended from a single primitive stock;
whether or not they may think fit to designate the races as distinct
species, for the sake of expressing their amount of difference. (21. See
Prof. Huxley to this effect in the 'Fortnightly Review,' 1865, p. 275.)
With our domestic animals the question whether the various races have
arisen from one or more species is somewhat different. Although it may be
admitted that all the races, as well as all the natural species within the
same genus, have sprung from the same primitive stock, yet it is a fit
subject for discussion, whether all the domestic races of the dog, for
instance, have acquired their present amount of difference since some one
species was first domesticated by man; or whether they owe some of their
characters to inheritance from distinct species, which had already been
differentiated in a state of nature. With man no such question can arise,
for he cannot be said to have been domesticated at any particular period.
During an early stage in the divergence of the races of man from a common
stock, the differences between the races and their number must have been
small; consequently as far as their distinguishing characters are
concerned, they then had less claim to rank as distinct species than the
existing so-called races. Nevertheless, so arbitrary is the term of
species, that such early races would perhaps have been ranked by some
naturalists as distinct species, if their differences, although extremely
slight, had been more constant than they are at present, and had not
graduated into each other.
It is however possible, though far from probable, that the early
progenitors of man might formerly have diverged much in character, until
they became more unlike each other than any now existing races; but that
subsequently, as suggested by Vogt (22. 'Lectures on Man,' Eng. translat.,
1864, p. 468.), they converged in character. When man selects the
offspring of two distinct species for the same object, he sometimes induces
a considerable amount of convergence, as far as general appearance is
concerned. This is the case, as shewn by von Nathusius (23. 'Die Rassen
des Schweines,' 1860, s. 46. 'Vorstudien fur Geschichte,' etc.,
Schweinesschadel, 1864, s. 104. With respect to cattle, see M. de
Quatrefages, 'Unite de l'Espece Humaine,' 1861, p. 119.), with the improved
breeds of the pig, which are descended from two distinct species; and in a
less marked manner with the improved breeds of cattle. A great anatomist,
Gratiolet, maintains that the anthropomorphous apes do not form a natural
sub-group; but that the orang is a highly developed gibbon or
semnopithecus, the chimpanzee a highly developed macacus, and the gorilla a
highly developed mandrill. If this conclusion, which rests almost
exclusively on brain-characters, be admitted, we should have a case of
convergence at least in external characters, for the anthropomorphous apes
are certainly more like each other in many points, than they are to other
apes. All analogical resemblances, as of a whale to a fish, may indeed be
said to be cases of convergence; but this term has never been applied to
superficial and adaptive resemblances. It would, however, be extremely
rash to attribute to convergence close similarity of character in many
points of structure amongst the modified descendants of widely distinct
beings. The form of a crystal is determined solely by the molecular
forces, and it is not surprising that dissimilar substances should
sometimes assume the same form; but with organic beings we should bear in
mind that the form of each depends on an infinity of complex relations,
namely on variations, due to causes far too intricate to be followed,--on
the nature of the variations preserved, these depending on the physical
conditions, and still more on the surrounding organisms which compete with
each,--and lastly, on inheritance (in itself a fluctuating element) from
innumerable progenitors, all of which have had their forms determined
through equally complex relations. It appears incredible that the modified
descendants of two organisms, if these differed from each other in a marked
manner, should ever afterwards converge so closely as to lead to a near
approach to identity throughout their whole organisation. In the case of
the convergent races of pigs above referred to, evidence of their descent
from two primitive stocks is, according to von Nathusius, still plainly
retained, in certain bones of their skulls. If the races of man had
descended, as is supposed by some naturalists, from two or more species,
which differed from each other as much, or nearly as much, as does the
orang from the gorilla, it can hardly be doubted that marked differences in
the structure of certain bones would still be discoverable in man as he now
exists.
Although the existing races of man differ in many respects, as in colour,
hair, shape of skull, proportions of the body, etc., yet if their whole
structure be taken into consideration they are found to resemble each other
closely in a multitude of points. Many of these are of so unimportant or
of so singular a nature, that it is extremely improbable that they should
have been independently acquired by aboriginally distinct species or races.
The same remark holds good with equal or greater force with respect to the
numerous points of mental similarity between the most distinct races of
man. The American aborigines, Negroes and Europeans are as different from
each other in mind as any three races that can be named; yet I was
incessantly struck, whilst living with the Feugians on board the "Beagle,"
with the many little traits of character, shewing how similar their minds
were to ours; and so it was with a full-blooded negro with whom I happened
once to be intimate.
He who will read Mr. Tylor's and Sir J. Lubbock's interesting works (24.
Tylor's 'Early History of Mankind,' 1865: with respect to gesture-
language, see p. 54. Lubbock's 'Prehistoric Times,' 2nd edit. 1869.) can
hardly fail to be deeply impressed with the close similarity between the
men of all races in tastes, dispositions and habits. This is shewn by the
pleasure which they all take in dancing, rude music, acting, painting,
tattooing, and otherwise decorating themselves; in their mutual
comprehension of gesture-language, by the same expression in their
features, and by the same inarticulate cries, when excited by the same
emotions. This similarity, or rather identity, is striking, when
contrasted with the different expressions and cries made by distinct
species of monkeys. There is good evidence that the art of shooting with
bows and arrows has not been handed down from any common progenitor of
mankind, yet as Westropp and Nilsson have remarked (25. 'On Analogous
Forms of Implements,' in 'Memoirs of Anthropological Society' by H.M.
Westropp. 'The Primitive Inhabitants of Scandinavia,' Eng. translat.,
edited by Sir J. Lubbock, 1868, p. 104.), the stone arrow-heads, brought
from the most distant parts of the world, and manufactured at the most
remote periods, are almost identical; and this fact can only be accounted
for by the various races having similar inventive or mental powers. The
same observation has been made by archaeologists (26. Westropp 'On
Cromlechs,' etc., 'Journal of Ethnological Soc.' as given in 'Scientific
Opinion,' June 2nd, 1869, p. 3.) with respect to certain widely-prevalent
ornaments, such as zig-zags, etc.; and with respect to various simple
beliefs and customs, such as the burying of the dead under megalithic
structures. I remember observing in South America (27. 'Journal of
Researches: Voyage of the "Beagle,"' p. 46.), that there, as in so many
other parts of the world, men have generally chosen the summits of lofty
hills, to throw up piles of stones, either as a record of some remarkable
event, or for burying their dead.
Now when naturalists observe a close agreement in numerous small details of
habits, tastes, and dispositions between two or more domestic races, or
between nearly-allied natural forms, they use this fact as an argument that
they are descended from a common progenitor who was thus endowed; and
consequently that all should be classed under the same species. The same
argument may be applied with much force to the races of man.
As it is improbable that the numerous and unimportant points of resemblance
between the several races of man in bodily structure and mental faculties
(I do not here refer to similar customs) should all have been independently
acquired, they must have been inherited from progenitors who had these same
characters. We thus gain some insight into the early state of man, before
he had spread step by step over the face of the earth. The spreading of
man to regions widely separated by the sea, no doubt, preceded any great
amount of divergence of character in the several races; for otherwise we
should sometimes meet with the same race in distinct continents; and this
is never the case. Sir J. Lubbock, after comparing the arts now practised
by savages in all parts of the world, specifies those which man could not
have known, when he first wandered from his original birthplace; for if
once learnt they would never have been forgotten. (28. 'Prehistoric
Times,' 1869, p. 574.) He thus shews that "the spear, which is but a
development of the knife-point, and the club, which is but a long hammer,
are the only things left." He admits, however, that the art of making fire
probably had been already discovered, for it is common to all the races now
existing, and was known to the ancient cave-inhabitants of Europe. Perhaps
the art of making rude canoes or rafts was likewise known; but as man
existed at a remote epoch, when the land in many places stood at a very
different level to what it does now, he would have been able, without the
aid of canoes, to have spread widely. Sir J. Lubbock further remarks how
improbable it is that our earliest ancestors could have "counted as high as
ten, considering that so many races now in existence cannot get beyond
four." Nevertheless, at this early period, the intellectual and social
faculties of man could hardly have been inferior in any extreme degree to
those possessed at present by the lowest savages; otherwise primeval man
could not have been so eminently successful in the struggle for life, as
proved by his early and wide diffusion.
From the fundamental differences between certain languages, some
philologists have inferred that when man first became widely diffused, he
was not a speaking animal; but it may be suspected that languages, far less
perfect than any now spoken, aided by gestures, might have been used, and
yet have left no traces on subsequent and more highly-developed tongues.
Without the use of some language, however imperfect, it appears doubtful
whether man's intellect could have risen to the standard implied by his
dominant position at an early period.
Whether primeval man, when he possessed but few arts, and those of the
rudest kind, and when his power of language was extremely imperfect, would
have deserved to be called man, must depend on the definition which we
employ. In a series of forms graduating insensibly from some ape-like
creature to man as he now exists, it would be impossible to fix on any
definite point where the term "man" ought to be used. But this is a matter
of very little importance. So again, it is almost a matter of indifference
whether the so-called races of man are thus designated, or are ranked as
species or sub-species; but the latter term appears the more appropriate.
Finally, we may conclude that when the principle of evolution is generally
accepted, as it surely will be before long, the dispute between the
monogenists and the polygenists will die a silent and unobserved death.
One other question ought not to be passed over without notice, namely,
whether, as is sometimes assumed, each sub-species or race of man has
sprung from a single pair of progenitors. With our domestic animals a new
race can readily be formed by carefully matching the varying offspring from
a single pair, or even from a single individual possessing some new
character; but most of our races have been formed, not intentionally from a
selected pair, but unconsciously by the preservation of many individuals
which have varied, however slightly, in some useful or desired manner. If
in one country stronger and heavier horses, and in another country lighter
and fleeter ones, were habitually preferred, we may feel sure that two
distinct sub-breeds would be produced in the course of time, without any
one pair having been separated and bred from, in either country. Many
races have been thus formed, and their manner of formation is closely
analogous to that of natural species. We know, also, that the horses taken
to the Falkland Islands have, during successive generations, become smaller
and weaker, whilst those which have run wild on the Pampas have acquired
larger and coarser heads; and such changes are manifestly due, not to any
one pair, but to all the individuals having been subjected to the same
conditions, aided, perhaps, by the principle of reversion. The new sub-
breeds in such cases are not descended from any single pair, but from many
individuals which have varied in different degrees, but in the same general
manner; and we may conclude that the races of man have been similarly
produced, the modifications being either the direct result of exposure to
different conditions, or the indirect result of some form of selection.
But to this latter subject we shall presently return.
ON THE EXTINCTION OF THE RACES OF MAN.
The partial or complete extinction of many races and sub-races of man is
historically known. Humboldt saw in South America a parrot which was the
sole living creature that could speak a word of the language of a lost
tribe. Ancient monuments and stone implements found in all parts of the
world, about which no tradition has been preserved by the present
inhabitants, indicate much extinction. Some small and broken tribes,
remnants of former races, still survive in isolated and generally
mountainous districts. In Europe the ancient races were all, according to
Shaaffhausen (29. Translation in 'Anthropological Review,' Oct. 1868, p.
431.), "lower in the scale than the rudest living savages"; they must
therefore have differed, to a certain extent, from any existing race. The
remains described by Professor Broca from Les Eyzies, though they
unfortunately appear to have belonged to a single family, indicate a race
with a most singular combination of low or simious, and of high
characteristics. This race is "entirely different from any other, ancient
or modern, that we have heard of." (30. 'Transactions, International
Congress of Prehistoric Archaeology' 1868, pp. 172-175. See also Broca
(tr.) in 'Anthropological Review,' Oct. 1868, p. 410.) It differed,
therefore, from the quaternary race of the caverns of Belgium.
Man can long resist conditions which appear extremely unfavourable for his
existence. (31. Dr. Gerland, 'Ueber das Aussterben der Naturvolker,'
1868, s. 82.) He has long lived in the extreme regions of the North, with
no wood for his canoes or implements, and with only blubber as fuel, and
melted snow as drink. In the southern extremity of America the Fuegians
survive without the protection of clothes, or of any building worthy to be
called a hovel. In South Africa the aborigines wander over arid plains,
where dangerous beasts abound. Man can withstand the deadly influence of
the Terai at the foot of the Himalaya, and the pestilential shores of
tropical Africa.
Extinction follows chiefly from the competition of tribe with tribe, and
race with race. Various checks are always in action, serving to keep down
the numbers of each savage tribe,--such as periodical famines, nomadic
habits and the consequent deaths of infants, prolonged suckling, wars,
accidents, sickness, licentiousness, the stealing of women, infanticide,
and especially lessened fertility. If any one of these checks increases in
power, even slightly, the tribe thus affected tends to decrease; and when
of two adjoining tribes one becomes less numerous and less powerful than
the other, the contest is soon settled by war, slaughter, cannibalism,
slavery, and absorption. Even when a weaker tribe is not thus abruptly
swept away, if it once begins to decrease, it generally goes on decreasing
until it becomes extinct. (32. Gerland (ibid. s. 12) gives facts in
support of this statement.)
When civilised nations come into contact with barbarians the struggle is
short, except where a deadly climate gives its aid to the native race. Of
the causes which lead to the victory of civilised nations, some are plain
and simple, others complex and obscure. We can see that the cultivation of
the land will be fatal in many ways to savages, for they cannot, or will
not, change their habits. New diseases and vices have in some cases proved
highly destructive; and it appears that a new disease often causes much
death, until those who are most susceptible to its destructive influence
are gradually weeded out (33. See remarks to this effect in Sir H.
Holland's 'Medical Notes and Reflections,' 1839, p. 390.); and so it may be
with the evil effects from spirituous liquors, as well as with the
unconquerably strong taste for them shewn by so many savages. It further
appears, mysterious as is the fact, that the first meeting of distinct and
separated people generates disease. (34. I have collected ('Journal of
Researches: Voyage of the "Beagle,"' p. 435) a good many cases bearing on
this subject; see also Gerland, ibid. s. 8. Poeppig speaks of the "breath
of civilisation as poisonous to savages.") Mr. Sproat, who in Vancouver
Island closely attended to the subject of extinction, believed that changed
habits of life, consequent on the advent of Europeans, induces much ill
health. He lays, also, great stress on the apparently trifling cause that
the natives become "bewildered and dull by the new life around them; they
lose the motives for exertion, and get no new ones in their place." (35.
Sproat, 'Scenes and Studies of Savage Life,' 1868, p. 284.)
The grade of their civilisation seems to be a most important element in the
success of competing nations. A few centuries ago Europe feared the
inroads of Eastern barbarians; now any such fear would be ridiculous. It
is a more curious fact, as Mr. Bagehot has remarked, that savages did not
formerly waste away before the classical nations, as they now do before
modern civilised nations; had they done so, the old moralists would have
mused over the event; but there is no lament in any writer of that period
over the perishing barbarians. (36. Bagehot, 'Physics and Politics,'
'Fortnightly Review,' April 1, 1868, p. 455.) The most potent of all the
causes of extinction, appears in many cases to be lessened fertility and
ill-health, especially amongst the children, arising from changed
conditions of life, notwithstanding that the new conditions may not be
injurious in themselves. I am much indebted to Mr. H.H. Howorth for having
called my attention to this subject, and for having given me information
respecting it. I have collected the following cases.
When Tasmania was first colonised the natives were roughly estimated by
some at 7000 and by others at 20,000. Their number was soon greatly
reduced, chiefly by fighting with the English and with each other. After
the famous hunt by all the colonists, when the remaining natives delivered
themselves up to the government, they consisted only of 120 individuals
(37. All the statements here given are taken from 'The Last of the
Tasmanians,' by J. Bonwick, 1870.), who were in 1832 transported to
Flinders Island. This island, situated between Tasmania and Australia, is
forty miles long, and from twelve to eighteen miles broad: it seems
healthy, and the natives were well treated. Nevertheless, they suffered
greatly in health. In 1834 they consisted (Bonwick, p. 250) of forty-seven
adult males, forty-eight adult females, and sixteen children, or in all of
111 souls. In 1835 only one hundred were left. As they continued rapidly
to decrease, and as they themselves thought that they should not perish so
quickly elsewhere, they were removed in 1847 to Oyster Cove in the southern
part of Tasmania. They then consisted (Dec. 20th, 1847) of fourteen men,
twenty-two women and ten children. (38. This is the statement of the
Governor of Tasmania, Sir W. Denison, 'Varieties of Vice-Regal Life,' 1870,
vol. i. p. 67.) But the change of site did no good. Disease and death
still pursued them, and in 1864 one man (who died in 1869), and three
elderly women alone survived. The infertility of the women is even a more
remarkable fact than the liability of all to ill-health and death. At the
time when only nine women were left at Oyster Cove, they told Mr. Bonwick
(p. 386), that only two had ever borne children: and these two had
together produced only three children!
With respect to the cause of this extraordinary state of things, Dr. Story
remarks that death followed the attempts to civilise the natives. "If left
to themselves to roam as they were wont and undisturbed, they would have
reared more children, and there would have been less mortality." Another
careful observer of the natives, Mr. Davis, remarks, "The births have been
few and the deaths numerous. This may have been in a great measure owing
to their change of living and food; but more so to their banishment from
the mainland of Van Diemen's Land, and consequent depression of spirits"
(Bonwick, pp. 388, 390).
Similar facts have been observed in two widely different parts of
Australia. The celebrated explorer, Mr. Gregory, told Mr. Bonwick, that in
Queensland "the want of reproduction was being already felt with the
blacks, even in the most recently settled parts, and that decay would set
in." Of thirteen aborigines from Shark's Bay who visited Murchison River,
twelve died of consumption within three months. (39. For these cases, see
Bonwick's 'Daily Life of the Tasmanians,' 1870, p. 90: and the 'Last of
the Tasmanians,' 1870, p. 386.)
The decrease of the Maories of New Zealand has been carefully investigated
by Mr. Fenton, in an admirable Report, from which all the following
statements, with one exception, are taken. (40. 'Observations on the
Aboriginal Inhabitants of New Zealand,' published by the Government, 1859.)
The decrease in number since 1830 is admitted by every one, including the
natives themselves, and is still steadily progressing. Although it has
hitherto been found impossible to take an actual census of the natives,
their numbers were carefully estimated by residents in many districts. The
result seems trustworthy, and shows that during the fourteen years,
previous to 1858, the decrease was 19.42 per cent. Some of the tribes,
thus carefully examined, lived above a hundred miles apart, some on the
coast, some inland; and their means of subsistence and habits differed to a
certain extent (p. 28). The total number in 1858 was believed to be
53,700, and in 1872, after a second interval of fourteen years, another
census was taken, and the number is given as only 36,359, shewing a
decrease of 32.29 per cent! (41. 'New Zealand,' by Alex. Kennedy, 1873,
p. 47.) Mr. Fenton, after shewing in detail the insufficiency of the
various causes, usually assigned in explanation of this extraordinary
decrease, such as new diseases, the profligacy of the women, drunkenness,
wars, etc., concludes on weighty grounds that it depends chiefly on the
unproductiveness of the women, and on the extraordinary mortality of the
young children (pp. 31, 34). In proof of this he shews (p. 33) that in
1844 there was one non-adult for every 2.57 adults; whereas in 1858 there
was only one non-adult for every 3.27 adults. The mortality of the adults
is also great. He adduces as a further cause of the decrease the
inequality of the sexes; for fewer females are born than males. To this
latter point, depending perhaps on a widely distinct cause, I shall return
in a future chapter. Mr. Fenton contrasts with astonishment the decrease
in New Zealand with the increase in Ireland; countries not very dissimilar
in climate, and where the inhabitants now follow nearly similar habits.
The Maories themselves (p. 35) "attribute their decadence, in some measure,
to the introduction of new food and clothing, and the attendant change of
habits"; and it will be seen, when we consider the influence of changed
conditions on fertility, that they are probably right. The diminution
began between the years 1830 and 1840; and Mr. Fenton shews (p. 40) that
about 1830, the art of manufacturing putrid corn (maize), by long steeping
in water, was discovered and largely practised; and this proves that a
change of habits was beginning amongst the natives, even when New Zealand
was only thinly inhabited by Europeans. When I visited the Bay of Islands
in 1835, the dress and food of the inhabitants had already been much
modified: they raised potatoes, maize, and other agricultural produce, and
exchanged them for English manufactured goods and tobacco.
It is evident from many statements in the life of Bishop Patteson (42.
'Life of J.C. Patteson,' by C.M. Younge, 1874; see more especially vol. i.
p. 530.), that the Melanesians of the New Hebrides and neighbouring
archipelagoes, suffered to an extraordinary degree in health, and perished
in large numbers, when they were removed to New Zealand, Norfolk Island,
and other salubrious places, in order to be educated as missionaries.
The decrease of the native population of the Sandwich Islands is as
notorious as that of New Zealand. It has been roughly estimated by those
best capable of judging, that when Cook discovered the Islands in 1779, the
population amounted to about 300,000. According to a loose census in 1823,
the numbers then were 142,050. In 1832, and at several subsequent periods,
an accurate census was officially taken, but I have been able to obtain
only the following returns:
Native Population Annual rate of decrease
per cent., assuming it to
(Except during 1832 and have been uniform between
1836, when the few the successive censuses;
foreigners in the islands these censuses being taken
Year were included.) at irregular intervals.
1832 130,313
4.46
1836 108,579
2.47
1853 71,019
0.81
1860 67,084
2.18
1866 58,765
2.17
1872 51,531
We here see that in the interval of forty years, between 1832 and 1872, the
population has decreased no less than sixty-eight per cent.! This has been
attributed by most writers to the profligacy of the women, to former bloody
wars, and to the severe labour imposed on conquered tribes and to newly
introduced diseases, which have been on several occasions extremely
destructive. No doubt these and other such causes have been highly
efficient, and may account for the extraordinary rate of decrease between
the years 1832 and 1836; but the most potent of all the causes seems to be
lessened fertility. According to Dr. Ruschenberger of the U.S. Navy, who
visited these islands between 1835 and 1837, in one district of Hawaii,
only twenty-five men out of 1134, and in another district only ten out of
637, had a family with as many as three children. Of eighty married women,
only thirty-nine had ever borne children; and "the official report gives an
average of half a child to each married couple in the whole island." This
is almost exactly the same average as with the Tasmanians at Oyster Cove.
Jarves, who published his History in 1843, says that "families who have
three children are freed from all taxes; those having more, are rewarded by
gifts of land and other encouragements." This unparalleled enactment by
the government well shews how infertile the race had become. The Rev. A.
Bishop stated in the Hawaiian 'Spectator' in 1839, that a large proportion
of the children die at early ages, and Bishop Staley informs me that this
is still the case, just as in New Zealand. This has been attributed to the
neglect of the children by the women, but it is probably in large part due
to innate weakness of constitution in the children, in relation to the
lessened fertility of their parents. There is, moreover, a further
resemblance to the case of New Zealand, in the fact that there is a large
excess of male over female births: the census of 1872 gives 31,650 males
to 25,247 females of all ages, that is 125.36 males for every 100 females;
whereas in all civilised countries the females exceed the males. No doubt
the profligacy of the women may in part account for their small fertility;
but their changed habits of life is a much more probable cause, and which
will at the same time account for the increased mortality, especially of
the children. The islands were visited by Cook in 1779, Vancouver in 1794,
and often subsequently by whalers. In 1819 missionaries arrived, and found
that idolatry had been already abolished, and other changes effected by the
king. After this period there was a rapid change in almost all the habits
of life of the natives, and they soon became "the most civilised of the
Pacific Islanders." One of my informants, Mr. Coan, who was born on the
islands, remarks that the natives have undergone a greater change in their
habits of life in the course of fifty years than Englishmen during a
thousand years. From information received from Bishop Staley, it does not
appear that the poorer classes have ever much changed their diet, although
many new kinds of fruit have been introduced, and the sugar-cane is in
universal use. Owing, however, to their passion for imitating Europeans,
they altered their manner of dressing at an early period, and the use of
alcoholic drinks became very general. Although these changes appear
inconsiderable, I can well believe, from what is known with respect to
animals, that they might suffice to lessen the fertility of the natives.
(43. The foregoing statements are taken chiefly from the following works:
Jarves' 'History of the Hawaiian Islands,' 1843, pp. 400-407. Cheever,
'Life in the Sandwich Islands,' 1851, p. 277. Ruschenberger is quoted by
Bonwick, 'Last of the Tasmanians,' 1870, p. 378. Bishop is quoted by Sir
E. Belcher, 'Voyage Round the World,' 1843, vol. i. p. 272. I owe the
census of the several years to the kindness of Mr. Coan, at the request of
Dr. Youmans of New York; and in most cases I have compared the Youmans
figures with those given in several of the above-named works. I have
omitted the census for 1850, as I have seen two widely different numbers
given.)
Lastly, Mr. Macnamara states (44. 'The Indian Medical Gazette,' Nov. 1,
1871, p. 240.) that the low and degraded inhabitants of the Andaman
Islands, on the eastern side of the Gulf of Bengal, are "eminently
susceptible to any change of climate: in fact, take them away from their
island homes, and they are almost certain to die, and that independently of
diet or extraneous influences." He further states that the inhabitants of
the Valley of Nepal, which is extremely hot in summer, and also the various
hill-tribes of India, suffer from dysentery and fever when on the plains;
and they die if they attempt to pass the whole year there.
We thus see that many of the wilder races of man are apt to suffer much in
health when subjected to changed conditions or habits of life, and not
exclusively from being transported to a new climate. Mere alterations in
habits, which do not appear injurious in themselves, seem to have this same
effect; and in several cases the children are particularly liable to
suffer. It has often been said, as Mr. Macnamara remarks, that man can
resist with impunity the greatest diversities of climate and other changes;
but this is true only of the civilised races. Man in his wild condition
seems to be in this respect almost as susceptible as his nearest allies,
the anthropoid apes, which have never yet survived long, when removed from
their native country.
Lessened fertility from changed conditions, as in the case of the
Tasmanians, Maories, Sandwich Islanders, and apparently the Australians, is
still more interesting than their liability to ill-health and death; for
even a slight degree of infertility, combined with those other causes which
tend to check the increase of every population, would sooner or later lead
to extinction. The diminution of fertility may be explained in some cases
by the profligacy of the women (as until lately with the Tahitians), but
Mr. Fenton has shewn that this explanation by no means suffices with the
New Zealanders, nor does it with the Tasmanians.
In the paper above quoted, Mr. Macnamara gives reasons for believing that
the inhabitants of districts subject to malaria are apt to be sterile; but
this cannot apply in several of the above cases. Some writers have
suggested that the aborigines of islands have suffered in fertility and
health from long continued inter-breeding; but in the above cases
infertility has coincided too closely with the arrival of Europeans for us
to admit this explanation. Nor have we at present any reason to believe
that man is highly sensitive to the evil effects of inter-breeding,
especially in areas so large as New Zealand, and the Sandwich archipelago
with its diversified stations. On the contrary, it is known that the
present inhabitants of Norfolk Island are nearly all cousins or near
relations, as are the Todas in India, and the inhabitants of some of the
Western Islands of Scotland; and yet they seem not to have suffered in
fertility. (45. On the close relationship of the Norfolk Islanders, Sir
W. Denison, 'Varieties of Vice-Regal Life,' vol. i. 1870, p. 410. For the
Todas, see Col. Marshall's work 1873, p. 110. For the Western Islands of
Scotland, Dr. Mitchell, 'Edinburgh Medical Journal,' March to June, 1865.)
A much more probable view is suggested by the analogy of the lower animals.
The reproductive system can be shewn to be susceptible to an extraordinary
degree (though why we know not) to changed conditions of life; and this
susceptibility leads both to beneficial and to evil results. A large
collection of facts on this subject is given in chap. xviii. of vol. ii. of
my 'Variation of Animals and Plants under Domestication,' I can here give
only the briefest abstract; and every one interested in the subject may
consult the above work. Very slight changes increase the health, vigour,
and fertility of most or all organic beings, whilst other changes are known
to render a large number of animals sterile. One of the most familiar
cases, is that of tamed elephants not breeding in India; though they often
breed in Ava, where the females are allowed to roam about the forests to
some extent, and are thus placed under more natural conditions. The case
of various American monkeys, both sexes of which have been kept for many
years together in their own countries, and yet have very rarely or never
bred, is a more apposite instance, because of their relationship to man.
It is remarkable how slight a change in the conditions often induces
sterility in a wild animal when captured; and this is the more strange as
all our domesticated animals have become more fertile than they were in a
state of nature; and some of them can resist the most unnatural conditions
with undiminished fertility. (46. For the evidence on this head, see
'Variation of Animals,' etc., vol. ii. p. 111.) Certain groups of animals
are much more liable than others to be affected by captivity; and generally
all the species of the same group are affected in the same manner. But
sometimes a single species in a group is rendered sterile, whilst the
others are not so; on the other hand, a single species may retain its
fertility whilst most of the others fail to breed. The males and females
of some species when confined, or when allowed to live almost, but not
quite free, in their native country, never unite; others thus circumstanced
frequently unite but never produce offspring; others again produce some
offspring, but fewer than in a state of nature; and as bearing on the above
cases of man, it is important to remark that the young are apt to be weak
and sickly, or malformed, and to perish at an early age.
Seeing how general is this law of the susceptibility of the reproductive
system to changed conditions of life, and that it holds good with our
nearest allies, the Quadrumana, I can hardly doubt that it applies to man
in his primeval state. Hence if savages of any race are induced suddenly
to change their habits of life, they become more or less sterile, and their
young offspring suffer in health, in the same manner and from the same
cause, as do the elephant and hunting-leopard in India, many monkeys in
America, and a host of animals of all kinds, on removal from their natural
conditions.
We can see why it is that aborigines, who have long inhabited islands, and
who must have been long exposed to nearly uniform conditions, should be
specially affected by any change in their habits, as seems to be the case.
Civilised races can certainly resist changes of all kinds far better than
savages; and in this respect they resemble domesticated animals, for though
the latter sometimes suffer in health (for instance European dogs in
India), yet they are rarely rendered sterile, though a few such instances
have been recorded. (47. 'Variation of Animals,' etc., vol. ii. p. 16.)
The immunity of civilised races and domesticated animals is probably due to
their having been subjected to a greater extent, and therefore having grown
somewhat more accustomed, to diversified or varying conditions, than the
majority of wild animals; and to their having formerly immigrated or been
carried from country to country, and to different families or sub-races
having inter-crossed. It appears that a cross with civilised races at once
gives to an aboriginal race an immunity from the evil consequences of
changed conditions. Thus the crossed offspring from the Tahitians and
English, when settled in Pitcairn Island, increased so rapidly that the
island was soon overstocked; and in June 1856 they were removed to Norfolk
Island. They then consisted of 60 married persons and 134 children, making
a total of 194. Here they likewise increased so rapidly, that although
sixteen of them returned to Pitcairn Island in 1859, they numbered in
January 1868, 300 souls; the males and females being in exactly equal
numbers. What a contrast does this case present with that of the
Tasmanians; the Norfolk Islanders INCREASED in only twelve and a half years
from 194 to 300; whereas the Tasmanians DECREASED during fifteen years from
120 to 46, of which latter number only ten were children. (48. These
details are taken from 'The Mutineers of the "Bounty,"' by Lady Belcher,
1870; and from 'Pitcairn Island,' ordered to be printed by the House of
Commons, May 29, 1863. The following statements about the Sandwich
Islanders are from the 'Honolulu Gazette,' and from Mr. Coan.)
So again in the interval between the census of 1866 and 1872 the natives of
full blood in the Sandwich Islands decreased by 8081, whilst the half-
castes, who are believed to be healthier, increased by 847; but I do not
know whether the latter number includes the offspring from the half-castes,
or only the half-castes of the first generation.
The cases which I have here given all relate to aborigines, who have been
subjected to new conditions as the result of the immigration of civilised
men. But sterility and ill-health would probably follow, if savages were
compelled by any cause, such as the inroad of a conquering tribe, to desert
their homes and to change their habits. It is an interesting circumstance
that the chief check to wild animals becoming domesticated, which implies
the power of their breeding freely when first captured, and one chief check
to wild men, when brought into contact with civilisation, surviving to form
a civilised race, is the same, namely, sterility from changed conditions of
life.
Finally, although the gradual decrease and ultimate extinction of the races
of man is a highly complex problem, depending on many causes which differ
in different places and at different times; it is the same problem as that
presented by the extinction of one of the higher animals--of the fossil
horse, for instance, which disappeared from South America, soon afterwards
to be replaced, within the same districts, by countless troups of the
Spanish horse. The New Zealander seems conscious of this parallelism, for
he compares his future fate with that of the native rat now almost
exterminated by the European rat. Though the difficulty is great to our
imagination, and really great, if we wish to ascertain the precise causes
and their manner of action, it ought not to be so to our reason, as long as
we keep steadily in mind that the increase of each species and each race is
constantly checked in various ways; so that if any new check, even a slight
one, be superadded, the race will surely decrease in number; and decreasing
numbers will sooner or later lead to extinction; the end, in most cases,
being promptly determined by the inroads of conquering tribes.
ON THE FORMATION OF THE RACES OF MAN.
In some cases the crossing of distinct races has led to the formation of a
new race. The singular fact that the Europeans and Hindoos, who belong to
the same Aryan stock, and speak a language fundamentally the same, differ
widely in appearance, whilst Europeans differ but little from Jews, who
belong to the Semitic stock, and speak quite another language, has been
accounted for by Broca (49. 'On Anthropology,' translation,
'Anthropological Review,' Jan. 1868, p. 38.), through certain Aryan
branches having been largely crossed by indigenous tribes during their wide
diffusion. When two races in close contact cross, the first result is a
heterogeneous mixture: thus Mr. Hunter, in describing the Santali or hill-
tribes of India, says that hundreds of imperceptible gradations may be
traced "from the black, squat tribes of the mountains to the tall olive-
coloured Brahman, with his intellectual brow, calm eyes, and high but
narrow head"; so that it is necessary in courts of justice to ask the
witnesses whether they are Santalis or Hindoos. (50. 'The Annals of Rural
Bengal,' 1868, p. 134.) Whether a heterogeneous people, such as the
inhabitants of some of the Polynesian islands, formed by the crossing of
two distinct races, with few or no pure members left, would ever become
homogeneous, is not known from direct evidence. But as with our
domesticated animals, a cross-breed can certainly be fixed and made uniform
by careful selection (51. 'The Variation of Animals and Plants under
Domestication,' vol. ii. p. 95.) in the course of a few generations, we may
infer that the free intercrossing of a heterogeneous mixture during a long
descent would supply the place of selection, and overcome any tendency to
reversion; so that the crossed race would ultimately become homogeneous,
though it might not partake in an equal degree of the characters of the two
parent-races.
Of all the differences between the races of man, the colour of the skin is
the most conspicuous and one of the best marked. It was formerly thought
that differences of this kind could be accounted for by long exposure to
different climates; but Pallas first shewed that this is not tenable, and
he has since been followed by almost all anthropologists. (52. Pallas,
'Act. Acad. St. Petersburg,' 1780, part ii. p. 69. He was followed by
Rudolphi, in his 'Beytrage zur Anthropologie,' 1812. An excellent summary
of the evidence is given by Godron, 'De l'Espece,' 1859, vol. ii. p. 246,
etc.) This view has been rejected chiefly because the distribution of the
variously coloured races, most of whom must have long inhabited their
present homes, does not coincide with corresponding differences of climate.
Some little weight may be given to such cases as that of the Dutch
families, who, as we hear on excellent authority (53. Sir Andrew Smith, as
quoted by Knox, 'Races of Man,' 1850, p. 473.), have not undergone the
least change of colour after residing for three centuries in South Africa.
An argument on the same side may likewise be drawn from the uniform
appearance in various parts of the world of gipsies and Jews, though the
uniformity of the latter has been somewhat exaggerated. (54. See De
Quatrefages on this head, 'Revue des Cours Scientifiques,' Oct. 17, 1868,
p. 731.) A very damp or a very dry atmosphere has been supposed to be more
influential in modifying the colour of the skin than mere heat; but as
D'Orbigny in South America, and Livingstone in Africa, arrived at
diametrically opposite conclusions with respect to dampness and dryness,
any conclusion on this head must be considered as very doubtful. (55.
Livingstone's 'Travels and Researches in S. Africa,' 1857, pp. 338, 339.
D'Orbigny, as quoted by Godron, 'De l'Espece,' vol. ii. p. 266.)
Various facts, which I have given elsewhere, prove that the colour of the
skin and hair is sometimes correlated in a surprising manner with a
complete immunity from the action of certain vegetable poisons, and from
the attacks of certain parasites. Hence it occurred to me, that negroes
and other dark races might have acquired their dark tints by the darker
individuals escaping from the deadly influence of the miasma of their
native countries, during a long series of generations.
I afterwards found that this same idea had long ago occurred to Dr. Wells.
(56. See a paper read before the Royal Soc. in 1813, and published in his
Essays in 1818. I have given an account of Dr. Wells' views in the
Historical Sketch (p. xvi.) to my 'Origin of Species.' Various cases of
colour correlated with constitutional peculiarities are given in my
'Variation of Animals and Plants under Domestication,' vol. ii. pp. 227,
335.) It has long been known that negroes, and even mulattoes, are almost
completely exempt from the yellow-fever, so destructive in tropical
America. (57. See, for instance, Nott and Gliddon, 'Types of Mankind,' p.
68.) They likewise escape to a large extent the fatal intermittent fevers,
that prevail along at least 2600 miles of the shores of Africa, and which
annually cause one-fifth of the white settlers to die, and another fifth to
return home invalided. (58. Major Tulloch, in a paper read before the
Statistical Society, April 20, 1840, and given in the 'Athenaeum,' 1840, p.
353.) This immunity in the negro seems to be partly inherent, depending on
some unknown peculiarity of constitution, and partly the result of
acclimatisation. Pouchet (59. 'The Plurality of the Human Race'
(translat.), 1864, p. 60.) states that the negro regiments recruited near
the Soudan, and borrowed from the Viceroy of Egypt for the Mexican war,
escaped the yellow-fever almost equally with the negroes originally brought
from various parts of Africa and accustomed to the climate of the West
Indies. That acclimatisation plays a part, is shewn by the many cases in
which negroes have become somewhat liable to tropical fevers, after having
resided for some time in a colder climate. (60. Quatrefages, 'Unite de
l'Espece Humaine,' 1861, p. 205. Waitz, 'Introduction to Anthropology,'
translat., vol. i. 1863, p. 124. Livingstone gives analogous cases in his
'Travels.') The nature of the climate under which the white races have
long resided, likewise has some influence on them; for during the fearful
epidemic of yellow fever in Demerara during 1837, Dr. Blair found that the
death-rate of the immigrants was proportional to the latitude of the
country whence they had come. With the negro the immunity, as far as it is
the result of acclimatisation, implies exposure during a prodigious length
of time; for the aborigines of tropical America who have resided there from
time immemorial, are not exempt from yellow fever; and the Rev. H.B.
Tristram states, that there are districts in Northern Africa which the
native inhabitants are compelled annually to leave, though the negroes can
remain with safety.
That the immunity of the negro is in any degree correlated with the colour
of his skin is a mere conjecture: it may be correlated with some
difference in his blood, nervous system, or other tissues. Nevertheless,
from the facts above alluded to, and from some connection apparently
existing between complexion and a tendency to consumption, the conjecture
seemed to me not improbable. Consequently I endeavoured, with but little
success (61. In the spring of 1862 I obtained permission from the
Director-General of the Medical department of the Army, to transmit to the
surgeons of the various regiments on foreign service a blank table, with
the following appended remarks, but I have received no returns. "As
several well-marked cases have been recorded with our domestic animals of a
relation between the colour of the dermal appendages and the constitution;
and it being notorious that there is some limited degree of relation
between the colour of the races of man and the climate inhabited by them;
the following investigation seems worth consideration. Namely, whether
there is any relation in Europeans between the colour of their hair, and
their liability to the diseases of tropical countries. If the surgeons of
the several regiments, when stationed in unhealthy tropical districts,
would be so good as first to count, as a standard of comparison, how many
men, in the force whence the sick are drawn, have dark and light-coloured
hair, and hair of intermediate or doubtful tints; and if a similar account
were kept by the same medical gentlemen, of all the men who suffered from
malarious and yellow fevers, or from dysentery, it would soon be apparent,
after some thousand cases had been tabulated, whether there exists any
relation between the colour of the hair and constitutional liability to
tropical diseases. Perhaps no such relation would be discovered, but the
investigation is well worth making. In case any positive result were
obtained, it might be of some practical use in selecting men for any
particular service. Theoretically the result would be of high interest, as
indicating one means by which a race of men inhabiting from a remote period
an unhealthy tropical climate, might have become dark-coloured by the
better preservation of dark-haired or dark-complexioned individuals during
a long succession of generations."), to ascertain how far it holds good.
The late Dr. Daniell, who had long lived on the West Coast of Africa, told
me that he did not believe in any such relation. He was himself unusually
fair, and had withstood the climate in a wonderful manner. When he first
arrived as a boy on the coast, an old and experienced negro chief predicted
from his appearance that this would prove the case. Dr. Nicholson, of
Antigua, after having attended to this subject, writes to me that dark-
coloured Europeans escape the yellow fever more than those that are light-
coloured. Mr. J.M. Harris altogether denies that Europeans with dark hair
withstand a hot climate better than other men: on the contrary, experience
has taught him in making a selection of men for service on the coast of
Africa, to choose those with red hair. (62. 'Anthropological Review,'
Jan. 1866, p. xxi. Dr. Sharpe also says, with respect to India ('Man a
Special Creation,' 1873, p. 118), "that it has been noticed by some medical
officers that Europeans with light hair and florid complexions suffer less
from diseases of tropical countries than persons with dark hair and sallow
complexions; and, so far as I know, there appear to be good grounds for
this remark." On the other hand, Mr. Heddle, of Sierra Leone, "who has had
more clerks killed under him than any other man," by the climate of the
West African Coast (W. Reade, 'African Sketch Book,' vol. ii. p. 522),
holds a directly opposite view, as does Capt. Burton.) As far, therefore,
as these slight indications go, there seems no foundation for the
hypothesis, that blackness has resulted from the darker and darker
individuals having survived better during long exposure to fever-generating
miasma.
Dr. Sharpe remarks (63. 'Man a Special Creation,' 1873, p. 119.), that a
tropical sun, which burns and blisters a white skin, does not injure a
black one at all; and, as he adds, this is not due to habit in the
individual, for children only six or eight months old are often carried
about naked, and are not affected. I have been assured by a medical man,
that some years ago during each summer, but not during the winter, his
hands became marked with light brown patches, like, although larger than
freckles, and that these patches were never affected by sun-burning, whilst
the white parts of his skin have on several occasions been much inflamed
and blistered. With the lower animals there is, also, a constitutional
difference in liability to the action of the sun between those parts of the
skin clothed with white hair and other parts. (64. 'Variation of Animals
and Plants under Domestication,' vol. ii. pp. 336, 337.) Whether the
saving of the skin from being thus burnt is of sufficient importance to
account for a dark tint having been gradually acquired by man through
natural selection, I am unable to judge. If it be so, we should have to
assume that the natives of tropical America have lived there for a much
shorter time than the Negroes in Africa, or the Papuans in the southern
parts of the Malay archipelago, just as the lighter-coloured Hindoos have
resided in India for a shorter time than the darker aborigines of the
central and southern parts of the peninsula.
Although with our present knowledge we cannot account for the differences
of colour in the races of man, through any advantage thus gained, or from
the direct action of climate; yet we must not quite ignore the latter
agency, for there is good reason to believe that some inherited effect is
thus produced. (65. See, for instance, Quatrefages ('Revue des Cours
Scientifiques,' Oct. 10, 1868, p. 724) on the effects of residence in
Abyssinia and Arabia, and other analogous cases. Dr. Rolle ('Der Mensch,
seine Abstammung,' etc., 1865, s. 99) states, on the authority of Khanikof,
that the greater number of German families settled in Georgia, have
acquired in the course of two generations dark hair and eyes. Mr. D.
Forbes informs me that the Quichuas in the Andes vary greatly in colour,
according to the position of the valleys inhabited by them.)
We have seen in the second chapter that the conditions of life affect the
development of the bodily frame in a direct manner, and that the effects
are transmitted. Thus, as is generally admitted, the European settlers in
the United States undergo a slight but extraordinary rapid change of
appearance. Their bodies and limbs become elongated; and I hear from Col.
Bernys that during the late war in the United States, good evidence was
afforded of this fact by the ridiculous appearance presented by the German
regiments, when dressed in ready-made clothes manufactured for the American
market, and which were much too long for the men in every way. There is,
also, a considerable body of evidence shewing that in the Southern States
the house-slaves of the third generation present a markedly different
appearance from the field-slaves. (66. Harlan, 'Medical Researches,' p.
532. Quatrefages ('Unite de l'Espece Humaine,' 1861, p. 128) has collected
much evidence on this head.)
If, however, we look to the races of man as distributed over the world, we
must infer that their characteristic differences cannot be accounted for by
the direct action of different conditions of life, even after exposure to
them for an enormous period of time. The Esquimaux live exclusively on
animal food; they are clothed in thick fur, and are exposed to intense cold
and to prolonged darkness; yet they do not differ in any extreme degree
from the inhabitants of Southern China, who live entirely on vegetable
food, and are exposed almost naked to a hot, glaring climate. The
unclothed Fuegians live on the marine productions of their inhospitable
shores; the Botocudos of Brazil wander about the hot forests of the
interior and live chiefly on vegetable productions; yet these tribes
resemble each other so closely that the Fuegians on board the "Beagle" were
mistaken by some Brazilians for Botocudos. The Botocudos again, as well as
the other inhabitants of tropical America, are wholly different from the
Negroes who inhabit the opposite shores of the Atlantic, are exposed to a
nearly similar climate, and follow nearly the same habits of life.
Nor can the differences between the races of man be accounted for by the
inherited effects of the increased or decreased use of parts, except to a
quite insignificant degree. Men who habitually live in canoes, may have
their legs somewhat stunted; those who inhabit lofty regions may have their
chests enlarged; and those who constantly use certain sense-organs may have
the cavities in which they are lodged somewhat increased in size, and their
features consequently a little modified. With civilised nations, the
reduced size of the jaws from lessened use--the habitual play of different
muscles serving to express different emotions--and the increased size of
the brain from greater intellectual activity, have together produced a
considerable effect on their general appearance when compared with savages.
(67. See Prof. Schaaffhausen, translat., in 'Anthropological Review,' Oct.
1868, p. 429.) Increased bodily stature, without any corresponding
increase in the size of the brain, may (judging from the previously adduced
case of rabbits), have given to some races an elongated skull of the
dolichocephalic type.
Lastly, the little-understood principle of correlated development has
sometimes come into action, as in the case of great muscular development
and strongly projecting supra-orbital ridges. The colour of the skin and
hair are plainly correlated, as is the texture of the hair with its colour
in the Mandans of North America. (68. Mr. Catlin states ('N. American
Indians,' 3rd ed., 1842, vol. i. p. 49) that in the whole tribe of the
Mandans, about one in ten or twelve of the members, of all ages and both
sexes, have bright silvery grey hair, which is hereditary. Now this hair
is as coarse and harsh as that of a horse's mane, whilst the hair of other
colours is fine and soft.) The colour also of the skin, and the odour
emitted by it, are likewise in some manner connected. With the breeds of
sheep the number of hairs within a given space and the number of excretory
pores are related. (69. On the odour of the skin, Godron, 'Sur l'Espece,'
tom. ii. p. 217. On the pores in the skin, Dr. Wilckens, 'Die Aufgaben der
Landwirth. Zootechnik,' 1869, s. 7.) If we may judge from the analogy of
our domesticated animals, many modifications of structure in man probably
come under this principle of correlated development.
We have now seen that the external characteristic differences between the
races of man cannot be accounted for in a satisfactory manner by the direct
action of the conditions of life, nor by the effects of the continued use
of parts, nor through the principle of correlation. We are therefore led
to enquire whether slight individual differences, to which man is eminently
liable, may not have been preserved and augmented during a long series of
generations through natural selection. But here we are at once met by the
objection that beneficial variations alone can be thus preserved; and as
far as we are enabled to judge, although always liable to err on this head,
none of the differences between the races of man are of any direct or
special service to him. The intellectual and moral or social faculties
must of course be excepted from this remark. The great variability of all
the external differences between the races of man, likewise indicates that
they cannot be of much importance; for if important, they would long ago
have been either fixed and preserved, or eliminated. In this respect man
resembles those forms, called by naturalists protean or polymorphic, which
have remained extremely variable, owing, as it seems, to such variations
being of an indifferent nature, and to their having thus escaped the action
of natural selection.
We have thus far been baffled in all our attempts to account for the
differences between the races of man; but there remains one important
agency, namely Sexual Selection, which appears to have acted powerfully on
man, as on many other animals. I do not intend to assert that sexual
selection will account for all the differences between the races. An
unexplained residuum is left, about which we can only say, in our
ignorance, that as individuals are continually born with, for instance,
heads a little rounder or narrower, and with noses a little longer or
shorter, such slight differences might become fixed and uniform, if the
unknown agencies which induced them were to act in a more constant manner,
aided by long-continued intercrossing. Such variations come under the
provisional class, alluded to in our second chapter, which for want of a
better term are often called spontaneous. Nor do I pretend that the
effects of sexual selection can be indicated with scientific precision; but
it can be shewn that it would be an inexplicable fact if man had not been
modified by this agency, which appears to have acted powerfully on
innumerable animals. It can further be shewn that the differences between
the races of man, as in colour, hairiness, form of features, etc., are of a
kind which might have been expected to come under the influence of sexual
selection. But in order to treat this subject properly, I have found it
necessary to pass the whole animal kingdom in review. I have therefore
devoted to it the Second Part of this work. At the close I shall return to
man, and, after attempting to shew how far he has been modified through
sexual selection, will give a brief summary of the chapters in this First
Part.
NOTE ON THE RESEMBLANCES AND DIFFERENCES IN THE STRUCTURE AND THE
DEVELOPMENT OF THE BRAIN IN MAN AND APES BY PROFESSOR HUXLEY, F.R.S.
The controversy respecting the nature and the extent of the differences in
the structure of the brain in man and the apes, which arose some fifteen
years ago, has not yet come to an end, though the subject matter of the
dispute is, at present, totally different from what it was formerly. It
was originally asserted and re-asserted, with singular pertinacity, that
the brain of all the apes, even the highest, differs from that of man, in
the absence of such conspicuous structures as the posterior lobes of the
cerebral hemispheres, with the posterior cornu of the lateral ventricle and
the hippocampus minor, contained in those lobes, which are so obvious in
man.
But the truth that the three structures in question are as well developed
in apes' as in human brains, or even better; and that it is characteristic
of all the Primates (if we exclude the Lemurs) to have these parts well
developed, stands at present on as secure a basis as any proposition in
comparative anatomy. Moreover, it is admitted by every one of the long
series of anatomists who, of late years, have paid special attention to the
arrangement of the complicated sulci and gyri which appear upon the surface
of the cerebral hemispheres in man and the higher apes, that they are
disposed after the very same pattern in him, as in them. Every principal
gyrus and sulcus of a chimpanzee's brain is clearly represented in that of
a man, so that the terminology which applies to the one answers for the
other. On this point there is no difference of opinion. Some years since,
Professor Bischoff published a memoir (70. 'Die Grosshirn-Windungen des
Menschen;' 'Abhandlungen der K. Bayerischen Akademie,' B. x. 1868.) on the
cerebral convolutions of man and apes; and as the purpose of my learned
colleague was certainly not to diminish the value of the differences
between apes and men in this respect, I am glad to make a citation from
him.
"That the apes, and especially the orang, chimpanzee and gorilla, come very
close to man in their organisation, much nearer than to any other animal,
is a well known fact, disputed by nobody. Looking at the matter from the
point of view of organisation alone, no one probably would ever have
disputed the view of Linnaeus, that man should be placed, merely as a
peculiar species, at the head of the mammalia and of those apes. Both
shew, in all their organs, so close an affinity, that the most exact
anatomical investigation is needed in order to demonstrate those
differences which really exist. So it is with the brains. The brains of
man, the orang, the chimpanzee, the gorilla, in spite of all the important
differences which they present, come very close to one another" (loc. cit.
p. 101).
There remains, then, no dispute as to the resemblance in fundamental
characters, between the ape's brain and man's: nor any as to the
wonderfully close similarity between the chimpanzee, orang and man, in even
the details of the arrangement of the gyri and sulci of the cerebral
hemispheres. Nor, turning to the differences between the brains of the
highest apes and that of man, is there any serious question as to the
nature and extent of these differences. It is admitted that the man's
cerebral hemispheres are absolutely and relatively larger than those of the
orang and chimpanzee; that his frontal lobes are less excavated by the
upward protrusion of the roof of the orbits; that his gyri and sulci are,
as a rule, less symmetrically disposed, and present a greater number of
secondary plications. And it is admitted that, as a rule, in man, the
temporo-occipital or "external perpendicular" fissure, which is usually so
strongly marked a feature of the ape's brain is but faintly marked. But it
is also clear, that none of these differences constitutes a sharp
demarcation between the man's and the ape's brain. In respect to the
external perpendicular fissure of Gratiolet, in the human brain for
instance, Professor Turner remarks: (71. 'Convolutions of the Human
Cerebrum Topographically Considered,' 1866, p. 12.)
"In some brains it appears simply as an indentation of the margin of the
hemisphere, but, in others, it extends for some distance more or less
transversely outwards. I saw it in the right hemisphere of a female brain
pass more than two inches outwards; and on another specimen, also the right
hemisphere, it proceeded for four-tenths of an inch outwards, and then
extended downwards, as far as the lower margin of the outer surface of the
hemisphere. The imperfect definition of this fissure in the majority of
human brains, as compared with its remarkable distinctness in the brain of
most Quadrumana, is owing to the presence, in the former, of certain
superficial, well marked, secondary convolutions which bridge it over and
connect the parietal with the occipital lobe. The closer the first of
these bridging gyri lies to the longitudinal fissure, the shorter is the
external parieto-occipital fissure" (loc. cit. p. 12).
The obliteration of the external perpendicular fissure of Gratiolet,
therefore, is not a constant character of the human brain. On the other
hand, its full development is not a constant character of the higher ape's
brain. For, in the chimpanzee, the more or less extensive obliteration of
the external perpendicular sulcus by "bridging convolutions," on one side
or the other, has been noted over and over again by Prof. Rolleston, Mr.
Marshall, M. Broca and Professor Turner. At the conclusion of a special
paper on this subject the latter writes: (72. Notes more especially on
the bridging convolutions in the Brain of the Chimpanzee, 'Proceedings of
the Royal Society of Edinburgh,' 1865-6.)
"The three specimens of the brain of a chimpanzee, just described, prove,
that the generalisation which Gratiolet has attempted to draw of the
complete absence of the first connecting convolution and the concealment of
the second, as essentially characteristic features in the brain of this
animal, is by no means universally applicable. In only one specimen did
the brain, in these particulars, follow the law which Gratiolet has
expressed. As regards the presence of the superior bridging convolution, I
am inclined to think that it has existed in one hemisphere, at least, in a
majority of the brains of this animal which have, up to this time, been
figured or described. The superficial position of the second bridging
convolution is evidently less frequent, and has as yet, I believe, only
been seen in the brain (A) recorded in this communication. The
asymmetrical arrangement in the convolutions of the two hemispheres, which
previous observers have referred to in their descriptions, is also well
illustrated in these specimens" (pp. 8, 9).
Even were the presence of the temporo-occipital, or external perpendicular,
sulcus, a mark of distinction between the higher apes and man, the value of
such a distinctive character would be rendered very doubtful by the
structure of the brain in the Platyrrhine apes. In fact, while the
temporo-occipital is one of the most constant of sulci in the Catarrhine,
or Old World, apes, it is never very strongly developed in the New World
apes; it is absent in the smaller Platyrrhini; rudimentary in Pithecia (73.
Flower, 'On the Anatomy of Pithecia Monachus,' 'Proceedings of the
Zoological Society,' 1862.); and more or less obliterated by bridging
convolutions in Ateles.
A character which is thus variable within the limits of a single group can
have no great taxonomic value.
It is further established, that the degree of asymmetry of the convolution
of the two sides in the human brain is subject to much individual
variation; and that, in those individuals of the Bushman race who have been
examined, the gyri and sulci of the two hemispheres are considerably less
complicated and more symmetrical than in the European brain, while, in some
individuals of the chimpanzee, their complexity and asymmetry become
notable. This is particularly the case in the brain of a young male
chimpanzee figured by M. Broca. ('L'ordre des Primates,' p. 165, fig. 11.)
Again, as respects the question of absolute size, it is established that
the difference between the largest and the smallest healthy human brain is
greater than the difference between the smallest healthy human brain and
the largest chimpanzee's or orang's brain.
Moreover, there is one circumstance in which the orang's and chimpanzee's
brains resemble man's, but in which they differ from the lower apes, and
that is the presence of two corpora candicantia--the Cynomorpha having but
one.
In view of these facts I do not hesitate in this year 1874, to repeat and
insist upon the proposition which I enunciated in 1863: (74. 'Man's Place
in Nature,' p. 102.)
"So far as cerebral structure goes, therefore, it is clear that man differs
less from the chimpanzee or the orang, than these do even from the monkeys,
and that the difference between the brain of the chimpanzee and of man is
almost insignificant when compared with that between the chimpanzee brain
and that of a Lemur."
In the paper to which I have referred, Professor Bischoff does not deny the
second part of this statement, but he first makes the irrelevant remark
that it is not wonderful if the brains of an orang and a Lemur are very
different; and secondly, goes on to assert that, "If we successively
compare the brain of a man with that of an orang; the brain of this with
that of a chimpanzee; of this with that of a gorilla, and so on of a
Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus,
Callithrix, Lemur, Stenops, Hapale, we shall not meet with a greater, or
even as great a, break in the degree of development of the convolutions, as
we find between the brain of a man and that of an orang or chimpanzee."
To which I reply, firstly, that whether this assertion be true or false, it
has nothing whatever to do with the proposition enunciated in 'Man's Place
in Nature,' which refers not to the development of the convolutions alone,
but to the structure of the whole brain. If Professor Bischoff had taken
the trouble to refer to p. 96 of the work he criticises, in fact, he would
have found the following passage: "And it is a remarkable circumstance
that though, so far as our present knowledge extends, there IS one true
structural break in the series of forms of Simian brains, this hiatus does
not lie between man and the manlike apes, but between the lower and the
lowest Simians, or in other words, between the Old and New World apes and
monkeys and the Lemurs. Every Lemur which has yet been examined, in fact,
has its cerebellum partially visible from above; and its posterior lobe,
with the contained posterior cornu and hippocampus minor, more or less
rudimentary. Every marmoset, American monkey, Old World monkey, baboon or
manlike ape, on the contrary, has its cerebellum entirely hidden,
posteriorly, by the cerebral lobes, and possesses a large posterior cornu
with a well-developed hippocampus minor."
This statement was a strictly accurate account of what was known when it
was made; and it does not appear to me to be more than apparently weakened
by the subsequent discovery of the relatively small development of the
posterior lobes in the Siamang and in the Howling monkey. Notwithstanding
the exceptional brevity of the posterior lobes in these two species, no one
will pretend that their brains, in the slightest degree, approach those of
the Lemurs. And if, instead of putting Hapale out of its natural place, as
Professor Bischoff most unaccountably does, we write the series of animals
he has chosen to mention as follows: Homo, Pithecus, Troglodytes,
Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus,
Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great
break in this series lies between Hapale and Lemur, and that this break is
considerably greater than that between any other two terms of that series.
Professor Bischoff ignores the fact that long before he wrote, Gratiolet
had suggested the separation of the Lemurs from the other Primates on the
very ground of the difference in their cerebral characters; and that
Professor Flower had made the following observations in the course of his
description of the brain of the Javan Loris: (75. 'Transactions of the
Zoological Society,' vol. v. 1862.)
"And it is especially remarkable that, in the development of the posterior
lobes, there is no approximation to the Lemurine, short hemisphered brain,
in those monkeys which are commonly supposed to approach this family in
other respects, viz. the lower members of the Platyrrhine group."
So far as the structure of the adult brain is concerned, then, the very
considerable additions to our knowledge, which have been made by the
researches of so many investigators, during the past ten years, fully
justify the statement which I made in 1863. But it has been said, that,
admitting the similarity between the adult brains of man and apes, they are
nevertheless, in reality, widely different, because they exhibit
fundamental differences in the mode of their development. No one would be
more ready than I to admit the force of this argument, if such fundamental
differences of development really exist. But I deny that they do exist.
On the contrary, there is a fundamental agreement in the development of the
brain in men and apes.
Gratiolet originated the statement that there is a fundamental difference
in the development of the brains of apes and that of man--consisting in
this; that, in the apes, the sulci which first make their appearance are
situated on the posterior region of the cerebral hemispheres, while, in the
human foetus, the sulci first become visible on the frontal lobes. (76.
"Chez tous les singes, les plis posterieurs se developpent les premiers;
les plis anterieurs se developpent plus tard, aussi la vertebre occipitale
et la parietale sont-elles relativement tres-grandes chez le foetus.
L'Homme presente une exception remarquable quant a l'epoque de l'apparition
des plis frontaux, qui sont les premiers indiques; mais le developpement
general du lobe frontal, envisage seulement par rapport a son volume, suit
les memes lois que dans les singes:" Gratiolet, 'Memoire sur les plis
cerebres de l'Homme et des Primateaux,' p. 39, Tab. iv, fig. 3.)
This general statement is based upon two observations, the one of a Gibbon
almost ready to be born, in which the posterior gyri were "well developed,"
while those of the frontal lobes were "hardly indicated" (77. Gratiolet's
words are (loc. cit. p. 39): "Dans le foetus dont il s'agit les plis
cerebraux posterieurs sont bien developpes, tandis que les plis du lobe
frontal sont a peine indiques." The figure, however (Pl. iv, fig. 3),
shews the fissure of Rolando, and one of the frontal sulci plainly enough.
Nevertheless, M. Alix, in his 'Notice sur les travaux anthropologiques de
Gratiolet' ('Mem. de la Societe d'Anthropologie de Paris,' 1868, page 32),
writes thus: "Gratiolet a eu entre les mains le cerveau d'un foetus de
Gibbon, singe eminemment superieur, et tellement rapproche de l'orang, que
des naturalistes tres-competents l'ont range parmi les anthropoides. M.
Huxley, par exemple, n'hesite pas sur ce point. Eh bien, c'est sur le
cerveau d'un foetus de Gibbon que Gratiolet a vu LES CIRCONVOLUTIONS DU
LOBE TEMPORO-SPHENOIDAL DEJA DEVELOPPEES LORSQU'IL N'EXISTENT PAS ENCORE DE
PLIS SUR LE LOBE FRONTAL. Il etait donc bien autorise a dire que, chez
l'homme les circonvolutions apparaissent d'a en w, tandis que chez les
singes elles se developpent d'w en a."), and the other of a human foetus at
the 22nd or 23rd week of uterogestation, in which Gratiolet notes that the
insula was uncovered, but that nevertheless "des incisures sement de lobe
anterieur, une scissure peu profonde indique la separation du lobe
occipital, tres-reduit, d'ailleurs des cette epoque. Le reste de la
surface cerebrale est encore absolument lisse."
Three views of this brain are given in Plate II, figs. 1, 2, 3, of the work
cited, shewing the upper, lateral and inferior views of the hemispheres,
but not the inner view. It is worthy of note that the figure by no means
bears out Gratiolet's description, inasmuch as the fissure (antero-
temporal) on the posterior half of the face of the hemisphere is more
marked than any of those vaguely indicated in the anterior half. If the
figure is correct, it in no way justifies Gratiolet's conclusion: "Il y a
donc entre ces cerveaux [those of a Callithrix and of a Gibbon] et celui du
foetus humain une difference fondamental. Chez celui-ci, longtemps avant
que les plis temporaux apparaissent, les plis frontaux, ESSAYENT
d'exister."
Since Gratiolet's time, however, the development of the gyri and sulci of
the brain has been made the subject of renewed investigation by Schmidt,
Bischoff, Pansch (78. 'Ueber die typische Anordnung der Furchen und
Windungen auf den Grosshirn-Hemispharen des Menschen und der Affen,'
'Archiv fur Anthropologie,' iii. 1868.), and more particularly by Ecker
(79. 'Zur Entwicklungs Geschichte der Furchen und Windungen der Grosshirn-
Hemispharen im Foetus des Menschen.' 'Archiv fur Anthropologie,' iii.
1868.), whose work is not only the latest, but by far the most complete,
memoir on the subject.
The final results of their inquiries may be summed up as follows:--
1. In the human foetus, the sylvian fissure is formed in the course of the
third month of uterogestation. In this, and in the fourth month, the
cerebral hemispheres are smooth and rounded (with the exception of the
sylvian depression), and they project backwards far beyond the cerebellum.
2. The sulci, properly so called, begin to appear in the interval between
the end of the fourth and the beginning of the sixth month of foetal life,
but Ecker is careful to point out that, not only the time, but the order,
of their appearance is subject to considerable individual variation. In no
case, however, are either the frontal or the temporal sulci the earliest.
The first which appears, in fact, lies on the inner face of the hemisphere
(whence doubtless Gratiolet, who does not seem to have examined that face
in his foetus, overlooked it), and is either the internal perpendicular
(occipito-parietal), or the calcarine sulcus, these two being close
together and eventually running into one another. As a rule the occipito-
parietal is the earlier of the two.
3. At the latter part of this period, another sulcus, the "posterio-
parietal," or "Fissure of Rolando" is developed, and it is followed, in the
course of the sixth month, by the other principal sulci of the frontal,
parietal, temporal and occipital lobes. There is, however, no clear
evidence that one of these constantly appears before the other; and it is
remarkable that, in the brain at the period described and figured by Ecker
(loc. cit. pp. 212-213, Taf. II, figs. 1, 2, 3, 4), the antero-temporal
sulcus (scissure parallele) so characteristic of the ape's brain, is as
well, if not better developed than the fissure of Rolando, and is much more
marked than the proper frontal sulci.
Taking the facts as they now stand, it appears to me that the order of the
appearance of the sulci and gyri in the foetal human brain is in perfect
harmony with the general doctrine of evolution, and with the view that man
has been evolved from some ape-like form; though there can be no doubt that
form was, in many respects, different from any member of the Primates now
living.
Von Baer taught us, half a century ago, that, in the course of their
development, allied animals put on at first, the characters of the greater
groups to which they belong, and, by degrees, assume those which restrict
them within the limits of their family, genus, and species; and he proved,
at the same time, that no developmental stage of a higher animal is
precisely similar to the adult condition of any lower animal. It is quite
correct to say that a frog passes through the condition of a fish, inasmuch
as at one period of its life the tadpole has all the characters of a fish,
and if it went no further, would have to be grouped among fishes. But it
is equally true that a tadpole is very different from any known fish.
In like manner, the brain of a human foetus, at the fifth month, may
correctly be said to be, not only the brain of an ape, but that of an
Arctopithecine or marmoset-like ape; for its hemispheres, with their great
posterior lobster, and with no sulci but the sylvian and the calcarine,
present the characteristics found only in the group of the Arctopithecine
Primates. But it is equally true, as Gratiolet remarks, that, in its
widely open sylvian fissure, it differs from the brain of any actual
marmoset. No doubt it would be much more similar to the brain of an
advanced foetus of a marmoset. But we know nothing whatever of the
development of the brain in the marmosets. In the Platyrrhini proper, the
only observation with which I am acquainted is due to Pansch, who found in
the brain of a foetal Cebus Apella, in addition to the sylvian fissure and
the deep calcarine fissure, only a very shallow antero-temporal fissure
(scissure parallele of Gratiolet).
Now this fact, taken together with the circumstance that the antero-
temporal sulcus is present in such Platyrrhini as the Saimiri, which
present mere traces of sulci on the anterior half of the exterior of the
cerebral hemispheres, or none at all, undoubtedly, so far as it goes,
affords fair evidence in favour of Gratiolet's hypothesis, that the
posterior sulci appear before the anterior, in the brains of the
Platyrrhini. But, it by no means follows, that the rule which may hold
good for the Platyrrhini extends to the Catarrhini. We have no information
whatever respecting the development of the brain in the Cynomorpha; and, as
regards the Anthropomorpha, nothing but the account of the brain of the
Gibbon, near birth, already referred to. At the present moment there is
not a shadow of evidence to shew that the sulci of a chimpanzee's, or
orang's, brain do not appear in the same order as a man's.
Gratiolet opens his preface with the aphorism: "Il est dangereux dans les
sciences de conclure trop vite." I fear he must have forgotten this sound
maxim by the time he had reached the discussion of the differences between
men and apes, in the body of his work. No doubt, the excellent author of
one of the most remarkable contributions to the just understanding of the
mammalian brain which has ever been made, would have been the first to
admit the insufficiency of his data had he lived to profit by the advance
of inquiry. The misfortune is that his conclusions have been employed by
persons incompetent to appreciate their foundation, as arguments in favour
of obscurantism. (80. For example, M. l'Abbe Lecomte in his terrible
pamphlet, 'Le Darwinisme et l'origine de l'Homme,' 1873.)
But it is important to remark that, whether Gratiolet was right or wrong in
his hypothesis respecting the relative order of appearance of the temporal
and frontal sulci, the fact remains; that before either temporal or frontal
sulci, appear, the foetal brain of man presents characters which are found
only in the lowest group of the Primates (leaving out the Lemurs); and that
this is exactly what we should expect to be the case, if man has resulted
from the gradual modification of the same form as that from which the other
Primates have sprung.
PART II. SEXUAL SELECTION.
CHAPTER VIII.
PRINCIPLES OF SEXUAL SELECTION.
Secondary sexual characters--Sexual selection--Manner of action--Excess of
males--Polygamy--The male alone generally modified through sexual
selection--Eagerness of the male--Variability of the male--Choice exerted
by the female--Sexual compared with natural selection--Inheritance, at
corresponding periods of life, at corresponding seasons of the year, and as
limited by sex--Relations between the several forms of inheritance--Causes
why one sex and the young are not modified through sexual selection--
Supplement on the proportional numbers of the two sexes throughout the
animal kingdom--The proportion of the sexes in relation to natural
selection.
With animals which have their sexes separated, the males necessarily differ
from the females in their organs of reproduction; and these are the primary
sexual characters. But the sexes often differ in what Hunter has called
secondary sexual characters, which are not directly connected with the act
of reproduction; for instance, the male possesses certain organs of sense
or locomotion, of which the female is quite destitute, or has them more
highly-developed, in order that he may readily find or reach her; or again
the male has special organs of prehension for holding her securely. These
latter organs, of infinitely diversified kinds, graduate into those which
are commonly ranked as primary, and in some cases can hardly be
distinguished from them; we see instances of this in the complex appendages
at the apex of the abdomen in male insects. Unless indeed we confine the
term "primary" to the reproductive glands, it is scarcely possible to
decide which ought to be called primary and which secondary.
The female often differs from the male in having organs for the nourishment
or protection of her young, such as the mammary glands of mammals, and the
abdominal sacks of the marsupials. In some few cases also the male
possesses similar organs, which are wanting in the female, such as the
receptacles for the ova in certain male fishes, and those temporarily
developed in certain male frogs. The females of most bees are provided
with a special apparatus for collecting and carrying pollen, and their
ovipositor is modified into a sting for the defence of the larvae and the
community. Many similar cases could be given, but they do not here concern
us. There are, however, other sexual differences quite unconnected with
the primary reproductive organs, and it is with these that we are more
especially concerned--such as the greater size, strength, and pugnacity of
the male, his weapons of offence or means of defence against rivals, his
gaudy colouring and various ornaments, his power of song, and other such
characters.
Besides the primary and secondary sexual differences, such as the
foregoing, the males and females of some animals differ in structures
related to different habits of life, and not at all, or only indirectly, to
the reproductive functions. Thus the females of certain flies (Culicidae
and Tabanidae) are blood-suckers, whilst the males, living on flowers, have
mouths destitute of mandibles. (1. Westwood, 'Modern Classification of
Insects,' vol. ii. 1840, p. 541. For the statement about Tanais, mentioned
below, I am indebted to Fritz Muller.) The males of certain moths and of
some crustaceans (e.g. Tanais) have imperfect, closed mouths, and cannot
feed. The complemental males of certain Cirripedes live like epiphytic
plants either on the female or the hermaphrodite form, and are destitute of
a mouth and of prehensile limbs. In these cases it is the male which has
been modified, and has lost certain important organs, which the females
possess. In other cases it is the female which has lost such parts; for
instance, the female glow-worm is destitute of wings, as also are many
female moths, some of which never leave their cocoons. Many female
parasitic crustaceans have lost their natatory legs. In some weevil-
beetles (Curculionidae) there is a great difference between the male and
female in the length of the rostrum or snout (2. Kirby and Spence,
'Introduction to Entomology,' vol. iii. 1826, p. 309.); but the meaning of
this and of many analogous differences, is not at all understood.
Differences of structure between the two sexes in relation to different
habits of life are generally confined to the lower animals; but with some
few birds the beak of the male differs from that of the female. In the
Huia of New Zealand the difference is wonderfully great, and we hear from
Dr. Buller (3. 'Birds of New Zealand,' 1872, p. 66.) that the male uses
his strong beak in chiselling the larvae of insects out of decayed wood,
whilst the female probes the softer parts with her far longer, much curved
and pliant beak: and thus they mutually aid each other. In most cases,
differences of structure between the sexes are more or less directly
connected with the propagation of the species: thus a female, which has to
nourish a multitude of ova, requires more food than the male, and
consequently requires special means for procuring it. A male animal, which
lives for a very short time, might lose its organs for procuring food
through disuse, without detriment; but he would retain his locomotive
organs in a perfect state, so that he might reach the female. The female,
on the other hand, might safely lose her organs for flying, swimming, or
walking, if she gradually acquired habits which rendered such powers
useless.
We are, however, here concerned only with sexual selection. This depends
on the advantage which certain individuals have over others of the same sex
and species solely in respect of reproduction. When, as in the cases above
mentioned, the two sexes differ in structure in relation to different
habits of life, they have no doubt been modified through natural selection,
and by inheritance limited to one and the same sex. So again the primary
sexual organs, and those for nourishing or protecting the young, come under
the same influence; for those individuals which generated or nourished
their offspring best, would leave, ceteris paribus, the greatest number to
inherit their superiority; whilst those which generated or nourished their
offspring badly, would leave but few to inherit their weaker powers. As
the male has to find the female, he requires organs of sense and
locomotion, but if these organs are necessary for the other purposes of
life, as is generally the case, they will have been developed through
natural selection. When the male has found the female, he sometimes
absolutely requires prehensile organs to hold her; thus Dr. Wallace informs
me that the males of certain moths cannot unite with the females if their
tarsi or feet are broken. The males of many oceanic crustaceans, when
adult, have their legs and antennae modified in an extraordinary manner for
the prehension of the female; hence we may suspect that it is because these
animals are washed about by the waves of the open sea, that they require
these organs in order to propagate their kind, and if so, their development
has been the result of ordinary or natural selection. Some animals
extremely low in the scale have been modified for this same purpose; thus
the males of certain parasitic worms, when fully grown, have the lower
surface of the terminal part of their bodies roughened like a rasp, and
with this they coil round and permanently hold the females. (4. M.
Perrier advances this case ('Revue Scientifique,' Feb. 1, 1873, p. 865) as
one fatal to the belief in sexual election, inasmuch as he supposes that I
attribute all the differences between the sexes to sexual selection. This
distinguished naturalist, therefore, like so many other Frenchmen, has not
taken the trouble to understand even the first principles of sexual
selection. An English naturalist insists that the claspers of certain male
animals could not have been developed through the choice of the female!
Had I not met with this remark, I should not have thought it possible for
any one to have read this chapter and to have imagined that I maintain that
the choice of the female had anything to do with the development of the
prehensile organs in the male.)
When the two sexes follow exactly the same habits of life, and the male has
the sensory or locomotive organs more highly developed than those of the
female, it may be that the perfection of these is indispensable to the male
for finding the female; but in the vast majority of cases, they serve only
to give one male an advantage over another, for with sufficient time, the
less well-endowed males would succeed in pairing with the females; and
judging from the structure of the female, they would be in all other
respects equally well adapted for their ordinary habits of life. Since in
such cases the males have acquired their present structure, not from being
better fitted to survive in the struggle for existence, but from having
gained an advantage over other males, and from having transmitted this
advantage to their male offspring alone, sexual selection must here have
come into action. It was the importance of this distinction which led me
to designate this form of selection as Sexual Selection. So again, if the
chief service rendered to the male by his prehensile organs is to prevent
the escape of the female before the arrival of other males, or when
assaulted by them, these organs will have been perfected through sexual
selection, that is by the advantage acquired by certain individuals over
their rivals. But in most cases of this kind it is impossible to
distinguish between the effects of natural and sexual selection. Whole
chapters could be filled with details on the differences between the sexes
in their sensory, locomotive, and prehensile organs. As, however, these
structures are not more interesting than others adapted for the ordinary
purposes of life I shall pass them over almost entirely, giving only a few
instances under each class.
There are many other structures and instincts which must have been
developed through sexual selection--such as the weapons of offence and the
means of defence of the males for fighting with and driving away their
rivals--their courage and pugnacity--their various ornaments--their
contrivances for producing vocal or instrumental music--and their glands
for emitting odours, most of these latter structures serving only to allure
or excite the female. It is clear that these characters are the result of
sexual and not of ordinary selection, since unarmed, unornamented, or
unattractive males would succeed equally well in the battle for life and in
leaving a numerous progeny, but for the presence of better endowed males.
We may infer that this would be the case, because the females, which are
unarmed and unornamented, are able to survive and procreate their kind.
Secondary sexual characters of the kind just referred to, will be fully
discussed in the following chapters, as being in many respects interesting,
but especially as depending on the will, choice, and rivalry of the
individuals of either sex. When we behold two males fighting for the
possession of the female, or several male birds displaying their gorgeous
plumage, and performing strange antics before an assembled body of females,
we cannot doubt that, though led by instinct, they know what they are
about, and consciously exert their mental and bodily powers.
Just as man can improve the breeds of his game-cocks by the selection of
those birds which are victorious in the cockpit, so it appears that the
strongest and most vigorous males, or those provided with the best weapons,
have prevailed under nature, and have led to the improvement of the natural
breed or species. A slight degree of variability leading to some
advantage, however slight, in reiterated deadly contests would suffice for
the work of sexual selection; and it is certain that secondary sexual
characters are eminently variable. Just as man can give beauty, according
to his standard of taste, to his male poultry, or more strictly can modify
the beauty originally acquired by the parent species, can give to the
Sebright bantam a new and elegant plumage, an erect and peculiar carriage--
so it appears that female birds in a state of nature, have by a long
selection of the more attractive males, added to their beauty or other
attractive qualities. No doubt this implies powers of discrimination and
taste on the part of the female which will at first appear extremely
improbable; but by the facts to be adduced hereafter, I hope to be able to
shew that the females actually have these powers. When, however, it is
said that the lower animals have a sense of beauty, it must not be supposed
that such sense is comparable with that of a cultivated man, with his
multiform and complex associated ideas. A more just comparison would be
between the taste for the beautiful in animals, and that in the lowest
savages, who admire and deck themselves with any brilliant, glittering, or
curious object.
From our ignorance on several points, the precise manner in which sexual
selection acts is somewhat uncertain. Nevertheless if those naturalists
who already believe in the mutability of species, will read the following
chapters, they will, I think, agree with me, that sexual selection has
played an important part in the history of the organic world. It is
certain that amongst almost all animals there is a struggle between the
males for the possession of the female. This fact is so notorious that it
would be superfluous to give instances. Hence the females have the
opportunity of selecting one out of several males, on the supposition that
their mental capacity suffices for the exertion of a choice. In many cases
special circumstances tend to make the struggle between the males
particularly severe. Thus the males of our migratory birds generally
arrive at their places of breeding before the females, so that many males
are ready to contend for each female. I am informed by Mr. Jenner Weir,
that the bird-catchers assert that this is invariably the case with the
nightingale and blackcap, and with respect to the latter he can himself
confirm the statement.
Mr. Swaysland of Brighton has been in the habit, during the last forty
years, of catching our migratory birds on their first arrival, and he has
never known the females of any species to arrive before their males.
During one spring he shot thirty-nine males of Ray's wagtail (Budytes Raii)
before he saw a single female. Mr. Gould has ascertained by the dissection
of those snipes which arrive the first in this country, that the males come
before the females. And the like holds good with most of the migratory
birds of the United States. (5. J.A. Allen, on the 'Mammals and Winter
Birds of Florida,' Bulletin of Comparative Zoology, Harvard College, p.
268.) The majority of the male salmon in our rivers, on coming up from the
sea, are ready to breed before the females. So it appears to be with frogs
and toads. Throughout the great class of insects the males almost always
are the first to emerge from the pupal state, so that they generally abound
for a time before any females can be seen. (6. Even with those plants in
which the sexes are separate, the male flowers are generally mature before
the female. As first shewn by C.K. Sprengel, many hermaphrodite plants are
dichogamous; that is, their male and female organs are not ready at the
same time, so that they cannot be self-fertilised. Now in such flowers,
the pollen is in general matured before the stigma, though there are
exceptional cases in which the female organs are beforehand.) The cause of
this difference between the males and females in their periods of arrival
and maturity is sufficiently obvious. Those males which annually first
migrated into any country, or which in the spring were first ready to
breed, or were the most eager, would leave the largest number of offspring;
and these would tend to inherit similar instincts and constitutions. It
must be borne in mind that it would have been impossible to change very
materially the time of sexual maturity in the females, without at the same
time interfering with the period of the production of the young--a period
which must be determined by the seasons of the year. On the whole there
can be no doubt that with almost all animals, in which the sexes are
separate, there is a constantly recurrent struggle between the males for
the possession of the females.
Our difficulty in regard to sexual selection lies in understanding how it
is that the males which conquer other males, or those which prove the most
attractive to the females, leave a greater number of offspring to inherit
their superiority than their beaten and less attractive rivals. Unless
this result does follow, the characters which give to certain males an
advantage over others, could not be perfected and augmented through sexual
selection. When the sexes exist in exactly equal numbers, the worst-
endowed males will (except where polygamy prevails), ultimately find
females, and leave as many offspring, as well fitted for their general
habits of life, as the best-endowed males. From various facts and
considerations, I formerly inferred that with most animals, in which
secondary sexual characters are well developed, the males considerably
exceeded the females in number; but this is not by any means always true.
If the males were to the females as two to one, or as three to two, or even
in a somewhat lower ratio, the whole affair would be simple; for the
better-armed or more attractive males would leave the largest number of
offspring. But after investigating, as far as possible, the numerical
proportion of the sexes, I do not believe that any great inequality in
number commonly exists. In most cases sexual selection appears to have
been effective in the following manner.
Let us take any species, a bird for instance, and divide the females
inhabiting a district into two equal bodies, the one consisting of the more
vigorous and better-nourished individuals, and the other of the less
vigorous and healthy. The former, there can be little doubt, would be
ready to breed in the spring before the others; and this is the opinion of
Mr. Jenner Weir, who has carefully attended to the habits of birds during
many years. There can also be no doubt that the most vigorous, best-
nourished and earliest breeders would on an average succeed in rearing the
largest number of fine offspring. (7. Here is excellent evidence on the
character of the offspring from an experienced ornithologist. Mr. J.A.
Allen, in speaking ('Mammals and Winter Birds of E. Florida,' p. 229) of
the later broods, after the accidental destruction of the first, says, that
these "are found to be smaller and paler-coloured than those hatched
earlier in the season. In cases where several broods are reared each year,
as a general rule the birds of the earlier broods seem in all respects the
most perfect and vigorous.") The males, as we have seen, are generally
ready to breed before the females; the strongest, and with some species the
best armed of the males, drive away the weaker; and the former would then
unite with the more vigorous and better-nourished females, because they are
the first to breed. (8. Hermann Muller has come to this same conclusion
with respect to those female bees which are the first to emerge from the
pupa each year. See his remarkable essay, 'Anwendung der Darwin'schen
Lehre auf Bienen,' 'Verh. d. V. Jahrg.' xxix. p. 45.) Such vigorous pairs
would surely rear a larger number of offspring than the retarded females,
which would be compelled to unite with the conquered and less powerful
males, supposing the sexes to be numerically equal; and this is all that is
wanted to add, in the course of successive generations, to the size,
strength and courage of the males, or to improve their weapons.
But in very many cases the males which conquer their rivals, do not obtain
possession of the females, independently of the choice of the latter. The
courtship of animals is by no means so simple and short an affair as might
be thought. The females are most excited by, or prefer pairing with, the
more ornamented males, or those which are the best songsters, or play the
best antics; but it is obviously probable that they would at the same time
prefer the more vigorous and lively males, and this has in some cases been
confirmed by actual observation. (9. With respect to poultry, I have
received information, hereafter to be given, to this effect. Even birds,
such as pigeons, which pair for life, the female, as I hear from Mr. Jenner
Weir, will desert her mate if he is injured or grows weak.) Thus the more
vigorous females, which are the first to breed, will have the choice of
many males; and though they may not always select the strongest or best
armed, they will select those which are vigorous and well armed, and in
other respects the most attractive. Both sexes, therefore, of such early
pairs would as above explained, have an advantage over others in rearing
offspring; and this apparently has sufficed during a long course of
generations to add not only to the strength and fighting powers of the
males, but likewise to their various ornaments or other attractions.
In the converse and much rarer case of the males selecting particular
females, it is plain that those which were the most vigorous and had
conquered others, would have the freest choice; and it is almost certain
that they would select vigorous as well as attractive females. Such pairs
would have an advantage in rearing offspring, more especially if the male
had the power to defend the female during the pairing-season as occurs with
some of the higher animals, or aided her in providing for the young. The
same principles would apply if each sex preferred and selected certain
individuals of the opposite sex; supposing that they selected not only the
more attractive, but likewise the more vigorous individuals.
NUMERICAL PROPORTION OF THE TWO SEXES.
I have remarked that sexual selection would be a simple affair if the males
were considerably more numerous than the females. Hence I was led to
investigate, as far as I could, the proportions between the two sexes of as
many animals as possible; but the materials are scanty. I will here give
only a brief abstract of the results, retaining the details for a
supplementary discussion, so as not to interfere with the course of my
argument. Domesticated animals alone afford the means of ascertaining the
proportional numbers at birth; but no records have been specially kept for
this purpose. By indirect means, however, I have collected a considerable
body of statistics, from which it appears that with most of our domestic
animals the sexes are nearly equal at birth. Thus 25,560 births of race-
horses have been recorded during twenty-one years, and the male births were
to the female births as 99.7 to 100. In greyhounds the inequality is
greater than with any other animal, for out of 6878 births during twelve
years, the male births were to the female as 110.1 to 100. It is, however,
in some degree doubtful whether it is safe to infer that the proportion
would be the same under natural conditions as under domestication; for
slight and unknown differences in the conditions affect the proportion of
the sexes. Thus with mankind, the male births in England are as 104.5, in
Russia as 108.9, and with the Jews of Livonia as 120, to 100 female births.
But I shall recur to this curious point of the excess of male births in the
supplement to this chapter. At the Cape of Good Hope, however, male
children of European extraction have been born during several years in the
proportion of between 90 and 99 to 100 female children.
For our present purpose we are concerned with the proportions of the sexes,
not only at birth, but also at maturity, and this adds another element of
doubt; for it is a well-ascertained fact that with man the number of males
dying before or during birth, and during the first two years of infancy, is
considerably larger than that of females. So it almost certainly is with
male lambs, and probably with some other animals. The males of some
species kill one another by fighting; or they drive one another about until
they become greatly emaciated. They must also be often exposed to various
dangers, whilst wandering about in eager search for the females. In many
kinds of fish the males are much smaller than the females, and they are
believed often to be devoured by the latter, or by other fishes. The
females of some birds appear to die earlier than the males; they are also
liable to be destroyed on their nests, or whilst in charge of their young.
With insects the female larvae are often larger than those of the males,
and would consequently be more likely to be devoured. In some cases the
mature females are less active and less rapid in their movements than the
males, and could not escape so well from danger. Hence, with animals in a
state of nature, we must rely on mere estimation, in order to judge of the
proportions of the sexes at maturity; and this is but little trustworthy,
except when the inequality is strongly marked. Nevertheless, as far as a
judgment can be formed, we may conclude from the facts given in the
supplement, that the males of some few mammals, of many birds, of some fish
and insects, are considerably more numerous than the females.
The proportion between the sexes fluctuates slightly during successive
years: thus with race-horses, for every 100 mares born the stallions
varied from 107.1 in one year to 92.6 in another year, and with greyhounds
from 116.3 to 95.3. But had larger numbers been tabulated throughout an
area more extensive than England, these fluctuations would probably have
disappeared; and such as they are, would hardly suffice to lead to
effective sexual selection in a state of nature. Nevertheless, in the
cases of some few wild animals, as shewn in the supplement, the proportions
seem to fluctuate either during different seasons or in different
localities in a sufficient degree to lead to such selection. For it should
be observed that any advantage, gained during certain years or in certain
localities by those males which were able to conquer their rivals, or were
the most attractive to the females, would probably be transmitted to the
offspring, and would not subsequently be eliminated. During the succeeding
seasons, when, from the equality of the sexes, every male was able to
procure a female, the stronger or more attractive males previously produced
would still have at least as good a chance of leaving offspring as the
weaker or less attractive.
POLYGAMY.
The practice of polygamy leads to the same results as would follow from an
actual inequality in the number of the sexes; for if each male secures two
or more females, many males cannot pair; and the latter assuredly will be
the weaker or less attractive individuals. Many mammals and some few birds
are polygamous, but with animals belonging to the lower classes I have
found no evidence of this habit. The intellectual powers of such animals
are, perhaps, not sufficient to lead them to collect and guard a harem of
females. That some relation exists between polygamy and the development of
secondary sexual characters, appears nearly certain; and this supports the
view that a numerical preponderance of males would be eminently favourable
to the action of sexual selection. Nevertheless many animals, which are
strictly monogamous, especially birds, display strongly-marked secondary
sexual characters; whilst some few animals, which are polygamous, do not
have such characters.
We will first briefly run through the mammals, and then turn to birds. The
gorilla seems to be polygamous, and the male differs considerably from the
female; so it is with some baboons, which live in herds containing twice as
many adult females as males. In South America the Mycetes caraya presents
well-marked sexual differences, in colour, beard, and vocal organs; and the
male generally lives with two or three wives: the male of the Cebus
capucinus differs somewhat from the female, and appears to be polygamous.
(10. On the Gorilla, Savage and Wyman, 'Boston Journal of Natural
History,' vol. v. 1845-47, p. 423. On Cynocephalus, Brehm, 'Thierleben,'
B. i. 1864, s. 77. On Mycetes, Rengger, 'Naturgeschichte der Saugethiere
von Paraguay,' 1830, ss. 14, 20. On Cebus, Brehm, ibid. s. 108.) Little
is known on this head with respect to most other monkeys, but some species
are strictly monogamous. The ruminants are eminently polygamous, and they
present sexual differences more frequently than almost any other group of
mammals; this holds good, especially in their weapons, but also in other
characters. Most deer, cattle, and sheep are polygamous; as are most
antelopes, though some are monogamous. Sir Andrew Smith, in speaking of
the antelopes of South Africa, says that in herds of about a dozen there
was rarely more than one mature male. The Asiatic Antilope saiga appears
to be the most inordinate polygamist in the world; for Pallas (11. Pallas,
'Spicilegia Zoolog., Fasc.' xii. 1777, p. 29. Sir Andrew Smith,
'Illustrations of the Zoology of S. Africa,' 1849, pl. 29, on the Kobus.
Owen, in his 'Anatomy of Vertebrates' (vol. iii. 1868, p. 633) gives a
table shewing incidentally which species of antelopes are gregarious.)
states that the male drives away all rivals, and collects a herd of about a
hundred females and kids together; the female is hornless and has softer
hair, but does not otherwise differ much from the male. The wild horse of
the Falkland Islands and of the Western States of N. America is polygamous,
but, except in his greater size and in the proportions of his body, differs
but little from the mare. The wild boar presents well-marked sexual
characters, in his great tusks and some other points. In Europe and in
India he leads a solitary life, except during the breeding-season; but as
is believed by Sir W. Elliot, who has had many opportunities in India of
observing this animal, he consorts at this season with several females.
Whether this holds good in Europe is doubtful, but it is supported by some
evidence. The adult male Indian elephant, like the boar, passes much of
his time in solitude; but as Dr. Campbell states, when with others, "It is
rare to find more than one male with a whole herd of females"; the larger
males expelling or killing the smaller and weaker ones. The male differs
from the female in his immense tusks, greater size, strength, and
endurance; so great is the difference in these respects that the males when
caught are valued at one-fifth more than the females. (12. Dr. Campbell,
in 'Proc. Zoolog. Soc.' 1869, p. 138. See also an interesting paper by
Lieut. Johnstone, in 'Proceedings, Asiatic Society of Bengal,' May 1868.)
The sexes of other pachydermatous animals differ very little or not at all,
and, as far as known, they are not polygamists. Nor have I heard of any
species in the Orders of Cheiroptera, Edentata, Insectivora and Rodents
being polygamous, excepting that amongst the Rodents, the common rat,
according to some rat-catchers, lives with several females. Nevertheless
the two sexes of some sloths (Edentata) differ in the character and colour
of certain patches of hair on their shoulders. (13. Dr. Gray, in 'Annals
and Magazine of Natural History,' 1871, p. 302.) And many kinds of bats
(Cheiroptera) present well-marked sexual differences, chiefly in the males
possessing odoriferous glands and pouches, and by their being of a lighter
colour. (14. See Dr. Dobson's excellent paper in 'Proceedings of the
Zoological Society,' 1873, p. 241.) In the great order of Rodents, as far
as I can learn, the sexes rarely differ, and when they do so, it is but
slightly in the tint of the fur.
As I hear from Sir Andrew Smith, the lion in South Africa sometimes lives
with a single female, but generally with more, and, in one case, was found
with as many as five females; so that he is polygamous. As far as I can
discover, he is the only polygamist amongst all the terrestrial Carnivora,
and he alone presents well-marked sexual characters. If, however, we turn
to the marine Carnivora, as we shall hereafter see, the case is widely
different; for many species of seals offer extraordinary sexual
differences, and they are eminently polygamous. Thus, according to Peron,
the male sea-elephant of the Southern Ocean always possesses several
females, and the sea-lion of Forster is said to be surrounded by from
twenty to thirty females. In the North, the male sea-bear of Steller is
accompanied by even a greater number of females. It is an interesting
fact, as Dr. Gill remarks (15. 'The Eared Seals,' American Naturalist,
vol. iv. Jan. 1871.), that in the monogamous species, "or those living in
small communities, there is little difference in size between the males and
females; in the social species, or rather those of which the males have
harems, the males are vastly larger than the females."
Amongst birds, many species, the sexes of which differ greatly from each
other, are certainly monogamous. In Great Britain we see well-marked
sexual differences, for instance, in the wild-duck which pairs with a
single female, the common blackbird, and the bullfinch which is said to
pair for life. I am informed by Mr. Wallace that the like is true of the
Chatterers or Cotingidae of South America, and of many other birds. In
several groups I have not been able to discover whether the species are
polygamous or monogamous. Lesson says that birds of paradise, so
remarkable for their sexual differences, are polygamous, but Mr. Wallace
doubts whether he had sufficient evidence. Mr. Salvin tells me he has been
led to believe that humming-birds are polygamous. The male widow-bird,
remarkable for his caudal plumes, certainly seems to be a polygamist. (16.
'The Ibis,' vol. iii. 1861, p. 133, on the Progne Widow-bird. See also on
the Vidua axillaris, ibid. vol. ii. 1860, p. 211. On the polygamy of the
Capercailzie and Great Bustard, see L. Lloyd, 'Game Birds of Sweden,' 1867,
pp. 19, and 182. Montagu and Selby speak of the Black Grouse as polygamous
and of the Red Grouse as monogamous.) I have been assured by Mr. Jenner
Weir and by others, that it is somewhat common for three starlings to
frequent the same nest; but whether this is a case of polygamy or polyandry
has not been ascertained.
The Gallinaceae exhibit almost as strongly marked sexual differences as
birds of paradise or humming-birds, and many of the species are, as is well
known, polygamous; others being strictly monogamous. What a contrast is
presented between the sexes of the polygamous peacock or pheasant, and the
monogamous guinea-fowl or partridge! Many similar cases could be given, as
in the grouse tribe, in which the males of the polygamous capercailzie and
black-cock differ greatly from the females; whilst the sexes of the
monogamous red grouse and ptarmigan differ very little. In the Cursores,
except amongst the bustards, few species offer strongly-marked sexual
differences, and the great bustard (Otis tarda) is said to be polygamous.
With the Grallatores, extremely few species differ sexually, but the ruff
(Machetes pugnax) affords a marked exception, and this species is believed
by Montagu to be a polygamist. Hence it appears that amongst birds there
often exists a close relation between polygamy and the development of
strongly-marked sexual differences. I asked Mr. Bartlett, of the
Zoological Gardens, who has had very large experience with birds, whether
the male tragopan (one of the Gallinaceae) was polygamous, and I was struck
by his answering, "I do not know, but should think so from his splendid
colours."
It deserves notice that the instinct of pairing with a single female is
easily lost under domestication. The wild-duck is strictly monogamous, the
domestic-duck highly polygamous. The Rev. W.D. Fox informs me that out of
some half-tamed wild-ducks, on a large pond in his neighbourhood, so many
mallards were shot by the gamekeeper that only one was left for every seven
or eight females; yet unusually large broods were reared. The guinea-fowl
is strictly monogamous; but Mr. Fox finds that his birds succeed best when
he keeps one cock to two or three hens. Canary-birds pair in a state of
nature, but the breeders in England successfully put one male to four or
five females. I have noticed these cases, as rendering it probable that
wild monogamous species might readily become either temporarily or
permanently polygamous.
Too little is known of the habits of reptiles and fishes to enable us to
speak of their marriage arrangements. The stickle-back (Gasterosteus),
however, is said to be a polygamist (17. Noel Humphreys, 'River Gardens,'
1857.); and the male during the breeding-season differs conspicuously from
the female.
To sum up on the means through which, as far as we can judge, sexual
selection has led to the development of secondary sexual characters. It
has been shewn that the largest number of vigorous offspring will be reared
from the pairing of the strongest and best-armed males, victorious in
contests over other males, with the most vigorous and best-nourished
females, which are the first to breed in the spring. If such females
select the more attractive, and at the same time vigorous males, they will
rear a larger number of offspring than the retarded females, which must
pair with the less vigorous and less attractive males. So it will be if
the more vigorous males select the more attractive and at the same time
healthy and vigorous females; and this will especially hold good if the
male defends the female, and aids in providing food for the young. The
advantage thus gained by the more vigorous pairs in rearing a larger number
of offspring has apparently sufficed to render sexual selection efficient.
But a large numerical preponderance of males over females will be still
more efficient; whether the preponderance is only occasional and local, or
permanent; whether it occurs at birth, or afterwards from the greater
destruction of the females; or whether it indirectly follows from the
practice of polygamy.
THE MALE GENERALLY MORE MODIFIED THAN THE FEMALE.
Throughout the animal kingdom, when the sexes differ in external
appearance, it is, with rare exceptions, the male which has been the more
modified; for, generally, the female retains a closer resemblance to the
young of her own species, and to other adult members of the same group.
The cause of this seems to lie in the males of almost all animals having
stronger passions than the females. Hence it is the males that fight
together and sedulously display their charms before the females; and the
victors transmit their superiority to their male offspring. Why both sexes
do not thus acquire the characters of their fathers, will be considered
hereafter. That the males of all mammals eagerly pursue the females is
notorious to every one. So it is with birds; but many cock birds do not so
much pursue the hen, as display their plumage, perform strange antics, and
pour forth their song in her presence. The male in the few fish observed
seems much more eager than the female; and the same is true of alligators,
and apparently of Batrachians. Throughout the enormous class of insects,
as Kirby remarks, "the law is that the male shall seek the female." (18.
Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 342.)
Two good authorities, Mr. Blackwall and Mr. C. Spence Bate, tell me that
the males of spiders and crustaceans are more active and more erratic in
their habits than the females. When the organs of sense or locomotion are
present in the one sex of insects and crustaceans and absent in the other,
or when, as is frequently the case, they are more highly developed in the
one than in the other, it is, as far as I can discover, almost invariably
the male which retains such organs, or has them most developed; and this
shews that the male is the more active member in the courtship of the
sexes. (19. One parasitic Hymenopterous insect (Westwood, 'Modern Class.
of Insects,' vol. ii. p. 160) forms an exception to the rule, as the male
has rudimentary wings, and never quits the cell in which it is born, whilst
the female has well-developed wings. Audouin believes that the females of
this species are impregnated by the males which are born in the same cells
with them; but it is much more probable that the females visit other cells,
so that close inter-breeding is thus avoided. We shall hereafter meet in
various classes, with a few exceptional cases, in which the female, instead
of the male, is the seeker and wooer.)
The female, on the other hand, with the rarest exceptions, is less eager
than the male. As the illustrious Hunter (20. 'Essays and Observations,'
edited by Owen, vol. i. 1861, p. 194.) long ago observed, she generally
"requires to be courted;" she is coy, and may often be seen endeavouring
for a long time to escape from the male. Every observer of the habits of
animals will be able to call to mind instances of this kind. It is shewn
by various facts, given hereafter, and by the results fairly attributable
to sexual selection, that the female, though comparatively passive,
generally exerts some choice and accepts one male in preference to others.
Or she may accept, as appearances would sometimes lead us to believe, not
the male which is the most attractive to her, but the one which is the
least distasteful. The exertion of some choice on the part of the female
seems a law almost as general as the eagerness of the male.
We are naturally led to enquire why the male, in so many and such distinct
classes, has become more eager than the female, so that he searches for
her, and plays the more active part in courtship. It would be no advantage
and some loss of power if each sex searched for the other; but why should
the male almost always be the seeker? The ovules of plants after
fertilisation have to be nourished for a time; hence the pollen is
necessarily brought to the female organs--being placed on the stigma, by
means of insects or the wind, or by the spontaneous movements of the
stamens; and in the Algae, etc., by the locomotive power of the
antherozooids. With lowly-organised aquatic animals, permanently affixed
to the same spot and having their sexes separate, the male element is
invariably brought to the female; and of this we can see the reason, for
even if the ova were detached before fertilisation, and did not require
subsequent nourishment or protection, there would yet be greater difficulty
in transporting them than the male element, because, being larger than the
latter, they are produced in far smaller numbers. So that many of the
lower animals are, in this respect, analogous with plants. (21. Prof.
Sachs ('Lehrbuch der Botanik,' 1870, S. 633) in speaking of the male and
female reproductive cells, remarks, "verhalt sich die eine bei der
Vereinigung activ,...die andere erscheint bei der Vereinigung passiv.")
The males of affixed and aquatic animals having been led to emit their
fertilising element in this way, it is natural that any of their
descendants, which rose in the scale and became locomotive, should retain
the same habit; and they would approach the female as closely as possible,
in order not to risk the loss of the fertilising element in a long passage
of it through the water. With some few of the lower animals, the females
alone are fixed, and the males of these must be the seekers. But it is
difficult to understand why the males of species, of which the progenitors
were primordially free, should invariably have acquired the habit of
approaching the females, instead of being approached by them. But in all
cases, in order that the males should seek efficiently, it would be
necessary that they should be endowed with strong passions; and the
acquirement of such passions would naturally follow from the more eager
leaving a larger number of offspring than the less eager.
The great eagerness of the males has thus indirectly led to their much more
frequently developing secondary sexual characters than the females. But
the development of such characters would be much aided, if the males were
more liable to vary than the females--as I concluded they were--after a
long study of domesticated animals. Von Nathusius, who has had very wide
experience, is strongly of the same opinion. (22. 'Vortrage uber
Viehzucht,' 1872, p. 63.) Good evidence also in favour of this conclusion
can be produced by a comparison of the two sexes in mankind. During the
Novara Expedition (23. 'Reise der Novara: Anthropolog. Theil,' 1867, ss.
216-269. The results were calculated by Dr. Weisbach from measurements
made by Drs. K. Scherzer and Schwarz. On the greater variability of the
males of domesticated animals, see my 'Variation of Animals and Plants
under Domestication,' vol. ii. 1868, p. 75.) a vast number of measurements
was made of various parts of the body in different races, and the men were
found in almost every case to present a greater range of variation than the
women; but I shall have to recur to this subject in a future chapter. Mr.
J. Wood (24. 'Proceedings of the Royal Society,' vol. xvi. July 1868, pp.
519 and 524.), who has carefully attended to the variation of the muscles
in man, puts in italics the conclusion that "the greatest number of
abnormalities in each subject is found in the males." He had previously
remarked that "altogether in 102 subjects, the varieties of redundancy were
found to be half as many again as in females, contrasting widely with the
greater frequency of deficiency in females before described." Professor
Macalister likewise remarks (25. 'Proc. Royal Irish Academy,' vol. x.
1868, p. 123.) that variations in the muscles "are probably more common in
males than females." Certain muscles which are not normally present in
mankind are also more frequently developed in the male than in the female
sex, although exceptions to this rule are said to occur. Dr. Burt Wilder
(26. 'Massachusetts Medical Society,' vol. ii. No. 3, 1868, p. 9.) has
tabulated the cases of 152 individuals with supernumerary digits, of which
86 were males, and 39, or less than half, females, the remaining 27 being
of unknown sex. It should not, however, be overlooked that women would
more frequently endeavour to conceal a deformity of this kind than men.
Again, Dr. L. Meyer asserts that the ears of man are more variable in form
than those of a woman. (27. 'Archiv fur Path. Anat. und Phys.' 1871, p.
488.) Lastly the temperature is more variable in man than in woman. (28.
The conclusions recently arrived at by Dr. J. Stockton Hough, on the
temperature of man, are given in the 'Pop. Sci. Review,' Jan. 1st, 1874, p.
97.)
The cause of the greater general variability in the male sex, than in the
female is unknown, except in so far as secondary sexual characters are
extraordinarily variable, and are usually confined to the males; and, as we
shall presently see, this fact is, to a certain extent, intelligible.
Through the action of sexual and natural selection male animals have been
rendered in very many instances widely different from their females; but
independently of selection the two sexes, from differing constitutionally,
tend to vary in a somewhat different manner. The female has to expend much
organic matter in the formation of her ova, whereas the male expends much
force in fierce contests with his rivals, in wandering about in search of
the female, in exerting his voice, pouring out odoriferous secretions,
etc.: and this expenditure is generally concentrated within a short
period. The great vigour of the male during the season of love seems often
to intensify his colours, independently of any marked difference from the
female. (29. Prof. Mantegazza is inclined to believe ('Lettera a Carlo
Darwin,' 'Archivio per l'Anthropologia,' 1871, p. 306) that the bright
colours, common in so many male animals, are due to the presence and
retention by them of the spermatic fluid; but this can hardly be the case;
for many male birds, for instance young pheasants, become brightly coloured
in the autumn of their first year.) In mankind, and even as low down in
the organic scale as in the Lepidoptera, the temperature of the body is
higher in the male than in the female, accompanied in the case of man by a
slower pulse. (30. For mankind, see Dr. J. Stockton Hough, whose
conclusions are given in the 'Popular Science Review,' 1874, p. 97. See
Girard's observations on the Lepidoptera, as given in the 'Zoological
Record,' 1869, p. 347.) On the whole the expenditure of matter and force
by the two sexes is probably nearly equal, though effected in very
different ways and at different rates.
From the causes just specified the two sexes can hardly fail to differ
somewhat in constitution, at least during the breeding-season; and,
although they may be subjected to exactly the same conditions, they will
tend to vary in a different manner. If such variations are of no service
to either sex, they will not be accumulated and increased by sexual or
natural selection. Nevertheless, they may become permanent if the exciting
cause acts permanently; and in accordance with a frequent form of
inheritance they may be transmitted to that sex alone in which they first
appeared. In this case the two sexes will come to present permanent, yet
unimportant, differences of character. For instance, Mr. Allen shews that
with a large number of birds inhabiting the northern and southern United
States, the specimens from the south are darker-coloured than those from
the north; and this seems to be the direct result of the difference in
temperature, light, etc., between the two regions. Now, in some few cases,
the two sexes of the same species appear to have been differently affected;
in the Agelaeus phoeniceus the males have had their colours greatly
intensified in the south; whereas with Cardinalis virginianus it is the
females which have been thus affected; with Quiscalus major the females
have been rendered extremely variable in tint, whilst the males remain
nearly uniform. (31. 'Mammals and Birds of E. Florida,' pp. 234, 280,
295.)
A few exceptional cases occur in various classes of animals, in which the
females instead of the males have acquired well pronounced secondary sexual
characters, such as brighter colours, greater size, strength, or pugnacity.
With birds there has sometimes been a complete transposition of the
ordinary characters proper to each sex; the females having become the more
eager in courtship, the males remaining comparatively passive, but
apparently selecting the more attractive females, as we may infer from the
results. Certain hen birds have thus been rendered more highly coloured or
otherwise ornamented, as well as more powerful and pugnacious than the
cocks; these characters being transmitted to the female offspring alone.
It may be suggested that in some cases a double process of selection has
been carried on; that the males have selected the more attractive females,
and the latter the more attractive males. This process, however, though it
might lead to the modification of both sexes, would not make the one sex
different from the other, unless indeed their tastes for the beautiful
differed; but this is a supposition too improbable to be worth considering
in the case of any animal, excepting man. There are, however, many animals
in which the sexes resemble each other, both being furnished with the same
ornaments, which analogy would lead us to attribute to the agency of sexual
selection. In such cases it may be suggested with more plausibility, that
there has been a double or mutual process of sexual selection; the more
vigorous and precocious females selecting the more attractive and vigorous
males, the latter rejecting all except the more attractive females. But
from what we know of the habits of animals, this view is hardly probable,
for the male is generally eager to pair with any female. It is more
probable that the ornaments common to both sexes were acquired by one sex,
generally the male, and then transmitted to the offspring of both sexes.
If, indeed, during a lengthened period the males of any species were
greatly to exceed the females in number, and then during another lengthened
period, but under different conditions, the reverse were to occur, a
double, but not simultaneous, process of sexual selection might easily be
carried on, by which the two sexes might be rendered widely different.
We shall hereafter see that many animals exist, of which neither sex is
brilliantly coloured or provided with special ornaments, and yet the
members of both sexes or of one alone have probably acquired simple
colours, such as white or black, through sexual selection. The absence of
bright tints or other ornaments may be the result of variations of the
right kind never having occurred, or of the animals themselves having
preferred plain black or white. Obscure tints have often been developed
through natural selection for the sake of protection, and the acquirement
through sexual selection of conspicuous colours, appears to have been
sometimes checked from the danger thus incurred. But in other cases the
males during long ages may have struggled together for the possession of
the females, and yet no effect will have been produced, unless a larger
number of offspring were left by the more successful males to inherit their
superiority, than by the less successful: and this, as previously shewn,
depends on many complex contingencies.
Sexual selection acts in a less rigorous manner than natural selection.
The latter produces its effects by the life or death at all ages of the
more or less successful individuals. Death, indeed, not rarely ensues from
the conflicts of rival males. But generally the less successful male
merely fails to obtain a female, or obtains a retarded and less vigorous
female later in the season, or, if polygamous, obtains fewer females; so
that they leave fewer, less vigorous, or no offspring. In regard to
structures acquired through ordinary or natural selection, there is in most
cases, as long as the conditions of life remain the same, a limit to the
amount of advantageous modification in relation to certain special
purposes; but in regard to structures adapted to make one male victorious
over another, either in fighting or in charming the female, there is no
definite limit to the amount of advantageous modification; so that as long
as the proper variations arise the work of sexual selection will go on.
This circumstance may partly account for the frequent and extraordinary
amount of variability presented by secondary sexual characters.
Nevertheless, natural selection will determine that such characters shall
not be acquired by the victorious males, if they would be highly injurious,
either by expending too much of their vital powers, or by exposing them to
any great danger. The development, however, of certain structures--of the
horns, for instance, in certain stags--has been carried to a wonderful
extreme; and in some cases to an extreme which, as far as the general
conditions of life are concerned, must be slightly injurious to the male.
From this fact we learn that the advantages which favoured males derive
from conquering other males in battle or courtship, and thus leaving a
numerous progeny, are in the long run greater than those derived from
rather more perfect adaptation to their conditions of life. We shall
further see, and it could never have been anticipated, that the power to
charm the female has sometimes been more important than the power to
conquer other males in battle.
LAWS OF INHERITANCE.
In order to understand how sexual selection has acted on many animals of
many classes, and in the course of ages has produced a conspicuous result,
it is necessary to bear in mind the laws of inheritance, as far as they are
known. Two distinct elements are included under the term "inheritance"--
the transmission, and the development of characters; but as these generally
go together, the distinction is often overlooked. We see this distinction
in those characters which are transmitted through the early years of life,
but are developed only at maturity or during old age. We see the same
distinction more clearly with secondary sexual characters, for these are
transmitted through both sexes, though developed in one alone. That they
are present in both sexes, is manifest when two species, having strongly-
marked sexual characters, are crossed, for each transmits the characters
proper to its own male and female sex to the hybrid offspring of either
sex. The same fact is likewise manifest, when characters proper to the
male are occasionally developed in the female when she grows old or becomes
diseased, as, for instance, when the common hen assumes the flowing tail-
feathers, hackles, comb, spurs, voice, and even pugnacity of the cock.
Conversely, the same thing is evident, more or less plainly, with castrated
males. Again, independently of old age or disease, characters are
occasionally transferred from the male to the female, as when, in certain
breeds of the fowl, spurs regularly appear in the young and healthy
females. But in truth they are simply developed in the female; for in
every breed each detail in the structure of the spur is transmitted through
the female to her male offspring. Many cases will hereafter be given,
where the female exhibits, more or less perfectly, characters proper to the
male, in whom they must have been first developed, and then transferred to
the female. The converse case of the first development of characters in
the female and of transference to the male, is less frequent; it will
therefore be well to give one striking instance. With bees the pollen-
collecting apparatus is used by the female alone for gathering pollen for
the larvae, yet in most of the species it is partially developed in the
males to whom it is quite useless, and it is perfectly developed in the
males of Bombus or the humble-bee. (32. H. Muller, 'Anwendung der
Darwin'schen Lehre,' etc., Verh. d. n. V. Jahrg., xxix. p. 42.) As not a
single other Hymenopterous insect, not even the wasp, which is closely
allied to the bee, is provided with a pollen-collecting apparatus, we have
no grounds for supposing that male bees primordially collected pollen as
well as the females; although we have some reason to suspect that male
mammals primordially suckled their young as well as the females. Lastly,
in all cases of reversion, characters are transmitted through two, three,
or many more generations, and are then developed under certain unknown
favourable conditions. This important distinction between transmission and
development will be best kept in mind by the aid of the hypothesis of
pangenesis. According to this hypothesis, every unit or cell of the body
throws off gemmules or undeveloped atoms, which are transmitted to the
offspring of both sexes, and are multiplied by self-division. They may
remain undeveloped during the early years of life or during successive
generations; and their development into units or cells, like those from
which they were derived, depends on their affinity for, and union with
other units or cells previously developed in the due order of growth.
INHERITANCE AT CORRESPONDING PERIODS OF LIFE.
This tendency is well established. A new character, appearing in a young
animal, whether it lasts throughout life or is only transient, will, in
general, reappear in the offspring at the same age and last for the same
time. If, on the other hand, a new character appears at maturity, or even
during old age, it tends to reappear in the offspring at the same advanced
age. When deviations from this rule occur, the transmitted characters much
oftener appear before, than after the corresponding age. As I have dwelt
on this subject sufficiently in another work (33. The 'Variation of
Animals and Plants under Domestication,' vol. ii. 1868, p. 75. In the last
chapter but one, the provisional hypothesis of pangenesis, above alluded
to, is fully explained.), I will here merely give two or three instances,
for the sake of recalling the subject to the reader's mind. In several
breeds of the Fowl, the down-covered chickens, the young birds in their
first true plumage, and the adults differ greatly from one another, as well
as from their common parent-form, the Gallus bankiva; and these characters
are faithfully transmitted by each breed to their offspring at the
corresponding periods of life. For instance, the chickens of spangled
Hamburgs, whilst covered with down, have a few dark spots on the head and
rump, but are not striped longitudinally, as in many other breeds; in their
first true plumage, "they are beautifully pencilled," that is each feather
is transversely marked by numerous dark bars; but in their second plumage
the feathers all become spangled or tipped with a dark round spot. (34.
These facts are given on the high authority of a great breeder, Mr. Teebay;
see Tegetmeier's 'Poultry Book,' 1868, p. 158. On the characters of
chickens of different breeds, and on the breeds of the pigeon, alluded to
in the following paragraph, see 'Variation of Animals,' etc., vol. i. pp.
160, 249; vol. ii. p. 77.) Hence in this breed variations have occurred
at, and been transmitted to, three distinct periods of life. The Pigeon
offers a more remarkable case, because the aboriginal parent species does
not undergo any change of plumage with advancing age, excepting that at
maturity the breast becomes more iridescent; yet there are breeds which do
not acquire their characteristic colours until they have moulted two,
three, or four times; and these modifications of plumage are regularly
transmitted.
INHERITANCE AT CORRESPONDING SEASONS OF THE YEAR.
With animals in a state of nature, innumerable instances occur of
characters appearing periodically at different seasons. We see this in the
horns of the stag, and in the fur of Artic animals which becomes thick and
white during the winter. Many birds acquire bright colours and other
decorations during the breeding-season alone. Pallas states (35. 'Novae
species Quadrupedum e Glirium ordine,' 1778, p. 7. On the transmission of
colour by the horse, see 'Variation of Animals and Plants under
Domestication,' vol. i. p. 51. Also vol. ii. p. 71, for a general
discussion on 'Inheritance as limited by Sex.'), that in Siberia domestic
cattle and horses become lighter-coloured during the winter; and I have
myself observed, and heard of similar strongly marked changes of colour,
that is, from brownish cream-colour or reddish-brown to a perfect white, in
several ponies in England. Although I do not know that this tendency to
change the colour of the coat during different seasons is transmitted, yet
it probably is so, as all shades of colour are strongly inherited by the
horse. Nor is this form of inheritance, as limited by the seasons, more
remarkable than its limitation by age or sex.
INHERITANCE AS LIMITED BY SEX.
The equal transmission of characters to both sexes is the commonest form of
inheritance, at least with those animals which do not present strongly-
marked sexual differences, and indeed with many of these. But characters
are somewhat commonly transferred exclusively to that sex, in which they
first appear. Ample evidence on this head has been advanced in my work on
'Variation under Domestication,' but a few instances may here be given.
There are breeds of the sheep and goat, in which the horns of the male
differ greatly in shape from those of the female; and these differences,
acquired under domestication, are regularly transmitted to the same sex.
As a rule, it is the females alone in cats which are tortoise-shell, the
corresponding colour in the males being rusty-red. With most breeds of the
fowl, the characters proper to each sex are transmitted to the same sex
alone. So general is this form of transmission that it is an anomaly when
variations in certain breeds are transmitted equally to both sexes. There
are also certain sub-breeds of the fowl in which the males can hardly be
distinguished from one another, whilst the females differ considerably in
colour. The sexes of the pigeon in the parent-species do not differ in any
external character; nevertheless, in certain domesticated breeds the male
is coloured differently from the female. (36. Dr. Chapuis, 'Le Pigeon
Voyageur Belge,' 1865, p. 87. Boitard et Corbie, 'Les Pigeons de Voliere,'
etc., 1824, p. 173. See, also, on similar differences in certain breeds at
Modena, 'Le variazioni dei Colombi domestici,' del Paolo Bonizzi, 1873.)
The wattle in the English Carrier pigeon, and the crop in the Pouter, are
more highly developed in the male than in the female; and although these
characters have been gained through long-continued selection by man, the
slight differences between the sexes are wholly due to the form of
inheritance which has prevailed; for they have arisen, not from, but rather
in opposition to, the wish of the breeder.
Most of our domestic races have been formed by the accumulation of many
slight variations; and as some of the successive steps have been
transmitted to one sex alone, and some to both sexes, we find in the
different breeds of the same species all gradations between great sexual
dissimilarity and complete similarity. Instances have already been given
with the breeds of the fowl and pigeon, and under nature analogous cases
are common. With animals under domestication, but whether in nature I will
not venture to say, one sex may lose characters proper to it, and may thus
come somewhat to resemble the opposite sex; for instance, the males of some
breeds of the fowl have lost their masculine tail-plumes and hackles. On
the other hand, the differences between the sexes may be increased under
domestication, as with merino sheep, in which the ewes have lost their
horns. Again, characters proper to one sex may suddenly appear in the
other sex; as in those sub-breeds of the fowl in which the hens acquire
spurs whilst young; or, as in certain Polish sub-breeds, in which the
females, as there is reason to believe, originally acquired a crest, and
subsequently transferred it to the males. All these cases are intelligible
on the hypothesis of pangenesis; for they depend on the gemmules of certain
parts, although present in both sexes, becoming, through the influence of
domestication, either dormant or developed in either sex.
There is one difficult question which it will be convenient to defer to a
future chapter; namely, whether a character at first developed in both
sexes, could through selection be limited in its development to one sex
alone. If, for instance, a breeder observed that some of his pigeons (of
which the characters are usually transferred in an equal degree to both
sexes) varied into pale blue, could he by long-continued selection make a
breed, in which the males alone should be of this tint, whilst the females
remained unchanged? I will here only say, that this, though perhaps not
impossible, would be extremely difficult; for the natural result of
breeding from the pale-blue males would be to change the whole stock of
both sexes to this tint. If, however, variations of the desired tint
appeared, which were from the first limited in their development to the
male sex, there would not be the least difficulty in making a breed with
the two sexes of a different colour, as indeed has been effected with a
Belgian breed, in which the males alone are streaked with black. In a
similar manner, if any variation appeared in a female pigeon, which was
from the first sexually limited in its development to the females, it would
be easy to make a breed with the females alone thus characterised; but if
the variation was not thus originally limited, the process would be
extremely difficult, perhaps impossible. (37. Since the publication of
the first edition of this work, it has been highly satisfactory to me to
find the following remarks (the 'Field,' Sept. 1872) from so experienced a
breeder as Mr. Tegetmeier. After describing some curious cases in pigeons,
of the transmission of colour by one sex alone, and the formation of a sub-
breed with this character, he says: "It is a singular circumstance that
Mr. Darwin should have suggested the possibility of modifying the sexual
colours of birds by a course of artificial selection. When he did so, he
was in ignorance of these facts that I have related; but it is remarkable
how very closely he suggested the right method of procedure.")
ON THE RELATION BETWEEN THE PERIOD OF DEVELOPMENT OF A CHARACTER AND ITS
TRANSMISSION TO ONE SEX OR TO BOTH SEXES.
Why certain characters should be inherited by both sexes, and other
characters by one sex alone, namely by that sex in which the character
first appeared, is in most cases quite unknown. We cannot even conjecture
why with certain sub-breeds of the pigeon, black striae, though transmitted
through the female, should be developed in the male alone, whilst every
other character is equally transferred to both sexes. Why, again, with
cats, the tortoise-shell colour should, with rare exceptions, be developed
in the female alone. The very same character, such as deficient or
supernumerary digits, colour-blindness, etc., may with mankind be inherited
by the males alone of one family, and in another family by the females
alone, though in both cases transmitted through the opposite as well as
through the same sex. (38. References are given in my 'Variation of
Animals and Plants under Domestication,' vol. ii. p. 72.) Although we are
thus ignorant, the two following rules seem often to hold good--that
variations which first appear in either sex at a late period of life, tend
to be developed in the same sex alone; whilst variations which first appear
early in life in either sex tend to be developed in both sexes. I am,
however, far from supposing that this is the sole determining cause. As I
have not elsewhere discussed this subject, and it has an important bearing
on sexual selection, I must here enter into lengthy and somewhat intricate
details.
It is in itself probable that any character appearing at an early age would
tend to be inherited equally by both sexes, for the sexes do not differ
much in constitution before the power of reproduction is gained. On the
other hand, after this power has been gained and the sexes have come to
differ in constitution, the gemmules (if I may again use the language of
pangenesis) which are cast off from each varying part in the one sex would
be much more likely to possess the proper affinities for uniting with the
tissues of the same sex, and thus becoming developed, than with those of
the opposite sex.
I was first led to infer that a relation of this kind exists, from the fact
that whenever and in whatever manner the adult male differs from the adult
female, he differs in the same manner from the young of both sexes. The
generality of this fact is quite remarkable: it holds good with almost all
mammals, birds, amphibians, and fishes; also with many crustaceans,
spiders, and some few insects, such as certain orthoptera and libellulae.
In all these cases the variations, through the accumulation of which the
male acquired his proper masculine characters, must have occurred at a
somewhat late period of life; otherwise the young males would have been
similarly characterised; and conformably with our rule, the variations are
transmitted to and developed in the adult males alone. When, on the other
hand, the adult male closely resembles the young of both sexes (these, with
rare exceptions, being alike), he generally resembles the adult female; and
in most of these cases the variations through which the young and old
acquired their present characters, probably occurred, according to our
rule, during youth. But there is here room for doubt, for characters are
sometimes transferred to the offspring at an earlier age than that at which
they first appeared in the parents, so that the parents may have varied
when adult, and have transferred their characters to their offspring whilst
young. There are, moreover, many animals, in which the two sexes closely
resemble each other, and yet both differ from their young: and here the
characters of the adults must have been acquired late in life;
nevertheless, these characters, in apparent contradiction to our rule, are
transferred to both sexes. We must not however, overlook the possibility
or even probability of successive variations of the same nature occurring,
under exposure to similar conditions, simultaneously in both sexes at a
rather late period of life; and in this case the variations would be
transferred to the offspring of both sexes at a corresponding late age; and
there would then be no real contradiction to the rule that variations
occurring late in life are transferred exclusively to the sex in which they
first appeared. This latter rule seems to hold true more generally than
the second one, namely, that variations which occur in either sex early in
life tend to be transferred to both sexes. As it was obviously impossible
even to estimate in how large a number of cases throughout the animal
kingdom these two propositions held good, it occurred to me to investigate
some striking or crucial instances, and to rely on the result.
An excellent case for investigation is afforded by the Deer family. In all
the species, but one, the horns are developed only in the males, though
certainly transmitted through the females, and capable of abnormal
development in them. In the reindeer, on the other hand, the female is
provided with horns; so that in this species, the horns ought, according to
our rule, to appear early in life, long before the two sexes are mature and
have come to differ much in constitution. In all the other species the
horns ought to appear later in life, which would lead to their development
in that sex alone, in which they first appeared in the progenitor of the
whole Family. Now in seven species, belonging to distinct sections of the
family and inhabiting different regions, in which the stags alone bear
horns, I find that the horns first appear at periods, varying from nine
months after birth in the roebuck, to ten, twelve or even more months in
the stags of the six other and larger species. (39. I am much obliged to
Mr. Cupples for having made enquiries for me in regard to the Roebuck and
Red Deer of Scotland from Mr. Robertson, the experienced head-forester to
the Marquis of Breadalbane. In regard to Fallow-deer, I have to thank Mr.
Eyton and others for information. For the Cervus alces of N. America, see
'Land and Water,' 1868, pp. 221 and 254; and for the C. Virginianus and
strongyloceros of the same continent, see J.D. Caton, in 'Ottawa Acad. of
Nat. Sc.' 1868, p. 13. For Cervus Eldi of Pegu, see Lieut. Beaven,
'Proccedings of the Zoological Society,' 1867, p. 762.) But with the
reindeer the case is widely different; for, as I hear from Prof. Nilsson,
who kindly made special enquiries for me in Lapland, the horns appear in
the young animals within four or five weeks after birth, and at the same
time in both sexes. So that here we have a structure, developed at a most
unusually early age in one species of the family, and likewise common to
both sexes in this one species alone.
In several kinds of antelopes, only the males are provided with horns,
whilst in the greater number both sexes bear horns. With respect to the
period of development, Mr. Blyth informs me that there was at one time in
the Zoological Gardens a young koodoo (Ant. strepsiceros), of which the
males alone are horned, and also the young of a closely-allied species, the
eland (Ant. oreas), in which both sexes are horned. Now it is in strict
conformity with our rule, that in the young male koodoo, although ten
months old, the horns were remarkably small, considering the size
ultimately attained by them; whilst in the young male eland, although only
three months old, the horns were already very much larger than in the
koodoo. It is also a noticeable fact that in the prong-horned antelope
(40. Antilocapra Americana. I have to thank Dr. Canfield for information
with respect to the horns of the female: see also his paper in
'Proceedings of the Zoological Society,' 1866, p. 109. Also Owen, 'Anatomy
of Vertebrates,' vol. iii. p. 627), only a few of the females, about one in
five, have horns, and these are in a rudimentary state, though sometimes
above four inches long: so that as far as concerns the possession of horns
by the males alone, this species is in an intermediate condition, and the
horns do not appear until about five or six months after birth. Therefore
in comparison with what little we know of the development of the horns in
other antelopes, and from what we do know with respect to the horns of
deer, cattle, etc., those of the prong-horned antelope appear at an
intermediate period of life,--that is, not very early, as in cattle and
sheep, nor very late, as in the larger deer and antelopes. The horns of
sheep, goats, and cattle, which are well developed in both sexes, though
not quite equal in size, can be felt, or even seen, at birth or soon
afterwards. (41. I have been assured that the horns of the sheep in North
Wales can always be felt, and are sometimes even an inch in length, at
birth. Youatt says ('Cattle,' 1834, p. 277), that the prominence of the
frontal bone in cattle penetrates the cutis at birth, and that the horny
matter is soon formed over it.) Our rule, however, seems to fail in some
breeds of sheep, for instance merinos, in which the rams alone are horned;
for I cannot find on enquiry (42. I am greatly indebted to Prof. Victor
Carus for having made enquiries for me, from the highest authorities, with
respect to the merino sheep of Saxony. On the Guinea coast of Africa there
is, however, a breed of sheep in which, as with merinos, the rams alone
bear horns; and Mr. Winwood Reade informs me that in one case observed by
him, a young ram, born on Feb. 10th, first shewed horns on March 6th, so
that in this instance, in conformity with rule, the development of the
horns occurred at a later period of life than in Welsh sheep, in which both
sexes are horned.), that the horns are developed later in life in this
breed than in ordinary sheep in which both sexes are horned. But with
domesticated sheep the presence or absence of horns is not a firmly fixed
character; for a certain proportion of the merino ewes bear small horns,
and some of the rams are hornless; and in most breeds hornless ewes are
occasionally produced.
Dr. W. Marshall has lately made a special study of the protuberances so
common on the heads of birds (43. 'Uber die knochernen Schadelhocker der
Vogel,' in the 'Niederland. Archiv fur Zoologie,' B.i. Heft 2, 1872.), and
he comes to the following conclusion:--that with those species in which
they are confined to the males, they are developed late in life; whereas
with those species in which they are common to the two sexes, they are
developed at a very early period. This is certainly a striking
confirmation of my two laws of inheritance.
In most of the species of the splendid family of the Pheasants, the males
differ conspicuously from the females, and they acquire their ornaments at
a rather late period of life. The eared pheasant (Crossoptilon auritum),
however, offers a remarkable exception, for both sexes possess the fine
caudal plumes, the large ear-tufts and the crimson velvet about the head; I
find that all these characters appear very early in life in accordance with
rule. The adult male can, however, be distinguished from the adult female
by the presence of spurs; and conformably with our rule, these do not begin
to be developed before the age of six months, as I am assured by Mr.
Bartlett, and even at this age, the two sexes can hardly be distinguished.
(44. In the common peacock (Pavo cristatus) the male alone possesses
spurs, whilst both sexes of the Java Peacock (P. muticus) offer the unusual
case of being furnished with spurs. Hence I fully expected that in the
latter species they would have been developed earlier in life than in the
common peacock; but M. Hegt of Amsterdam informs me, that with young birds
of the previous year, of both species, compared on April 23rd, 1869, there
was no difference in the development of the spurs. The spurs, however,
were as yet represented merely by slight knobs or elevations. I presume
that I should have been informed if any difference in the rate of
development had been observed subsequently.) The male and female Peacock
differ conspicuously from each other in almost every part of their plumage,
except in the elegant head-crest, which is common to both sexes; and this
is developed very early in life, long before the other ornaments, which are
confined to the male. The wild-duck offers an analogous case, for the
beautiful green speculum on the wings is common to both sexes, though
duller and somewhat smaller in the female, and it is developed early in
life, whilst the curled tail-feathers and other ornaments of the male are
developed later. (45. In some other species of the Duck family the
speculum differs in a greater degree in the two sexes; but I have not been
able to discover whether its full development occurs later in life in the
males of such species, than in the male of the common duck, as ought to be
the case according to our rule. With the allied Mergus cucullatus we have,
however, a case of this kind: the two sexes differ conspicuously in
general plumage, and to a considerable degree in the speculum, which is
pure white in the male and greyish-white in the female. Now the young
males at first entirely resemble the females, and have a greyish-white
speculum, which becomes pure white at an earlier age than that at which the
adult male acquires his other and more strongly-marked sexual differences:
see Audubon, 'Ornithological Biography,' vol. iii. 1835, pp. 249-250.)
Between such extreme cases of close sexual resemblance and wide
dissimilarity, as those of the Crossoptilon and peacock, many intermediate
ones could be given, in which the characters follow our two rules in their
order of development.
As most insects emerge from the pupal state in a mature condition, it is
doubtful whether the period of development can determine the transference
of their characters to one or to both sexes. But we do not know that the
coloured scales, for instance, in two species of butterflies, in one of
which the sexes differ in colour, whilst in the other they are alike, are
developed at the same relative age in the cocoon. Nor do we know whether
all the scales are simultaneously developed on the wings of the same
species of butterfly, in which certain coloured marks are confined to one
sex, whilst others are common to both sexes. A difference of this kind in
the period of development is not so improbable as it may at first appear;
for with the Orthoptera, which assume their adult state, not by a single
metamorphosis, but by a succession of moults, the young males of some
species at first resemble the females, and acquire their distinctive
masculine characters only at a later moult. Strictly analogous cases occur
at the successive moults of certain male crustaceans.
We have as yet considered the transference of characters, relatively to
their period of development, only in species in a natural state; we will
now turn to domesticated animals, and first touch on monstrosities and
diseases. The presence of supernumerary digits, and the absence of certain
phalanges, must be determined at an early embryonic period--the tendency to
profuse bleeding is at least congenital, as is probably colour-blindness--
yet these peculiarities, and other similar ones, are often limited in their
transmission to one sex; so that the rule that characters, developed at an
early period, tend to be transmitted to both sexes, here wholly fails. But
this rule, as before remarked, does not appear to be nearly so general as
the converse one, namely, that characters which appear late in life in one
sex are transmitted exclusively to the same sex. From the fact of the
above abnormal peculiarities becoming attached to one sex, long before the
sexual functions are active, we may infer that there must be some
difference between the sexes at an extremely early age. With respect to
sexually-limited diseases, we know too little of the period at which they
originate, to draw any safe conclusion. Gout, however, seems to fall under
our rule, for it is generally caused by intemperance during manhood, and is
transmitted from the father to his sons in a much more marked manner than
to his daughters.
In the various domestic breeds of sheep, goats, and cattle, the males
differ from their respective females in the shape or development of their
horns, forehead, mane, dewlap, tail, and hump on the shoulders; and these
peculiarities, in accordance with our rule, are not fully developed until a
rather late period of life. The sexes of dogs do not differ, except that
in certain breeds, especially in the Scotch deer-hound, the male is much
larger and heavier than the female; and, as we shall see in a future
chapter, the male goes on increasing in size to an unusually late period of
life, which, according to rule, will account for his increased size being
transmitted to his male offspring alone. On the other hand, the tortoise-
shell colour, which is confined to female cats, is quite distinct at birth,
and this case violates the rule. There is a breed of pigeons in which the
males alone are streaked with black, and the streaks can be detected even
in the nestlings; but they become more conspicuous at each successive
moult, so that this case partly opposes and partly supports the rule. With
the English Carrier and Pouter pigeons, the full development of the wattle
and the crop occurs rather late in life, and conformably with the rule,
these characters are transmitted in full perfection to the males alone.
The following cases perhaps come within the class previously alluded to, in
which both sexes have varied in the same manner at a rather late period of
life, and have consequently transferred their new characters to both sexes
at a corresponding late period; and if so, these cases are not opposed to
our rule:--there exist sub-breeds of the pigeon, described by Neumeister
(46. 'Das Ganze der Taubenzucht,' 1837, ss. 21, 24. For the case of the
streaked pigeons, see Dr. Chapuis, 'Le pigeon voyageur Belge,' 1865, p.
87.), in which both sexes change their colour during two or three moults
(as is likewise the case with the Almond Tumbler); nevertheless, these
changes, though occurring rather late in life, are common to both sexes.
One variety of the Canary-bird, namely the London Prize, offers a nearly
analogous case.
With the breeds of the Fowl the inheritance of various characters by one or
both sexes, seems generally determined by the period at which such
characters are developed. Thus in all the many breeds in which the adult
male differs greatly in colour from the female, as well as from the wild
parent-species, he differs also from the young male, so that the newly-
acquired characters must have appeared at a rather late period of life. On
the other hand, in most of the breeds in which the two sexes resemble each
other, the young are coloured in nearly the same manner as their parents,
and this renders it probable that their colours first appeared early in
life. We have instances of this fact in all black and white breeds, in
which the young and old of both sexes are alike; nor can it be maintained
that there is something peculiar in a black or white plumage, which leads
to its transference to both sexes; for the males alone of many natural
species are either black or white, the females being differently coloured.
With the so-called Cuckoo sub-breeds of the fowl, in which the feathers are
transversely pencilled with dark stripes, both sexes and the chickens are
coloured in nearly the same manner. The laced plumage of the Sebright
bantam is the same in both sexes, and in the young chickens the wing-
feathers are distinctly, though imperfectly laced. Spangled Hamburgs,
however, offer a partial exception; for the two sexes, though not quite
alike, resemble each other more closely than do the sexes of the aboriginal
parent-species; yet they acquire their characteristic plumage late in life,
for the chickens are distinctly pencilled. With respect to other
characters besides colour, in the wild-parent species and in most of the
domestic breeds, the males alone possess a well-developed comb; but in the
young of the Spanish fowl it is largely developed at a very early age, and,
in accordance with this early development in the male, it is of unusual
size in the adult female. In the Game breeds pugnacity is developed at a
wonderfully early age, of which curious proofs could be given; and this
character is transmitted to both sexes, so that the hens, from their
extreme pugnacity, are now generally exhibited in separate pens. With the
Polish breeds the bony protuberance of the skull which supports the crest
is partially developed even before the chickens are hatched, and the crest
itself soon begins to grow, though at first feebly (47. For full
particulars and references on all these points respecting the several
breeds of the Fowl, see 'Variation of Animals and Plants under
Domestication,' vol. i. pp. 250, 256. In regard to the higher animals, the
sexual differences which have arisen under domestication are described in
the same work under the head of each species.); and in this breed the
adults of both sexes are characterised by a great bony protuberance and an
immense crest.
Finally, from what we have now seen of the relation which exists in many
natural species and domesticated races, between the period of the
development of their characters and the manner of their transmission--for
example, the striking fact of the early growth of the horns in the
reindeer, in which both sexes bear horns, in comparison with their much
later growth in the other species in which the male alone bears horns--we
may conclude that one, though not the sole cause of characters being
exclusively inherited by one sex, is their development at a late age. And
secondly, that one, though apparently a less efficient cause of characters
being inherited by both sexes, is their development at an early age, whilst
the sexes differ but little in constitution. It appears, however, that
some difference must exist between the sexes even during a very early
embryonic period, for characters developed at this age not rarely become
attached to one sex.
SUMMARY AND CONCLUDING REMARKS.
From the foregoing discussion on the various laws of inheritance, we learn
that the characters of the parents often, or even generally, tend to become
developed in the offspring of the same sex, at the same age, and
periodically at the same season of the year, in which they first appeared
in the parents. But these rules, owing to unknown causes, are far from
being fixed. Hence during the modification of a species, the successive
changes may readily be transmitted in different ways; some to one sex, and
some to both; some to the offspring at one age, and some to the offspring
at all ages. Not only are the laws of inheritance extremely complex, but
so are the causes which induce and govern variability. The variations thus
induced are preserved and accumulated by sexual selection, which is in
itself an extremely complex affair, depending, as it does, on the ardour in
love, the courage, and the rivalry of the males, as well as on the powers
of perception, the taste, and will of the female. Sexual selection will
also be largely dominated by natural selection tending towards the general
welfare of the species. Hence the manner in which the individuals of
either or both sexes have been affected through sexual selection cannot
fail to be complex in the highest degree.
When variations occur late in life in one sex, and are transmitted to the
same sex at the same age, the other sex and the young are left unmodified.
When they occur late in life, but are transmitted to both sexes at the same
age, the young alone are left unmodified. Variations, however, may occur
at any period of life in one sex or in both, and be transmitted to both
sexes at all ages, and then all the individuals of the species are
similarly modified. In the following chapters it will be seen that all
these cases frequently occur in nature.
Sexual selection can never act on any animal before the age for
reproduction arrives. From the great eagerness of the male it has
generally acted on this sex and not on the females. The males have thus
become provided with weapons for fighting with their rivals, with organs
for discovering and securely holding the female, and for exciting or
charming her. When the sexes differ in these respects, it is also, as we
have seen, an extremely general law that the adult male differs more or
less from the young male; and we may conclude from this fact that the
successive variations, by which the adult male became modified, did not
generally occur much before the age for reproduction. Whenever some or
many of the variations occurred early in life, the young males would
partake more or less of the characters of the adult males; and differences
of this kind between the old and young males may be observed in many
species of animals.
It is probable that young male animals have often tended to vary in a
manner which would not only have been of no use to them at an early age,
but would have been actually injurious--as by acquiring bright colours,
which would render them conspicuous to their enemies, or by acquiring
structures, such as great horns, which would expend much vital force in
their development. Variations of this kind occurring in the young males
would almost certainly be eliminated through natural selection. With the
adult and experienced males, on the other hand, the advantages derived from
the acquisition of such characters, would more than counterbalance some
exposure to danger, and some loss of vital force.
As variations which give to the male a better chance of conquering other
males, or of finding, securing, or charming the opposite sex, would, if
they happened to arise in the female, be of no service to her, they would
not be preserved in her through sexual selection. We have also good
evidence with domesticated animals, that variations of all kinds are, if
not carefully selected, soon lost through intercrossing and accidental
deaths. Consequently in a state of nature, if variations of the above kind
chanced to arise in the female line, and to be transmitted exclusively in
this line, they would be extremely liable to be lost. If, however, the
females varied and transmitted their newly acquired characters to their
offspring of both sexes, the characters which were advantageous to the
males would be preserved by them through sexual selection, and the two
sexes would in consequence be modified in the same manner, although such
characters were of no use to the females: but I shall hereafter have to
recur to these more intricate contingencies. Lastly, the females may
acquire, and apparently have often acquired by transference, characters
from the male sex.
As variations occurring later in life, and transmitted to one sex alone,
have incessantly been taken advantage of and accumulated through sexual
selection in relation to the reproduction of the species; therefore it
appears, at first sight, an unaccountable fact that similar variations have
not frequently been accumulated through natural selection, in relation to
the ordinary habits of life. If this had occurred, the two sexes would
often have been differently modified, for the sake, for instance, of
capturing prey or of escaping from danger. Differences of this kind
between the two sexes do occasionally occur, especially in the lower
classes. But this implies that the two sexes follow different habits in
their struggles for existence, which is a rare circumstance with the higher
animals. The case, however, is widely different with the reproductive
functions, in which respect the sexes necessarily differ. For variations
in structure which are related to these functions, have often proved of
value to one sex, and from having arisen at a late period of life, have
been transmitted to one sex alone; and such variations, thus preserved and
transmitted, have given rise to secondary sexual characters.
In the following chapters, I shall treat of the secondary sexual characters
in animals of all classes, and shall endeavour in each case to apply the
principles explained in the present chapter. The lowest classes will
detain us for a very short time, but the higher animals, especially birds,
must be treated at considerable length. It should be borne in mind that
for reasons already assigned, I intend to give only a few illustrative
instances of the innumerable structures by the aid of which the male finds
the female, or, when found, holds her. On the other hand, all structures
and instincts by the aid of which the male conquers other males, and by
which he allures or excites the female, will be fully discussed, as these
are in many ways the most interesting.
SUPPLEMENT ON THE PROPORTIONAL NUMBERS OF THE TWO SEXES IN ANIMALS
BELONGING TO VARIOUS CLASSES.
As no one, as far as I can discover, has paid attention to the relative
numbers of the two sexes throughout the animal kingdom, I will here give
such materials as I have been able to collect, although they are extremely
imperfect. They consist in only a few instances of actual enumeration, and
the numbers are not very large. As the proportions are known with
certainty only in mankind, I will first give them as a standard of
comparison.
MAN.
In England during ten years (from 1857 to 1866) the average number of
children born alive yearly was 707,120, in the proportion of 104.5 males to
100 females. But in 1857 the male births throughout England were as 105.2,
and in 1865 as 104.0 to 100. Looking to separate districts, in
Buckinghamshire (where about 5000 children are annually born) the MEAN
proportion of male to female births, during the whole period of the above
ten years, was as 102.8 to 100; whilst in N. Wales (where the average
annual births are 12,873) it was as high as 106.2 to 100. Taking a still
smaller district, viz., Rutlandshire (where the annual births average only
739), in 1864 the male births were as 114.6, and in 1862 as only 97.0 to
100; but even in this small district the average of the 7385 births during
the whole ten years, was as 104.5 to 100: that is in the same ratio as
throughout England. (48. 'Twenty-ninth Annual Report of the Registrar-
General for 1866.' In this report (p. xii.) a special decennial table is
given.) The proportions are sometimes slightly disturbed by unknown
causes; thus Prof. Faye states "that in some districts of Norway there has
been during a decennial period a steady deficiency of boys, whilst in
others the opposite condition has existed." In France during forty-four
years the male to the female births have been as 106.2 to 100; but during
this period it has occurred five times in one department, and six times in
another, that the female births have exceeded the males. In Russia the
average proportion is as high as 108.9, and in Philadelphia in the United
States as 110.5 to 100. (49. For Norway and Russia, see abstract of Prof.
Faye's researches, in 'British and Foreign Medico-Chirurg. Review,' April
1867, pp. 343, 345. For France, the 'Annuaire pour l'An 1867,' p. 213.
For Philadelphia, Dr. Stockton Hough, 'Social Science Assoc.' 1874. For
the Cape of Good Hope, Quetelet as quoted by Dr. H.H. Zouteveen, in the
Dutch Translation of this work (vol. i. p. 417), where much information is
given on the proportion of the sexes.) The average for Europe, deduced by
Bickes from about seventy million births, is 106 males to 100 females. On
the other hand, with white children born at the Cape of Good Hope, the
proportion of males is so low as to fluctuate during successive years
between 90 and 99 males for every 100 females. It is a singular fact that
with Jews the proportion of male births is decidedly larger than with
Christians: thus in Prussia the proportion is as 113, in Breslau as 114,
and in Livonia as 120 to 100; the Christian births in these countries being
the same as usual, for instance, in Livonia as 104 to 100. (50. In regard
to the Jews, see M. Thury, 'La Loi de Production des Sexes,' 1863, p. 25.)
Prof. Faye remarks that "a still greater preponderance of males would be
met with, if death struck both sexes in equal proportion in the womb and
during birth. But the fact is, that for every 100 still-born females, we
have in several countries from 134.6 to 144.9 still-born males. During the
first four or five years of life, also, more male children die than
females, for example in England, during the first year, 126 boys die for
every 100 girls--a proportion which in France is still more unfavourable."
(51. 'British and Foreign Medico-Chirurg. Review,' April 1867, p. 343.
Dr. Stark also remarks ('Tenth Annual Report of Births, Deaths, etc., in
Scotland,' 1867, p. xxviii.) that "These examples may suffice to show that,
at almost every stage of life, the males in Scotland have a greater
liability to death and a higher death-rate than the females. The fact,
however, of this peculiarity being most strongly developed at that
infantile period of life when the dress, food, and general treatment of
both sexes are alike, seems to prove that the higher male death-rate is an
impressed, natural, and constitutional peculiarity due to sex alone.") Dr.
Stockton Hough accounts for these facts in part by the more frequent
defective development of males than of females. We have before seen that
the male sex is more variable in structure than the female; and variations
in important organs would generally be injurious. But the size of the
body, and especially of the head, being greater in male than female infants
is another cause: for the males are thus more liable to be injured during
parturition. Consequently the still-born males are more numerous; and, as
a highly competent judge, Dr. Crichton Browne (52. 'West Riding Lunatic
Asylum Reports,' vol. i. 1871, p. 8. Sir J. Simpson has proved that the
head of the male infant exceeds that of the female by 3/8ths of an inch in
circumference, and by 1/8th in transverse diameter. Quetelet has shewn
that woman is born smaller than man; see Dr. Duncan, 'Fecundity, Fertility,
and Sterility,' 1871, p. 382.), believes, male infants often suffer in
health for some years after birth. Owing to this excess in the death-rate
of male children, both at birth and for some time subsequently, and owing
to the exposure of grown men to various dangers, and to their tendency to
emigrate, the females in all old-settled countries, where statistical
records have been kept, are found to preponderate considerably over the
males. (53. With the savage Guaranys of Paraguay, according to the
accurate Azara ('Voyages dans l'Amerique merid.' tom. ii. 1809, pp. 60,
179), the women are to the men in the proportion of 14 to 13.)
It seems at first sight a mysterious fact that in different nations, under
different conditions and climates, in Naples, Prussia, Westphalia, Holland,
France, England and the United States, the excess of male over female
births is less when they are illegitimate than when legitimate. (54.
Babbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also p. 90,
on still-born children. On illegitimate children in England, see 'Report
of Registrar-General for 1866,' p. xv.) This has been explained by
different writers in many different ways, as from the mothers being
generally young, from the large proportion of first pregnancies, etc. But
we have seen that male infants, from the large size of their heads, suffer
more than female infants during parturition; and as the mothers of
illegitimate children must be more liable than other women to undergo bad
labours, from various causes, such as attempts at concealment by tight
lacing, hard work, distress of mind, etc., their male infants would
proportionably suffer. And this probably is the most efficient of all the
causes of the proportion of males to females born alive being less amongst
illegitimate children than amongst the legitimate. With most animals the
greater size of the adult male than of the female, is due to the stronger
males having conquered the weaker in their struggles for the possession of
the females, and no doubt it is owing to this fact that the two sexes of at
least some animals differ in size at birth. Thus we have the curious fact
that we may attribute the more frequent deaths of male than female infants,
especially amongst the illegitimate, at least in part to sexual selection.
It has often been supposed that the relative age of the two parents
determine the sex of the offspring; and Prof. Leuckart (55. Leuckart, in
Wagner 'Handworterbuch der Phys.' B. iv. 1853, s. 774.) has advanced what
he considers sufficient evidence, with respect to man and certain
domesticated animals, that this is one important though not the sole factor
in the result. So again the period of impregnation relatively to the state
of the female has been thought by some to be the efficient cause; but
recent observations discountenance this belief. According to Dr. Stockton
Hough (56. 'Social Science Association of Philadelphia,' 1874.), the
season of the year, the poverty or wealth of the parents, residence in the
country or in cities, the crossing of foreign immigrants, etc., all
influence the proportion of the sexes. With mankind, polygamy has also
been supposed to lead to the birth of a greater proportion of female
infants; but Dr. J. Campbell (57. 'Anthropological Review,' April 1870, p.
cviii.) carefully attended to this subject in the harems of Siam, and
concludes that the proportion of male to female births is the same as from
monogamous unions. Hardly any animal has been rendered so highly
polygamous as the English race-horse, and we shall immediately see that his
male and female offspring are almost exactly equal in number. I will now
give the facts which I have collected with respect to the proportional
numbers of the sexes of various animals; and will then briefly discuss how
far selection has come into play in determining the result.
HORSES.
Mr. Tegetmeier has been so kind as to tabulate for me from the 'Racing
Calendar' the births of race-horses during a period of twenty-one years,
viz., from 1846 to 1867; 1849 being omitted, as no returns were that year
published. The total births were 25,560 (58. During eleven years a record
was kept of the number of mares which proved barren or prematurely slipped
their foals; and it deserves notice, as shewing how infertile these highly-
nurtured and rather closely-interbred animals have become, that not far
from one-third of the mares failed to produce living foals. Thus during
1866, 809 male colts and 816 female colts were born, and 743 mares failed
to produce offspring. During 1867, 836 males and 902 females were born,
and 794 mares failed.), consisting of 12,763 males and 12,797 females, or
in the proportion of 99.7 males to 100 females. As these numbers are
tolerably large, and as they are drawn from all parts of England, during
several years, we may with much confidence conclude that with the domestic
horse, or at least with the race-horse, the two sexes are produced in
almost equal numbers. The fluctuations in the proportions during
successive years are closely like those which occur with mankind, when a
small and thinly-populated area is considered; thus in 1856 the male horses
were as 107.1, and in 1867 as only 92.6 to 100 females. In the tabulated
returns the proportions vary in cycles, for the males exceeded the females
during six successive years; and the females exceeded the males during two
periods each of four years; this, however, may be accidental; at least I
can detect nothing of the kind with man in the decennial table in the
Registrar's Report for 1866.
DOGS.
During a period of twelve years, from 1857 to 1868, the births of a large
number of greyhounds, throughout England, were sent to the 'Field'
newspaper; and I am again indebted to Mr. Tegetmeier for carefully
tabulating the results. The recorded births were 6878, consisting of 3605
males and 3273 females, that is, in the proportion of 110.1 males to 100
females. The greatest fluctuations occurred in 1864, when the proportion
was as 95.3 males, and in 1867, as 116.3 males to 100 females. The above
average proportion of 110.1 to 100 is probably nearly correct in the case
of the greyhound, but whether it would hold with other domesticated breeds
is in some degree doubtful. Mr. Cupples has enquired from several great
breeders of dogs, and finds that all without exception believe that females
are produced in excess; but he suggests that this belief may have arisen
from females being less valued, and from the consequent disappointment
producing a stronger impression on the mind.
SHEEP.
The sexes of sheep are not ascertained by agriculturists until several
months after birth, at the period when the males are castrated; so that the
following returns do not give the proportions at birth. Moreover, I find
that several great breeders in Scotland, who annually raise some thousand
sheep, are firmly convinced that a larger proportion of males than of
females die during the first year or two. Therefore the proportion of
males would be somewhat larger at birth than at the age of castration.
This is a remarkable coincidence with what, as we have seen, occurs with
mankind, and both cases probably depend on the same cause. I have received
returns from four gentlemen in England who have bred Lowland sheep, chiefly
Leicesters, during the last ten to sixteen years; they amount altogether to
8965 births, consisting of 4407 males and 4558 females; that is in the
proportion of 96.7 males to 100 females. With respect to Cheviot and
black-faced sheep bred in Scotland, I have received returns from six
breeders, two of them on a large scale, chiefly for the years 1867-1869,
but some of the returns extend back to 1862. The total number recorded
amounts to 50,685, consisting of 25,071 males and 25,614 females or in the
proportion of 97.9 males to 100 females. If we take the English and Scotch
returns together, the total number amounts to 59,650, consisting of 29,478
males and 30,172 females, or as 97.7 to 100. So that with sheep at the age
of castration the females are certainly in excess of the males, but
probably this would not hold good at birth. (59. I am much indebted to
Mr. Cupples for having procured for me the above returns from Scotland, as
well as some of the following returns on cattle. Mr. R. Elliot, of
Laighwood, first called my attention to the premature deaths of the males,
--a statement subsequently confirmed by Mr. Aitchison and others. To this
latter gentleman, and to Mr. Payan, I owe my thanks for large returns as to
sheep.)
Of CATTLE I have received returns from nine gentlemen of 982 births, too
few to be trusted; these consisted of 477 bull-calves and 505 cow-calves;
i.e., in the proportion of 94.4 males to 100 females. The Rev. W.D. Fox
informs me that in 1867 out of 34 calves born on a farm in Derbyshire only
one was a bull. Mr. Harrison Weir has enquired from several breeders of
PIGS, and most of them estimate the male to the female births as about 7 to
6. This same gentleman has bred RABBITS for many years, and has noticed
that a far greater number of bucks are produced than does. But estimations
are of little value.
Of mammalia in a state of nature I have been able to learn very little. In
regard to the common rat, I have received conflicting statements. Mr. R.
Elliot, of Laighwood, informs me that a rat-catcher assured him that he had
always found the males in great excess, even with the young in the nest.
In consequence of this, Mr. Elliot himself subsequently examined some
hundred old ones, and found the statement true. Mr. F. Buckland has bred a
large number of white rats, and he also believes that the males greatly
exceed the females. In regard to Moles, it is said that "the males are
much more numerous than the females" (60. Bell, 'History of British
Quadrupeds,' p. 100.): and as the catching of these animals is a special
occupation, the statement may perhaps be trusted. Sir A. Smith, in
describing an antelope of S. Africa (61. 'Illustrations of the Zoology of
S. Africa,' 1849, pl. 29.) (Kobus ellipsiprymnus), remarks, that in the
herds of this and other species, the males are few in number compared with
the females: the natives believe that they are born in this proportion;
others believe that the younger males are expelled from the herds, and Sir
A. Smith says, that though he has himself never seen herds consisting of
young males alone, others affirm that this does occur. It appears probable
that the young when expelled from the herd, would often fall a prey to the
many beasts of prey of the country.
BIRDS.
With respect to the FOWL, I have received only one account, namely, that
out of 1001 chickens of a highly-bred stock of Cochins, reared during eight
years by Mr. Stretch, 487 proved males and 514 females; i.e., as 94.7 to
100. In regard to domestic pigeons there is good evidence either that the
males are produced in excess, or that they live longer; for these birds
invariably pair, and single males, as Mr. Tegetmeier informs me, can always
be purchased cheaper than females. Usually the two birds reared from the
two eggs laid in the same nest are a male and a female; but Mr. Harrison
Weir, who has been so large a breeder, says that he has often bred two
cocks from the same nest, and seldom two hens; moreover, the hen is
generally the weaker of the two, and more liable to perish.
With respect to birds in a state of nature, Mr. Gould and others (62.
Brehm ('Thierleben,' B. iv. s. 990) comes to the same conclusion.) are
convinced that the males are generally the more numerous; and as the young
males of many species resemble the females, the latter would naturally
appear to be the more numerous. Large numbers of pheasants are reared by
Mr. Baker of Leadenhall from eggs laid by wild birds, and he informs Mr.
Jenner Weir that four or five males to one female are generally produced.
An experienced observer remarks (63. On the authority of L. Lloyd, 'Game
Birds of Sweden,' 1867, pp. 12, 132.), that in Scandinavia the broods of
the capercailzie and black-cock contain more males than females; and that
with the Dal-ripa (a kind of ptarmigan) more males than females attend the
leks or places of courtship; but this latter circumstance is accounted for
by some observers by a greater number of hen birds being killed by vermin.
From various facts given by White of Selborne (64. 'Nat. Hist. of
Selborne,' letter xxix. edit. of 1825, vol. i. p. 139.), it seems clear
that the males of the partridge must be in considerable excess in the south
of England; and I have been assured that this is the case in Scotland. Mr.
Weir on enquiring from the dealers, who receive at certain seasons large
numbers of ruffs (Machetes pugnax), was told that the males are much the
more numerous. This same naturalist has also enquired for me from the
birdcatchers, who annually catch an astonishing number of various small
species alive for the London market, and he was unhesitatingly answered by
an old and trustworthy man, that with the chaffinch the males are in large
excess: he thought as high as 2 males to 1 female, or at least as high as
5 to 3. (65. Mr. Jenner Weir received similar information, on making
enquiries during the following year. To shew the number of living
chaffinches caught, I may mention that in 1869 there was a match between
two experts, and one man caught in a day 62, and another 40, male
chaffinches. The greatest number ever caught by one man in a single day
was 70.) The males of the blackbird, he likewise maintained, were by far
the more numerous, whether caught by traps or by netting at night. These
statements may apparently be trusted, because this same man said that the
sexes are about equal with the lark, the twite (Linaria montana), and
goldfinch. On the other hand, he is certain that with the common linnet,
the females preponderate greatly, but unequally during different years;
during some years he has found the females to the males as four to one. It
should, however, be borne in mind, that the chief season for catching birds
does not begin till September, so that with some species partial migrations
may have begun, and the flocks at this period often consist of hens alone.
Mr. Salvin paid particular attention to the sexes of the humming-birds in
Central America, and is convinced that with most of the species the males
are in excess; thus one year he procured 204 specimens belonging to ten
species, and these consisted of 166 males and of only 38 females. With two
other species the females were in excess: but the proportions apparently
vary either during different seasons or in different localities; for on one
occasion the males of Campylopterus hemileucurus were to the females as 5
to 2, and on another occasion (66. 'Ibis,' vol. ii. p. 260, as quoted in
Gould's 'Trochilidae,' 1861, p. 52. For the foregoing proportions, I am
indebted to Mr. Salvin for a table of his results.) in exactly the reversed
ratio. As bearing on this latter point, I may add, that Mr. Powys found in
Corfu and Epirus the sexes of the chaffinch keeping apart, and "the females
by far the most numerous"; whilst in Palestine Mr. Tristram found "the male
flocks appearing greatly to exceed the female in number." (67. 'Ibis,'
1860, p. 137; and 1867, p. 369.) So again with the Quiscalus major, Mr. G.
Taylor says, that in Florida there were "very few females in proportion to
the males," (68. 'Ibis,' 1862, p. 187.) whilst in Honduras the proportion
was the other way, the species there having the character of a polygamist.
FISH.
With fish the proportional numbers of the sexes can be ascertained only by
catching them in the adult or nearly adult state; and there are many
difficulties in arriving at any just conclusion. (69. Leuckart quotes
Bloch (Wagner, 'Handworterbuch der Phys.' B. iv. 1853, s. 775), that with
fish there are twice as many males as females.) Infertile females might
readily be mistaken for males, as Dr. Gunther has remarked to me in regard
to trout. With some species the males are believed to die soon after
fertilising the ova. With many species the males are of much smaller size
than the females, so that a large number of males would escape from the
same net by which the females were caught. M. Carbonnier (70. Quoted in
the 'Farmer,' March 18, 1869, p. 369.), who has especially attended to the
natural history of the pike (Esox lucius), states that many males, owing to
their small size, are devoured by the larger females; and he believes that
the males of almost all fish are exposed from this same cause to greater
danger than the females. Nevertheless, in the few cases in which the
proportional numbers have been actually observed, the males appear to be
largely in excess. Thus Mr. R. Buist, the superintendent of the
Stormontfield experiments, says that in 1865, out of 70 salmon first landed
for the purpose of obtaining the ova, upwards of 60 were males. In 1867 he
again "calls attention to the vast disproportion of the males to the
females. We had at the outset at least ten males to one female."
Afterwards females sufficient for obtaining ova were procured. He adds,
"from the great proportion of the males, they are constantly fighting and
tearing each other on the spawning-beds." (71. 'The Stormontfield
Piscicultural Experiments,' 1866, p. 23. The 'Field' newspaper, June 29,
1867.) This disproportion, no doubt, can be accounted for in part, but
whether wholly is doubtful, by the males ascending the rivers before the
females. Mr. F. Buckland remarks in regard to trout, that "it is a curious
fact that the males preponderate very largely in number over the females.
It INVARIABLY happens that when the first rush of fish is made to the net,
there will be at least seven or eight males to one female found captive. I
cannot quite account for this; either the males are more numerous than the
females, or the latter seek safety by concealment rather than flight." He
then adds, that by carefully searching the banks sufficient females for
obtaining ova can be found. (72. 'Land and Water,' 1868, p. 41.) Mr. H.
Lee informs me that out of 212 trout, taken for this purpose in Lord
Portsmouth's park, 150 were males and 62 females.
The males of the Cyprinidae likewise seem to be in excess; but several
members of this Family, viz., the carp, tench, bream and minnow, appear
regularly to follow the practice, rare in the animal kingdom, of polyandry;
for the female whilst spawning is always attended by two males, one on each
side, and in the case of the bream by three or four males. This fact is so
well known, that it is always recommended to stock a pond with two male
tenches to one female, or at least with three males to two females. With
the minnow, an excellent observer states, that on the spawning-beds the
males are ten times as numerous as the females; when a female comes amongst
the males, "she is immediately pressed closely by a male on each side; and
when they have been in that situation for a time, are superseded by other
two males." (73. Yarrell, 'Hist. British Fishes,' vol. i. 1826, p. 307;
on the Cyprinus carpio, p. 331; on the Tinca vulgaris, p. 331; on the
Abramis brama, p. 336. See, for the minnow (Leuciscus phoxinus), 'Loudon's
Magazine of Natural History,' vol. v. 1832, p. 682.)
INSECTS.
In this great Class, the Lepidoptera almost alone afford means for judging
of the proportional numbers of the sexes; for they have been collected with
special care by many good observers, and have been largely bred from the
egg or caterpillar state. I had hoped that some breeders of silk-moths
might have kept an exact record, but after writing to France and Italy, and
consulting various treatises, I cannot find that this has ever been done.
The general opinion appears to be that the sexes are nearly equal, but in
Italy, as I hear from Professor Canestrini, many breeders are convinced
that the females are produced in excess. This same naturalist, however,
informs me, that in the two yearly broods of the Ailanthus silk-moth
(Bombyx cynthia), the males greatly preponderate in the first, whilst in
the second the two sexes are nearly equal, or the females rather in excess.
In regard to Butterflies in a state of nature, several observers have been
much struck by the apparently enormous preponderance of the males. (74.
Leuckart quotes Meinecke (Wagner, 'Handworterbuch der Phys.' B. iv. 1853,
s. 775) that the males of Butterflies are three or four times as numerous
as the females.) Thus Mr. Bates (75. 'The Naturalist on the Amazons,'
vol. ii. 1863, pp. 228, 347.), in speaking of several species, about a
hundred in number, which inhabit the upper Amazons, says that the males are
much more numerous than the females, even in the proportion of a hundred to
one. In North America, Edwards, who had great experience, estimates in the
genus Papilio the males to the females as four to one; and Mr. Walsh, who
informed me of this statement, says that with P. turnus this is certainly
the case. In South Africa, Mr. R. Trimen found the males in excess in 19
species (76. Four of these cases are given by Mr. Trimen in his
'Rhopalocera Africae Australis.'); and in one of these, which swarms in
open places, he estimated the number of males as fifty to one female. With
another species, in which the males are numerous in certain localities, he
collected only five females during seven years. In the island of Bourbon,
M. Maillard states that the males of one species of Papilio are twenty
times as numerous as the females. (77. Quoted by Trimen, 'Transactions of
the Ent. Society,' vol. v. part iv. 1866, p. 330.) Mr. Trimen informs me
that as far as he has himself seen, or heard from others, it is rare for
the females of any butterfly to exceed the males in number; but three South
African species perhaps offer an exception. Mr. Wallace (78.
'Transactions, Linnean Society,' vol. xxv. p. 37.) states that the females
of Ornithoptera croesus, in the Malay archipelago, are more common and more
easily caught than the males; but this is a rare butterfly. I may here
add, that in Hyperythra, a genus of moths, Guenee says, that from four to
five females are sent in collections from India for one male.
When this subject of the proportional numbers of the sexes of insects was
brought before the Entomological Society (79. 'Proceedings, Entomological
Society,' Feb. 17, 1868.), it was generally admitted that the males of most
Lepidoptera, in the adult or imago state, are caught in greater numbers
than the females: but this fact was attributed by various observers to the
more retiring habits of the females, and to the males emerging earlier from
the cocoon. This latter circumstance is well known to occur with most
Lepidoptera, as well as with other insects. So that, as M. Personnat
remarks, the males of the domesticated Bombyx Yamamai, are useless at the
beginning of the season, and the females at the end, from the want of
mates. (80. Quoted by Dr. Wallace in 'Proceedings, Entomological
Society,' 3rd series, vol. v. 1867, p. 487.) I cannot, however, persuade
myself that these causes suffice to explain the great excess of males, in
the above cases of certain butterflies which are extremely common in their
native countries. Mr. Stainton, who has paid very close attention during
many years to the smaller moths, informs me that when he collected them in
the imago state, he thought that the males were ten times as numerous as
the females, but that since he has reared them on a large scale from the
caterpillar state, he is convinced that the females are the more numerous.
Several entomologists concur in this view. Mr. Doubleday, however, and
some others, take an opposite view, and are convinced that they have reared
from the eggs and caterpillars a larger proportion of males than of
females.
Besides the more active habits of the males, their earlier emergence from
the cocoon, and in some cases their frequenting more open stations, other
causes may be assigned for an apparent or real difference in the
proportional numbers of the sexes of Lepidoptera, when captured in the
imago state, and when reared from the egg or caterpillar state. I hear
from Professor Canestrini, that it is believed by many breeders in Italy,
that the female caterpillar of the silk-moth suffers more from the recent
disease than the male; and Dr. Staudinger informs me that in rearing
Lepidoptera more females die in the cocoon than males. With many species
the female caterpillar is larger than the male, and a collector would
naturally choose the finest specimens, and thus unintentionally collect a
larger number of females. Three collectors have told me that this was
their practice; but Dr. Wallace is sure that most collectors take all the
specimens which they can find of the rarer kinds, which alone are worth the
trouble of rearing. Birds when surrounded by caterpillars would probably
devour the largest; and Professor Canestrini informs me that in Italy some
breeders believe, though on insufficient evidence, that in the first broods
of the Ailanthus silk-moth, the wasps destroy a larger number of the female
than of the male caterpillars. Dr. Wallace further remarks that female
caterpillars, from being larger than the males, require more time for their
development, and consume more food and moisture: and thus they would be
exposed during a longer time to danger from ichneumons, birds, etc., and in
times of scarcity would perish in greater numbers. Hence it appears quite
possible that in a state of nature, fewer female Lepidoptera may reach
maturity than males; and for our special object we are concerned with their
relative numbers at maturity, when the sexes are ready to propagate their
kind.
The manner in which the males of certain moths congregate in extraordinary
numbers round a single female, apparently indicates a great excess of
males, though this fact may perhaps be accounted for by the earlier
emergence of the males from their cocoons. Mr. Stainton informs me that
from twelve to twenty males, may often be seen congregated round a female
Elachista rufocinerea. It is well known that if a virgin Lasiocampa
quercus or Saturnia carpini be exposed in a cage, vast numbers of males
collect round her, and if confined in a room will even come down the
chimney to her. Mr. Doubleday believes that he has seen from fifty to a
hundred males of both these species attracted in the course of a single day
by a female in confinement. In the Isle of Wight Mr. Trimen exposed a box
in which a female of the Lasiocampa had been confined on the previous day,
and five males soon endeavoured to gain admittance. In Australia, Mr.
Verreaux, having placed the female of a small Bombyx in a box in his
pocket, was followed by a crowd of males, so that about 200 entered the
house with him. (81. Blanchard, 'Metamorphoses, Moeurs des Insectes,'
1868, pp. 225-226.)
Mr. Doubleday has called my attention to M. Staudinger's (82.
'Lepidopteren-Doubletten Liste,' Berlin, No. x. 1866.) list of Lepidoptera,
which gives the prices of the males and females of 300 species or well-
marked varieties of butterflies (Rhopalocera). The prices for both sexes
of the very common species are of course the same; but in 114 of the rarer
species they differ; the males being in all cases, excepting one, the
cheaper. On an average of the prices of the 113 species, the price of the
male to that of the female is as 100 to 149; and this apparently indicates
that inversely the males exceed the females in the same proportion. About
2000 species or varieties of moths (Heterocera) are catalogued, those with
wingless females being here excluded on account of the difference in habits
between the two sexes: of these 2000 species, 141 differ in price
according to sex, the males of 130 being cheaper, and those of only 11
being dearer than the females. The average price of the males of the 130
species, to that of the females, is as 100 to 143. With respect to the
butterflies in this priced list, Mr. Doubleday thinks (and no man in
England has had more experience), that there is nothing in the habits of
the species which can account for the difference in the prices of the two
sexes, and that it can be accounted for only by an excess in the number of
the males. But I am bound to add that Dr. Staudinger informs me, that he
is himself of a different opinion. He thinks that the less active habits
of the females and the earlier emergence of the males will account for his
collectors securing a larger number of males than of females, and
consequently for the lower prices of the former. With respect to specimens
reared from the caterpillar-state, Dr. Staudinger believes, as previously
stated, that a greater number of females than of males die whilst confined
to the cocoons. He adds that with certain species one sex seems to
preponderate over the other during certain years.
Of direct observations on the sexes of Lepidoptera, reared either from eggs
or caterpillars, I have received only the few following cases: (See
following table.)
So that in these eight lots of cocoons and eggs, males were produced in
excess. Taken together the proportion of males is as 122.7 to 100 females.
But the numbers are hardly large enough to be trustworthy.
On the whole, from these various sources of evidence, all pointing in the
same direction, I infer that with most species of Lepidoptera, the mature
males generally exceed the females in number, whatever the proportions may
be at their first emergence from the egg.
Males Females
The Rev. J. Hellins* of Exeter reared, during
1868, imagos of 73 species, which
consisted of 153 137
Mr. Albert Jones of Eltham reared, during
1868, imagos of 9 species, which
consisted of 159 126
During 1869 he reared imagos from 4 species
consisting of 114 112
Mr. Buckler of Emsworth, Hants, during 1869,
reared imagos from 74 species,
consisting of 180 169
Dr. Wallace of Colchester reared from one
brood of Bombyx cynthia 52 48
Dr. Wallace raised, from cocoons of Bombyx
Pernyi sent from China, during 1869 224 123
Dr. Wallace raised, during 1868 and 1869, from
two lots of cocoons of Bombyx yamamai 52 46
Total 934 761
(*83. This naturalist has been so kind as to send me some results from
former years, in which the females seemed to preponderate; but so many of
the figures were estimates, that I found it impossible to tabulate them.)
With reference to the other Orders of insects, I have been able to collect
very little reliable information. With the stag-beetle (Lucanus cervus)
"the males appear to be much more numerous than the females"; but when, as
Cornelius remarked during 1867, an unusual number of these beetles appeared
in one part of Germany, the females appeared to exceed the males as six to
one. With one of the Elateridae, the males are said to be much more
numerous than the females, and "two or three are often found united with
one female (84. Gunther's 'Record of Zoological Literature,' 1867, p. 260.
On the excess of female Lucanus, ibid, p. 250. On the males of Lucanus in
England, Westwood,' 'Modern Classification of Insects,' vol. i. p. 187. On
the Siagonium, ibid. p. 172.); so that here polyandry seems to prevail."
With Siagonium (Staphylinidae), in which the males are furnished with
horns, "the females are far more numerous than the opposite sex." Mr.
Janson stated at the Entomological Society that the females of the bark
feeding Tomicus villosus are so common as to be a plague, whilst the males
are so rare as to be hardly known.
It is hardly worth while saying anything about the proportion of the sexes
in certain species and even groups of insects, for the males are unknown or
very rare, and the females are parthenogenetic, that is, fertile without
sexual union; examples of this are afforded by several of the Cynipidae.
(85. Walsh in 'The American Entomologist,' vol. i. 1869, p. 103. F.
Smith, 'Record of Zoological Lit.' 1867, p. 328.) In all the gall-making
Cynipidae known to Mr. Walsh, the females are four or five times as
numerous as the males; and so it is, as he informs me, with the gall-making
Cecidomyiidae (Diptera). With some common species of Saw-flies
(Tenthredinae) Mr. F. Smith has reared hundreds of specimens from larvae of
all sizes, but has never reared a single male; on the other hand, Curtis
says (86. 'Farm Insects,' pp. 45-46.), that with certain species
(Athalia), bred by him, the males were to the females as six to one; whilst
exactly the reverse occurred with the mature insects of the same species
caught in the fields. In the family of bees, Hermann Muller (87.
'Anwendung der Darwin'schen Lehre,' Verh. d. n. Jahrg., xxiv.), collected a
large number of specimens of many species, and reared others from the
cocoons, and counted the sexes. He found that the males of some species
greatly exceeded the females in number; in others the reverse occurred; and
in others the two sexes were nearly equal. But as in most cases the males
emerge from the cocoons before the females, they are at the commencement of
the breeding-season practically in excess. Muller also observed that the
relative number of the two sexes in some species differed much in different
localities. But as H. Muller has himself remarked to me, these remarks
must be received with some caution, as one sex might more easily escape
observation than the other. Thus his brother Fritz Muller has noticed in
Brazil that the two sexes of the same species of bee sometimes frequent
different kinds of flowers. With respect to the Orthoptera, I know hardly
anything about the relative number of the sexes: Korte (88. 'Die Strich,
Zug oder Wanderheuschrecke,' 1828, p. 20.), however, says that out of 500
locusts which he examined, the males were to the females as five to six.
With the Neuroptera, Mr. Walsh states that in many, but by no means in all
the species of the Odonatous group, there is a great overplus of males: in
the genus Hetaerina, also, the males are generally at least four times as
numerous as the females. In certain species in the genus Gomphus the males
are equally in excess, whilst in two other species, the females are twice
or thrice as numerous as the males. In some European species of Psocus
thousands of females may be collected without a single male, whilst with
other species of the same genus both sexes are common. (89. 'Observations
on N. American Neuroptera,' by H. Hagen and B.D. Walsh, 'Proceedings, Ent.
Soc. Philadelphia,' Oct. 1863, pp. 168, 223, 239.) In England, Mr.
MacLachlan has captured hundreds of the female Apatania muliebris, but has
never seen the male; and of Boreus hyemalis only four or five males have
been seen here. (90. 'Proceedings, Ent. Soc. London,' Feb. 17, 1868.)
With most of these species (excepting the Tenthredinae) there is at present
no evidence that the females are subject to parthenogenesis; and thus we
see how ignorant we are of the causes of the apparent discrepancy in the
proportion of the two sexes.
In the other classes of the Articulata I have been able to collect still
less information. With spiders, Mr. Blackwall, who has carefully attended
to this class during many years, writes to me that the males from their
more erratic habits are more commonly seen, and therefore appear more
numerous. This is actually the case with a few species; but he mentions
several species in six genera, in which the females appear to be much more
numerous than the males. (91. Another great authority with respect to
this class, Prof. Thorell of Upsala ('On European Spiders,' 1869-70, part
i. p. 205), speaks as if female spiders were generally commoner than the
males.) The small size of the males in comparison with the females (a
peculiarity which is sometimes carried to an extreme degree), and their
widely different appearance, may account in some instances for their rarity
in collections. (92. See, on this subject, Mr. O.P. Cambridge, as quoted
in 'Quarterly Journal of Science,' 1868, page 429.)
Some of the lower Crustaceans are able to propagate their kind sexually,
and this will account for the extreme rarity of the males; thus von Siebold
(93. 'Beitrage zur Parthenogenesis,' p. 174.) carefully examined no less
than 13,000 specimens of Apus from twenty-one localities, and amongst these
he found only 319 males. With some other forms (as Tanais and Cypris), as
Fritz Muller informs me, there is reason to believe that the males are much
shorter-lived than the females; and this would explain their scarcity,
supposing the two sexes to be at first equal in number. On the other hand,
Muller has invariably taken far more males than females of the Diastylidae
and of Cypridina on the shores of Brazil: thus with a species in the
latter genus, 63 specimens caught the same day included 57 males; but he
suggests that this preponderance may be due to some unknown difference in
the habits of the two sexes. With one of the higher Brazilian crabs,
namely a Gelasimus, Fritz Muller found the males to be more numerous than
the females. According to the large experience of Mr. C. Spence Bate, the
reverse seems to be the case with six common British crabs, the names of
which he has given me.
THE PROPORTION OF THE SEXES IN RELATION TO NATURAL SELECTION.
There is reason to suspect that in some cases man has by selection
indirectly influenced his own sex-producing powers. Certain women tend to
produce during their whole lives more children of one sex than of the
other: and the same holds good of many animals, for instance, cows and
horses; thus Mr. Wright of Yeldersley House informs me that one of his Arab
mares, though put seven times to different horses, produced seven fillies.
Though I have very little evidence on this head, analogy would lead to the
belief, that the tendency to produce either sex would be inherited like
almost every other peculiarity, for instance, that of producing twins; and
concerning the above tendency a good authority, Mr. J. Downing, has
communicated to me facts which seem to prove that this does occur in
certain families of short-horn cattle. Col. Marshall (94. 'The Todas,'
1873, pp. 100, 111, 194, 196.) has recently found on careful examination
that the Todas, a hill-tribe of India, consist of 112 males and 84 females
of all ages--that is in a ratio of 133.3 males to 100 females. The Todas,
who are polyandrous in their marriages, during former times invariably
practised female infanticide; but this practice has now been discontinued
for a considerable period. Of the children born within late years, the
males are more numerous than the females, in the proportion of 124 to 100.
Colonel Marshall accounts for this fact in the following ingenious manner.
"Let us for the purpose of illustration take three families as representing
an average of the entire tribe; say that one mother gives birth to six
daughters and no sons; a second mother has six sons only, whilst the third
mother has three sons and three daughters. The first mother, following the
tribal custom, destroys four daughters and preserves two. The second
retains her six sons. The third kills two daughters and keeps one, as also
her three sons. We have then from the three families, nine sons and three
daughters, with which to continue the breed. But whilst the males belong
to families in which the tendency to produce sons is great, the females are
of those of a converse inclination. Thus the bias strengthens with each
generation, until, as we find, families grow to have habitually more sons
than daughters."
That this result would follow from the above form of infanticide seems
almost certain; that is if we assume that a sex-producing tendency is
inherited. But as the above numbers are so extremely scanty, I have
searched for additional evidence, but cannot decide whether what I have
found is trustworthy; nevertheless the facts are, perhaps, worth giving.
The Maories of New Zealand have long practised infanticide; and Mr. Fenton
(95. 'Aboriginal Inhabitants of New Zealand: Government Report,' 1859, p.
36.) states that he "has met with instances of women who have destroyed
four, six, and even seven children, mostly females. However, the universal
testimony of those best qualified to judge, is conclusive that this custom
has for many years been almost extinct. Probably the year 1835 may be
named as the period of its ceasing to exist." Now amongst the New
Zealanders, as with the Todas, male births are considerably in excess. Mr.
Fenton remarks (p. 30), "One fact is certain, although the exact period of
the commencement of this singular condition of the disproportion of the
sexes cannot be demonstratively fixed, it is quite clear that this course
of decrease was in full operation during the years 1830 to 1844, when the
non-adult population of 1844 was being produced, and has continued with
great energy up to the present time." The following statements are taken
from Mr. Fenton (p. 26), but as the numbers are not large, and as the
census was not accurate, uniform results cannot be expected. It should be
borne in mind in this and the following cases, that the normal state of
every population is an excess of women, at least in all civilised
countries, chiefly owing to the greater mortality of the male sex during
youth, and partly to accidents of all kinds later in life. In 1858, the
native population of New Zealand was estimated as consisting of 31,667
males and 24,303 females of all ages, that is in the ratio of 130.3 males
to 100 females. But during this same year, and in certain limited
districts, the numbers were ascertained with much care, and the males of
all ages were here 753 and the females 616; that is in the ratio of 122.2
males to 100 females. It is more important for us that during this same
year of 1858, the NON-ADULT males within the same district were found to be
178, and the NON-ADULT females 142, that is in the ratio of 125.3 to 100.
It may be added that in 1844, at which period female infanticide had only
lately ceased, the NON-ADULT males in one district were 281, and the NON-
ADULT females only 194, that is in the ratio of 144.8 males to 100 females.
In the Sandwich Islands, the males exceed the females in number.
Infanticide was formerly practised there to a frightful extent, but was by
no means confined to female infants, as is shewn by Mr. Ellis (96.
'Narrative of a Tour through Hawaii,' 1826, p. 298.), and as I have been
informed by Bishop Staley and the Rev. Mr. Coan. Nevertheless, another
apparently trustworthy writer, Mr. Jarves (97. 'History of the Sandwich
Islands,' 1843, p. 93.), whose observations apply to the whole archipelago,
remarks:--"Numbers of women are to be found, who confess to the murder of
from three to six or eight children," and he adds, "females from being
considered less useful than males were more often destroyed." From what is
known to occur in other parts of the world, this statement is probable; but
must be received with much caution. The practice of infanticide ceased
about the year 1819, when idolatry was abolished and missionaries settled
in the Islands. A careful census in 1839 of the adult and taxable men and
women in the island of Kauai and in one district of Oahu (Jarves, p. 404),
gives 4723 males and 3776 females; that is in the ratio of 125.08 to 100.
At the same time the number of males under fourteen years in Kauai and
under eighteen in Oahu was 1797, and of females of the same ages 1429; and
here we have the ratio of 125.75 males to 100 females.
In a census of all the islands in 1850 (98. This is given in the Rev. H.T.
Cheever's 'Life in the Sandwich Islands,' 1851, p. 277.), the males of all
ages amount to 36,272, and the females to 33,128, or as 109.49 to 100. The
males under seventeen years amounted to 10,773, and the females under the
same age to 9593, or as 112.3 to 100. From the census of 1872, the
proportion of males of all ages (including half-castes) to females, is as
125.36 to 100. It must be borne in mind that all these returns for the
Sandwich Islands give the proportion of living males to living females, and
not of the births; and judging from all civilised countries the proportion
of males would have been considerably higher if the numbers had referred to
births. (99. Dr. Coulter, in describing ('Journal R. Geograph. Soc.' vol.
v. 1835, p. 67) the state of California about the year 1830, says that the
natives, reclaimed by the Spanish missionaries, have nearly all perished,
or are perishing, although well treated, not driven from their native land,
and kept from the use of spirits. He attributes this, in great part, to
the undoubted fact that the men greatly exceed the women in number; but he
does not know whether this is due to a failure of female offspring, or to
more females dying during early youth. The latter alternative, according
to all analogy, is very improbable. He adds that "infanticide, properly so
called, is not common, though very frequent recourse is had to abortion."
If Dr. Coulter is correct about infanticide, this case cannot be advanced
in support of Colonel Marshall's view. From the rapid decrease of the
reclaimed natives, we may suspect that, as in the cases lately given, their
fertility has been diminished from changed habits of life.
I had hoped to gain some light on this subject from the breeding of dogs;
inasmuch as in most breeds, with the exception, perhaps, of greyhounds,
many more female puppies are destroyed than males, just as with the Toda
infants. Mr. Cupples assures me that this is usual with Scotch deer-
hounds. Unfortunately, I know nothing of the proportion of the sexes in
any breed, excepting greyhounds, and there the male births are to the
females as 110.1 to 100. Now from enquiries made from many breeders, it
seems that the females are in some respects more esteemed, though otherwise
troublesome; and it does not appear that the female puppies of the best-
bred dogs are systematically destroyed more than the males, though this
does sometimes take place to a limited extent. Therefore I am unable to
decide whether we can, on the above principles, account for the
preponderance of male births in greyhounds. On the other hand, we have
seen that with horses, cattle, and sheep, which are too valuable for the
young of either sex to be destroyed, if there is any difference, the
females are slightly in excess.)
From the several foregoing cases we have some reason to believe that
infanticide practised in the manner above explained, tends to make a male-
producing race; but I am far from supposing that this practice in the case
of man, or some analogous process with other species, has been the sole
determining cause of an excess of males. There may be some unknown law
leading to this result in decreasing races, which have already become
somewhat infertile. Besides the several causes previously alluded to, the
greater facility of parturition amongst savages, and the less consequent
injury to their male infants, would tend to increase the proportion of
live-born males to females. There does not, however, seem to be any
necessary connection between savage life and a marked excess of males; that
is if we may judge by the character of the scanty offspring of the lately
existing Tasmanians and of the crossed offspring of the Tahitians now
inhabiting Norfolk Island.
As the males and females of many animals differ somewhat in habits and are
exposed in different degrees to danger, it is probable that in many cases,
more of one sex than of the other are habitually destroyed. But as far as
I can trace out the complication of causes, an indiscriminate though large
destruction of either sex would not tend to modify the sex-producing power
of the species. With strictly social animals, such as bees or ants, which
produce a vast number of sterile and fertile females in comparison with the
males, and to whom this preponderance is of paramount importance, we can
see that those communities would flourish best which contained females
having a strong inherited tendency to produce more and more females; and in
such cases an unequal sex-producing tendency would be ultimately gained
through natural selection. With animals living in herds or troops, in
which the males come to the front and defend the herd, as with the bisons
of North America and certain baboons, it is conceivable that a male-
producing tendency might be gained by natural selection; for the
individuals of the better defended herds would leave more numerous
descendants. In the case of mankind the advantage arising from having a
preponderance of men in the tribe is supposed to be one chief cause of the
practice of female infanticide.
In no case, as far as we can see, would an inherited tendency to produce
both sexes in equal numbers or to produce one sex in excess, be a direct
advantage or disadvantage to certain individuals more than to others; for
instance, an individual with a tendency to produce more males than females
would not succeed better in the battle for life than an individual with an
opposite tendency; and therefore a tendency of this kind could not be
gained through natural selection. Nevertheless, there are certain animals
(for instance, fishes and cirripedes) in which two or more males appear to
be necessary for the fertilisation of the female; and the males accordingly
largely preponderate, but it is by no means obvious how this male-producing
tendency could have been acquired. I formerly thought that when a tendency
to produce the two sexes in equal numbers was advantageous to the species,
it would follow from natural selection, but I now see that the whole
problem is so intricate that it is safer to leave its solution for the
future.
CHAPTER IX.
SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM.
These characters absent in the lowest classes--Brilliant colours--Mollusca
--Annelids--Crustacea, secondary sexual characters strongly developed;
dimorphism; colour; characters not acquired before maturity--Spiders,
sexual colours of; stridulation by the males--Myriapoda.
With animals belonging to the lower classes, the two sexes are not rarely
united in the same individual, and therefore secondary sexual characters
cannot be developed. In many cases where the sexes are separate, both are
permanently attached to some support, and the one cannot search or struggle
for the other. Moreover it is almost certain that these animals have too
imperfect senses and much too low mental powers to appreciate each other's
beauty or other attractions, or to feel rivalry.
Hence in these classes or sub-kingdoms, such as the Protozoa, Coelenterata,
Echinodermata, Scolecida, secondary sexual characters, of the kind which we
have to consider, do not occur: and this fact agrees with the belief that
such characters in the higher classes have been acquired through sexual
selection, which depends on the will, desire, and choice of either sex.
Nevertheless some few apparent exceptions occur; thus, as I hear from Dr.
Baird, the males of certain Entozoa, or internal parasitic worms, differ
slightly in colour from the females; but we have no reason to suppose that
such differences have been augmented through sexual selection.
Contrivances by which the male holds the female, and which are
indispensable for the propagation of the species, are independent of sexual
selection, and have been acquired through ordinary selection.
Many of the lower animals, whether hermaphrodites or with separate sexes,
are ornamented with the most brilliant tints, or are shaded and striped in
an elegant manner; for instance, many corals and sea-anemones (Actiniae),
some jelly-fish (Medusae, Porpita, etc.), some Planariae, many star-fishes,
Echini, Ascidians, etc.; but we may conclude from the reasons already
indicated, namely, the union of the two sexes in some of these animals, the
permanently affixed condition of others, and the low mental powers of all,
that such colours do not serve as a sexual attraction, and have not been
acquired through sexual selection. It should be borne in mind that in no
case have we sufficient evidence that colours have been thus acquired,
except where one sex is much more brilliantly or conspicuously coloured
than the other, and where there is no difference in habits between the
sexes sufficient to account for their different colours. But the evidence
is rendered as complete as it can ever be, only when the more ornamented
individuals, almost always the males, voluntarily display their attractions
before the other sex; for we cannot believe that such display is useless,
and if it be advantageous, sexual selection will almost inevitably follow.
We may, however, extend this conclusion to both sexes, when coloured alike,
if their colours are plainly analogous to those of one sex alone in certain
other species of the same group.
How, then, are we to account for the beautiful or even gorgeous colours of
many animals in the lowest classes? It appears doubtful whether such
colours often serve as a protection; but that we may easily err on this
head, will be admitted by every one who reads Mr. Wallace's excellent essay
on this subject. It would not, for instance, at first occur to any one
that the transparency of the Medusae, or jelly-fish, is of the highest
service to them as a protection; but when we are reminded by Haeckel that
not only the Medusae, but many floating Mollusca, crustaceans, and even
small oceanic fishes partake of this same glass-like appearance, often
accompanied by prismatic colours, we can hardly doubt that they thus escape
the notice of pelagic birds and other enemies. M. Giard is also convinced
(1. 'Archives de Zoolog. Exper.' Oct. 1872, p. 563.) that the bright tints
of certain sponges and ascidians serve as a protection. Conspicuous
colours are likewise beneficial to many animals as a warning to their
would-be devourers that they are distasteful, or that they possess some
special means of defence; but this subject will be discussed more
conveniently hereafter.
We can, in our ignorance of most of the lowest animals, only say that their
bright tints result either from the chemical nature or the minute structure
of their tissues, independently of any benefit thus derived. Hardly any
colour is finer than that of arterial blood; but there is no reason to
suppose that the colour of the blood is in itself any advantage; and though
it adds to the beauty of the maiden's cheek, no one will pretend that it
has been acquired for this purpose. So again with many animals, especially
the lower ones, the bile is richly coloured; thus, as I am informed by Mr.
Hancock, the extreme beauty of the Eolidae (naked sea-slugs) is chiefly due
to the biliary glands being seen through the translucent integuments--this
beauty being probably of no service to these animals. The tints of the
decaying leaves in an American forest are described by every one as
gorgeous; yet no one supposes that these tints are of the least advantage
to the trees. Bearing in mind how many substances closely analogous to
natural organic compounds have been recently formed by chemists, and which
exhibit the most splendid colours, it would have been a strange fact if
substances similarly coloured had not often originated, independently of
any useful end thus gained, in the complex laboratory of living organisms.
THE SUB-KINGDOM OF THE MOLLUSCA.
Throughout this great division of the animal kingdom, as far as I can
discover, secondary sexual characters, such as we are here considering,
never occur. Nor could they be expected in the three lowest classes,
namely, in the Ascidians, Polyzoa, and Brachiopods (constituting the
Molluscoida of some authors), for most of these animals are permanently
affixed to a support or have their sexes united in the same individual. In
the Lamellibranchiata, or bivalve shells, hermaphroditism is not rare. In
the next higher class of the Gasteropoda, or univalve shells, the sexes are
either united or separate. But in the latter case the males never possess
special organs for finding, securing, or charming the females, or for
fighting with other males. As I am informed by Mr. Gwyn Jeffreys, the sole
external difference between the sexes consists in the shell sometimes
differing a little in form; for instance, the shell of the male periwinkle
(Littorina littorea) is narrower and has a more elongated spire than that
of the female. But differences of this nature, it may be presumed, are
directly connected with the act of reproduction, or with the development of
the ova.
The Gasteropoda, though capable of locomotion and furnished with imperfect
eyes, do not appear to be endowed with sufficient mental powers for the
members of the same sex to struggle together in rivalry, and thus to
acquire secondary sexual characters. Nevertheless with the pulmoniferous
gasteropods, or land-snails, the pairing is preceded by courtship; for
these animals, though hermaphrodites, are compelled by their structure to
pair together. Agassiz remarks, "Quiconque a eu l'occasion d'observer les
amours des limacons, ne saurait mettre en doute la seduction deployee dans
les mouvements et les allures qui preparent et accomplissent le double
embrassement de ces hermaphrodites." (2. 'De l'Espece et de la Class.'
etc., 1869, p. 106.) These animals appear also susceptible of some degree
of permanent attachment: an accurate observer, Mr. Lonsdale, informs me
that he placed a pair of land-snails, (Helix pomatia), one of which was
weakly, into a small and ill-provided garden. After a short time the
strong and healthy individual disappeared, and was traced by its track of
slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale
concluded that it had deserted its sickly mate; but after an absence of
twenty-four hours it returned, and apparently communicated the result of
its successful exploration, for both then started along the same track and
disappeared over the wall.
Even in the highest class of the Mollusca, the Cephalopoda or cuttle-
fishes, in which the sexes are separate, secondary sexual characters of the
present kind do not, as far as I can discover, occur. This is a surprising
circumstance, as these animals possess highly-developed sense-organs and
have considerable mental powers, as will be admitted by every one who has
watched their artful endeavours to escape from an enemy. (3. See, for
instance, the account which I have given in my 'Journal of Researches,'
1845, p. 7.) Certain Cephalopoda, however, are characterised by one
extraordinary sexual character, namely that the male element collects
within one of the arms or tentacles, which is then cast off, and clinging
by its sucking-discs to the female, lives for a time an independent life.
So completely does the cast-off arm resemble a separate animal, that it was
described by Cuvier as a parasitic worm under the name of Hectocotyle. But
this marvellous structure may be classed as a primary rather than as a
secondary sexual character.
Although with the Mollusca sexual selection does not seem to have come into
play; yet many univalve and bivalve shells, such as volutes, cones,
scallops, etc., are beautifully coloured and shaped. The colours do not
appear in most cases to be of any use as a protection; they are probably
the direct result, as in the lowest classes, of the nature of the tissues;
the patterns and the sculpture of the shell depending on its manner of
growth. The amount of light seems to be influential to a certain extent;
for although, as repeatedly stated by Mr. Gwyn Jeffreys, the shells of some
species living at a profound depth are brightly coloured, yet we generally
see the lower surfaces, as well as the parts covered by the mantle, less
highly-coloured than the upper and exposed surfaces. (4. I have given
('Geological Observations on Volcanic Islands,' 1844, p. 53) a curious
instance of the influence of light on the colours of a frondescent
incrustation, deposited by the surf on the coast-rocks of Ascension and
formed by the solution of triturated sea-shells.) In some cases, as with
shells living amongst corals or brightly-tinted seaweeds, the bright
colours may serve as a protection. (5. Dr. Morse has lately discussed
this subject in his paper on the 'Adaptive Coloration of Mollusca,' 'Proc.
Boston Soc. of Nat. Hist.' vol. xiv. April 1871.) But that many of the
nudibranch Mollusca, or sea-slugs, are as beautifully coloured as any
shells, may be seen in Messrs. Alder and Hancock's magnificent work; and
from information kindly given me by Mr. Hancock, it seems extremely
doubtful whether these colours usually serve as a protection. With some
species this may be the case, as with one kind which lives on the green
leaves of algae, and is itself bright-green. But many brightly-coloured,
white, or otherwise conspicuous species, do not seek concealment; whilst
again some equally conspicuous species, as well as other dull-coloured
kinds live under stones and in dark recesses. So that with these
nudibranch molluscs, colour apparently does not stand in any close relation
to the nature of the places which they inhabit.
These naked sea-slugs are hermaphrodites, yet they pair together, as do
land-snails, many of which have extremely pretty shells. It is conceivable
that two hermaphrodites, attracted by each other's greater beauty, might
unite and leave offspring which would inherit their parents' greater
beauty. But with such lowly-organised creatures this is extremely
improbable. Nor is it at all obvious how the offspring from the more
beautiful pairs of hermaphrodites would have any advantage over the
offspring of the less beautiful, so as to increase in number, unless indeed
vigour and beauty generally coincided. We have not here the case of a
number of males becoming mature before the females, with the more beautiful
males selected by the more vigorous females. If, indeed, brilliant colours
were beneficial to a hermaphrodite animal in relation to its general habits
of life, the more brightly-tinted individuals would succeed best and would
increase in number; but this would be a case of natural and not of sexual
selection.
SUB-KINGDOM OF THE VERMES: CLASS, ANNELIDA (OR SEA-WORMS).
In this class, although the sexes, when separate, sometimes differ from
each other in characters of such importance that they have been placed
under distinct genera or even families, yet the differences do not seem of
the kind which can be safely attributed to sexual selection. These animals
are often beautifully coloured, but as the sexes do not differ in this
respect, we are but little concerned with them. Even the Nemertians,
though so lowly organised, "vie in beauty and variety of colouring with any
other group in the invertebrate series"; yet Dr. McIntosh (6. See his
beautiful monograph on 'British Annelids,' part i. 1873, p. 3.) cannot
discover that these colours are of any service. The sedentary annelids
become duller-coloured, according to M. Quatrefages (7. See M. Perrier:
'L'Origine de l'Homme d'apres Darwin,' 'Revue Scientifique', Feb. 1873, p.
866.), after the period of reproduction; and this I presume may be
attributed to their less vigorous condition at that time. All these worm-
like animals apparently stand too low in the scale for the individuals of
either sex to exert any choice in selecting a partner, or for the
individuals of the same sex to struggle together in rivalry.
SUB-KINGDOM OF THE ARTHROPODA: CLASS, CRUSTACEA.
In this great class we first meet with undoubted secondary sexual
characters, often developed in a remarkable manner. Unfortunately the
habits of crustaceans are very imperfectly known, and we cannot explain the
uses of many structures peculiar to one sex. With the lower parasitic
species the males are of small size, and they alone are furnished with
perfect swimming-legs, antennae and sense-organs; the females being
destitute of these organs, with their bodies often consisting of a mere
distorted mass. But these extraordinary differences between the two sexes
are no doubt related to their widely different habits of life, and
consequently do not concern us. In various crustaceans, belonging to
distinct families, the anterior antennae are furnished with peculiar
thread-like bodies, which are believed to act as smelling-organs, and these
are much more numerous in the males than in the females. As the males,
without any unusual development of their olfactory organs, would almost
certainly be able sooner or later to find the females, the increased number
of the smelling-threads has probably been acquired through sexual
selection, by the better provided males having been the more successful in
finding partners and in producing offspring. Fritz Muller has described a
remarkable dimorphic species of Tanais, in which the male is represented by
two distinct forms, which never graduate into each other. In the one form
the male is furnished with more numerous smelling-threads, and in the other
form with more powerful and more elongated chelae or pincers, which serve
to hold the female. Fritz Muller suggests that these differences between
the two male forms of the same species may have originated in certain
individuals having varied in the number of the smelling-threads, whilst
other individuals varied in the shape and size of their chelae; so that of
the former, those which were best able to find the female, and of the
latter, those which were best able to hold her, have left the greatest
number of progeny to inherit their respective advantages. (8. 'Facts and
Arguments for Darwin,' English translat., 1869, p. 20. See the previous
discussion on the olfactory threads. Sars has described a somewhat
analogous case (as quoted in 'Nature,' 1870, p. 455) in a Norwegian
crustacean, the Pontoporeia affinis.)
[Fig.4. Labidocera Darwinii (from Lubbock). Labelled are:
a. Part of right anterior antenna of male, forming a prehensile organ.
b. Posterior pair of thoracic legs of male.
c. Ditto of female.]
In some of the lower crustaceans, the right anterior antenna of the male
differs greatly in structure from the left, the latter resembling in its
simple tapering joints the antennae of the female. In the male the
modified antenna is either swollen in the middle or angularly bent, or
converted (Fig. 4) into an elegant, and sometimes wonderfully complex,
prehensile organ. (9. See Sir J. Lubbock in 'Annals and Mag. of Nat.
Hist.' vol. xi. 1853, pl. i. and x.; and vol. xii. (1853), pl. vii. See
also Lubbock in 'Transactions, Entomological Society,' vol. iv. new series,
1856-1858, p. 8. With respect to the zigzagged antennae mentioned below,
see Fritz Muller, 'Facts and Arguments for Darwin,' 1869, p. 40, foot-
note.) It serves, as I hear from Sir J. Lubbock, to hold the female, and
for this same purpose one of the two posterior legs (b) on the same side of
the body is converted into a forceps. In another family the inferior or
posterior antennae are "curiously zigzagged" in the males alone.
[Fig. 5. Anterior part of body of Callianassa (from Milne-Edwards),
showing the unequal and differently-constructed right and left-hand chelae
of the male. N.B.--The artist by mistake has reversed the drawing, and
made the left-hand chela the largest.
Fig. 6. Second leg of male Orchestia Tucuratinga (from Fritz Muller).
Fig. 7. Ditto of female.]
In the higher crustaceans the anterior legs are developed into chelae or
pincers; and these are generally larger in the male than in the female,--so
much so that the market value of the male edible crab (Cancer pagurus),
according to Mr. C. Spence Bate, is five times as great as that of the
female. In many species the chelae are of unequal size on the opposite
side of the body, the right-hand one being, as I am informed by Mr. Bate,
generally, though not invariably, the largest. This inequality is also
often much greater in the male than in the female. The two chelae of the
male often differ in structure (Figs. 5, 6, and 7), the smaller one
resembling that of the female. What advantage is gained by their
inequality in size on the opposite sides of the body, and by the inequality
being much greater in the male than in the female; and why, when they are
of equal size, both are often much larger in the male than in the female,
is not known. As I hear from Mr. Bate, the chelae are sometimes of such
length and size that they cannot possibly be used for carrying food to the
mouth. In the males of certain fresh-water prawns (Palaemon) the right leg
is actually longer than the whole body. (10. See a paper by Mr. C. Spence
Bate, with figures, in 'Proceedings, Zoological Society,' 1868, p. 363; and
on the nomenclature of the genus, ibid. p. 585. I am greatly indebted to
Mr. Spence Bate for nearly all the above statements with respect to the
chelae of the higher crustaceans.) The great size of the one leg with its
chelae may aid the male in fighting with his rivals; but this will not
account for their inequality in the female on the opposite sides of the
body. In Gelasimus, according to a statement quoted by Milne Edwards (11.
'Hist. Nat. des Crust.' tom. ii. 1837, p. 50.), the male and the female
live in the same burrow, and this shews that they pair; the male closes the
mouth of the burrow with one of its chelae, which is enormously developed;
so that here it indirectly serves as a means of defence. Their main use,
however, is probably to seize and to secure the female, and this in some
instances, as with Gammarus, is known to be the case. The male of the
hermit or soldier crab (Pagurus) for weeks together, carries about the
shell inhabited by the female. (12. Mr. C. Spence Bate, 'British
Association, Fourth Report on the Fauna of S. Devon.') The sexes, however,
of the common shore-crab (Carcinus maenas), as Mr. Bate informs me, unite
directly after the female has moulted her hard shell, when she is so soft
that she would be injured if seized by the strong pincers of the male; but
as she is caught and carried about by the male before moulting, she could
then be seized with impunity.
[Fig.8. Orchestia Darwinii (from Fritz Muller), showing the differently-
constructed chelae of the two male forms.]
Fritz Muller states that certain species of Melita are distinguished from
all other amphipods by the females having "the coxal lamellae of the
penultimate pair of feet produced into hook-like processes, of which the
males lay hold with the hands of the first pair." The development of these
hook-like processes has probably followed from those females which were the
most securely held during the act of reproduction, having left the largest
number of offspring. Another Brazilian amphipod (see Orchestia darwinii,
Fig. 8) presents a case of dimorphism, like that of Tanais; for there are
two male forms, which differ in the structure of their chelae. (13. Fritz
Muller, 'Facts and Arguments for Darwin,' 1869, pp. 25-28.) As either
chela would certainly suffice to hold the female,--for both are now used
for this purpose,--the two male forms probably originated by some having
varied in one manner and some in another; both forms having derived certain
special, but nearly equal advantages, from their differently shaped organs.
It is not known that male crustaceans fight together for the possession of
the females, but it is probably the case; for with most animals when the
male is larger than the female, he seems to owe his greater size to his
ancestors having fought with other males during many generations. In most
of the orders, especially in the highest or the Brachyura, the male is
larger than the female; the parasitic genera, however, in which the sexes
follow different habits of life, and most of the Entomostraca must be
excepted. The chelae of many crustaceans are weapons well adapted for
fighting. Thus when a Devil-crab (Portunus puber) was seen by a son of Mr.
Bate fighting with a Carcinus maenas, the latter was soon thrown on its
back, and had every limb torn from its body. When several males of a
Brazilian Gelasimus, a species furnished with immense pincers, were placed
together in a glass vessel by Fritz Muller, they mutilated and killed one
another. Mr. Bate put a large male Carcinus maenas into a pan of water,
inhabited by a female which was paired with a smaller male; but the latter
was soon dispossessed. Mr. Bate adds, "if they fought, the victory was a
bloodless one, for I saw no wounds." This same naturalist separated a male
sand-skipper (so common on our sea-shores), Gammarus marinus, from its
female, both of whom were imprisoned in the same vessel with many
individuals of the same species. The female, when thus divorced, soon
joined the others. After a time the male was put again into the same
vessel; and he then, after swimming about for a time, dashed into the
crowd, and without any fighting at once took away his wife. This fact
shews that in the Amphipoda, an order low in the scale, the males and
females recognise each other, and are mutually attached.
The mental powers of the Crustacea are probably higher than at first sight
appears probable. Any one who tries to catch one of the shore-crabs, so
common on tropical coasts, will perceive how wary and alert they are.
There is a large crab (Birgus latro), found on coral islands, which makes a
thick bed of the picked fibres of the cocoa-nut, at the bottom of a deep
burrow. It feeds on the fallen fruit of this tree by tearing off the husk,
fibre by fibre; and it always begins at that end where the three eye-like
depressions are situated. It then breaks through one of these eyes by
hammering with its heavy front pincers, and turning round, extracts the
albuminous core with its narrow posterior pincers. But these actions are
probably instinctive, so that they would be performed as well by a young
animal as by an old one. The following case, however, can hardly be so
considered: a trustworthy naturalist, Mr. Gardner (14. 'Travels in the
Interior of Brazil,' 1846, p. 111. I have given, in my 'Journal of
Researches,' p. 463, an account of the habits of the Birgus.), whilst
watching a shore-crab (Gelasimus) making its burrow, threw some shells
towards the hole. One rolled in, and three other shells remained within a
few inches of the mouth. In about five minutes the crab brought out the
shell which had fallen in, and carried it away to a distance of a foot; it
then saw the three other shells lying near, and evidently thinking that
they might likewise roll in, carried them to the spot where it had laid the
first. It would, I think, be difficult to distinguish this act from one
performed by man by the aid of reason.
Mr. Bate does not know of any well-marked case of difference of colour in
the two sexes of our British crustaceans, in which respect the sexes of the
higher animals so often differ. In some cases, however, the males and
females differ slightly in tint, but Mr. Bate thinks not more than may be
accounted for by their different habits of life, such as by the male
wandering more about, and being thus more exposed to the light. Dr. Power
tried to distinguish by colour the sexes of the several species which
inhabit the Mauritius, but failed, except with one species of Squilla,
probably S. stylifera, the male of which is described as being "of a
beautiful bluish-green," with some of the appendages cherry-red, whilst the
female is clouded with brown and grey, "with the red about her much less
vivid than in the male." (15. Mr. Ch. Fraser, in 'Proc. Zoolog. Soc.'
1869, p. 3. I am indebted to Mr. Bate for Dr. Power's statement.) In this
case, we may suspect the agency of sexual selection. From M. Bert's
observations on Daphnia, when placed in a vessel illuminated by a prism, we
have reason to believe that even the lowest crustaceans can distinguish
colours. With Saphirina (an oceanic genus of Entomostraca), the males are
furnished with minute shields or cell-like bodies, which exhibit beautiful
changing colours; these are absent in the females, and in both sexes of one
species. (16. Claus, 'Die freilebenden Copepoden,' 1863, s. 35.) It
would, however, be extremely rash to conclude that these curious organs
serve to attract the females. I am informed by Fritz Muller, that in the
female of a Brazilian species of Gelasimus, the whole body is of a nearly
uniform greyish-brown. In the male the posterior part of the cephalo-
thorax is pure white, with the anterior part of a rich green, shading into
dark brown; and it is remarkable that these colours are liable to change in
the course of a few minutes--the white becoming dirty grey or even black,
the green "losing much of its brilliancy." It deserves especial notice
that the males do not acquire their bright colours until they become
mature. They appear to be much more numerous than the females; they differ
also in the larger size of their chelae. In some species of the genus,
probably in all, the sexes pair and inhabit the same burrow. They are
also, as we have seen, highly intelligent animals. From these various
considerations it seems probable that the male in this species has become
gaily ornamented in order to attract or excite the female.
It has just been stated that the male Gelasimus does not acquire his
conspicuous colours until mature and nearly ready to breed. This seems a
general rule in the whole class in respect to the many remarkable
structural differences between the sexes. We shall hereafter find the same
law prevailing throughout the great sub-kingdom of the Vertebrata; and in
all cases it is eminently distinctive of characters which have been
acquired through sexual selection. Fritz Muller (17. 'Facts and
Arguments,' etc., p. 79.) gives some striking instances of this law; thus
the male sand-hopper (Orchestia) does not, until nearly full grown, acquire
his large claspers, which are very differently constructed from those of
the female; whilst young, his claspers resemble those of the female.
CLASS, ARACHNIDA (SPIDERS).
The sexes do not generally differ much in colour, but the males are often
darker than the females, as may be seen in Mr. Blackwall's magnificent
work. (18. 'A History of the Spiders of Great Britain,' 1861-64. For the
following facts, see pp. 77, 88, 102.) In some species, however, the
difference is conspicuous: thus the female of Sparassus smaragdulus is
dullish green, whilst the adult male has the abdomen of a fine yellow, with
three longitudinal stripes of rich red. In certain species of Thomisus the
sexes closely resemble each other, in others they differ much; and
analogous cases occur in many other genera. It is often difficult to say
which of the two sexes departs most from the ordinary coloration of the
genus to which the species belong; but Mr. Blackwall thinks that, as a
general rule, it is the male; and Canestrini (19. This author has recently
published a valuable essay on the 'Caratteri sessuali secondarii degli
Arachnidi,' in the 'Atti della Soc. Veneto-Trentina di Sc. Nat. Padova,'
vol. i. Fasc. 3, 1873.) remarks that in certain genera the males can be
specifically distinguished with ease, but the females with great
difficulty. I am informed by Mr. Blackwall that the sexes whilst young
usually resemble each other; and both often undergo great changes in colour
during their successive moults, before arriving at maturity. In other
cases the male alone appears to change colour. Thus the male of the above
bright-coloured Sparassus at first resembles the female, and acquires his
peculiar tints only when nearly adult. Spiders are possessed of acute
senses, and exhibit much intelligence; as is well known, the females often
shew the strongest affection for their eggs, which they carry about
enveloped in a silken web. The males search eagerly for the females, and
have been seen by Canestrini and others to fight for possession of them.
This same author says that the union of the two sexes has been observed in
about twenty species; and he asserts positively that the female rejects
some of the males who court her, threatens them with open mandibles, and at
last after long hesitation accepts the chosen one. From these several
considerations, we may admit with some confidence that the well-marked
differences in colour between the sexes of certain species are the results
of sexual selection; though we have not here the best kind of evidence,--
the display by the male of his ornaments. From the extreme variability of
colour in the male of some species, for instance of Theridion lineatum, it
would appear that these sexual characters of the males have not as yet
become well fixed. Canestrini draws the same conclusion from the fact that
the males of certain species present two forms, differing from each other
in the size and length of their jaws; and this reminds us of the above
cases of dimorphic crustaceans.
The male is generally much smaller than the female, sometimes to an
extraordinary degree (20. Aug. Vinson ('Araneides des Iles de la Reunion,'
pl. vi. figs. 1 and 2) gives a good instance of the small size of the male,
in Epeira nigra. In this species, as I may add, the male is testaceous and
the female black with legs banded with red. Other even more striking cases
of inequality in size between the sexes have been recorded ('Quarterly
Journal of Science,' July 1868, p. 429); but I have not seen the original
accounts.), and he is forced to be extremely cautious in making his
advances, as the female often carries her coyness to a dangerous pitch. De
Geer saw a male that "in the midst of his preparatory caresses was seized
by the object of his attentions, enveloped by her in a web and then
devoured, a sight which, as he adds, filled him with horror and
indignation." (21. Kirby and Spence, 'Introduction to Entomology,' vol.
i. 1818, p. 280.) The Rev. O.P. Cambridge (22. 'Proceedings, Zoological
Society,' 1871, p. 621.) accounts in the following manner for the extreme
smallness of the male in the genus Nephila. "M. Vinson gives a graphic
account of the agile way in which the diminutive male escapes from the
ferocity of the female, by gliding about and playing hide and seek over her
body and along her gigantic limbs: in such a pursuit it is evident that
the chances of escape would be in favour of the smallest males, while the
larger ones would fall early victims; thus gradually a diminutive race of
males would be selected, until at last they would dwindle to the smallest
possible size compatible with the exercise of their generative functions,--
in fact, probably to the size we now see them, i.e., so small as to be a
sort of parasite upon the female, and either beneath her notice, or too
agile and too small for her to catch without great difficulty."
Westring has made the interesting discovery that the males of several
species of Theridion (23. Theridion (Asagena, Sund.) serratipes, 4-
punctatum et guttatum; see Westring, in Kroyer, 'Naturhist. Tidskrift,'
vol. iv. 1842-1843, p. 349; and vol. ii. 1846-1849, p. 342. See, also, for
other species, 'Araneae Suecicae,' p. 184.) have the power of making a
stridulating sound, whilst the females are mute. The apparatus consists of
a serrated ridge at the base of the abdomen, against which the hard hinder
part of the thorax is rubbed; and of this structure not a trace can be
detected in the females. It deserves notice that several writers,
including the well-known arachnologist Walckenaer, have declared that
spiders are attracted by music. (24. Dr. H.H. van Zouteveen, in his Dutch
translation of this work (vol. i. p. 444), has collected several cases.)
From the analogy of the Orthoptera and Homoptera, to be described in the
next chapter, we may feel almost sure that the stridulation serves, as
Westring also believes, to call or to excite the female; and this is the
first case known to me in the ascending scale of the animal kingdom of
sounds emitted for this purpose. (25. Hilgendorf, however, has lately
called attention to an analogous structure in some of the higher
crustaceans, which seems adapted to produce sound; see 'Zoological Record,'
1869, p. 603.)
CLASS, MYRIAPODA.
In neither of the two orders in this class, the millipedes and centipedes,
can I find any well-marked instances of such sexual differences as more
particularly concern us. In Glomeris limbata, however, and perhaps in some
few other species, the males differ slightly in colour from the females;
but this Glomeris is a highly variable species. In the males of the
Diplopoda, the legs belonging either to one of the anterior or of the
posterior segments of the body are modified into prehensile hooks which
serve to secure the female. In some species of Iulus the tarsi of the male
are furnished with membranous suckers for the same purpose. As we shall
see when we treat of Insects, it is a much more unusual circumstance, that
it is the female in Lithobius, which is furnished with prehensile
appendages at the extremity of her body for holding the male. (26.
Walckenaer et P. Gervais, 'Hist. Nat. des Insectes: Apteres,' tom. iv.
1847, pp. 17, 19, 68.)
CHAPTER X.
SECONDARY SEXUAL CHARACTERS OF INSECTS.
Diversified structures possessed by the males for seizing the females--
Differences between the sexes, of which the meaning is not understood--
Difference in size between the sexes--Thysanura--Diptera--Hemiptera--
Homoptera, musical powers possessed by the males alone--Orthoptera, musical
instruments of the males, much diversified in structure; pugnacity;
colours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity
and odours--Coleoptera, colours; furnished with great horns, apparently as
an ornament; battles, stridulating organs generally common to both sexes.
In the immense class of insects the sexes sometimes differ in their
locomotive-organs, and often in their sense-organs, as in the pectinated
and beautifully plumose antennae of the males of many species. In Chloeon,
one of the Ephemerae, the male has great pillared eyes, of which the female
is entirely destitute. (1. Sir J. Lubbock, 'Transact. Linnean Soc.' vol.
xxv, 1866, p. 484. With respect to the Mutillidae see Westwood, 'Modern
Class. of Insects,' vol. ii. p. 213.) The ocelli are absent in the females
of certain insects, as in the Mutillidae; and here the females are likewise
wingless. But we are chiefly concerned with structures by which one male
is enabled to conquer another, either in battle or courtship, through his
strength, pugnacity, ornaments, or music. The innumerable contrivances,
therefore, by which the male is able to seize the female, may be briefly
passed over. Besides the complex structures at the apex of the abdomen,
which ought perhaps to be ranked as primary organs (2. These organs in the
male often differ in closely-allied species, and afford excellent specific
characters. But their importance, from a functional point of view, as Mr.
R. MacLachlan has remarked to me, has probably been overrated. It has been
suggested, that slight differences in these organs would suffice to prevent
the intercrossing of well-marked varieties or incipient species, and would
thus aid in their development. That this can hardly be the case, we may
infer from the many recorded cases (see, for instance, Bronn, 'Geschichte
der Natur,' B. ii. 1843, s. 164; and Westwood, 'Transact. Ent. Soc.' vol.
iii. 1842, p. 195) of distinct species having been observed in union. Mr.
MacLachlan informs me (vide 'Stett. Ent. Zeitung,' 1867, s. 155) that when
several species of Phryganidae, which present strongly-pronounced
differences of this kind, were confined together by Dr. Aug. Meyer, THEY
COUPLED, and one pair produced fertile ova.), "it is astonishing," as Mr.
B.D. Walsh (3. 'The Practical Entomologist,' Philadelphia, vol. ii. May
1867, p 88.) has remarked, "how many different organs are worked in by
nature for the seemingly insignificant object of enabling the male to grasp
the female firmly." The mandibles or jaws are sometimes used for this
purpose; thus the male Corydalis cornutus (a neuropterous insect in some
degree allied to the Dragon flies, etc.) has immense curved jaws, many
times longer than those of the female; and they are smooth instead of being
toothed, so that he is thus enabled to seize her without injury. (4. Mr.
Walsh, ibid. p. 107.) One of the stag-beetles of North America (Lucanus
elaphus) uses his jaws, which are much larger than those of the female, for
the same purpose, but probably likewise for fighting. In one of the sand-
wasps (Ammophila) the jaws in the two sexes are closely alike, but are used
for widely different purposes: the males, as Professor Westwood observes,
"are exceedingly ardent, seizing their partners round the neck with their
sickle-shaped jaws" (5. 'Modern Classification of Insects,' vol. ii. 1840,
pp. 205, 206. Mr. Walsh, who called my attention to the double use of the
jaws, says that he has repeatedly observed this fact.); whilst the females
use these organs for burrowing in sand-banks and making their nests.
[Fig. 9. Crabro cribrarius. Upper figure, male; lower figure, female.]
The tarsi of the front-legs are dilated in many male beetles, or are
furnished with broad cushions of hairs; and in many genera of water-beetles
they are armed with a round flat sucker, so that the male may adhere to the
slippery body of the female. It is a much more unusual circumstance that
the females of some water-beetles (Dytiscus) have their elytra deeply
grooved, and in Acilius sulcatus thickly set with hairs, as an aid to the
male. The females of some other water-beetles (Hydroporus) have their
elytra punctured for the same purpose. (6. We have here a curious and
inexplicable case of dimorphism, for some of the females of four European
species of Dytiscus, and of certain species of Hydroporus, have their
elytra smooth; and no intermediate gradations between the sulcated or
punctured, and the quite smooth elytra have been observed. See Dr. H.
Schaum, as quoted in the 'Zoologist,' vols. v.-vi. 1847-48, p. 1896. Also
Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 305.)
In the male of Crabro cribrarius (Fig. 9), it is the tibia which is dilated
into a broad horny plate, with minute membraneous dots, giving to it a
singular appearance like that of a riddle. (7. Westwood, 'Modern Class.'
vol. ii. p. 193. The following statement about Penthe, and others in
inverted commas, are taken from Mr. Walsh, 'Practical Entomologist,'
Philadelphia, vol. iii. p. 88.) In the male of Penthe (a genus of beetles)
a few of the middle joints of the antennae are dilated and furnished on the
inferior surface with cushions of hair, exactly like those on the tarsi of
the Carabidae, "and obviously for the same end." In male dragon-flies,
"the appendages at the tip of the tail are modified in an almost infinite
variety of curious patterns to enable them to embrace the neck of the
female." Lastly, in the males of many insects, the legs are furnished with
peculiar spines, knobs or spurs; or the whole leg is bowed or thickened,
but this is by no means invariably a sexual character; or one pair, or all
three pairs are elongated, sometimes to an extravagant length. (8. Kirby
and Spence, 'Introduct.' etc., vol. iii. pp. 332-336.)
[Fig. 10. Taphroderes distortus (much enlarged). Upper figure, male;
lower figure, female.]
The sexes of many species in all the orders present differences, of which
the meaning is not understood. One curious case is that of a beetle (Fig.
10), the male of which has left mandible much enlarged; so that the mouth
is greatly distorted. In another Carabidous beetle, Eurygnathus (9.
'Insecta Maderensia,' 1854, page 20.), we have the case, unique as far as
known to Mr. Wollaston, of the head of the female being much broader and
larger, though in a variable degree, than that of the male. Any number of
such cases could be given. They abound in the Lepidoptera: one of the
most extraordinary is that certain male butterflies have their fore-legs
more or less atrophied, with the tibiae and tarsi reduced to mere
rudimentary knobs. The wings, also, in the two sexes often differ in
neuration (10. E. Doubleday, 'Annals and Mag. of Nat. Hist.' vol. i. 1848,
p. 379. I may add that the wings in certain Hymenoptera (see Shuckard,
'Fossorial Hymenoptera,' 1837, pp. 39-43) differ in neuration according to
sex.), and sometimes considerably in outline, as in the Aricoris epitus,
which was shewn to me in the British Museum by Mr. A. Butler. The males of
certain South American butterflies have tufts of hair on the margins of the
wings, and horny excrescences on the discs of the posterior pair. (11.
H.W. Bates, in 'Journal of Proc. Linn. Soc.' vol. vi. 1862, p. 74. Mr.
Wonfor's observations are quoted in 'Popular Science Review,' 1868, p.
343.) In several British butterflies, as shewn by Mr. Wonfor, the males
alone are in parts clothed with peculiar scales.
The use of the bright light of the female glow-worm has been subject to
much discussion. The male is feebly luminous, as are the larvae and even
the eggs. It has been supposed by some authors that the light serves to
frighten away enemies, and by others to guide the male to the female. At
last, Mr. Belt (12. 'The Naturalist in Nicaragua,' 1874, pp. 316-320. On
the phosphorescence of the eggs, see 'Annals and Magazine of Natural
History,' Nov. 1871, p. 372.) appears to have solved the difficulty: he
finds that all the Lampyridae which he has tried are highly distasteful to
insectivorous mammals and birds. Hence it is in accordance with Mr. Bates'
view, hereafter to be explained, that many insects mimic the Lampyridae
closely, in order to be mistaken for them, and thus to escape destruction.
He further believes that the luminous species profit by being at once
recognised as unpalatable. It is probable that the same explanation may be
extended to the Elaters, both sexes of which are highly luminous. It is
not known why the wings of the female glow-worm have not been developed;
but in her present state she closely resembles a larva, and as larvae are
so largely preyed on by many animals, we can understand why she has been
rendered so much more luminous and conspicuous than the male; and why the
larvae themselves are likewise luminous.
DIFFERENCE IN SIZE BETWEEN THE SEXES.
With insects of all kinds the males are commonly smaller than the females;
and this difference can often be detected even in the larval state. So
considerable is the difference between the male and female cocoons of the
silk-moth (Bombyx mori), that in France they are separated by a particular
mode of weighing. (13. Robinet, 'Vers a Soie,' 1848, p. 207.) In the
lower classes of the animal kingdom, the greater size of the females seems
generally to depend on their developing an enormous number of ova; and this
may to a certain extent hold good with insects. But Dr. Wallace has
suggested a much more probable explanation. He finds, after carefully
attending to the development of the caterpillars of Bombyx cynthia and
yamamai, and especially to that of some dwarfed caterpillars reared from a
second brood on unnatural food, "that in proportion as the individual moth
is finer, so is the time required for its metamorphosis longer; and for
this reason the female, which is the larger and heavier insect, from having
to carry her numerous eggs, will be preceded by the male, which is smaller
and has less to mature." (14. 'Transact. Ent. Soc.' 3rd series, vol. v.
p. 486.) Now as most insects are short-lived, and as they are exposed to
many dangers, it would manifestly be advantageous to the female to be
impregnated as soon as possible. This end would be gained by the males
being first matured in large numbers ready for the advent of the females;
and this again would naturally follow, as Mr. A.R. Wallace has remarked
(15. 'Journal of Proc. Ent. Soc.' Feb. 4, 1867, p. lxxi.), through natural
selection; for the smaller males would be first matured, and thus would
procreate a large number of offspring which would inherit the reduced size
of their male parents, whilst the larger males from being matured later
would leave fewer offspring.
There are, however, exceptions to the rule of male insects being smaller
than the females: and some of these exceptions are intelligible. Size and
strength would be an advantage to the males, which fight for the possession
of the females; and in these cases, as with the stag-beetle (Lucanus), the
males are larger than the females. There are, however, other beetles which
are not known to fight together, of which the males exceed the females in
size; and the meaning of this fact is not known; but in some of these
cases, as with the huge Dynastes and Megasoma, we can at least see that
there would be no necessity for the males to be smaller than the females,
in order to be matured before them, for these beetles are not short-lived,
and there would be ample time for the pairing of the sexes. So again, male
dragon-flies (Libellulidae) are sometimes sensibly larger, and never
smaller, than the females (16. For this and other statements on the size
of the sexes, see Kirby and Spence, ibid. vol. iii. p. 300; on the duration
of life in insects, see p. 344.); and as Mr. MacLachlan believes, they do
not generally pair with the females until a week or fortnight has elapsed,
and until they have assumed their proper masculine colours. But the most
curious case, shewing on what complex and easily-overlooked relations, so
trifling a character as difference in size between the sexes may depend, is
that of the aculeate Hymenoptera; for Mr. F. Smith informs me that
throughout nearly the whole of this large group, the males, in accordance
with the general rule, are smaller than the females, and emerge about a
week before them; but amongst the Bees, the males of Apis mellifica,
Anthidium manicatum, and Anthophora acervorum, and amongst the Fossores,
the males of the Methoca ichneumonides, are larger than the females. The
explanation of this anomaly is that a marriage flight is absolutely
necessary with these species, and the male requires great strength and size
in order to carry the female through the air. Increased size has here been
acquired in opposition to the usual relation between size and the period of
development, for the males, though larger, emerge before the smaller
females.
We will now review the several Orders, selecting such facts as more
particularly concern us. The Lepidoptera (Butterflies and Moths) will be
retained for a separate chapter.
ORDER, THYSANURA.
The members of this lowly organised order are wingless, dull-coloured,
minute insects, with ugly, almost misshapen heads and bodies. Their sexes
do not differ, but they are interesting as shewing us that the males pay
sedulous court to the females even low down in the animal scale. Sir J.
Lubbock (17. 'Transact. Linnean Soc.' vol. xxvi. 1868, p. 296.) says: "it
is very amusing to see these little creatures (Smynthurus luteus)
coquetting together. The male, which is much smaller than the female, runs
round her, and they butt one another, standing face to face and moving
backward and forward like two playful lambs. Then the female pretends to
run away and the male runs after her with a queer appearance of anger, gets
in front and stands facing her again; then she turns coyly round, but he,
quicker and more active, scuttles round too, and seems to whip her with his
antennae; then for a bit they stand face to face, play with their antennae,
and seem to be all in all to one another."
ORDER, DIPTERA (FLIES).
The sexes differ little in colour. The greatest difference, known to Mr.
F. Walker, is in the genus Bibio, in which the males are blackish or quite
black, and the females obscure brownish-orange. The genus Elaphomyia,
discovered by Mr. Wallace (18. 'The Malay Archipelago,' vol. ii. 1869, p.
313.) in New Guinea, is highly remarkable, as the males are furnished with
horns, of which the females are quite destitute. The horns spring from
beneath the eyes, and curiously resemble those of a stag, being either
branched or palmated. In one of the species, they equal the whole body in
length. They might be thought to be adapted for fighting, but as in one
species they are of a beautiful pink colour, edged with black, with a pale
central stripe, and as these insects have altogether a very elegant
appearance, it is perhaps more probable that they serve as ornaments. That
the males of some Diptera fight together is certain; Prof. Westwood (19.
'Modern Classification of Insects,' vol. ii. 1840, p. 526.) has several
times seen this with the Tipulae. The males of other Diptera apparently
try to win the females by their music: H. Muller (20. 'Anwendung,' etc.,
'Verh. d. n. V. Jahrg.' xxix. p. 80. Mayer, in 'American Naturalist,'
1874, p. 236.) watched for some time two males of an Eristalis courting a
female; they hovered above her, and flew from side to side, making a high
humming noise at the same time. Gnats and mosquitoes (Culicidae) also seem
to attract each other by humming; and Prof. Mayer has recently ascertained
that the hairs on the antennae of the male vibrate in unison with the notes
of a tuning-fork, within the range of the sounds emitted by the female.
The longer hairs vibrate sympathetically with the graver notes, and the
shorter hairs with the higher ones. Landois also asserts that he has
repeatedly drawn down a whole swarm of gnats by uttering a particular note.
It may be added that the mental faculties of the Diptera are probably
higher than in most other insects, in accordance with their highly-
developed nervous system. (21. See Mr. B.T. Lowne's interesting work, 'On
the Anatomy of the Blow-fly, Musca vomitoria,' 1870, p. 14. He remarks (p.
33) that, "the captured flies utter a peculiar plaintive note, and that
this sound causes other flies to disappear.")
ORDER, HEMIPTERA (FIELD-BUGS).
Mr. J.W. Douglas, who has particularly attended to the British species, has
kindly given me an account of their sexual differences. The males of some
species are furnished with wings, whilst the females are wingless; the
sexes differ in the form of their bodies, elytra, antennae and tarsi; but
as the signification of these differences are unknown, they may be here
passed over. The females are generally larger and more robust than the
males. With British, and, as far as Mr. Douglas knows, with exotic
species, the sexes do not commonly differ much in colour; but in about six
British species the male is considerably darker than the female, and in
about four other species the female is darker than the male. Both sexes of
some species are beautifully coloured; and as these insects emit an
extremely nauseous odour, their conspicuous colours may serve as a signal
that they are unpalatable to insectivorous animals. In some few cases
their colours appear to be directly protective: thus Prof. Hoffmann
informs me that he could hardly distinguish a small pink and green species
from the buds on the trunks of lime-trees, which this insect frequents.
Some species of Reduvidae make a stridulating noise; and, in the case of
Pirates stridulus, this is said (22. Westwood, 'Modern Classification of
Insects,' vol. ii. p. 473.) to be effected by the movement of the neck
within the pro-thoracic cavity. According to Westring, Reduvius personatus
also stridulates. But I have no reason to suppose that this is a sexual
character, excepting that with non-social insects there seems to be no use
for sound-producing organs, unless it be as a sexual call.
ORDER: HOMOPTERA.
Every one who has wandered in a tropical forest must have been astonished
at the din made by the male Cicadae. The females are mute; as the Grecian
poet Xenarchus says, "Happy the Cicadas live, since they all have voiceless
wives." The noise thus made could be plainly heard on board the "Beagle,"
when anchored at a quarter of a mile from the shore of Brazil; and Captain
Hancock says it can be heard at the distance of a mile. The Greeks
formerly kept, and the Chinese now keep these insects in cages for the sake
of their song, so that it must be pleasing to the ears of some men. (23.
These particulars are taken from Westwood's 'Modern Classification of
Insects,' vol. ii. 1840, p. 422. See, also, on the Fulgoridae, Kirby and
Spence, 'Introduct.' vol. ii. p. 401.) The Cicadidae usually sing during
the day, whilst the Fulgoridae appear to be night-songsters. The sound,
according to Landois (24. 'Zeitschrift fur wissenschaft Zoolog.' B. xvii.
1867, ss. 152-158.), is produced by the vibration of the lips of the
spiracles, which are set into motion by a current of air emitted from the
tracheae; but this view has lately been disputed. Dr. Powell appears to
have proved (25. 'Transactions of the New Zealand Institute,' vol. v.
1873, p. 286.) that it is produced by the vibration of a membrane, set into
action by a special muscle. In the living insect, whilst stridulating,
this membrane can be seen to vibrate; and in the dead insect the proper
sound is heard, if the muscle, when a little dried and hardened, is pulled
with the point of a pin. In the female the whole complex musical apparatus
is present, but is much less developed than in the male, and is never used
for producing sound.
With respect to the object of the music, Dr. Hartman, in speaking of the
Cicada septemdecim of the United States, says (26. I am indebted to Mr.
Walsh for having sent me this extract from 'A Journal of the Doings of
Cicada septemdecim,' by Dr. Hartman.), "the drums are now (June 6th and
7th, 1851) heard in all directions. This I believe to be the marital
summons from the males. Standing in thick chestnut sprouts about as high
as my head, where hundreds were around me, I observed the females coming
around the drumming males." He adds, "this season (Aug. 1868) a dwarf
pear-tree in my garden produced about fifty larvae of Cic. pruinosa; and I
several times noticed the females to alight near a male while he was
uttering his clanging notes." Fritz Muller writes to me from S. Brazil
that he has often listened to a musical contest between two or three males
of a species with a particularly loud voice, seated at a considerable
distance from each other: as soon as one had finished his song, another
immediately began, and then another. As there is so much rivalry between
the males, it is probable that the females not only find them by their
sounds, but that, like female birds, they are excited or allured by the
male with the most attractive voice.
I have not heard of any well-marked cases of ornamental differences between
the sexes of the Homoptera. Mr. Douglas informs me that there are three
British species, in which the male is black or marked with black bands,
whilst the females are pale-coloured or obscure.
ORDER, ORTHOPTERA (CRICKETS AND GRASSHOPPERS).
The males in the three saltatorial families in this Order are remarkable
for their musical powers, namely the Achetidae or crickets, the Locustidae
for which there is no equivalent English name, and the Acridiidae or
grasshoppers. The stridulation produced by some of the Locustidae is so
loud that it can be heard during the night at the distance of a mile (27.
L. Guilding, 'Transactions of the Linnean Society,' vol. xv. p. 154.); and
that made by certain species is not unmusical even to the human ear, so
that the Indians on the Amazons keep them in wicker cages. All observers
agree that the sounds serve either to call or excite the mute females.
With respect to the migratory locusts of Russia, Korte has given (28. I
state this on the authority of Koppen, 'Uber die Heuschrecken in
Sudrussland,' 1866, p. 32, for I have in vain endeavoured to procure
Korte's work.) an interesting case of selection by the female of a male.
The males of this species (Pachytylus migratorius) whilst coupled with the
female stridulate from anger or jealousy, if approached by other males.
The house-cricket when surprised at night uses its voice to warn its
fellows. (29. Gilbert White, 'Natural History of Selborne,' vol. ii.
1825, p. 262.) In North America the Katy-did (Platyphyllum concavum, one
of the Locustidae) is described (30. Harris, 'Insects of New England,'
1842, p. 128.) as mounting on the upper branches of a tree, and in the
evening beginning "his noisy babble, while rival notes issue from the
neighbouring trees, and the groves resound with the call of Katy-did-she-
did the live-long night." Mr. Bates, in speaking of the European field-
cricket (one of the Achetidae), says "the male has been observed to place
himself in the evening at the entrance of his burrow, and stridulate until
a female approaches, when the louder notes are succeeded by a more subdued
tone, whilst the successful musician caresses with his antennae the mate he
has won." (31. 'The Naturalist on the Amazons,' vol. i. 1863, p. 252. Mr.
Bates gives a very interesting discussion on the gradations in the musical
apparatus of the three families. See also Westwood, 'Modern Classification
of Insects,' vol. ii. pp. 445 and 453.) Dr. Scudder was able to excite one
of these insects to answer him, by rubbing on a file with a quill. (32.
'Proceedings of the Boston Society of Natural History,' vol. xi. April
1868.) In both sexes a remarkable auditory apparatus has been discovered
by Von Siebold, situated in the front legs. (33. 'Nouveau Manuel d'Anat.
Comp.' (French translat.), tom. 1, 1850, p. 567.)
[Fig.11. Gryllus campestris (from Landois).
Right-hand figure, under side of part of a wing-nervure, much magnified,
showing the teeth, st.
Left-hand figure, upper surface of wing-cover, with the projecting, smooth
nervure, r, across which the teeth (st) are scraped.
Fig.12. Teeth of Nervure of Gryllus domesticus (from Landois).]
In the three Families the sounds are differently produced. In the males of
the Achetidae both wing-covers have the same apparatus; and this in the
field-cricket (see Gryllus campestris, Fig. 11) consists, as described by
Landois (34. 'Zeitschrift fur wissenschaft. Zoolog.' B. xvii. 1867, s.
117.), of from 131 to 138 sharp, transverse ridges or teeth (st) on the
under side of one of the nervures of the wing-cover. This toothed nervure
is rapidly scraped across a projecting, smooth, hard nervure (r) on the
upper surface of the opposite wing. First one wing is rubbed over the
other, and then the movement is reversed. Both wings are raised a little
at the same time, so as to increase the resonance. In some species the
wing-covers of the males are furnished at the base with a talc-like plate.
(35. Westwood, 'Modern Classification of Insects,' vol. i. p. 440.) I
here give a drawing (Fig. 12) of the teeth on the under side of the nervure
of another species of Gryllus, viz., G. domesticus. With respect to the
formation of these teeth, Dr. Gruber has shewn (36. 'Ueber der Tonapparat
der Locustiden, ein Beitrag zum Darwinismus,' 'Zeitschrift fur
wissenschaft. Zoolog.' B. xxii. 1872, p. 100.) that they have been
developed by the aid of selection, from the minute scales and hairs with
which the wings and body are covered, and I came to the same conclusion
with respect to those of the Coleoptera. But Dr. Gruber further shews that
their development is in part directly due to the stimulus from the friction
of one wing over the other.
[Fig.13. Chlorocoelus Tanana (from Bates).
a,b. Lobes of opposite wing-covers.]
In the Locustidae the opposite wing-covers differ from each other in
structure (Fig. 13), and the action cannot, as in the last family, be
reversed. The left wing, which acts as the bow, lies over the right wing
which serves as the fiddle. One of the nervures (a) on the under surface
of the former is finely serrated, and is scraped across the prominent
nervures on the upper surface of the opposite or right wing. In our
British Phasgonura viridissima it appeared to me that the serrated nervure
is rubbed against the rounded hind-corner of the opposite wing, the edge of
which is thickened, coloured brown, and very sharp. In the right wing, but
not in the left, there is a little plate, as transparent as talc,
surrounded by nervures, and called the speculum. In Ephippiger vitium, a
member of this same family, we have a curious subordinate modification; for
the wing-covers are greatly reduced in size, but "the posterior part of the
pro-thorax is elevated into a kind of dome over the wing-covers, and which
has probably the effect of increasing the sound." (37. Westwood 'Modern
Classification of Insects,' vol. i. p. 453.)
We thus see that the musical apparatus is more differentiated or
specialised in the Locustidae (which include, I believe, the most powerful
performers in the Order), than in the Achetidae, in which both wing-covers
have the same structure and the same function. (38. Landois, 'Zeitschrift
fur wissenschaft Zoolog.' B. xvii. 1867, ss. 121, 122.) Landois, however,
detected in one of the Locustidae, namely in Decticus, a short and narrow
row of small teeth, mere rudiments, on the inferior surface of the right
wing-cover, which underlies the other and is never used as the bow. I
observed the same rudimentary structure on the under side of the right
wing-cover in Phasgonura viridissima. Hence we may infer with confidence
that the Locustidae are descended from a form, in which, as in the existing
Achetidae, both wing-covers had serrated nervures on the under surface, and
could be indifferently used as the bow; but that in the Locustidae the two
wing-covers gradually became differentiated and perfected, on the principle
of the division of labour, the one to act exclusively as the bow, and the
other as the fiddle. Dr. Gruber takes the same view, and has shewn that
rudimentary teeth are commonly found on the inferior surface of the right
wing. By what steps the more simple apparatus in the Achetidae originated,
we do not know, but it is probable that the basal portions of the wing-
covers originally overlapped each other as they do at present; and that the
friction of the nervures produced a grating sound, as is now the case with
the wing-covers of the females. (39. Mr. Walsh also informs me that he
has noticed that the female of the Platyphyllum concavum, "when captured
makes a feeble grating noise by shuffling her wing-covers together.") A
grating sound thus occasionally and accidentally made by the males, if it
served them ever so little as a love-call to the females, might readily
have been intensified through sexual selection, by variations in the
roughness of the nervures having been continually preserved.
[Fig.14. Hind-leg of Stenobothrus pratorum:
r, the stridulating ridge;
lower figure, the teeth forming the ridge, much magnified (from Landois).
Fig.15. Pneumora (from specimens in the British Museum).
Upper figure, male;
lower figure, female.]
In the last and third family, namely the Acridiidae or grasshoppers, the
stridulation is produced in a very different manner, and according to Dr.
Scudder, is not so shrill as in the preceding Families. The inner surface
of the femur (Fig. 14, r) is furnished with a longitudinal row of minute,
elegant, lancet-shaped, elastic teeth, from 85 to 93 in number (40.
Landois, ibid. s. 113.); and these are scraped across the sharp, projecting
nervures on the wing-covers, which are thus made to vibrate and resound.
Harris (41. 'Insects of New England,' 1842, p. 133.) says that when one of
the males begins to play, he first "bends the shank of the hind-leg beneath
the thigh, where it is lodged in a furrow designed to receive it, and then
draws the leg briskly up and down. He does not play both fiddles together,
but alternately, first upon one and then on the other." In many species,
the base of the abdomen is hollowed out into a great cavity which is
believed to act as a resounding board. In Pneumora (Fig. 15), a S. African
genus belonging to the same family, we meet with a new and remarkable
modification; in the males a small notched ridge projects obliquely from
each side of the abdomen, against which the hind femora are rubbed. (42.
Westwood, 'Modern Classification,' vol i. p. 462.) As the male is
furnished with wings (the female being wingless), it is remarkable that the
thighs are not rubbed in the usual manner against the wing-covers; but this
may perhaps be accounted for by the unusually small size of the hind-legs.
I have not been able to examine the inner surface of the thighs, which,
judging from analogy, would be finely serrated. The species of Pneumora
have been more profoundly modified for the sake of stridulation than any
other orthopterous insect; for in the male the whole body has been
converted into a musical instrument, being distended with air, like a great
pellucid bladder, so as to increase the resonance. Mr. Trimen informs me
that at the Cape of Good Hope these insects make a wonderful noise during
the night.
In the three foregoing families, the females are almost always destitute of
an efficient musical apparatus. But there are a few exceptions to this
rule, for Dr. Gruber has shewn that both sexes of Ephippiger vitium are
thus provided; though the organs differ in the male and female to a certain
extent. Hence we cannot suppose that they have been transferred from the
male to the female, as appears to have been the case with the secondary
sexual characters of many other animals. They must have been independently
developed in the two sexes, which no doubt mutually call to each other
during the season of love. In most other Locustidae (but not according to
Landois in Decticus) the females have rudiments of the stridulatory organs
proper to the male; from whom it is probable that these have been
transferred. Landois also found such rudiments on the under surface of the
wing-covers of the female Achetidae, and on the femora of the female
Acridiidae. In the Homoptera, also, the females have the proper musical
apparatus in a functionless state; and we shall hereafter meet in other
divisions of the animal kingdom with many instances of structures proper to
the male being present in a rudimentary condition of the female.
Landois has observed another important fact, namely, that in the females of
the Acridiidae, the stridulating teeth on the femora remain throughout life
in the same condition in which they first appear during the larval state in
both sexes. In the males, on the other hand, they become further
developed, and acquire their perfect structure at the last moult, when the
insect is mature and ready to breed.
From the facts now given, we see that the means by which the males of the
Orthoptera produce their sounds are extremely diversified, and are
altogether different from those employed by the Homoptera. (43. Landois
has recently found in certain Orthoptera rudimentary structures closely
similar to the sound-producing organs in the Homoptera; and this is a
surprising fact. See 'Zeitschrift fur wissenschaft Zoolog.' B. xxii. Heft
3, 1871, p. 348.) But throughout the animal kingdom we often find the same
object gained by the most diversified means; this seems due to the whole
organisation having undergone multifarious changes in the course of ages,
and as part after part varied different variations were taken advantage of
for the same general purpose. The diversity of means for producing sound
in the three families of the Orthoptera and in the Homoptera, impresses the
mind with the high importance of these structures to the males, for the
sake of calling or alluring the females. We need feel no surprise at the
amount of modification which the Orthoptera have undergone in this respect,
as we now know, from Dr. Scudder's remarkable discovery (44.
'Transactions, Entomological Society,' 3rd series, vol. ii. ('Journal of
Proceedings,' p. 117).), that there has been more than ample time. This
naturalist has lately found a fossil insect in the Devonian formation of
New Brunswick, which is furnished with "the well-known tympanum or
stridulating apparatus of the male Locustidae." The insect, though in most
respects related to the Neuroptera, appears, as is so often the case with
very ancient forms, to connect the two related Orders of the Neuroptera and
Orthoptera.
I have but little more to say on the Orthoptera. Some of the species are
very pugnacious: when two male field-crickets (Gryllus campestris) are
confined together, they fight till one kills the other; and the species of
Mantis are described as manoeuvring with their sword-like front-limbs, like
hussars with their sabres. The Chinese keep these insects in little bamboo
cages, and match them like game-cocks. (45. Westwood, 'Modern
Classification of Insects,' vol. i. p. 427; for crickets, p. 445.) With
respect to colour, some exotic locusts are beautifully ornamented; the
posterior wings being marked with red, blue, and black; but as throughout
the Order the sexes rarely differ much in colour, it is not probable that
they owe their bright tints to sexual selection. Conspicuous colours may
be of use to these insects, by giving notice that they are unpalatable.
Thus it has been observed (46. Mr. Ch. Horne, in 'Proceedings of the
Entomological Society,' May 3, 1869, p. xii.) that a bright-coloured Indian
locust was invariably rejected when offered to birds and lizards. Some
cases, however, are known of sexual differences in colour in this Order.
The male of an American cricket (47. The Oecanthus nivalis, Harris,
'Insects of New England,' 1842, p. 124. The two sexes of OE. pellucidus of
Europe differ, as I hear from Victor Carus, in nearly the same manner.) is
described as being as white as ivory, whilst the female varies from almost
white to greenish-yellow or dusky. Mr. Walsh informs me that the adult
male of Spectrum femoratum (one of the Phasmidae) "is of a shining
brownish-yellow colour; the adult female being of a dull, opaque, cinereous
brown; the young of both sexes being green." Lastly, I may mention that
the male of one curious kind of cricket (48. Platyblemnus: Westwood,
'Modern Classification,' vol. i. p. 447.) is furnished with "a long
membranous appendage, which falls over the face like a veil;" but what its
use may be, is not known.
ORDER, NEUROPTERA.
Little need here be said, except as to colour. In the Ephemeridae the
sexes often differ slightly in their obscure tints (49. B.D. Walsh, the
'Pseudo-neuroptera of Illinois,' in 'Proceedings of the Entomological
Society of Philadelphia,' 1862, p. 361.); but it is not probable that the
males are thus rendered attractive to the females. The Libellulidae, or
dragon-flies, are ornamented with splendid green, blue, yellow, and
vermilion metallic tints; and the sexes often differ. Thus, as Prof.
Westwood remarks (50. 'Modern Classification,' vol. ii. p. 37.), the males
of some of the Agrionidae, "are of a rich blue with black wings, whilst the
females are fine green with colourless wings." But in Agrion Ramburii
these colours are exactly reversed in the two sexes. (51. Walsh, ibid. p.
381. I am indebted to this naturalist for the following facts on
Hetaerina, Anax, and Gomphus.) In the extensive N. American genus of
Hetaerina, the males alone have a beautiful carmine spot at the base of
each wing. In Anax junius the basal part of the abdomen in the male is a
vivid ultramarine blue, and in the female grass-green. In the allied genus
Gomphus, on the other hand, and in some other genera, the sexes differ but
little in colour. In closely-allied forms throughout the animal kingdom,
similar cases of the sexes differing greatly, or very little, or not at
all, are of frequent occurrence. Although there is so wide a difference in
colour between the sexes of many Libellulidae, it is often difficult to say
which is the more brilliant; and the ordinary coloration of the two sexes
is reversed, as we have just seen, in one species of Agrion. It is not
probable that their colours in any case have been gained as a protection.
Mr. MacLachlan, who has closely attended to this family, writes to me that
dragon-flies--the tyrants of the insect-world--are the least liable of any
insect to be attacked by birds or other enemies, and he believes that their
bright colours serve as a sexual attraction. Certain dragon-flies
apparently are attracted by particular colours: Mr. Patterson observed
(52. 'Transactions, Ent. Soc.' vol. i. 1836, p. lxxxi.) that the
Agrionidae, of which the males are blue, settled in numbers on the blue
float of a fishing line; whilst two other species were attracted by shining
white colours.
It is an interesting fact, first noticed by Schelver, that, in several
genera belonging to two sub-families, the males on first emergence from the
pupal state, are coloured exactly like the females; but that their bodies
in a short time assume a conspicuous milky-blue tint, owing to the
exudation of a kind of oil, soluble in ether and alcohol. Mr. MacLachlan
believes that in the male of Libellula depressa this change of colour does
not occur until nearly a fortnight after the metamorphosis, when the sexes
are ready to pair.
Certain species of Neurothemis present, according to Brauer (53. See
abstract in the 'Zoological Record' for 1867, p. 450.), a curious case of
dimorphism, some of the females having ordinary wings, whilst others have
them "very richly netted, as in the males of the same species." Brauer
"explains the phenomenon on Darwinian principles by the supposition that
the close netting of the veins is a secondary sexual character in the
males, which has been abruptly transferred to some of the females, instead
of, as generally occurs, to all of them." Mr. MacLachlan informs me of
another instance of dimorphism in several species of Agrion, in which some
individuals are of an orange colour, and these are invariably females.
This is probably a case of reversion; for in the true Libellulae, when the
sexes differ in colour, the females are orange or yellow; so that supposing
Agrion to be descended from some primordial form which resembled the
typical Libellulae in its sexual characters, it would not be surprising
that a tendency to vary in this manner should occur in the females alone.
Although many dragon-flies are large, powerful, and fierce insects, the
males have not been observed by Mr. MacLachlan to fight together,
excepting, as he believes, in some of the smaller species of Agrion. In
another group in this Order, namely, the Termites or white ants, both sexes
at the time of swarming may be seen running about, "the male after the
female, sometimes two chasing one female, and contending with great
eagerness who shall win the prize." (54. Kirby and Spence, 'Introduction
to Entomology,' vol. ii. 1818, p. 35.) The Atropos pulsatorius is said to
make a noise with its jaws, which is answered by other individuals. (55.
Houzeau, 'Les Facultes Mentales,' etc. Tom. i. p. 104.)
ORDER, HYMENOPTERA.
That inimitable observer, M. Fabre (56. See an interesting article, 'The
Writings of Fabre,' in 'Nat. Hist. Review,' April 1862, p. 122.), in
describing the habits of Cerceris, a wasp-like insect, remarks that "fights
frequently ensue between the males for the possession of some particular
female, who sits an apparently unconcerned beholder of the struggle for
supremacy, and when the victory is decided, quietly flies away in company
with the conqueror." Westwood (57. 'Journal of Proceedings of
Entomological Society,' Sept. 7, 1863, p. 169.) says that the males of one
of the saw-flies (Tenthredinae) "have been found fighting together, with
their mandibles locked." As M. Fabre speaks of the males of Cerceris
striving to obtain a particular female, it may be well to bear in mind that
insects belonging to this Order have the power of recognising each other
after long intervals of time, and are deeply attached. For instance,
Pierre Huber, whose accuracy no one doubts, separated some ants, and when,
after an interval of four months, they met others which had formerly
belonged to the same community, they recognised and caressed one another
with their antennae. Had they been strangers they would have fought
together. Again, when two communities engage in a battle, the ants on the
same side sometimes attack each other in the general confusion, but they
soon perceive their mistake, and the one ant soothes the other. (58. P.
Huber, 'Recherches sur les Moeurs des Fourmis,' 1810, pp. 150, 165.)
In this Order slight differences in colour, according to sex, are common,
but conspicuous differences are rare except in the family of Bees; yet both
sexes of certain groups are so brilliantly coloured--for instance in
Chrysis, in which vermilion and metallic greens prevail--that we are
tempted to attribute the result to sexual selection. In the Ichneumonidae,
according to Mr. Walsh (59. 'Proceedings of the Entomological Society of
Philadelphia,' 1866, pp. 238, 239.), the males are almost universally
lighter-coloured than the females. On the other hand, in the
Tenthredinidae the males are generally darker than the females. In the
Siricidae the sexes frequently differ; thus the male of Sirex juvencus is
banded with orange, whilst the female is dark purple; but it is difficult
to say which sex is the more ornamented. In Tremex columbae the female is
much brighter coloured than the male. I am informed by Mr. F. Smith, that
the male ants of several species are black, the females being testaceous.
In the family of Bees, especially in the solitary species, as I hear from
the same entomologist, the sexes often differ in colour. The males are
generally the brighter, and in Bombus as well as in Apathus, much more
variable in colour than the females. In Anthophora retusa the male is of a
rich fulvous-brown, whilst the female is quite black: so are the females
of several species of Xylocopa, the males being bright yellow. On the
other hand the females of some species, as of Andraena fulva, are much
brighter coloured than the males. Such differences in colour can hardly be
accounted for by the males being defenceless and thus requiring protection,
whilst the females are well defended by their stings. H. Muller (60.
'Anwendung der Darwinschen Lehre auf Bienen,' Verh. d. n. V. Jahrg. xxix.),
who has particularly attended to the habits of bees, attributes these
differences in colour in chief part to sexual selection. That bees have a
keen perception of colour is certain. He says that the males search
eagerly and fight for the possession of the females; and he accounts
through such contests for the mandibles of the males being in certain
species larger than those of the females. In some cases the males are far
more numerous than the females, either early in the season, or at all times
and places, or locally; whereas the females in other cases are apparently
in excess. In some species the more beautiful males appear to have been
selected by the females; and in others the more beautiful females by the
males. Consequently in certain genera (Muller, p. 42), the males of the
several species differ much in appearance, whilst the females are almost
indistinguishable; in other genera the reverse occurs. H. Muller believes
(p. 82) that the colours gained by one sex through sexual selection have
often been transferred in a variable degree to the other sex, just as the
pollen-collecting apparatus of the female has often been transferred to the
male, to whom it is absolutely useless. (61. M. Perrier in his article
'la Selection sexuelle d'apres Darwin' ('Revue Scientifique,' Feb. 1873, p.
868), without apparently having reflected much on the subject, objects that
as the males of social bees are known to be produced from unfertilised ova,
they could not transmit new characters to their male offspring. This is an
extraordinary objection. A female bee fertilised by a male, which
presented some character facilitating the union of the sexes, or rendering
him more attractive to the female, would lay eggs which would produce only
females; but these young females would next year produce males; and will it
be pretended that such males would not inherit the characters of their male
grandfathers? To take a case with ordinary animals as nearly parallel as
possible: if a female of any white quadruped or bird were crossed by a
male of a black breed, and the male and female offspring were paired
together, will it be pretended that the grandchildren would not inherit a
tendency to blackness from their male grandfather? The acquirement of new
characters by the sterile worker-bees is a much more difficult case, but I
have endeavoured to shew in my 'Origin of Species,' how these sterile
beings are subjected to the power of natural selection.)
Mutilla Europaea makes a stridulating noise; and according to Goureau (62.
Quoted by Westwood, 'Modern Classification of Insects,' vol. ii. p. 214.)
both sexes have this power. He attributes the sound to the friction of the
third and preceding abdominal segments, and I find that these surfaces are
marked with very fine concentric ridges; but so is the projecting thoracic
collar into which the head articulates, and this collar, when scratched
with the point of a needle, emits the proper sound. It is rather
surprising that both sexes should have the power of stridulating, as the
male is winged and the female wingless. It is notorious that Bees express
certain emotions, as of anger, by the tone of their humming; and according
to H. Muller (p. 80), the males of some species make a peculiar singing
noise whilst pursuing the females.
ORDER, COLEOPTERA (BEETLES).
Many beetles are coloured so as to resemble the surfaces which they
habitually frequent, and they thus escape detection by their enemies.
Other species, for instance diamond-beetles, are ornamented with splendid
colours, which are often arranged in stripes, spots, crosses, and other
elegant patterns. Such colours can hardly serve directly as a protection,
except in the case of certain flower-feeding species; but they may serve as
a warning or means of recognition, on the same principle as the
phosphorescence of the glow-worm. As with beetles the colours of the two
sexes are generally alike, we have no evidence that they have been gained
through sexual selection; but this is at least possible, for they have been
developed in one sex and then transferred to the other; and this view is
even in some degree probable in those groups which possess other well-
marked secondary sexual characters. Blind beetles, which cannot of course
behold each other's beauty, never, as I hear from Mr. Waterhouse, jun.,
exhibit bright colours, though they often have polished coats; but the
explanation of their obscurity may be that they generally inhabit caves and
other obscure stations.
Some Longicorns, especially certain Prionidae, offer an exception to the
rule that the sexes of beetles do not differ in colour. Most of these
insects are large and splendidly coloured. The males in the genus Pyrodes
(63. Pyrodes pulcherrimus, in which the sexes differ conspicuously, has
been described by Mr. Bates in 'Transact. Ent. Soc.' 1869, p. 50. I will
specify the few other cases in which I have heard of a difference in colour
between the sexes of beetles. Kirby and Spence ('Introduct. to
Entomology,' vol. iii. p. 301) mention a Cantharis, Meloe, Rhagium, and the
Leptura testacea; the male of the latter being testaceous, with a black
thorax, and the female of a dull red all over. These two latter beetles
belong to the family of Longicorns. Messrs. R. Trimen and Waterhouse,
jun., inform me of two Lamellicorns, viz., a Peritrichia and Trichius, the
male of the latter being more obscurely coloured than the female. In
Tillus elongatus the male is black, and the female always, as it is
believed, of a dark blue colour, with a red thorax. The male, also, of
Orsodacna atra, as I hear from Mr. Walsh, is black, the female (the so-
called O. ruficollis) having a rufous thorax.), which I saw in Mr. Bates's
collection, are generally redder but rather duller than the females, the
latter being coloured of a more or less splendid golden-green. On the
other hand, in one species the male is golden-green, the female being
richly tinted with red and purple. In the genus Esmeralda the sexes differ
so greatly in colour that they have been ranked as distinct species; in one
species both are of a beautiful shining green, but the male has a red
thorax. On the whole, as far as I could judge, the females of those
Prionidae, in which the sexes differ, are coloured more richly than the
males, and this does not accord with the common rule in regard to colour,
when acquired through sexual selection.
[Fig.16. Chalcosoma atlas.
Upper figure, male (reduced);
lower figure, female (nat. size).
Fig. 17. Copris isidis.
Fig. 18. Phanaeus faunus.
Fig. 19. Dipelicus cantori.
Fig. 20. Onthophagus rangifer, enlarged.
(In Figs. 17 to 20 the left-hand figures are males.)]
A most remarkable distinction between the sexes of many beetles is
presented by the great horns which rise from the head, thorax, and clypeus
of the males; and in some few cases from the under surface of the body.
These horns, in the great family of the Lamellicorns, resemble those of
various quadrupeds, such as stags, rhinoceroses, etc., and are wonderful
both from their size and diversified shapes. Instead of describing them, I
have given figures of the males and females of some of the more remarkable
forms. (Figs. 16 to 20.) The females generally exhibit rudiments of the
horns in the form of small knobs or ridges; but some are destitute of even
the slightest rudiment. On the other hand, the horns are nearly as well
developed in the female as in the male Phanaeus lancifer; and only a little
less well developed in the females of some other species of this genus and
of Copris. I am informed by Mr. Bates that the horns do not differ in any
manner corresponding with the more important characteristic differences
between the several subdivisions of the family: thus within the same
section of the genus Onthophagus, there are species which have a single
horn, and others which have two.
In almost all cases, the horns are remarkable from their excessive
variability; so that a graduated series can be formed, from the most highly
developed males to others so degenerate that they can barely be
distinguished from the females. Mr. Walsh (64. 'Proceedings of the
Entomological Society of Philadephia,' 1864, p. 228.) found that in
Phanaeus carnifex the horns were thrice as long in some males as in others.
Mr. Bates, after examining above a hundred males of Onthophagus rangifer
(Fig. 20), thought that he had at last discovered a species in which the
horns did not vary; but further research proved the contrary.
The extraordinary size of the horns, and their widely different structure
in closely-allied forms, indicate that they have been formed for some
purpose; but their excessive variability in the males of the same species
leads to the inference that this purpose cannot be of a definite nature.
The horns do not shew marks of friction, as if used for any ordinary work.
Some authors suppose (65. Kirby and Spence, 'Introduction to Entomology,'
vol. iii. P. 300.) that as the males wander about much more than the
females, they require horns as a defence against their enemies; but as the
horns are often blunt, they do not seem well adapted for defence. The most
obvious conjecture is that they are used by the males for fighting
together; but the males have never been observed to fight; nor could Mr.
Bates, after a careful examination of numerous species, find any sufficient
evidence, in their mutilated or broken condition, of their having been thus
used. If the males had been habitual fighters, the size of their bodies
would probably have been increased through sexual selection, so as to have
exceeded that of the females; but Mr. Bates, after comparing the two sexes
in above a hundred species of the Copridae, did not find any marked
difference in this respect amongst well-developed individuals. In Lethrus,
moreover, a beetle belonging to the same great division of the
Lamellicorns, the males are known to fight, but are not provided with
horns, though their mandibles are much larger than those of the female.
The conclusion that the horns have been acquired as ornaments is that which
best agrees with the fact of their having been so immensely, yet not
fixedly, developed,--as shewn by their extreme variability in the same
species, and by their extreme diversity in closely-allied species. This
view will at first appear extremely improbable; but we shall hereafter find
with many animals standing much higher in the scale, namely fishes,
amphibians, reptiles and birds, that various kinds of crests, knobs, horns
and combs have been developed apparently for this sole purpose.
[Fig.21. Onitis furcifer, male viewed from beneath.
Fig.22. Onitis furcifer.
Left-hand figure, male, viewed laterally.
Right-hand figure, female.
a. Rudiment of cephalic horn.
b. Trace of thoracic horn or crest.]
The males of Onitis furcifer (Fig. 21), and of some other species of the
genus, are furnished with singular projections on their anterior femora,
and with a great fork or pair of horns on the lower surface of the thorax.
Judging from other insects, these may aid the male in clinging to the
female. Although the males have not even a trace of a horn on the upper
surface of the body, yet the females plainly exhibit a rudiment of a single
horn on the head (Fig. 22, a), and of a crest (b) on the thorax. That the
slight thoracic crest in the female is a rudiment of a projection proper to
the male, though entirely absent in the male of this particular species, is
clear: for the female of Bubas bison (a genus which comes next to Onitis)
has a similar slight crest on the thorax, and the male bears a great
projection in the same situation. So, again, there can hardly be a doubt
that the little point (a) on the head of the female Onitis furcifer, as
well as on the head of the females of two or three allied species, is a
rudimentary representative of the cephalic horn, which is common to the
males of so many Lamellicorn beetles, as in Phanaeus (Fig. 18).
The old belief that rudiments have been created to complete the scheme of
nature is here so far from holding good, that we have a complete inversion
of the ordinary state of things in the family. We may reasonably suspect
that the males originally bore horns and transferred them to the females in
a rudimentary condition, as in so many other Lamellicorns. Why the males
subsequently lost their horns, we know not; but this may have been caused
through the principle of compensation, owing to the development of the
large horns and projections on the lower surface; and as these are confined
to the males, the rudiments of the upper horns on the females would not
have been thus obliterated.
[Fig. 23. Bledius taurus, magnified.
Left-hand figure, male;
right-hand figure, female.]
The cases hitherto given refer to the Lamellicorns, but the males of some
few other beetles, belonging to two widely distinct groups, namely, the
Curculionidae and Staphylinidae, are furnished with horns--in the former on
the lower surface of the body (66. Kirby and Spence, 'Introduction to
Entomology,' vol. iii. p. 329.), in the latter on the upper surface of the
head and thorax. In the Staphylinidae, the horns of the males are
extraordinarily variable in the same species, just as we have seen with the
Lamellicorns. In Siagonium we have a case of dimorphism, for the males can
be divided into two sets, differing greatly in the size of their bodies and
in the development of their horns, without intermediate gradations. In a
species of Bledius (Fig. 23), also belonging to the Staphylinidae,
Professor Westwood states that, "male specimens can be found in the same
locality in which the central horn of the thorax is very large, but the
horns of the head quite rudimental; and others, in which the thoracic horn
is much shorter, whilst the protuberances on the head are long." (67.
'Modern Classification of Insects,' vol. i. p. 172: Siagonium, p. 172. In
the British Museum I noticed one male specimen of Siagonium in an
intermediate condition, so that the dimorphism is not strict.) Here we
apparently have a case of compensation, which throws light on that just
given, of the supposed loss of the upper horns by the males of Onitis.
LAW OF BATTLE.
Some male beetles, which seem ill-fitted for fighting, nevertheless engage
in conflicts for the possession of the females. Mr. Wallace (68. 'The
Malay Archipelago,' vol. ii. 1869, p. 276. Riley, Sixth 'Report on Insects
of Missouri,' 1874, p. 115.) saw two males of Leptorhynchus angustatus, a
linear beetle with a much elongated rostrum, "fighting for a female, who
stood close by busy at her boring. They pushed at each other with their
rostra, and clawed and thumped, apparently in the greatest rage." The
smaller male, however, "soon ran away, acknowledging himself vanquished."
In some few cases male beetles are well adapted for fighting, by possessing
great toothed mandibles, much larger than those of the females. This is
the case with the common stag-beetle (Lucanus cervus), the males of which
emerge from the pupal state about a week before the other sex, so that
several may often be seen pursuing the same female. At this season they
engage in fierce conflicts. When Mr. A.H. Davis (69. 'Entomological
Magazine,' vol. i. 1833, p. 82. See also on the conflicts of this species,
Kirby and Spence, ibid. vol. iii. p. 314; and Westwood, ibid. vol. i. p.
187.) enclosed two males with one female in a box, the larger male severely
pinched the smaller one, until he resigned his pretensions. A friend
informs me that when a boy he often put the males together to see them
fight, and he noticed that they were much bolder and fiercer than the
females, as with the higher animals. The males would seize hold of his
finger, if held in front of them, but not so the females, although they
have stronger jaws. The males of many of the Lucanidae, as well as of the
above-mentioned Leptorhynchus, are larger and more powerful insects than
the females. The two sexes of Lethrus cephalotes (one of the Lamellicorns)
inhabit the same burrow; and the male has larger mandibles than the female.
If, during the breeding-season, a strange male attempts to enter the
burrow, he is attacked; the female does not remain passive, but closes the
mouth of the burrow, and encourages her mate by continually pushing him on
from behind; and the battle lasts until the aggressor is killed or runs
away. (70. Quoted from Fischer, in 'Dict. Class. d'Hist. Nat.' tom. x. p.
324.) The two sexes of another Lamellicorn beetle, the Ateuchus
cicatricosus, live in pairs, and seem much attached to each other; the male
excites the females to roll the balls of dung in which the ova are
deposited; and if she is removed, he becomes much agitated. If the male is
removed the female ceases all work, and as M. Brulerie believes, would
remain on the same spot until she died. (71. 'Ann. Soc. Entomolog.
France,' 1866, as quoted in 'Journal of Travel,' by A. Murray, 1868, p.
135.)
[Fig. 24. Chiasognathus Grantii, reduced.
Upper figure, male;
lower figure, female.]
The great mandibles of the male Lucanidae are extremely variable both in
size and structure, and in this respect resemble the horns on the head and
thorax of many male Lamellicorns and Staphylinidae. A perfect series can
be formed from the best-provided to the worst-provided or degenerate males.
Although the mandibles of the common stag-beetle, and probably of many
other species, are used as efficient weapons for fighting, it is doubtful
whether their great size can thus be accounted for. We have seen that they
are used by the Lucanus elaphus of N. America for seizing the female. As
they are so conspicuous and so elegantly branched, and as owing to their
great length they are not well adapted for pinching, the suspicion has
crossed my mind that they may in addition serve as an ornament, like the
horns on the head and thorax of the various species above described. The
male Chiasognathus grantii of S. Chile--a splendid beetle belonging to the
same family--has enormously developed mandibles (Fig. 24); he is bold and
pugnacious; when threatened he faces round, opens his great jaws, and at
the same time stridulates loudly. But the mandibles were not strong enough
to pinch my finger so as to cause actual pain.
Sexual selection, which implies the possession of considerable perceptive
powers and of strong passions, seems to have been more effective with the
Lamellicorns than with any other family of beetles. With some species the
males are provided with weapons for fighting; some live in pairs and shew
mutual affection; many have the power of stridulating when excited; many
are furnished with the most extraordinary horns, apparently for the sake of
ornament; and some, which are diurnal in their habits, are gorgeously
coloured. Lastly, several of the largest beetles in the world belong to
this family, which was placed by Linnaeus and Fabricius as the head of the
Order. (72. Westwood, 'Modern Classification,' vol. i. p. 184.)
STRIDULATING ORGANS.
Beetles belonging to many and widely distinct families possess these
organs. The sound thus produced can sometimes be heard at the distance of
several feet or even yards (73. Wollaston, 'On Certain Musical
Curculionidae,' 'Annals and Mag. of Nat. Hist.' vol. vi. 1860, p. 14.), but
it is not comparable with that made by the Orthoptera. The rasp generally
consists of a narrow, slightly-raised surface, crossed by very fine,
parallel ribs, sometimes so fine as to cause iridescent colours, and having
a very elegant appearance under the microscope. In some cases, as with
Typhoeus, minute, bristly or scale-like prominences, with which the whole
surrounding surface is covered in approximately parallel lines, could be
traced passing into the ribs of the rasp. The transition takes place by
their becoming confluent and straight, and at the same time more prominent
and smooth. A hard ridge on an adjoining part of the body serves as the
scraper for the rasp, but this scraper in some cases has been specially
modified for the purpose. It is rapidly moved across the rasp, or
conversely the rasp across the scraper.
[Fig.25. Necrophorus (from Landois).
r. The two rasps.
Left-hand figure, part of the rasp highly magnified.]
These organs are situated in widely different positions. In the carrion-
beetles (Necrophorus) two parallel rasps (r, Fig. 25) stand on the dorsal
surface of the fifth abdominal segment, each rasp (74. Landois,
'Zeitschrift fur wissenschaft Zoolog.' B. xvii. 1867, s. 127.) consisting
of 126 to 140 fine ribs. These ribs are scraped against the posterior
margins of the elytra, a small portion of which projects beyond the general
outline. In many Crioceridae, and in Clythra 4-punctata (one of the
Chrysomelidae), and in some Tenebrionidae, etc. (75. I am greatly indebted
to Mr. G.R. Crotch for having sent me many prepared specimens of various
beetles belonging to these three families and to others, as well as for
valuable information. He believes that the power of stridulation in the
Clythra has not been previously observed. I am also much indebted to Mr.
E.W. Janson, for information and specimens. I may add that my son, Mr. F.
Darwin, finds that Dermestes murinus stridulates, but he searched in vain
for the apparatus. Scolytus has lately been described by Dr. Chapman as a
stridulator, in the 'Entomologist's Monthly Magazine,' vol. vi. p. 130.),
the rasp is seated on the dorsal apex of the abdomen, on the pygidium or
pro-pygidium, and is scraped in the same manner by the elytra. In
Heterocerus, which belongs to another family, the rasps are placed on the
sides of the first abdominal segment, and are scraped by ridges on the
femora. (76. Schiodte, translated, in 'Annals and Magazine of Natural
History,' vol. xx. 1867, p. 37.) In certain Curculionidae and Carabidae
(77. Westring has described (Kroyer, 'Naturhist. Tidskrift,' B. ii. 1848-
49, p. 334) the stridulating organs in these two, as well as in other
families. In the Carabidae I have examined Elaphrus uliginosus and
Blethisa multipunctata, sent to me by Mr. Crotch. In Blethisa the
transverse ridges on the furrowed border of the abdominal segment do not,
as far as I could judge, come into play in scraping the rasps on the
elytra.), the parts are completely reversed in position, for the rasps are
seated on the inferior surface of the elytra, near their apices, or along
their outer margins, and the edges of the abdominal segments serve as the
scrapers. In Pelobius Hermanni (one of Dytiscidae or water-beetles) a
strong ridge runs parallel and near to the sutural margin of the elytra,
and is crossed by ribs, coarse in the middle part, but becoming gradually
finer at both ends, especially at the upper end; when this insect is held
under water or in the air, a stridulating noise is produced by the extreme
horny margin of the abdomen being scraped against the rasps. In a great
number of long-horned beetles (Longicornia) the organs are situated quite
otherwise, the rasp being on the meso-thorax, which is rubbed against the
pro-thorax; Landois counted 238 very fine ribs on the rasp of Cerambyx
heros.
[Fig.26. Hind-leg of Geotrupes stercorarius (from Landois).
r. Rasp. c. Coxa. f. Femur. t. Tibia. tr. Tarsi.]
Many Lamellicorns have the power of stridulating, and the organs differ
greatly in position. Some species stridulate very loudly, so that when Mr.
F. Smith caught a Trox sabulosus, a gamekeeper, who stood by, thought he
had caught a mouse; but I failed to discover the proper organs in this
beetle. In Geotrupes and Typhoeus, a narrow ridge runs obliquely across
(r, Fig. 26) the coxa of each hind-leg (having in G. stercorarius 84 ribs),
which is scraped by a specially projecting part of one of the abdominal
segments. In the nearly allied Copris lunaris, an excessively narrow fine
rasp runs along the sutural margin of the elytra, with another short rasp
near the basal outer margin; but in some other Coprini the rasp is seated,
according to Leconte (78. I am indebted to Mr. Walsh, of Illinois, for
having sent me extracts from Leconte's 'Introduction to Entomology,' pp.
101, 143.), on the dorsal surface of the abdomen. In Oryctes it is seated
on the pro-pygidium; and, according to the same entomologist, in some other
Dynastini, on the under surface of the elytra. Lastly, Westring states
that in Omaloplia brunnea the rasp is placed on the pro-sternum, and the
scraper on the meta-sternum, the parts thus occupying the under surface of
the body, instead of the upper surface as in the Longicorns.
We thus see that in the different coleopterous families the stridulating
organs are wonderfully diversified in position, but not much in structure.
Within the same family some species are provided with these organs, and
others are destitute of them. This diversity is intelligible, if we
suppose that originally various beetles made a shuffling or hissing noise
by the rubbing together of any hard and rough parts of their bodies, which
happened to be in contact; and that from the noise thus produced being in
some way useful, the rough surfaces were gradually developed into regular
stridulating organs. Some beetles as they move, now produce, either
intentionally or unintentionally, a shuffling noise, without possessing any
proper organs for the purpose. Mr. Wallace informs me that the Euchirus
longimanus (a Lamellicorn, with the anterior legs wonderfully elongated in
the male) "makes, whilst moving, a low hissing sound by the protrusion and
contraction of the abdomen; and when seized it produces a grating sound by
rubbing its hind-legs against the edges of the elytra." The hissing sound
is clearly due to a narrow rasp running along the sutural margin of each
elytron; and I could likewise make the grating sound by rubbing the
shagreened surface of the femur against the granulated margin of the
corresponding elytron; but I could not here detect any proper rasp; nor is
it likely that I could have overlooked it in so large an insect. After
examining Cychrus, and reading what Westring has written about this beetle,
it seems very doubtful whether it possesses any true rasp, though it has
the power of emitting a sound.
From the analogy of the Orthoptera and Homoptera, I expected to find the
stridulating organs in the Coleoptera differing according to sex; but
Landois, who has carefully examined several species, observed no such
difference; nor did Westring; nor did Mr. G.R. Crotch in preparing the many
specimens which he had the kindness to send me. Any difference in these
organs, if slight, would, however, be difficult to detect, on account of
their great variability. Thus, in the first pair of specimens of
Necrophorus humator and of Pelobius which I examined, the rasp was
considerably larger in the male than in the female; but not so with
succeeding specimens. In Geotrupes stercorarius the rasp appeared to me
thicker, opaquer, and more prominent in three males than in the same number
of females; in order, therefore, to discover whether the sexes differed in
their power of stridulating, my son, Mr. F. Darwin, collected fifty-seven
living specimens, which he separated into two lots, according as they made
a greater or lesser noise, when held in the same manner. He then examined
all these specimens, and found that the males were very nearly in the same
proportion to the females in both the lots. Mr. F. Smith has kept alive
numerous specimens of Monoynchus pseudacori (Curculionidae), and is
convinced that both sexes stridulate, and apparently in an equal degree.
Nevertheless, the power of stridulating is certainly a sexual character in
some few Coleoptera. Mr. Crotch discovered that the males alone of two
species of Heliopathes (Tenebrionidae) possess stridulating organs. I
examined five males of H. gibbus, and in all these there was a well-
developed rasp, partially divided into two, on the dorsal surface of the
terminal abdominal segment; whilst in the same number of females there was
not even a rudiment of the rasp, the membrane of this segment being
transparent, and much thinner than in the male. In H. cribratostriatus the
male has a similar rasp, excepting that it is not partially divided into
two portions, and the female is completely destitute of this organ; the
male in addition has on the apical margins of the elytra, on each side of
the suture, three or four short longitudinal ridges, which are crossed by
extremely fine ribs, parallel to and resembling those on the abdominal
rasp; whether these ridges serve as an independent rasp, or as a scraper
for the abdominal rasp, I could not decide: the female exhibits no trace
of this latter structure.
Again, in three species of the Lamellicorn genus Oryctes, we have a nearly
parallel case. In the females of O. gryphus and nasicornis the ribs on the
rasp of the pro-pygidium are less continuous and less distinct than in the
males; but the chief difference is that the whole upper surface of this
segment, when held in the proper light, is seen to be clothed with hairs,
which are absent or are represented by excessively fine down in the males.
It should be noticed that in all Coleoptera the effective part of the rasp
is destitute of hairs. In O. senegalensis the difference between the sexes
is more strongly marked, and this is best seen when the proper abdominal
segment is cleaned and viewed as a transparent object. In the female the
whole surface is covered with little separate crests, bearing spines;
whilst in the male these crests in proceeding towards the apex, become more
and more confluent, regular, and naked; so that three-fourths of the
segment is covered with extremely fine parallel ribs, which are quite
absent in the female. In the females, however, of all three species of
Oryctes, a slight grating or stridulating sound is produced, when the
abdomen of a softened specimen is pushed backwards and forwards.
In the case of the Heliopathes and Oryctes there can hardly be a doubt that
the males stridulate in order to call or to excite the females; but with
most beetles the stridulation apparently serves both sexes as a mutual
call. Beetles stridulate under various emotions, in the same manner as
birds use their voices for many purposes besides singing to their mates.
The great Chiasognathus stridulates in anger or defiance; many species do
the same from distress or fear, if held so that they cannot escape; by
striking the hollow stems of trees in the Canary Islands, Messrs. Wollaston
and Crotch were able to discover the presence of beetles belonging to the
genus Acalles by their stridulation. Lastly, the male Ateuchus stridulates
to encourage the female in her work, and from distress when she is removed.
(79. M. P. de la Brulerie, as quoted in 'Journal of Travel,' A. Murray,
vol. i. 1868, p. 135.) Some naturalists believe that beetles make this
noise to frighten away their enemies; but I cannot think that a quadruped
or bird, able to devour a large beetle, would be frightened by so slight a
sound. The belief that the stridulation serves as a sexual call is
supported by the fact that death-ticks (Anobium tessellatum) are well known
to answer each other's ticking, and, as I have myself observed, a tapping
noise artificially made. Mr. Doubleday also informs me that he has
sometimes observed a female ticking (80. According to Mr. Doubleday, "the
noise is produced by the insect raising itself on its legs as high as it
can, and then striking its thorax five or six times, in rapid succession,
against the substance upon which it is sitting." For references on this
subject see Landois, 'Zeitschrift fur wissen. Zoolog.' B. xvii. s. 131.
Olivier says (as quoted by Kirby and Spence, 'Introduction to Entomology,'
vol. ii. p. 395) that the female of Pimelia striata produces a rather loud
sound by striking her abdomen against any hard substance, "and that the
male, obedient to this call, soon attends her, and they pair."), and in an
hour or two afterwards has found her united with a male, and on one
occasion surrounded by several males. Finally, it is probable that the two
sexes of many kinds of beetles were at first enabled to find each other by
the slight shuffling noise produced by the rubbing together of the
adjoining hard parts of their bodies; and that as those males or females
which made the greatest noise succeeded best in finding partners,
rugosities on various parts of their bodies were gradually developed by
means of sexual selection into true stridulating organs.
CHAPTER XI.
INSECTS, continued.
ORDER LEPIDOPTERA. (BUTTERFLIES AND MOTHS.)
Courtship of butterflies--Battles--Ticking noise--Colours common to both
sexes, or more brilliant in the males--Examples--Not due to the direct
action of the conditions of life--Colours adapted for protection--Colours
of moths--Display--Perceptive powers of the Lepidoptera--Variability--
Causes of the difference in colour between the males and females--Mimicry,
female butterflies more brilliantly coloured than the males--Bright colours
of caterpillars--Summary and concluding remarks on the secondary sexual
characters of insects--Birds and insects compared.
In this great Order the most interesting points for us are the differences
in colour between the sexes of the same species, and between the distinct
species of the same genus. Nearly the whole of the following chapter will
be devoted to this subject; but I will first make a few remarks on one or
two other points. Several males may often be seen pursuing and crowding
round the same female. Their courtship appears to be a prolonged affair,
for I have frequently watched one or more males pirouetting round a female
until I was tired, without seeing the end of the courtship. Mr. A.G.
Butler also informs me that he has several times watched a male courting a
female for a full quarter of an hour; but she pertinaciously refused him,
and at last settled on the ground and closed her wings, so as to escape
from his addresses.
Although butterflies are weak and fragile creatures, they are pugnacious,
and an emperor butterfly (1. Apatura Iris: 'The Entomologist's Weekly
Intelligence,' 1859, p. 139. For the Bornean Butterflies, see C.
Collingwood, 'Rambles of a Naturalist,' 1868, p. 183.) has been captured
with the tips of its wings broken from a conflict with another male. Mr.
Collingwood, in speaking of the frequent battles between the butterflies of
Borneo, says, "They whirl round each other with the greatest rapidity, and
appear to be incited by the greatest ferocity."
The Ageronia feronia makes a noise like that produced by a toothed wheel
passing under a spring catch, and which can be heard at the distance of
several yards: I noticed this sound at Rio de Janeiro, only when two of
these butterflies were chasing each other in an irregular course, so that
it is probably made during the courtship of the sexes. (2. See my
'Journal of Researches,' 1845, p. 33. Mr. Doubleday has detected ('Proc.
Ent. Soc.' March 3, 1845, p. 123) a peculiar membranous sac at the base of
the front wings, which is probably connected with the production of the
sound. For the case of Thecophora, see 'Zoological Record,' 1869, p. 401.
For Mr. Buchanan White's observations, the Scottish Naturalist, July 1872,
p. 214.)
Some moths also produce sounds; for instance, the males Theocophora fovea.
On two occasions Mr. F. Buchanan White (3. 'The Scottish Naturalist,' July
1872, p. 213.) heard a sharp quick noise made by the male of Hylophila
prasinana, and which he believes to be produced, as in Cicada, by an
elastic membrane, furnished with a muscle. He quotes, also, Guenee, that
Setina produces a sound like the ticking of a watch, apparently by the aid
of "two large tympaniform vesicles, situated in the pectoral region"; and
these "are much more developed in the male than in the female." Hence the
sound-producing organs in the Lepidoptera appear to stand in some relation
with the sexual functions. I have not alluded to the well-known noise made
by the Death's Head Sphinx, for it is generally heard soon after the moth
has emerged from its cocoon.
Giard has always observed that the musky odour, which is emitted by two
species of Sphinx moths, is peculiar to the males (4. 'Zoological Record,'
1869, p. 347.); and in the higher classes we shall meet with many instances
of the males alone being odoriferous.
Every one must have admired the extreme beauty of many butterflies and of
some moths; and it may be asked, are their colours and diversified patterns
the result of the direct action of the physical conditions to which these
insects have been exposed, without any benefit being thus derived? Or have
successive variations been accumulated and determined as a protection, or
for some unknown purpose, or that one sex may be attractive to the other?
And, again, what is the meaning of the colours being widely different in
the males and females of certain species, and alike in the two sexes of
other species of the same genus? Before attempting to answer these
questions a body of facts must be given.
With our beautiful English butterflies, the admiral, peacock, and painted
lady (Vanessae), as well as many others, the sexes are alike. This is also
the case with the magnificent Heliconidae, and most of the Danaidae in the
tropics. But in certain other tropical groups, and in some of our English
butterflies, as the purple emperor, orange-tip, etc. (Apatura Iris and
Anthocharis cardamines), the sexes differ either greatly or slightly in
colour. No language suffices to describe the splendour of the males of
some tropical species. Even within the same genus we often find species
presenting extraordinary differences between the sexes, whilst others have
their sexes closely alike. Thus in the South American genus Epicalia, Mr.
Bates, to whom I am indebted for most of the following facts, and for
looking over this whole discussion, informs me that he knows twelve
species, the two sexes of which haunt the same stations (and this is not
always the case with butterflies), and which, therefore, cannot have been
differently affected by external conditions. (5. See also Mr. Bates's
paper in 'Proc. Ent. Soc. of Philadelphia,' 1865, p. 206. Also Mr. Wallace
on the same subject, in regard to Diadema, in 'Transactions, Entomological
Society of London,' 1869, p. 278.) In nine of these twelve species the
males rank amongst the most brilliant of all butterflies, and differ so
greatly from the comparatively plain females that they were formerly placed
in distinct genera. The females of these nine species resemble each other
in their general type of coloration; and they likewise resemble both sexes
of the species in several allied genera found in various parts of the
world. Hence we may infer that these nine species, and probably all the
others of the genus, are descended from an ancestral form which was
coloured in nearly the same manner. In the tenth species the female still
retains the same general colouring, but the male resembles her, so that he
is coloured in a much less gaudy and contrasted manner than the males of
the previous species. In the eleventh and twelfth species, the females
depart from the usual type, for they are gaily decorated almost like the
males, but in a somewhat less degree. Hence in these two latter species
the bright colours of the males seem to have been transferred to the
females; whilst in the tenth species the male has either retained or
recovered the plain colours of the female, as well as of the parent-form of
the genus. The sexes in these three cases have thus been rendered nearly
alike, though in an opposite manner. In the allied genus Eubagis, both
sexes of some of the species are plain-coloured and nearly alike; whilst
with the greater number the males are decorated with beautiful metallic
tints in a diversified manner, and differ much from their females. The
females throughout the genus retain the same general style of colouring, so
that they resemble one another much more closely than they resemble their
own males.
In the genus Papilio, all the species of the Aeneas group are remarkable
for their conspicuous and strongly contrasted colours, and they illustrate
the frequent tendency to gradation in the amount of difference between the
sexes. In a few species, for instance in P. ascanius, the males and
females are alike; in others the males are either a little brighter, or
very much more superb than the females. The genus Junonia, allied to our
Vanessae, offers a nearly parallel case, for although the sexes of most of
the species resemble each other, and are destitute of rich colours, yet in
certain species, as in J. oenone, the male is rather more bright-coloured
than the female, and in a few (for instance J. andremiaja) the male is so
different from the female that he might be mistaken for an entirely
distinct species.
Another striking case was pointed out to me in the British Museum by Mr. A.
Butler, namely, one of the tropical American Theclae, in which both sexes
are nearly alike and wonderfully splendid; in another species the male is
coloured in a similarly gorgeous manner, whilst the whole upper surface of
the female is of a dull uniform brown. Our common little English blue
butterflies of the genus Lycaena, illustrate the various differences in
colour between the sexes, almost as well, though not in so striking a
manner, as the above exotic genera. In Lycaena agestis both sexes have
wings of a brown colour, bordered with small ocellated orange spots, and
are thus alike. In L. oegon the wings of the males are of a fine blue,
bordered with black, whilst those of the female are brown, with a similar
border, closely resembling the wings of L. agestis. Lastly, in L. arion
both sexes are of a blue colour and are very like, though in the female the
edges of the wings are rather duskier, with the black spots plainer; and in
a bright blue Indian species both sexes are still more alike.
I have given the foregoing details in order to shew, in the first place,
that when the sexes of butterflies differ, the male as a general rule is
the more beautiful, and departs more from the usual type of colouring of
the group to which the species belongs. Hence in most groups the females
of the several species resemble each other much more closely than do the
males. In some cases, however, to which I shall hereafter allude, the
females are coloured more splendidly than the males. In the second place,
these details have been given to bring clearly before the mind that within
the same genus, the two sexes frequently present every gradation from no
difference in colour, to so great a difference that it was long before the
two were placed by entomologists in the same genus. In the third place, we
have seen that when the sexes nearly resemble each other, this appears due
either to the male having transferred his colours to the female, or to the
male having retained, or perhaps recovered, the primordial colours of the
group. It also deserves notice that in those groups in which the sexes
differ, the females usually somewhat resemble the males, so that when the
males are beautiful to an extraordinary degree, the females almost
invariably exhibit some degree of beauty. From the many cases of gradation
in the amount of difference between the sexes, and from the prevalence of
the same general type of coloration throughout the whole of the same group,
we may conclude that the causes have generally been the same which have
determined the brilliant colouring of the males alone of some species, and
of both sexes of other species.
As so many gorgeous butterflies inhabit the tropics, it has often been
supposed that they owe their colours to the great heat and moisture of
these zones; but Mr. Bates (6. 'The Naturalist on the Amazons,' vol. i.
1863, p. 19.) has shown by the comparison of various closely-allied groups
of insects from the temperate and tropical regions, that this view cannot
be maintained; and the evidence becomes conclusive when brilliantly-
coloured males and plain-coloured females of the same species inhabit the
same district, feed on the same food, and follow exactly the same habits of
life. Even when the sexes resemble each other, we can hardly believe that
their brilliant and beautifully-arranged colours are the purposeless result
of the nature of the tissues and of the action of the surrounding
conditions.
With animals of all kinds, whenever colour has been modified for some
special purpose, this has been, as far as we can judge, either for direct
or indirect protection, or as an attraction between the sexes. With many
species of butterflies the upper surfaces of the wings are obscure; and
this in all probability leads to their escaping observation and danger.
But butterflies would be particularly liable to be attacked by their
enemies when at rest; and most kinds whilst resting raise their wings
vertically over their backs, so that the lower surface alone is exposed to
view. Hence it is this side which is often coloured so as to imitate the
objects on which these insects commonly rest. Dr. Rossler, I believe,
first noticed the similarity of the closed wings of certain Vanessae and
other butterflies to the bark of trees. Many analogous and striking facts
could be given. The most interesting one is that recorded by Mr. Wallace
(7. See the interesting article in the 'Westminster Review,' July 1867, p.
10. A woodcut of the Kallima is given by Mr. Wallace in 'Hardwicke's
Science Gossip,' September 1867, p. 196.) of a common Indian and Sumatran
butterfly (Kallima) which disappears like magic when it settles on a bush;
for it hides its head and antennae between its closed wings, which, in
form, colour and veining, cannot be distinguished from a withered leaf with
its footstalk. In some other cases the lower surfaces of the wings are
brilliantly coloured, and yet are protective; thus in Thecla rubi the wings
when closed are of an emerald green, and resemble the young leaves of the
bramble, on which in spring this butterfly may often be seen seated. It is
also remarkable that in very many species in which the sexes differ greatly
in colour on their upper surface, the lower surface is closely similar or
identical in both sexes, and serves as a protection. (8. Mr. G. Fraser,
in 'Nature,' April 1871, p. 489.)
Although the obscure tints both of the upper and under sides of many
butterflies no doubt serve to conceal them, yet we cannot extend this view
to the brilliant and conspicuous colours on the upper surface of such
species as our admiral and peacock Vanessae, our white cabbage-butterflies
(Pieris), or the great swallow-tail Papilio which haunts the open fens--for
these butterflies are thus rendered visible to every living creature. In
these species both sexes are alike; but in the common brimstone butterfly
(Gonepteryx rhamni), the male is of an intense yellow, whilst the female is
much paler; and in the orange-tip (Anthocharis cardamines) the males alone
have their wings tipped with bright orange. Both the males and females in
these cases are conspicuous, and it is not credible that their difference
in colour should stand in any relation to ordinary protection. Prof.
Weismann remarks (9. 'Einfluss der Isolirung auf die Artbildung,' 1872, p.
58.), that the female of one of the Lycaenae expands her brown wings when
she settles on the ground, and is then almost invisible; the male, on the
other hand, as if aware of the danger incurred from the bright blue of the
upper surface of his wings, rests with them closed; and this shows that the
blue colour cannot be in any way protective. Nevertheless, it is probable
that conspicuous colours are indirectly beneficial to many species, as a
warning that they are unpalatable. For in certain other cases, beauty has
been gained through the imitation of other beautiful species, which inhabit
the same district and enjoy an immunity from attack by being in some way
offensive to their enemies; but then we have to account for the beauty of
the imitated species.
As Mr. Walsh has remarked to me, the females of our orange-tip butterfly,
above referred to, and of an American species (Anth. genutia) probably shew
us the primordial colours of the parent-species of the genus; for both
sexes of four or five widely-distributed species are coloured in nearly the
same manner. As in several previous cases, we may here infer that it is
the males of Anth. cardamines and genutia which have departed from the
usual type of the genus. In the Anth. sara from California, the orange-
tips to the wings have been partially developed in the female; but they are
paler than in the male, and slightly different in some other respects. In
an allied Indian form, the Iphias glaucippe, the orange-tips are fully
developed in both sexes. In this Iphias, as pointed out to me by Mr. A.
Butler, the under surface of the wings marvellously resembles a pale-
coloured leaf; and in our English orange-tip, the under surface resembles
the flower-head of the wild parsley, on which the butterfly often rests at
night. (10. See the interesting observations by T.W. Wood, 'The Student,'
Sept. 1868, p. 81.) The same reason which compels us to believe that the
lower surfaces have here been coloured for the sake of protection, leads us
to deny that the wings have been tipped with bright orange for the same
purpose, especially when this character is confined to the males.
Most Moths rest motionless during the whole or greater part of the day with
their wings depressed; and the whole upper surface is often shaded and
coloured in an admirable manner, as Mr. Wallace has remarked, for escaping
detection. The front-wings of the Bombycidae and Noctuidae (11. Mr.
Wallace in 'Hardwicke's Science Gossip,' September 1867, p. 193.), when at
rest, generally overlap and conceal the hind-wings; so that the latter
might be brightly coloured without much risk; and they are in fact often
thus coloured. During flight, moths would often be able to escape from
their enemies; nevertheless, as the hind-wings are then fully exposed to
view, their bright colours must generally have been acquired at some little
risk. But the following fact shews how cautious we ought to be in drawing
conclusions on this head. The common Yellow Under-wings (Triphaena) often
fly about during the day or early evening, and are then conspicuous from
the colour of their hind-wings. It would naturally be thought that this
would be a source of danger; but Mr. J. Jenner Weir believes that it
actually serves them as a means of escape, for birds strike at these
brightly coloured and fragile surfaces, instead of at the body. For
instance, Mr. Weir turned into his aviary a vigorous specimen of Triphaena
pronuba, which was instantly pursued by a robin; but the bird's attention
being caught by the coloured wings, the moth was not captured until after
about fifty attempts, and small portions of the wings were repeatedly
broken off. He tried the same experiment, in the open air, with a swallow
and T. fimbria; but the large size of this moth probably interfered with
its capture. (12. See also, on this subject, Mr. Weir's paper in
'Transactions, Entomological Society,' 1869, p. 23.) We are thus reminded
of a statement made by Mr. Wallace (13. 'Westminster Review,' July 1867,
p. 16.), namely, that in the Brazilian forests and Malayan islands, many
common and highly-decorated butterflies are weak flyers, though furnished
with a broad expanse of wing; and they "are often captured with pierced and
broken wings, as if they had been seized by birds, from which they had
escaped: if the wings had been much smaller in proportion to the body, it
seems probable that the insect would more frequently have been struck or
pierced in a vital part, and thus the increased expanse of the wings may
have been indirectly beneficial."
DISPLAY.
The bright colours of many butterflies and of some moths are specially
arranged for display, so that they may be readily seen. During the night
colours are not visible, and there can be no doubt that the nocturnal
moths, taken as a body, are much less gaily decorated than butterflies, all
of which are diurnal in their habits. But the moths of certain families,
such as the Zygaenidae, several Sphingidae, Uraniidae, some Arctiidae and
Saturniidae, fly about during the day or early evening, and many of these
are extremely beautiful, being far brighter coloured than the strictly
nocturnal kinds. A few exceptional cases, however, of bright-coloured
nocturnal species have been recorded. (14. For instance, Lithosia; but
Prof. Westwood ('Modern Class. of Insects,' vol. ii. p. 390) seems
surprised at this case. On the relative colours of diurnal and nocturnal
Lepidoptera, see ibid. pp. 333 and 392; also Harris, 'Treatise on the
Insects of New England,' 1842, p. 315.)
There is evidence of another kind in regard to display. Butterflies, as
before remarked, elevate their wings when at rest, but whilst basking in
the sunshine often alternately raise and depress them, thus exposing both
surfaces to full view; and although the lower surface is often coloured in
an obscure manner as a protection, yet in many species it is as highly
decorated as the upper surface, and sometimes in a very different manner.
In some tropical species the lower surface is even more brilliantly
coloured than the upper. (15. Such differences between the upper and
lower surfaces of the wings of several species of Papilio may be seen in
the beautiful plates to Mr. Wallace's 'Memoir on the Papilionidae of the
Malayan Region,' in 'Transactions of the Linnean Society,' vol. xxv. part
i. 1865.) In the English fritillaries (Argynnis) the lower surface alone
is ornamented with shining silver. Nevertheless, as a general rule, the
upper surface, which is probably more fully exposed, is coloured more
brightly and diversely than the lower. Hence the lower surface generally
affords to entomologists the more useful character for detecting the
affinities of the various species. Fritz Muller informs me that three
species of Castnia are found near his house in S. Brazil: of two of them
the hind-wings are obscure, and are always covered by the front-wings when
these butterflies are at rest; but the third species has black hind-wings,
beautifully spotted with red and white, and these are fully expanded and
displayed whenever the butterfly rests. Other such cases could be added.
If we now turn to the enormous group of moths, which, as I hear from Mr.
Stainton, do not habitually expose the under surface of their wings to full
view, we find this side very rarely coloured with a brightness greater
than, or even equal to, that of the upper side. Some exceptions to the
rule, either real or apparent, must be noticed, as the case of Hypopyra.
(16. See Mr. Wormald on this moth: 'Proceedings of the Entomological
Society,' March 2, 1868.) Mr. Trimen informs me that in Guenee's great
work, three moths are figured, in which the under surface is much the more
brilliant. For instance, in the Australian Gastrophora the upper surface
of the fore-wing is pale greyish-ochreous, while the lower surface is
magnificently ornamented by an ocellus of cobalt-blue, placed in the midst
of a black mark, surrounded by orange-yellow, and this by bluish-white.
But the habits of these three moths are unknown; so that no explanation can
be given of their unusual style of colouring. Mr. Trimen also informs me
that the lower surface of the wings in certain other Geometrae (17. See
also an account of the S. American genus Erateina (one of the Geometrae) in
'Transactions, Ent. Soc.' new series, vol. v. pl. xv. and xvi.) and
quadrifid Noctuae are either more variegated or more brightly-coloured than
the upper surface; but some of these species have the habit of "holding
their wings quite erect over their backs, retaining them in this position
for a considerable time," and thus exposing the under surface to view.
Other species, when settled on the ground or herbage, now and then suddenly
and slightly lift up their wings. Hence the lower surface of the wings
being brighter than the upper surface in certain moths is not so anomalous
as it at first appears. The Saturniidae include some of the most beautiful
of all moths, their wings being decorated, as in our British Emperor moth,
with fine ocelli; and Mr. T.W. Wood (18. 'Proc Ent. Soc. of London,' July
6, 1868, p. xxvii.) observes that they resemble butterflies in some of
their movements; "for instance, in the gentle waving up and down of the
wings as if for display, which is more characteristic of diurnal than of
nocturnal Lepidoptera."
It is a singular fact that no British moths which are brilliantly coloured,
and, as far as I can discover, hardly any foreign species, differ much in
colour according to sex; though this is the case with many brilliant
butterflies. The male, however, of one American moth, the Saturnia Io, is
described as having its fore-wings deep yellow, curiously marked with
purplish-red spots; whilst the wings of the female are purple-brown, marked
with grey lines. (19. Harris, 'Treatise,' etc., edited by Flint, 1862, p.
395.) The British moths which differ sexually in colour are all brown, or
of various dull yellow tints, or nearly white. In several species the
males are much darker than the females (20. For instance, I observe in my
son's cabinet that the males are darker than the females in the Lasiocampa
quercus, Odonestis potatoria, Hypogymna dispar, Dasychira pudibunda, and
Cycnia mendica. In this latter species the difference in colour between
the two sexes is strongly marked; and Mr. Wallace informs me that we here
have, as he believes, an instance of protective mimicry confined to one
sex, as will hereafter be more fully explained. The white female of the
Cycnia resembles the very common Spilosoma menthrasti, both sexes of which
are white; and Mr. Stainton observed that this latter moth was rejected
with utter disgust by a whole brood of young turkeys, which were fond of
eating other moths; so that if the Cycnia was commonly mistaken by British
birds for the Spilosoma, it would escape being devoured, and its white
deceptive colour would thus be highly beneficial.), and these belong to
groups which generally fly about during the afternoon. On the other hand,
in many genera, as Mr. Stainton informs me, the males have the hind-wings
whiter than those of the female--of which fact Agrotis exclamationis offers
a good instance. In the Ghost Moth (Hepialus humuli) the difference is
more strongly marked; the males being white, and the females yellow with
darker markings. (21. It is remarkable, that in the Shetland Islands the
male of this moth, instead of differing widely from the female, frequently
resembles her closely in colour (see Mr. MacLachlan, 'Transactions,
Entomological Society,' vol. ii. 1866, p. 459). Mr. G. Fraser suggests
('Nature,' April 1871, p. 489) that at the season of the year when the
ghost-moth appears in these northern islands, the whiteness of the males
would not be needed to render them visible to the females in the twilight
night.) It is probable that in these cases the males are thus rendered
more conspicuous, and more easily seen by the females whilst flying about
in the dusk.
From the several foregoing facts it is impossible to admit that the
brilliant colours of butterflies, and of some few moths, have commonly been
acquired for the sake of protection. We have seen that their colours and
elegant patterns are arranged and exhibited as if for display. Hence I am
led to believe that the females prefer or are most excited by the more
brilliant males; for on any other supposition the males would, as far as we
can see, be ornamented to no purpose. We know that ants and certain
Lamellicorn beetles are capable of feeling an attachment for each other,
and that ants recognise their fellows after an interval of several months.
Hence there is no abstract improbability in the Lepidoptera, which probably
stand nearly or quite as high in the scale as these insects, having
sufficient mental capacity to admire bright colours. They certainly
discover flowers by colour. The Humming-bird Sphinx may often be seen to
swoop down from a distance on a bunch of flowers in the midst of green
foliage; and I have been assured by two persons abroad, that these moths
repeatedly visit flowers painted on the walls of a room, and vainly
endeavour to insert their proboscis into them. Fritz Muller informs me
that several kinds of butterflies in S. Brazil shew an unmistakable
preference for certain colours over others: he observed that they very
often visited the brilliant red flowers of five or six genera of plants,
but never the white or yellow flowering species of the same and other
genera, growing in the same garden; and I have received other accounts to
the same effect. As I hear from Mr. Doubleday, the common white butterfly
often flies down to a bit of paper on the ground, no doubt mistaking it for
one of its own species. Mr. Collingwood (22. 'Rambles of a Naturalist in
the Chinese Seas,' 1868, p. 182.) in speaking of the difficulty in
collecting certain butterflies in the Malay Archipelago, states that "a
dead specimen pinned upon a conspicuous twig will often arrest an insect of
the same species in its headlong flight, and bring it down within easy
reach of the net, especially if it be of the opposite sex."
The courtship of butterflies is, as before remarked, a prolonged affair.
The males sometimes fight together in rivalry; and many may be seen
pursuing or crowding round the same female. Unless, then, the females
prefer one male to another, the pairing must be left to mere chance, and
this does not appear probable. If, on the other band, the females
habitually, or even occasionally, prefer the more beautiful males, the
colours of the latter will have been rendered brighter by degrees, and will
have been transmitted to both sexes or to one sex, according to the law of
inheritance which has prevailed. The process of sexual selection will have
been much facilitated, if the conclusion can be trusted, arrived at from
various kinds of evidence in the supplement to the ninth chapter; namely,
that the males of many Lepidoptera, at least in the imago state, greatly
exceed the females in number.
Some facts, however, are opposed to the belief that female butterflies
prefer the more beautiful males; thus, as I have been assured by several
collectors, fresh females may frequently be seen paired with battered,
faded, or dingy males; but this is a circumstance which could hardly fail
often to follow from the males emerging from their cocoons earlier than the
females. With moths of the family of the Bombycidae, the sexes pair
immediately after assuming the imago state; for they cannot feed, owing to
the rudimentary condition of their mouths. The females, as several
entomologists have remarked to me, lie in an almost torpid state, and
appear not to evince the least choice in regard to their partners. This is
the case with the common silk-moth (B. mori), as I have been told by some
continental and English breeders. Dr. Wallace, who has had great
experience in breeding Bombyx cynthia, is convinced that the females evince
no choice or preference. He has kept above 300 of these moths together,
and has often found the most vigorous females mated with stunted males.
The reverse appears to occur seldom; for, as he believes, the more vigorous
males pass over the weakly females, and are attracted by those endowed with
most vitality. Nevertheless, the Bombycidae, though obscurely-coloured,
are often beautiful to our eyes from their elegant and mottled shades.
I have as yet only referred to the species in which the males are brighter
coloured than the females, and I have attributed their beauty to the
females for many generations having chosen and paired with the more
attractive males. But converse cases occur, though rarely, in which the
females are more brilliant than the males; and here, as I believe, the
males have selected the more beautiful females, and have thus slowly added
to their beauty. We do not know why in various classes of animals the
males of some few species have selected the more beautiful females instead
of having gladly accepted any female, as seems to be the general rule in
the animal kingdom: but if, contrary to what generally occurs with the
Lepidoptera, the females were much more numerous than the males, the latter
would be likely to pick out the more beautiful females. Mr. Butler shewed
me several species of Callidryas in the British Museum, in some of which
the females equalled, and in others greatly surpassed the males in beauty;
for the females alone have the borders of their wings suffused with crimson
and orange, and spotted with black. The plainer males of these species
closely resemble each other, shewing that here the females have been
modified; whereas in those cases, where the males are the more ornate, it
is these which have been modified, the females remaining closely alike.
In England we have some analogous cases, though not so marked. The females
alone of two species of Thecla have a bright-purple or orange patch on
their fore-wings. In Hipparchia the sexes do not differ much; but it is
the female of H. janira which has a conspicuous light-brown patch on her
wings; and the females of some of the other species are brighter coloured
than their males. Again, the females of Colias edusa and hyale have
"orange or yellow spots on the black marginal border, represented in the
males only by thin streaks"; and in Pieris it is the females which "are
ornamented with black spots on the fore-wings, and these are only partially
present in the males." Now the males of many butterflies are known to
support the females during their marriage flight; but in the species just
named it is the females which support the males; so that the part which the
two sexes play is reversed, as is their relative beauty. Throughout the
animal kingdom the males commonly take the more active share in wooing, and
their beauty seems to have been increased by the females having accepted
the more attractive individuals; but with these butterflies, the females
take the more active part in the final marriage ceremony, so that we may
suppose that they likewise do so in the wooing; and in this case we can
understand how it is that they have been rendered the more beautiful. Mr.
Meldola, from whom the foregoing statements have been taken, says in
conclusion: "Though I am not convinced of the action of sexual selection
in producing the colours of insects, it cannot be denied that these facts
are strikingly corroborative of Mr. Darwin's views." (23. 'Nature,' April
27, 1871, p. 508. Mr. Meldola quotes Donzel, in 'Soc. Ent. de France,'
1837, p. 77, on the flight of butterflies whilst pairing. See also Mr. G.
Fraser, in 'Nature,' April 20, 1871, p. 489, on the sexual differences of
several British butterflies.)
As sexual selection primarily depends on variability, a few words must be
added on this subject. In respect to colour there is no difficulty, for
any number of highly variable Lepidoptera could be named. One good
instance will suffice. Mr. Bates shewed me a whole series of specimens of
Papilio sesostris and P. childrenae; in the latter the males varied much in
the extent of the beautifully enamelled green patch on the fore-wings, and
in the size of the white mark, and of the splendid crimson stripe on the
hind-wings; so that there was a great contrast amongst the males between
the most and the least gaudy. The male of Papilio sesostris is much less
beautiful than of P. childrenae; and it likewise varies a little in the
size of the green patch on the fore-wings, and in the occasional appearance
of the small crimson stripe on the hind-wings, borrowed, as it would seem,
from its own female; for the females of this and of many other species in
the Aeneas group possess this crimson stripe. Hence between the brightest
specimens of P. sesostris and the dullest of P. childrenae, there was but a
small interval; and it was evident that as far as mere variability is
concerned, there would be no difficulty in permanently increasing the
beauty of either species by means of selection. The variability is here
almost confined to the male sex; but Mr. Wallace and Mr. Bates have shewn
(24. Wallace on the Papilionidae of the Malayan Region, in 'Transact.
Linn. Soc.' vol. xxv. 1865, pp. 8, 36. A striking case of a rare variety,
strictly intermediate between two other well-marked female varieties, is
given by Mr. Wallace. See also Mr. Bates, in 'Proc. Entomolog. Soc.' Nov.
19, 1866, p. xl.) that the females of some species are extremely variable,
the males being nearly constant. In a future chapter I shall have occasion
to shew that the beautiful eye-like spots, or ocelli, found on the wings of
many Lepidoptera, are eminently variable. I may here add that these ocelli
offer a difficulty on the theory of sexual selection; for though appearing
to us so ornamental, they are never present in one sex and absent in the
other, nor do they ever differ much in the two sexes. (25. Mr. Bates was
so kind as to lay this subject before the Entomological Society, and I have
received answers to this effect from several entomologists.) This fact is
at present inexplicable; but if it should hereafter be found that the
formation of an ocellus is due to some change in the tissues of the wings,
for instance, occurring at a very early period of development, we might
expect, from what we know of the laws of inheritance, that it would be
transmitted to both sexes, though arising and perfected in one sex alone.
On the whole, although many serious objections may be urged, it seems
probable that most of the brilliantly-coloured species of Lepidoptera owe
their colours to sexual selection, excepting in certain cases, presently to
be mentioned, in which conspicuous colours have been gained through mimicry
as a protection. From the ardour of the male throughout the animal
kingdom, he is generally willing to accept any female; and it is the female
which usually exerts a choice. Hence, if sexual selection has been
efficient with the Lepidoptera, the male, when the sexes differ, ought to
be the more brilliantly coloured, and this undoubtedly is the case. When
both sexes are brilliantly coloured and resemble each other, the characters
acquired by the males appear to have been transmitted to both. We are led
to this conclusion by cases, even within the same genus, of gradation from
an extraordinary amount of difference to identity in colour between the two
sexes.
But it may be asked whether the difference in colour between the sexes may
not be accounted for by other means besides sexual selection. Thus the
males and females of the same species of butterfly are in several cases
known (26. H.W. Bates, 'The Naturalist on the Amazons,' vol. ii. 1863, p.
228. A.R. Wallace, in 'Transactions, Linnean Society,' vol. xxv. 1865, p.
10.) to inhabit different stations, the former commonly basking in the
sunshine, the latter haunting gloomy forests. It is therefore possible
that different conditions of life may have acted directly on the two sexes;
but this is not probable (27. On this whole subject see 'The Variation of
Animals and Plants under Domestication,' 1868, vol. ii. chap. xxiii.) as in
the adult state they are exposed to different conditions during a very
short period; and the larvae of both are exposed to the same conditions.
Mr. Wallace believes that the difference between the sexes is due not so
much to the males having been modified, as to the females having in all or
almost all cases acquired dull colours for the sake of protection. It
seems to me, on the contrary, far more probable that it is the males which
have been chiefly modified through sexual selection, the females having
been comparatively little changed. We can thus understand how it is that
the females of allied species generally resemble one another so much more
closely than do the males. They thus shew us approximately the primordial
colouring of the parent-species of the group to which they belong. They
have, however, almost always been somewhat modified by the transfer to them
of some of the successive variations, through the accumulation of which the
males were rendered beautiful. But I do not wish to deny that the females
alone of some species may have been specially modified for protection. In
most cases the males and females of distinct species will have been exposed
during their prolonged larval state to different conditions, and may have
been thus affected; though with the males any slight change of colour thus
caused will generally have been masked by the brilliant tints gained
through sexual selection. When we treat of Birds, I shall have to discuss
the whole question, as to how far the differences in colour between the
sexes are due to the males having been modified through sexual selection
for ornamental purposes, or to the females having been modified through
natural selection for the sake of protection, so that I will here say but
little on the subject.
In all the cases in which the more common form of equal inheritance by both
sexes has prevailed, the selection of bright-coloured males would tend to
make the females bright-coloured; and the selection of dull-coloured
females would tend to make the males dull. If both processes were carried
on simultaneously, they would tend to counteract each other; and the final
result would depend on whether a greater number of females from being well
protected by obscure colours, or a greater number of males by being
brightly-coloured and thus finding partners, succeeded in leaving more
numerous offspring.
In order to account for the frequent transmission of characters to one sex
alone, Mr. Wallace expresses his belief that the more common form of equal
inheritance by both sexes can be changed through natural selection into
inheritance by one sex alone, but in favour of this view I can discover no
evidence. We know from what occurs under domestication that new characters
often appear, which from the first are transmitted to one sex alone; and by
the selection of such variations there would not be the slightest
difficulty in giving bright colours to the males alone, and at the same
time or subsequently, dull colours to the females alone. In this manner
the females of some butterflies and moths have, it is probable, been
rendered inconspicuous for the sake of protection, and widely different
from their males.
I am, however, unwilling without distinct evidence to admit that two
complex processes of selection, each requiring the transference of new
characters to one sex alone, have been carried on with a multitude of
species,--that the males have been rendered more brilliant by beating their
rivals, and the females more dull-coloured by having escaped from their
enemies. The male, for instance, of the common brimstone butterfly
(Gonepteryx), is of a far more intense yellow than the female, though she
is equally conspicuous; and it does not seem probable that she specially
acquired her pale tints as a protection, though it is probable that the
male acquired his bright colours as a sexual attraction. The female of
Anthocharis cardamines does not possess the beautiful orange wing-tips of
the male; consequently she closely resembles the white butterflies (Pieris)
so common in our gardens; but we have no evidence that this resemblance is
beneficial to her. As, on the other hand, she resembles both sexes of
several other species of the genus inhabiting various quarters of the
world, it is probable that she has simply retained to a large extent her
primordial colours.
Finally, as we have seen, various considerations lead to the conclusion
that with the greater number of brilliantly-coloured Lepidoptera it is the
male which has been chiefly modified through sexual selection; the amount
of difference between the sexes mostly depending on the form of inheritance
which has prevailed. Inheritance is governed by so many unknown laws or
conditions, that it seems to us to act in a capricious manner (28. The
'Variation of Animals and Plants under Domestication,' vol. ii. chap. xii.
p. 17.); and we can thus, to a certain extent, understand how it is that
with closely allied species the sexes either differ to an astonishing
degree, or are identical in colour. As all the successive steps in the
process of variation are necessarily transmitted through the female, a
greater or less number of such steps might readily become developed in her;
and thus we can understand the frequent gradations from an extreme
difference to none at all between the sexes of allied species. These cases
of gradation, it may be added, are much too common to favour the
supposition that we here see females actually undergoing the process of
transition and losing their brightness for the sake of protection; for we
have every reason to conclude that at any one time the greater number of
species are in a fixed condition.
MIMICRY.
This principle was first made clear in an admirable paper by Mr. Bates (29.
'Transact. Linn. Soc.' vol. xxiii. 1862, p. 495.), who thus threw a flood
of light on many obscure problems. It had previously been observed that
certain butterflies in S. America belonging to quite distinct families,
resembled the Heliconidae so closely in every stripe and shade of colour,
that they could not be distinguished save by an experienced entomologist.
As the Heliconidae are coloured in their usual manner, whilst the others
depart from the usual colouring of the groups to which they belong, it is
clear that the latter are the imitators, and the Heliconidae the imitated.
Mr. Bates further observed that the imitating species are comparatively
rare, whilst the imitated abound, and that the two sets live mingled
together. From the fact of the Heliconidae being conspicuous and beautiful
insects, yet so numerous in individuals and species, he concluded that they
must be protected from the attacks of enemies by some secretion or odour;
and this conclusion has now been amply confirmed (30. 'Proc. Entomological
Soc.' Dec. 3, 1866, p. xlv.), especially by Mr. Belt. Hence Mr. Bates
inferred that the butterflies which imitate the protected species have
acquired their present marvellously deceptive appearance through variation
and natural selection, in order to be mistaken for the protected kinds, and
thus to escape being devoured. No explanation is here attempted of the
brilliant colours of the imitated, but only of the imitating butterflies.
We must account for the colours of the former in the same general manner,
as in the cases previously discussed in this chapter. Since the
publication of Mr. Bates' paper, similar and equally striking facts have
been observed by Mr. Wallace in the Malayan region, by Mr. Trimen in South
Africa, and by Mr. Riley in the United States. (31. Wallace, 'Transact.
Linn. Soc.' vol. xxv. 1865 p. i.; also, 'Transact. Ent. Soc.' vol. iv. (3rd
series), 1867, p. 301. Trimen, 'Linn. Transact.' vol. xxvi. 1869, p. 497.
Riley, 'Third Annual Report on the Noxious Insects of Missouri,' 1871, pp.
163-168. This latter essay is valuable, as Mr. Riley here discusses all
the objections which have been raised against Mr. Bates's theory.)
As some writers have felt much difficulty in understanding how the first
steps in the process of mimicry could have been effected through natural
selection, it may be well to remark that the process probably commenced
long ago between forms not widely dissimilar in colour. In this case even
a slight variation would be beneficial, if it rendered the one species more
like the other; and afterwards the imitated species might be modified to an
extreme degree through sexual selection or other means, and if the changes
were gradual, the imitators might easily be led along the same track, until
they differed to an equally extreme degree from their original condition;
and they would thus ultimately assume an appearance or colouring wholly
unlike that of the other members of the group to which they belonged. It
should also be remembered that many species of Lepidoptera are liable to
considerable and abrupt variations in colour. A few instances have been
given in this chapter; and many more may be found in the papers of Mr.
Bates and Mr. Wallace.
With several species the sexes are alike, and imitate the two sexes of
another species. But Mr. Trimen gives, in the paper already referred to,
three cases in which the sexes of the imitated form differ from each other
in colour, and the sexes of the imitating form differ in a like manner.
Several cases have also been recorded where the females alone imitate
brilliantly-coloured and protected species, the males retaining "the normal
aspect of their immediate congeners." It is here obvious that the
successive variations by which the female has been modified have been
transmitted to her alone. It is, however, probable that some of the many
successive variations would have been transmitted to, and developed in, the
males had not such males been eliminated by being thus rendered less
attractive to the females; so that only those variations were preserved
which were from the first strictly limited in their transmission to the
female sex. We have a partial illustration of these remarks in a statement
by Mr. Belt (32. 'The Naturalist in Nicaragua,' 1874, p. 385.); that the
males of some of the Leptalides, which imitate protected species, still
retain in a concealed manner some of their original characters. Thus in
the males "the upper half of the lower wing is of a pure white, whilst all
the rest of the wings is barred and spotted with black, red and yellow,
like the species they mimic. The females have not this white patch, and
the males usually conceal it by covering it with the upper wing, so that I
cannot imagine its being of any other use to them than as an attraction in
courtship, when they exhibit it to the females, and thus gratify their
deep-seated preference for the normal colour of the Order to which the
Leptalides belong."
BRIGHT COLOURS OF CATERPILLARS.
Whilst reflecting on the beauty of many butterflies, it occurred to me that
some caterpillars were splendidly coloured; and as sexual selection could
not possibly have here acted, it appeared rash to attribute the beauty of
the mature insect to this agency, unless the bright colours of their larvae
could be somehow explained. In the first place, it may be observed that
the colours of caterpillars do not stand in any close correlation with
those of the mature insect. Secondly, their bright colours do not serve in
any ordinary manner as a protection. Mr. Bates informs me, as an instance
of this, that the most conspicuous caterpillar which he ever beheld (that
of a Sphinx) lived on the large green leaves of a tree on the open llanos
of South America; it was about four inches in length, transversely banded
with black and yellow, and with its head, legs, and tail of a bright red.
Hence it caught the eye of any one who passed by, even at the distance of
many yards, and no doubt that of every passing bird.
I then applied to Mr. Wallace, who has an innate genius for solving
difficulties. After some consideration he replied: "Most caterpillars
require protection, as may be inferred from some kinds being furnished with
spines or irritating hairs, and from many being coloured green like the
leaves on which they feed, or being curiously like the twigs of the trees
on which they live." Another instance of protection, furnished me by Mr.
J. Mansel Weale, may be added, namely, that there is a caterpillar of a
moth which lives on the mimosas in South Africa, and fabricates for itself
a case quite indistinguishable from the surrounding thorns. From such
considerations Mr. Wallace thought it probable that conspicuously coloured
caterpillars were protected by having a nauseous taste; but as their skin
is extremely tender, and as their intestines readily protrude from a wound,
a slight peck from the beak of a bird would be as fatal to them as if they
had been devoured. Hence, as Mr. Wallace remarks, "distastefulness alone
would be insufficient to protect a caterpillar unless some outward sign
indicated to its would-be destroyer that its prey was a disgusting morsel."
Under these circumstances it would be highly advantageous to a caterpillar
to be instantaneously and certainly recognised as unpalatable by all birds
and other animals. Thus the most gaudy colours would be serviceable, and
might have been gained by variation and the survival of the most easily-
recognised individuals.
This hypothesis appears at first sight very bold, but when it was brought
before the Entomological Society (33. 'Proceedings, Entomological
Society,' Dec. 3, 1866, p. xlv. and March 4, 1867, p. lxxx.) it was
supported by various statements; and Mr. J. Jenner Weir, who keeps a large
number of birds in an aviary, informs me that he has made many trials, and
finds no exception to the rule, that all caterpillars of nocturnal and
retiring habits with smooth skins, all of a green colour, and all which
imitate twigs, are greedily devoured by his birds. The hairy and spinose
kinds are invariably rejected, as were four conspicuously-coloured species.
When the birds rejected a caterpillar, they plainly shewed, by shaking
their heads, and cleansing their beaks, that they were disgusted by the
taste. (34. See Mr. J. Jenner Weir's paper on Insects and Insectivorous
Birds, in 'Transact. Ent. Soc.' 1869, p. 21; also Mr. Butler's paper, ibid.
p. 27. Mr. Riley has given analogous facts in the 'Third Annual Report on
the Noxious Insects of Missouri,' 1871, p. 148. Some opposed cases are,
however, given by Dr. Wallace and M. H. d'Orville; see 'Zoological Record,'
1869, p. 349.) Three conspicuous kinds of caterpillars and moths were also
given to some lizards and frogs, by Mr. A. Butler, and were rejected,
though other kinds were eagerly eaten. Thus the probability of Mr.
Wallace's view is confirmed, namely, that certain caterpillars have been
made conspicuous for their own good, so as to be easily recognised by their
enemies, on nearly the same principle that poisons are sold in coloured
bottles by druggists for the good of man. We cannot, however, at present
thus explain the elegant diversity in the colours of many caterpillars; but
any species which had at some former period acquired a dull, mottled, or
striped appearance, either in imitation of surrounding objects, or from the
direct action of climate, etc., almost certainly would not become uniform
in colour, when its tints were rendered intense and bright; for in order to
make a caterpillar merely conspicuous, there would be no selection in any
definite direction.
SUMMARY AND CONCLUDING REMARKS ON INSECTS.
Looking back to the several Orders, we see that the sexes often differ in
various characters, the meaning of which is not in the least understood.
The sexes, also, often differ in their organs of sense and means of
locomotion, so that the males may quickly discover and reach the females.
They differ still oftener in the males possessing diversified contrivances
for retaining the females when found. We are, however, here concerned only
in a secondary degree with sexual differences of these kinds.
In almost all the Orders, the males of some species, even of weak and
delicate kinds, are known to be highly pugnacious; and some few are
furnished with special weapons for fighting with their rivals. But the law
of battle does not prevail nearly so widely with insects as with the higher
animals. Hence it probably arises, that it is in only a few cases that the
males have been rendered larger and stronger than the females. On the
contrary, they are usually smaller, so that they may be developed within a
shorter time, to be ready in large numbers for the emergence of the
females.
In two families of the Homoptera and in three of the Orthoptera, the males
alone possess sound-producing organs in an efficient state. These are used
incessantly during the breeding-season, not only for calling the females,
but apparently for charming or exciting them in rivalry with other males.
No one who admits the agency of selection of any kind, will, after reading
the above discussion, dispute that these musical instruments have been
acquired through sexual selection. In four other Orders the members of one
sex, or more commonly of both sexes, are provided with organs for producing
various sounds, which apparently serve merely as call-notes. When both
sexes are thus provided, the individuals which were able to make the
loudest or most continuous noise would gain partners before those which
were less noisy, so that their organs have probably been gained through
sexual selection. It is instructive to reflect on the wonderful diversity
of the means for producing sound, possessed by the males alone, or by both
sexes, in no less than six Orders. We thus learn how effectual sexual
selection has been in leading to modifications which sometimes, as with the
Homoptera, relate to important parts of the organisation.
From the reasons assigned in the last chapter, it is probable that the
great horns possessed by the males of many Lamellicorn, and some other
beetles, have been acquired as ornaments. From the small size of insects,
we are apt to undervalue their appearance. If we could imagine a male
Chalcosoma (Fig. 16), with its polished bronzed coat of mail, and its vast
complex horns, magnified to the size of a horse, or even of a dog, it would
be one of the most imposing animals in the world.
The colouring of insects is a complex and obscure subject. When the male
differs slightly from the female, and neither are brilliantly-coloured, it
is probable that the sexes have varied in a slightly different manner, and
that the variations have been transmitted by each sex to the same without
any benefit or evil thus accruing. When the male is brilliantly-coloured
and differs conspicuously from the female, as with some dragon-flies and
many butterflies, it is probable that he owes his colours to sexual
selection; whilst the female has retained a primordial or very ancient type
of colouring, slightly modified by the agencies before explained. But in
some cases the female has apparently been made obscure by variations
transmitted to her alone, as a means of direct protection; and it is almost
certain that she has sometimes been made brilliant, so as to imitate other
protected species inhabiting the same district. When the sexes resemble
each other and both are obscurely coloured, there is no doubt that they
have been in a multitude of cases so coloured for the sake of protection.
So it is in some instances when both are brightly-coloured, for they thus
imitate protected species, or resemble surrounding objects such as flowers;
or they give notice to their enemies that they are unpalatable. In other
cases in which the sexes resemble each other and are both brilliant,
especially when the colours are arranged for display, we may conclude that
they have been gained by the male sex as an attraction, and have been
transferred to the female. We are more especially led to this conclusion
whenever the same type of coloration prevails throughout a whole group, and
we find that the males of some species differ widely in colour from the
females, whilst others differ slightly or not at all with intermediate
gradations connecting these extreme states.
In the same manner as bright colours have often been partially transferred
from the males to the females, so it has been with the extraordinary horns
of many Lamellicorn and some other beetles. So again, the sound-producing
organs proper to the males of the Homoptera and Orthoptera have generally
been transferred in a rudimentary, or even in a nearly perfect condition,
to the females; yet not sufficiently perfect to be of any use. It is also
an interesting fact, as bearing on sexual selection, that the stridulating
organs of certain male Orthoptera are not fully developed until the last
moult; and that the colours of certain male dragon-flies are not fully
developed until some little time after their emergence from the pupal
state, and when they are ready to breed.
Sexual selection implies that the more attractive individuals are preferred
by the opposite sex; and as with insects, when the sexes differ, it is the
male which, with some rare exceptions, is the more ornamented, and departs
more from the type to which the species belongs;--and as it is the male
which searches eagerly for the female, we must suppose that the females
habitually or occasionally prefer the more beautiful males, and that these
have thus acquired their beauty. That the females in most or all the
Orders would have the power of rejecting any particular male, is probable
from the many singular contrivances possessed by the males, such as great
jaws, adhesive cushions, spines, elongated legs, etc., for seizing the
female; for these contrivances show that there is some difficulty in the
act, so that her concurrence would seem necessary. Judging from what we
know of the perceptive powers and affections of various insects, there is
no antecedent improbability in sexual selection having come largely into
play; but we have as yet no direct evidence on this head, and some facts
are opposed to the belief. Nevertheless, when we see many males pursuing
the same female, we can hardly believe that the pairing is left to blind
chance--that the female exerts no choice, and is not influenced by the
gorgeous colours or other ornaments with which the male is decorated.
If we admit that the females of the Homoptera and Orthoptera appreciate the
musical tones of their male partners, and that the various instruments have
been perfected through sexual selection, there is little improbability in
the females of other insects appreciating beauty in form or colour, and
consequently in such characters having been thus gained by the males. But
from the circumstance of colour being so variable, and from its having been
so often modified for the sake of protection, it is difficult to decide in
how large a proportion of cases sexual selection has played a part. This
is more especially difficult in those Orders, such as Orthoptera,
Hymenoptera, and Coleoptera, in which the two sexes rarely differ much in
colour; for we are then left to mere analogy. With the Coleoptera,
however, as before remarked, it is in the great Lamellicorn group, placed
by some authors at the head of the Order, and in which we sometimes see a
mutual attachment between the sexes, that we find the males of some species
possessing weapons for sexual strife, others furnished with wonderful
horns, many with stridulating organs, and others ornamented with splendid
metallic tints. Hence it seems probable that all these characters have
been gained through the same means, namely sexual selection. With
butterflies we have the best evidence, as the males sometimes take pains to
display their beautiful colours; and we cannot believe that they would act
thus, unless the display was of use to them in their courtship.
When we treat of Birds, we shall see that they present in their secondary
sexual characters the closest analogy with insects. Thus, many male birds
are highly pugnacious, and some are furnished with special weapons for
fighting with their rivals. They possess organs which are used during the
breeding-season for producing vocal and instrumental music. They are
frequently ornamented with combs, horns, wattles and plumes of the most
diversified kinds, and are decorated with beautiful colours, all evidently
for the sake of display. We shall find that, as with insects, both sexes
in certain groups are equally beautiful, and are equally provided with
ornaments which are usually confined to the male sex. In other groups both
sexes are equally plain-coloured and unornamented. Lastly, in some few
anomalous cases, the females are more beautiful than the males. We shall
often find, in the same group of birds, every gradation from no difference
between the sexes, to an extreme difference. We shall see that female
birds, like female insects, often possess more or less plain traces or
rudiments of characters which properly belong to the males and are of use
only to them. The analogy, indeed, in all these respects between birds and
insects is curiously close. Whatever explanation applies to the one class
probably applies to the other; and this explanation, as we shall hereafter
attempt to shew in further detail, is sexual selection.
CHAPTER XII.
SECONDARY SEXUAL CHARACTERS OF FISHES, AMPHIBIANS, AND REPTILES.
FISHES: Courtship and battles of the males--Larger size of the females--
Males, bright colours and ornamental appendages; other strange characters--
Colours and appendages acquired by the males during the breeding-season
alone--Fishes with both sexes brilliantly coloured--Protective colours--The
less conspicuous colours of the female cannot be accounted for on the
principle of protection--Male fishes building nests, and taking charge of
the ova and young.
AMPHIBIANS: Differences in structure and colour between the sexes--Vocal
organs.
REPTILES: Chelonians--Crocodiles--Snakes, colours in some cases
protective--Lizards, battles of--Ornamental appendages--Strange differences
in structure between the sexes--Colours--Sexual differences almost as great
as with birds.
We have now arrived at the great sub-kingdom of the Vertebrata, and will
commence with the lowest class, that of fishes. The males of Plagiostomous
fishes (sharks, rays) and of Chimaeroid fishes are provided with claspers
which serve to retain the female, like the various structures possessed by
many of the lower animals. Besides the claspers, the males of many rays
have clusters of strong sharp spines on their heads, and several rows along
"the upper outer surface of their pectoral fins." These are present in the
males of some species, which have other parts of their bodies smooth. They
are only temporarily developed during the breeding-season; and Dr. Gunther
suspects that they are brought into action as prehensile organs by the
doubling inwards and downwards of the two sides of the body. It is a
remarkable fact that the females and not the males of some species, as of
Raia clavata, have their backs studded with large hook-formed spines. (1.
Yarrell's 'Hist. of British Fishes,' vol. ii. 1836, pp 417, 425, 436. Dr.
Gunther informs me that the spines in R. clavata are peculiar to the
female.)
The males alone of the capelin (Mallotus villosus, one of Salmonidae), are
provided with a ridge of closely-set, brush-like scales, by the aid of
which two males, one on each side, hold the female, whilst she runs with
great swiftness on the sandy beach, and there deposits her spawn. (2. The
'American Naturalist,' April 1871, p. 119.) The widely distinct
Monacanthus scopas presents a somewhat analogous structure. The male, as
Dr. Gunther informs me, has a cluster of stiff, straight spines, like those
of a comb, on the sides of the tail; and these in a specimen six inches
long were nearly one and a half inches in length; the female has in the
same place a cluster of bristles, which may be compared with those of a
tooth-brush. In another species, M. peronii, the male has a brush like
that possessed by the female of the last species, whilst the sides of the
tail in the female are smooth. In some other species of the same genus the
tail can be perceived to be a little roughened in the male and perfectly
smooth in the female; and lastly in others, both sexes have smooth sides.
The males of many fish fight for the possession of the females. Thus the
male stickleback (Gasterosteus leiurus) has been described as "mad with
delight," when the female comes out of her hiding-place and surveys the
nest which he has made for her. "He darts round her in every direction,
then to his accumulated materials for the nest, then back again in an
instant; and as she does not advance he endeavours to push her with his
snout, and then tries to pull her by the tail and side-spine to the nest."
(3. See Mr. R. Warington's interesting articles in 'Annals and Magazine of
Natural History,' October 1852, and November 1855.) The males are said to
be polygamists (4. Noel Humphreys, 'River Gardens,' 1857.); they are
extraordinarily bold and pugnacious, whilst "the females are quite
pacific." Their battles are at times desperate; "for these puny combatants
fasten tight on each other for several seconds, tumbling over and over
again until their strength appears completely exhausted." With the rough-
tailed stickleback (G. trachurus) the males whilst fighting swim round and
round each other, biting and endeavouring to pierce each other with their
raised lateral spines. The same writer adds (5. Loudon's 'Magazine of
Natural History,' vol. iii. 1830, p. 331.), "the bite of these little
furies is very severe. They also use their lateral spines with such fatal
effect, that I have seen one during a battle absolutely rip his opponent
quite open, so that he sank to the bottom and died." When a fish is
conquered, "his gallant bearing forsakes him; his gay colours fade away;
and he hides his disgrace among his peaceable companions, but is for some
time the constant object of his conqueror's persecution."
The male salmon is as pugnacious as the little stickleback; and so is the
male trout, as I hear from Dr. Gunther. Mr. Shaw saw a violent contest
between two male salmon which lasted the whole day; and Mr. R. Buist,
Superintendent of Fisheries, informs me that he has often watched from the
bridge at Perth the males driving away their rivals, whilst the females
were spawning. The males "are constantly fighting and tearing each other
on the spawning-beds, and many so injure each other as to cause the death
of numbers, many being seen swimming near the banks of the river in a state
of exhaustion, and apparently in a dying state." (6. The 'Field,' June
29, 1867. For Mr. Shaw's Statement, see 'Edinburgh Review,' 1843. Another
experienced observer (Scrope's 'Days of Salmon Fishing,' p. 60) remarks
that like the stag, the male would, if he could, keep all other males
away.) Mr. Buist informs me, that in June 1868, the keeper of the
Stormontfield breeding-ponds visited the northern Tyne and found about 300
dead salmon, all of which with one exception were males; and he was
convinced that they had lost their lives by fighting.
[Fig. 27. Head of male common salmon (Salmo salar) during the breeding-
season.
[This drawing, as well as all the others in the present chapter, have been
executed by the well-known artist, Mr. G. Ford, from specimens in the
British Museum, under the kind superintendence of Dr. Gunther.]
Fig. 28. Head of female salmon.]
The most curious point about the male salmon is that during the breeding-
season, besides a slight change in colour, "the lower jaw elongates, and a
cartilaginous projection turns upwards from the point, which, when the jaws
are closed, occupies a deep cavity between the intermaxillary bones of the
upper jaw." (7. Yarrell, 'History of British Fishes,' vol. ii. 1836, p.
10.) (Figs. 27 and 28.) In our salmon this change of structure lasts only
during the breeding-season; but in the Salmo lycaodon of N.W. America the
change, as Mr. J.K. Lord (8. 'The Naturalist in Vancouver's Island,' vol.
i. 1866, p. 54.) believes, is permanent, and best marked in the older males
which have previously ascended the rivers. In these old males the jaw
becomes developed into an immense hook-like projection, and the teeth grow
into regular fangs, often more than half an inch in length. With the
European salmon, according to Mr. Lloyd (9. 'Scandinavian Adventures,'
vol. i. 1854, pp. 100, 104.), the temporary hook-like structure serves to
strengthen and protect the jaws, when one male charges another with
wonderful violence; but the greatly developed teeth of the male American
salmon may be compared with the tusks of many male mammals, and they
indicate an offensive rather than a protective purpose.
The salmon is not the only fish in which the teeth differ in the two sexes;
as this is the case with many rays. In the thornback (Raia clavata) the
adult male has sharp, pointed teeth, directed backwards, whilst those of
the female are broad and flat, and form a pavement; so that these teeth
differ in the two sexes of the same species more than is usual in distinct
genera of the same family. The teeth of the male become sharp only when he
is adult: whilst young they are broad and flat like those of the female.
As so frequently occurs with secondary sexual characters, both sexes of
some species of rays (for instance R. batis), when adult, possess sharp
pointed teeth; and here a character, proper to and primarily gained by the
male, appears to have been transmitted to the offspring of both sexes. The
teeth are likewise pointed in both sexes of R. maculata, but only when
quite adult; the males acquiring them at an earlier age than the females.
We shall hereafter meet with analogous cases in certain birds, in which the
male acquires the plumage common to both sexes when adult, at a somewhat
earlier age than does the female. With other species of rays the males
even when old never possess sharp teeth, and consequently the adults of
both sexes are provided with broad, flat teeth like those of the young, and
like those of the mature females of the above-mentioned species. (10. See
Yarrell's account of the rays in his 'History of British Fishes,' vol. ii.
1836, p. 416, with an excellent figure, and pp. 422, 432.) As the rays are
bold, strong and voracious fish, we may suspect that the males require
their sharp teeth for fighting with their rivals; but as they possess many
parts modified and adapted for the prehension of the female, it is possible
that their teeth may be used for this purpose.
In regard to size, M. Carbonnier (11. As quoted in 'The Farmer,' 1868, p.
369.) maintains that the female of almost all fishes is larger than the
male; and Dr. Gunther does not know of a single instance in which the male
is actually larger than the female. With some Cyprinodonts the male is not
even half as large. As in many kinds of fishes the males habitually fight
together, it is surprising that they have not generally become larger and
stronger than the females through the effects of sexual selection. The
males suffer from their small size, for according to M. Carbonnier, they
are liable to be devoured by the females of their own species when
carnivorous, and no doubt by other species. Increased size must be in some
manner of more importance to the females, than strength and size are to the
males for fighting with other males; and this perhaps is to allow of the
production of a vast number of ova.
[Fig. 29. Callionymus lyra.
Upper figure, male;
lower figure, female.
N.B. The lower figure is more reduced than the upper.]
In many species the male alone is ornamented with bright colours; or these
are much brighter in the male than the female. The male, also, is
sometimes provided with appendages which appear to be of no more use to him
for the ordinary purposes of life, than are the tail feathers to the
peacock. I am indebted for most of the following facts to the kindness of
Dr. Gunther. There is reason to suspect that many tropical fishes differ
sexually in colour and structure; and there are some striking cases with
our British fishes. The male Callionymus lyra has been called the gemmeous
dragonet "from its brilliant gem-like colours." When fresh caught from the
sea the body is yellow of various shades, striped and spotted with vivid
blue on the head; the dorsal fins are pale brown with dark longitudinal
bands; the ventral, caudal, and anal fins being bluish-black. The female,
or sordid dragonet, was considered by Linnaeus, and by many subsequent
naturalists, as a distinct species; it is of a dingy reddish-brown, with
the dorsal fin brown and the other fins white. The sexes differ also in
the proportional size of the head and mouth, and in the position of the
eyes (12. I have drawn up this description from Yarrell's 'British
Fishes,' vol. i. 1836, pp. 261 and 266.); but the most striking difference
is the extraordinary elongation in the male (Fig. 29) of the dorsal fin.
Mr. W. Saville Kent remarks that this "singular appendage appears from my
observations of the species in confinement, to be subservient to the same
end as the wattles, crests, and other abnormal adjuncts of the male in
gallinaceous birds, for the purpose of fascinating their mates." (13.
'Nature,' July 1873, p. 264.) The young males resemble the adult females
in structure and colour. Throughout the genus Callionymus (14. 'Catalogue
of Acanth. Fishes in the British Museum,' by Dr. Gunther, 1861, pp. 138-
151.), the male is generally much more brightly spotted than the female,
and in several species, not only the dorsal, but the anal fin is much
elongated in the males.
The male of the Cottus scorpius, or sea-scorpion, is slenderer and smaller
than the female. There is also a great difference in colour between them.
It is difficult, as Mr. Lloyd (15. 'Game Birds of Sweden,' etc., 1867, p.
466.) remarks, "for any one, who has not seen this fish during the
spawning-season, when its hues are brightest, to conceive the admixture of
brilliant colours with which it, in other respects so ill-favoured, is at
that time adorned." Both sexes of the Labrus mixtus, although very
different in colour, are beautiful; the male being orange with bright blue
stripes, and the female bright red with some black spots on the back.
[Fig. 30. Xiphophorus Hellerii.
Upper figure, male;
lower figure, female.]
In the very distinct family of the Cyprinodontidae--inhabitants of the
fresh waters of foreign lands--the sexes sometimes differ much in various
characters. In the male of the Mollienesia petenensis (16. With respect
to this and the following species I am indebted to Dr. Gunther for
information: see also his paper on the 'Fishes of Central America,' in
'Transact. Zoological Soc.' vol. vi. 1868, p. 485.), the dorsal fin is
greatly developed and is marked with a row of large, round, ocellated,
bright-coloured spots; whilst the same fin in the female is smaller, of a
different shape, and marked only with irregularly curved brown spots. In
the male the basal margin of the anal fin is also a little produced and
dark coloured. In the male of an allied form, the Xiphophorus Hellerii
(Fig. 30), the inferior margin of the caudal fin is developed into a long
filament, which, as I hear from Dr. Gunther, is striped with bright
colours. This filament does not contain any muscles, and apparently cannot
be of any direct use to the fish. As in the case of the Callionymus, the
males whilst young resemble the adult females in colour and structure.
Sexual differences such as these may be strictly compared with those which
are so frequent with gallinaceous birds. (17. Dr. Gunther makes this
remark; 'Catalogue of Fishes in the British Museum,' vol. iii. 1861, p.
141.)
[Fig.31. Plecostomus barbatus.
Upper figure, head of male;
lower figure, female.]
In a siluroid fish, inhabiting the fresh waters of South America, the
Plecostomus barbatus (18. See Dr. Gunther on this genus, in 'Proceedings
of the Zoological Society,' 1868, p. 232.) (Fig. 31), the male has its
mouth and inter-operculum fringed with a beard of stiff hairs, of which the
female shows hardly a trace. These hairs are of the nature of scales. In
another species of the same genus, soft flexible tentacles project from the
front part of the head of the male, which are absent in the female. These
tentacles are prolongations of the true skin, and therefore are not
homologous with the stiff hairs of the former species; but it can hardly be
doubted that both serve the same purpose. What this purpose may be, it is
difficult to conjecture; ornament does not here seem probable, but we can
hardly suppose that stiff hairs and flexible filaments can be useful in any
ordinary way to the males alone. In that strange monster, the Chimaera
monstrosa, the male has a hook-shaped bone on the top of the head, directed
forwards, with its end rounded and covered with sharp spines; in the female
"this crown is altogether absent," but what its use may be to the male is
utterly unknown. (19. F. Buckland, in 'Land and Water,' July 1868, p.
377, with a figure. Many other cases could be added of structures peculiar
to the male, of which the uses are not known.)
The structures as yet referred to are permanent in the male after he has
arrived at maturity; but with some Blennies, and in another allied genus
(20. Dr. Gunther, 'Catalogue of Fishes,' vol. iii. pp. 221 and 240.), a
crest is developed on the head of the male only during the breeding-season,
and the body at the same time becomes more brightly-coloured. There can be
little doubt that this crest serves as a temporary sexual ornament, for the
female does not exhibit a trace of it. In other species of the same genus
both sexes possess a crest, and in at least one species neither sex is thus
provided. In many of the Chromidae, for instance in Geophagus and
especially in Cichla, the males, as I hear from Professor Agassiz (21. See
also 'A Journey in Brazil,' by Prof. and Mrs. Agassiz, 1868, p. 220.), have
a conspicuous protuberance on the forehead, which is wholly wanting in the
females and in the young males. Professor Agassiz adds, "I have often
observed these fishes at the time of spawning when the protuberance is
largest, and at other seasons when it is totally wanting, and the two sexes
shew no difference whatever in the outline of the profile of the head. I
never could ascertain that it subserves any special function, and the
Indians on the Amazon know nothing about its use." These protuberances
resemble, in their periodical appearance, the fleshy carbuncles on the
heads of certain birds; but whether they serve as ornaments must remain at
present doubtful.
I hear from Professor Agassiz and Dr. Gunther, that the males of those
fishes, which differ permanently in colour from the females, often become
more brilliant during the breeding-season. This is likewise the case with
a multitude of fishes, the sexes of which are identical in colour at all
other seasons of the year. The tench, roach, and perch may be given as
instances. The male salmon at this season is "marked on the cheeks with
orange-coloured stripes, which give it the appearance of a Labrus, and the
body partakes of a golden orange tinge. The females are dark in colour,
and are commonly called black-fish." (22. Yarrell, 'History of British
Fishes,' vol. ii. 1836, pp. 10, 12, 35.) An analogous and even greater
change takes place with the Salmo eriox or bull trout; the males of the
char (S. umbla) are likewise at this season rather brighter in colour than
the females. (23. W. Thompson, in 'Annals and Magazine of Natural
History,' vol. vi. 1841, p. 440.) The colours of the pike (Esox
reticulatus) of the United States, especially of the male, become, during
the breeding-season, exceedingly intense, brilliant, and iridescent. (24.
'The American Agriculturalist,' 1868, p. 100.) Another striking instance
out of many is afforded by the male stickleback (Gasterosteus leiurus),
which is described by Mr. Warington (25. 'Annals and Mag. of Nat. Hist.'
Oct. 1852.), as being then "beautiful beyond description." The back and
eyes of the female are simply brown, and the belly white. The eyes of the
male, on the other hand, are "of the most splendid green, having a metallic
lustre like the green feathers of some humming-birds. The throat and belly
are of a bright crimson, the back of an ashy-green, and the whole fish
appears as though it were somewhat translucent and glowed with an internal
incandescence." After the breeding season these colours all change, the
throat and belly become of a paler red, the back more green, and the
glowing tints subside.
With respect to the courtship of fishes, other cases have been observed
since the first edition of this book appeared, besides that already given
of the stickleback. Mr. W.S. Kent says that the male of the Labrus mixtus,
which, as we have seen, differs in colour from the female, makes "a deep
hollow in the sand of the tank, and then endeavours in the most persuasive
manner to induce a female of the same species to share it with him,
swimming backwards and forwards between her and the completed nest, and
plainly exhibiting the greatest anxiety for her to follow." The males of
Cantharus lineatus become, during the breeding-season, of deep leaden-
black; they then retire from the shoal, and excavate a hollow as a nest.
"Each male now mounts vigilant guard over his respective hollow, and
vigorously attacks and drives away any other fish of the same sex. Towards
his companions of the opposite sex his conduct is far different; many of
the latter are now distended with spawn, and these he endeavours by all the
means in his power to lure singly to his prepared hollow, and there to
deposit the myriad ova with which they are laden, which he then protects
and guards with the greatest care." (26. 'Nature,' May 1873, p. 25.)
A more striking case of courtship, as well as of display, by the males of a
Chinese Macropus has been given by M. Carbonnier, who carefully observed
these fishes under confinement. (27. 'Bulletin de la Societe d'Acclimat.'
Paris, July 1869, and Jan. 1870.) The males are most beautifully coloured,
more so than the females. During the breeding-season they contend for the
possession of the females; and, in the act of courtship, expand their fins,
which are spotted and ornamented with brightly coloured rays, in the same
manner, according to M. Carbonnier, as the peacock. They then also bound
about the females with much vivacity, and appear by "l'etalage de leurs
vives couleurs chercher a attirer l'attention des femelles, lesquelles ne
paraissaient indifferentes a ce manege, elles nageaient avec une molle
lenteur vers les males et semblaient se complaire dans leur voisinage."
After the male has won his bride, he makes a little disc of froth by
blowing air and mucus out of his mouth. He then collects the fertilised
ova, dropped by the female, in his mouth; and this caused M. Carbonnier
much alarm, as he thought that they were going to be devoured. But the
male soon deposits them in the disc of froth, afterwards guarding them,
repairing the froth, and taking care of the young when hatched. I mention
these particulars because, as we shall presently see, there are fishes, the
males of which hatch their eggs in their mouths; and those who do not
believe in the principle of gradual evolution might ask how could such a
habit have originated; but the difficulty is much diminished when we know
that there are fishes which thus collect and carry the eggs; for if delayed
by any cause in depositing them, the habit of hatching them in their mouths
might have been acquired.
To return to our more immediate subject. The case stands thus: female
fishes, as far as I can learn, never willingly spawn except in the presence
of the males; and the males never fertilise the ova except in the presence
of the females. The males fight for the possession of the females. In
many species, the males whilst young resemble the females in colour; but
when adult become much more brilliant, and retain their colours throughout
life. In other species the males become brighter than the females and
otherwise more highly ornamented, only during the season of love. The
males sedulously court the females, and in one case, as we have seen, take
pains in displaying their beauty before them. Can it be believed that they
would thus act to no purpose during their courtship? And this would be the
case, unless the females exert some choice and select those males which
please or excite them most. If the female exerts such choice, all the
above facts on the ornamentation of the males become at once intelligible
by the aid of sexual selection.
We have next to inquire whether this view of the bright colours of certain
male fishes having been acquired through sexual selection can, through the
law of the equal transmission of characters to both sexes, be extended to
those groups in which the males and females are brilliant in the same, or
nearly the same degree and manner. In such a genus as Labrus, which
includes some of the most splendid fishes in the world--for instance, the
Peacock Labrus (L. pavo), described (28. Bory Saint Vincent, in 'Dict.
Class. d'Hist. Nat.' tom. ix. 1826, p. 151.), with pardonable exaggeration,
as formed of polished scales of gold, encrusting lapis-lazuli, rubies,
sapphires, emeralds, and amethysts--we may, with much probability, accept
this belief; for we have seen that the sexes in at least one species of the
genus differ greatly in colour. With some fishes, as with many of the
lowest animals, splendid colours may be the direct result of the nature of
their tissues and of the surrounding conditions, without the aid of
selection of any kind. The gold-fish (Cyprinus auratus), judging from the
analogy of the golden variety of the common carp, is perhaps a case in
point, as it may owe its splendid colours to a single abrupt variation, due
to the conditions to which this fish has been subjected under confinement.
It is, however, more probable that these colours have been intensified
through artificial selection, as this species has been carefully bred in
China from a remote period. (29. Owing to some remarks on this subject,
made in my work 'On the Variation of Animals under Domestication,' Mr. W.F.
Mayers ('Chinese Notes and Queries,' Aug. 1868, p. 123) has searched the
ancient Chinese encyclopedias. He finds that gold-fish were first reared
in confinement during the Sung Dynasty, which commenced A.D. 960. In the
year 1129 these fishes abounded. In another place it is said that since
the year 1548 there has been "produced at Hangchow a variety called the
fire-fish, from its intensely red colour. It is universally admired, and
there is not a household where it is not cultivated, IN RIVALRY AS TO ITS
COLOUR, and as a source of profit.") Under natural conditions it does not
seem probable that beings so highly organised as fishes, and which live
under such complex relations, should become brilliantly coloured without
suffering some evil or receiving some benefit from so great a change, and
consequently without the intervention of natural selection.
What, then, are we to conclude in regard to the many fishes, both sexes of
which are splendidly coloured? Mr. Wallace (30. 'Westminster Review,'
July 1867, p. 7.) believes that the species which frequent reefs, where
corals and other brightly-coloured organisms abound, are brightly coloured
in order to escape detection by their enemies; but according to my
recollection they were thus rendered highly conspicuous. In the fresh-
waters of the tropics there are no brilliantly-coloured corals or other
organisms for the fishes to resemble; yet many species in the Amazons are
beautifully coloured, and many of the carnivorous Cyprinidae in India are
ornamented with "bright longitudinal lines of various tints." (31.
'Indian Cyprinidae,' by Mr. M'Clelland, 'Asiatic Researches,' vol. xix.
part ii. 1839, p. 230.) Mr. M'Clelland, in describing these fishes, goes
so far as to suppose that "the peculiar brilliancy of their colours" serves
as "a better mark for king-fishers, terns, and other birds which are
destined to keep the number of these fishes in check"; but at the present
day few naturalists will admit that any animal has been made conspicuous as
an aid to its own destruction. It is possible that certain fishes may have
been rendered conspicuous in order to warn birds and beasts of prey that
they were unpalatable, as explained when treating of caterpillars; but it
is not, I believe, known that any fish, at least any fresh-water fish, is
rejected from being distasteful to fish-devouring animals. On the whole,
the most probable view in regard to the fishes, of which both sexes are
brilliantly coloured, is that their colours were acquired by the males as a
sexual ornament, and were transferred equally, or nearly so, to the other
sex.
We have now to consider whether, when the male differs in a marked manner
from the female in colour or in other ornaments, he alone has been
modified, the variations being inherited by his male offspring alone; or
whether the female has been specially modified and rendered inconspicuous
for the sake of protection, such modifications being inherited only by the
females. It is impossible to doubt that colour has been gained by many
fishes as a protection: no one can examine the speckled upper surface of a
flounder, and overlook its resemblance to the sandy bed of the sea on which
it lives. Certain fishes, moreover, can through the action of the nervous
system change their colours in adaptation to surrounding objects, and that
within a short time. (32. G. Pouchet, 'L'Institut.' Nov. 1, 1871, p.
134.) One of the most striking instances ever recorded of an animal being
protected by its colour (as far as it can be judged of in preserved
specimens), as well as by its form, is that given by Dr. Gunther (33.
'Proc. Zoolog. Soc.' 1865, p. 327, pl. xiv. and xv.) of a pipe-fish, which,
with its reddish streaming filaments, is hardly distinguishable from the
sea-weed to which it clings with its prehensile tail. But the question now
under consideration is whether the females alone have been modified for
this object. We can see that one sex will not be modified through natural
selection for the sake of protection more than the other, supposing both to
vary, unless one sex is exposed for a longer period to danger, or has less
power of escaping from such danger than the other; and it does not appear
that with fishes the sexes differ in these respects. As far as there is
any difference, the males, from being generally smaller and from wandering
more about, are exposed to greater danger than the females; and yet, when
the sexes differ, the males are almost always the more conspicuously
coloured. The ova are fertilised immediately after being deposited; and
when this process lasts for several days, as in the case of the salmon (34.
Yarrell, 'British Fishes,' vol. ii. p. 11.), the female, during the whole
time, is attended by the male. After the ova are fertilised they are, in
most cases, left unprotected by both parents, so that the males and
females, as far as oviposition is concerned, are equally exposed to danger,
and both are equally important for the production of fertile ova;
consequently the more or less brightly-coloured individuals of either sex
would be equally liable to be destroyed or preserved, and both would have
an equal influence on the colours of their offspring.
Certain fishes, belonging to several families, make nests, and some of them
take care of their young when hatched. Both sexes of the bright coloured
Crenilabrus massa and melops work together in building their nests with
sea-weed, shells, etc. (35. According to the observations of M. Gerbe;
see Gunther's 'Record of Zoolog. Literature,' 1865, p. 194.) But the males
of certain fishes do all the work, and afterwards take exclusive charge of
the young. This is the case with the dull-coloured gobies (36. Cuvier,
'Regne Animal,' vol. ii. 1829, p. 242.), in which the sexes are not known
to differ in colour, and likewise with the sticklebacks (Gasterosteus), in
which the males become brilliantly coloured during the spawning season.
The male of the smooth-tailed stickleback (G. leiurus) performs the duties
of a nurse with exemplary care and vigilance during a long time, and is
continually employed in gently leading back the young to the nest, when
they stray too far. He courageously drives away all enemies including the
females of his own species. It would indeed be no small relief to the
male, if the female, after depositing her eggs, were immediately devoured
by some enemy, for he is forced incessantly to drive her from the nest.
(37. See Mr. Warington's most interesting description of the habits of the
Gasterosteus leiurus in 'Annals and Magazine of Nat. History,' November
1855.)
The males of certain other fishes inhabiting South America and Ceylon,
belonging to two distinct Orders, have the extraordinary habit of hatching
within their mouths, or branchial cavities, the eggs laid by the females.
(38. Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.' Sept. 15, 1857.
Also Prof. Turner, in 'Journal of Anatomy and Physiology,' Nov. 1, 1866, p.
78. Dr. Gunther has likewise described other cases.) I am informed by
Professor Agassiz that the males of the Amazonian species which follow this
habit, "not only are generally brighter than the females, but the
difference is greater at the spawning-season than at any other time." The
species of Geophagus act in the same manner; and in this genus, a
conspicuous protuberance becomes developed on the forehead of the males
during the breeding-season. With the various species of Chromids, as
Professor Agassiz likewise informs me, sexual differences in colour may be
observed, "whether they lay their eggs in the water among aquatic plants,
or deposit them in holes, leaving them to come out without further care, or
build shallow nests in the river mud, over which they sit, as our Pomotis
does. It ought also to be observed that these sitters are among the
brightest species in their respective families; for instance, Hygrogonus is
bright green, with large black ocelli, encircled with the most brilliant
red." Whether with all the species of Chromids it is the male alone which
sits on the eggs is not known. It is, however, manifest that the fact of
the eggs being protected or unprotected by the parents, has had little or
no influence on the differences in colour between the sexes. It is further
manifest, in all the cases in which the males take exclusive charge of the
nests and young, that the destruction of the brighter-coloured males would
be far more influential on the character of the race, than the destruction
of the brighter-coloured females; for the death of the male during the
period of incubation or nursing would entail the death of the young, so
that they could not inherit his peculiarities; yet, in many of these very
cases the males are more conspicuously coloured than the females.
In most of the Lophobranchii (Pipe-fish, Hippocampi, etc.) the males have
either marsupial sacks or hemispherical depressions on the abdomen, in
which the ova laid by the female are hatched. The males also shew great
attachment to their young. (39. Yarrell, 'History of British Fishes,'
vol. ii. 1836, pp. 329, 338.) The sexes do not commonly differ much in
colour; but Dr. Gunther believes that the male Hippocampi are rather
brighter than the females. The genus Solenostoma, however, offers a
curious exceptional case (40. Dr. Gunther, since publishing an account of
this species in 'The Fishes of Zanzibar,' by Col. Playfair, 1866, p. 137,
has re-examined the specimens, and has given me the above information.),
for the female is much more vividly-coloured and spotted than the male, and
she alone has a marsupial sack and hatches the eggs; so that the female of
Solenostoma differs from all the other Lophobranchii in this latter
respect, and from almost all other fishes, in being more brightly-coloured
than the male. It is improbable that this remarkable double inversion of
character in the female should be an accidental coincidence. As the males
of several fishes, which take exclusive charge of the eggs and young, are
more brightly coloured than the females, and as here the female Solenostoma
takes the same charge and is brighter than the male, it might be argued
that the conspicuous colours of that sex which is the more important of the
two for the welfare of the offspring, must be in some manner protective.
But from the large number of fishes, of which the males are either
permanently or periodically brighter than the females, but whose life is
not at all more important for the welfare of the species than that of the
female, this view can hardly be maintained. When we treat of birds we
shall meet with analogous cases, where there has been a complete inversion
of the usual attributes of the two sexes, and we shall then give what
appears to be the probable explanation, namely, that the males have
selected the more attractive females, instead of the latter having
selected, in accordance with the usual rule throughout the animal kingdom,
the more attractive males.
On the whole we may conclude, that with most fishes, in which the sexes
differ in colour or in other ornamental characters, the males originally
varied, with their variations transmitted to the same sex, and accumulated
through sexual selection by attracting or exciting the females. In many
cases, however, such characters have been transferred, either partially or
completely, to the females. In other cases, again, both sexes have been
coloured alike for the sake of protection; but in no instance does it
appear that the female alone has had her colours or other characters
specially modified for this latter purpose.
The last point which need be noticed is that fishes are known to make
various noises, some of which are described as being musical. Dr. Dufosse,
who has especially attended to this subject, says that the sounds are
voluntarily produced in several ways by different fishes: by the friction
of the pharyngeal bones--by the vibration of certain muscles attached to
the swim bladder, which serves as a resounding board--and by the vibration
of the intrinsic muscles of the swim bladder. By this latter means the
Trigla produces pure and long-drawn sounds which range over nearly an
octave. But the most interesting case for us is that of two species of
Ophidium, in which the males alone are provided with a sound-producing
apparatus, consisting of small movable bones, with proper muscles, in
connection with the swim bladder. (41. 'Comptes-Rendus,' tom. xlvi. 1858,
p. 353; tom. xlvii. 1858, p. 916; tom. liv. 1862, p. 393. The noise made
by the Umbrinas (Sciaena aquila), is said by some authors to be more like
that of a flute or organ, than drumming: Dr. Zouteveen, in the Dutch
translation of this work (vol. ii. p. 36), gives some further particulars
on the sounds made by fishes.) The drumming of the Umbrinas in the
European seas is said to be audible from a depth of twenty fathoms; and the
fishermen of Rochelle assert "that the males alone make the noise during
the spawning-time; and that it is possible by imitating it, to take them
without bait." (42. The Rev. C. Kingsley, in 'Nature,' May 1870, p. 40.)
From this statement, and more especially from the case of Ophidium, it is
almost certain that in this, the lowest class of the Vertebrata, as with so
many insects and spiders, sound-producing instruments have, at least in
some cases, been developed through sexual selection, as a means for
bringing the sexes together.
AMPHIBIANS.
URODELA.
[Fig. 32. Triton cristatus (half natural size, from Bell's 'British
Reptiles').
Upper figure, male during the breeding season;
lower figure, female.]
I will begin with the tailed amphibians. The sexes of salamanders or newts
often differ much both in colour and structure. In some species prehensile
claws are developed on the fore-legs of the males during the breeding-
season: and at this season in the male Triton palmipes the hind-feet are
provided with a swimming-web, which is almost completely absorbed during
the winter; so that their feet then resemble those of the female. (43.
Bell, 'History of British Reptiles,' 2nd ed., 1849, pp. 156-159.) This
structure no doubt aids the male in his eager search and pursuit of the
female. Whilst courting her he rapidly vibrates the end of his tail. With
our common newts (Triton punctatus and cristatus) a deep, much indented
crest is developed along the back and tail of the male during the breeding-
season, which disappears during the winter. Mr. St. George Mivart informs
me that it is not furnished with muscles, and therefore cannot be used for
locomotion. As during the season of courtship it becomes edged with bright
colours, there can hardly be a doubt that it is a masculine ornament. In
many species the body presents strongly contrasted, though lurid tints, and
these become more vivid during the breeding-season. The male, for
instance, of our common little newt (Triton punctatus) is "brownish-grey
above, passing into yellow beneath, which in the spring becomes a rich
bright orange, marked everywhere with round dark spots." The edge of the
crest also is then tipped with bright red or violet. The female is usually
of a yellowish-brown colour with scattered brown dots, and the lower
surface is often quite plain. (44. Bell, 'History of British Reptiles,'
2nd ed., 1849, pp. 146, 151.) The young are obscurely tinted. The ova are
fertilised during the act of deposition, and are not subsequently tended by
either parent. We may therefore conclude that the males have acquired
their strongly-marked colours and ornamental appendages through sexual
selection; these being transmitted either to the male offspring alone, or
to both sexes.
ANURA OR BATRACHIA.
With many frogs and toads the colours evidently serve as a protection, such
as the bright green tints of tree frogs and the obscure mottled shades of
many terrestrial species. The most conspicuously-coloured toad which I
ever saw, the Phryniscus nigricans (45. 'Zoology of the Voyage of the
"Beagle,"' 1843. Bell, ibid. p. 49.), had the whole upper surface of the
body as black as ink, with the soles of the feet and parts of the abdomen
spotted with the brightest vermilion. It crawled about the bare sandy or
open grassy plains of La Plata under a scorching sun, and could not fail to
catch the eye of every passing creature. These colours are probably
beneficial by making this animal known to all birds of prey as a nauseous
mouthful.
In Nicaragua there is a little frog "dressed in a bright livery of red and
blue" which does not conceal itself like most other species, but hops about
during the daytime, and Mr. Belt says (46. 'The Naturalist in Nicaragua,'
1874, p. 321.) that as soon as he saw its happy sense of security, he felt
sure that it was uneatable. After several trials he succeeded in tempting
a young duck to snatch up a young one, but it was instantly rejected; and
the duck "went about jerking its head, as if trying to throw off some
unpleasant taste."
With respect to sexual differences of colour, Dr. Gunther does not know of
any striking instance either with frogs or toads; yet he can often
distinguish the male from the female by the tints of the former being a
little more intense. Nor does he know of any striking difference in
external structure between the sexes, excepting the prominences which
become developed during the breeding-season on the front legs of the male,
by which he is enabled to hold the female. (47. The male alone of the
Bufo sikimmensis (Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 204) has two
plate-like callosities on the thorax and certain rugosities on the fingers,
which perhaps subserve the same end as the above-mentioned prominences.)
It is surprising that these animals have not acquired more strongly-marked
sexual characters; for though cold-blooded their passions are strong. Dr.
Gunther informs me that he has several times found an unfortunate female
toad dead and smothered from having been so closely embraced by three or
four males. Frogs have been observed by Professor Hoffman in Giessen
fighting all day long during the breeding-season, and with so much violence
that one had its body ripped open.
Frogs and toads offer one interesting sexual difference, namely, in the
musical powers possessed by the males; but to speak of music, when applied
to the discordant and overwhelming sounds emitted by male bull-frogs and
some other species, seems, according to our taste, a singularly
inappropriate expression. Nevertheless, certain frogs sing in a decidedly
pleasing manner. Near Rio Janeiro I used often to sit in the evening to
listen to a number of little Hylae, perched on blades of grass close to the
water, which sent forth sweet chirping notes in harmony. The various
sounds are emitted chiefly by the males during the breeding-season, as in
the case of the croaking of our common frog. (48. Bell, 'History British
Reptiles,' 1849, p. 93.) In accordance with this fact the vocal organs of
the males are more highly-developed than those of the females. In some
genera the males alone are provided with sacs which open into the larynx.
(49. J. Bishop, in 'Todd's Cyclopaedia of Anatomy and Physiology,' vol.
iv. p. 1503.) For instance, in the edible frog (Rana esculenta) "the sacs
are peculiar to the males, and become, when filled with air in the act of
croaking, large globular bladders, standing out one on each side of the
head, near the corners of the mouth." The croak of the male is thus
rendered exceedingly powerful; whilst that of the female is only a slight
groaning noise. (50. Bell, ibid. pp. 112-114.) In the several genera of
the family the vocal organs differ considerably in structure, and their
development in all cases may be attributed to sexual selection.
REPTILES.
CHELONIA.
Tortoises and turtles do not offer well-marked sexual differences. In some
species, the tail of the male is longer than that of the female. In some,
the plastron or lower surface of the shell of the male is slightly concave
in relation to the back of the female. The male of the mud-turtle of the
United States (Chrysemys picta) has claws on its front feet twice as long
as those of the female; and these are used when the sexes unite. (51. Mr.
C.J. Maynard, 'The American Naturalist,' Dec. 1869, p. 555.) With the huge
tortoise of the Galapagos Islands (Testudo nigra) the males are said to
grow to a larger size than the females: during the pairing-season, and at
no other time, the male utters a hoarse bellowing noise, which can be heard
at the distance of more than a hundred yards; the female, on the other
hand, never uses her voice. (52. See my 'Journal of Researches during the
Voyage of the "Beagle,"' 1845, p. 384.)
With the Testudo elegans of India, it is said "that the combats of the
males may be heard at some distance, from the noise they produce in butting
against each other." (53. Dr. Gunther, 'Reptiles of British India,' 1864,
p. 7.)
CROCODILIA.
The sexes apparently do not differ in colour; nor do I know that the males
fight together, though this is probable, for some kinds make a prodigious
display before the females. Bartram (54. 'Travels through Carolina,'
etc., 1791, p. 128.) describes the male alligator as striving to win the
female by splashing and roaring in the midst of a lagoon, "swollen to an
extent ready to burst, with its head and tail lifted up, he springs or
twirls round on the surface of the water, like an Indian chief rehearsing
his feats of war." During the season of love, a musky odour is emitted by
the submaxiliary glands of the crocodile, and pervades their haunts. (55.
Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.)
OPHIDIA.
Dr. Gunther informs me that the males are always smaller than the females,
and generally have longer and slenderer tails; but he knows of no other
difference in external structure. In regard to colour, be can almost
always distinguish the male from the female, by his more strongly-
pronounced tints; thus the black zigzag band on the back of the male
English viper is more distinctly defined than in the female. The
difference is much plainer in the rattle-snakes of N. America, the male of
which, as the keeper in the Zoological Gardens shewed me, can at once be
distinguished from the female by having more lurid yellow about its whole
body. In S. Africa the Bucephalus capensis presents an analogous
difference, for the female "is never so fully variegated with yellow on the
sides as the male." (56. Sir Andrew Smith, 'Zoology of S. Africa:
Reptilia,' 1849, pl. x.) The male of the Indian Dipsas cynodon, on the
other hand, is blackish-brown, with the belly partly black, whilst the
female is reddish or yellowish-olive, with the belly either uniform
yellowish or marbled with black. In the Tragops dispar of the same country
the male is bright green, and the female bronze-coloured. (57. Dr. A.
Gunther, 'Reptiles of British India,' Ray Soc., 1864, pp. 304, 308.) No
doubt the colours of some snakes are protective, as shewn by the green
tints of tree-snakes, and the various mottled shades of the species which
live in sandy places; but it is doubtful whether the colours of many kinds,
for instance of the common English snake and viper, serve to conceal them;
and this is still more doubtful with the many foreign species which are
coloured with extreme elegance. The colours of certain species are very
different in the adult and young states. (58. Dr. Stoliczka, 'Journal of
Asiatic Society of Bengal,' vol. xxxix, 1870, pp. 205, 211.)
During the breeding-season the anal scent-glands of snakes are in active
function (59. Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.); and
so it is with the same glands in lizards, and as we have seen with the
submaxiliary glands of crocodiles. As the males of most animals search for
the females, these odoriferous glands probably serve to excite or charm the
female, rather than to guide her to the spot where the male may be found.
Male snakes, though appearing so sluggish, are amorous; for many have been
observed crowding round the same female, and even round her dead body.
They are not known to fight together from rivalry. Their intellectual
powers are higher than might have been anticipated. In the Zoological
Gardens they soon learn not to strike at the iron bar with which their
cages are cleaned; and Dr. Keen of Philadelphia informs me that some snakes
which he kept learned after four or five times to avoid a noose, with which
they were at first easily caught. An excellent observer in Ceylon, Mr. E.
Layard, saw (60. 'Rambles in Ceylon,' in 'Annals and Magazine of Natural
History,' 2nd series, vol. ix. 1852, p. 333.) a cobra thrust its head
through a narrow hole and swallow a toad. "With this encumbrance he could
not withdraw himself; finding this, he reluctantly disgorged the precious
morsel, which began to move off; this was too much for snake philosophy to
bear, and the toad was again seized, and again was the snake, after violent
efforts to escape, compelled to part with its prey. This time, however, a
lesson had been learnt, and the toad was seized by one leg, withdrawn, and
then swallowed in triumph."
The keeper in the Zoological Gardens is positive that certain snakes, for
instance Crotalus and Python, distinguish him from all other persons.
Cobras kept together in the same cage apparently feel some attachment
towards each other. (61. Dr. Gunther, 'Reptiles of British India,' 1864,
p. 340.)
It does not, however, follow because snakes have some reasoning power,
strong passions and mutual affection, that they should likewise be endowed
with sufficient taste to admire brilliant colours in their partners, so as
to lead to the adornment of the species through sexual selection.
Nevertheless, it is difficult to account in any other manner for the
extreme beauty of certain species; for instance, of the coral-snakes of S.
America, which are of a rich red with black and yellow transverse bands. I
well remember how much surprise I felt at the beauty of the first coral-
snake which I saw gliding across a path in Brazil. Snakes coloured in this
peculiar manner, as Mr. Wallace states on the authority of Dr. Gunther (62.
'Westminster Review,' July 1st, 1867, p. 32.), are found nowhere else in
the world except in S. America, and here no less than four genera occur.
One of these, Elaps, is venomous; a second and widely-distinct genus is
doubtfully venomous, and the two others are quite harmless. The species
belonging to these distinct genera inhabit the same districts, and are so
like each other that no one "but a naturalist would distinguish the
harmless from the poisonous kinds." Hence, as Mr. Wallace believes, the
innocuous kinds have probably acquired their colours as a protection, on
the principle of imitation; for they would naturally be thought dangerous
by their enemies. The cause, however, of the bright colours of the
venomous Elaps remains to be explained, and this may perhaps be sexual
selection.
Snakes produce other sounds besides hissing. The deadly Echis carinata has
on its sides some oblique rows of scales of a peculiar structure with
serrated edges; and when this snake is excited these scales are rubbed
against each other, which produces "a curious prolonged, almost hissing
sound." (63. Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 196.) With
respect to the rattling of the rattle-snake, we have at last some definite
information: for Professor Aughey states (64. The 'American Naturalist,'
1873, p. 85.), that on two occasions, being himself unseen, he watched from
a little distance a rattle-snake coiled up with head erect, which continued
to rattle at short intervals for half an hour: and at last he saw another
snake approach, and when they met they paired. Hence he is satisfied that
one of the uses of the rattle is to bring the sexes together.
Unfortunately he did not ascertain whether it was the male or the female
which remained stationary and called for the other. But it by no means
follows from the above fact that the rattle may not be of use to these
snakes in other ways, as a warning to animals which would otherwise attack
them. Nor can I quite disbelieve the several accounts which have appeared
of their thus paralysing their prey with fear. Some other snakes also make
a distinct noise by rapidly vibrating their tails against the surrounding
stalks of plants; and I have myself heard this in the case of a
Trigonocephalus in S. America.
LACERTILIA.
The males of some, probably of many kinds of lizards, fight together from
rivalry. Thus the arboreal Anolis cristatellus of S. America is extremely
pugnacious: "During the spring and early part of the summer, two adult
males rarely meet without a contest. On first seeing one another, they nod
their heads up and down three or four times, and at the same time expanding
the frill or pouch beneath the throat; their eyes glisten with rage, and
after waving their tails from side to side for a few seconds, as if to
gather energy, they dart at each other furiously, rolling over and over,
and holding firmly with their teeth. The conflict generally ends in one of
the combatants losing his tail, which is often devoured by the victor."
The male of this species is considerably larger than the female (65. Mr.
N.L. Austen kept these animals alive for a considerable time; see 'Land and
Water,' July 1867, p. 9.); and this, as far as Dr. Gunther has been able to
ascertain, is the general rule with lizards of all kinds. The male alone
of the Cyrtodactylus rubidus of the Andaman Islands possesses pre-anal
pores; and these pores, judging from analogy, probably serve to emit an
odour. (66. Stoliczka, 'Journal of the Asiatic Society of Bengal,' vol.
xxxiv. 1870, p. 166.)
[Fig.33. Sitana minor.
Male with the gular pouch expanded (from Gunther's 'Reptiles of India')']
The sexes often differ greatly in various external characters. The male of
the above-mentioned Anolis is furnished with a crest which runs along the
back and tail, and can be erected at pleasure; but of this crest the female
does not exhibit a trace. In the Indian Cophotis ceylanica, the female has
a dorsal crest, though much less developed than in the male; and so it is,
as Dr. Gunther informs me, with the females of many Iguanas, Chameleons,
and other lizards. In some species, however, the crest is equally
developed in both sexes, as in the Iguana tuberculata. In the genus
Sitana, the males alone are furnished with a large throat pouch (Fig. 33),
which can be folded up like a fan, and is coloured blue, black, and red;
but these splendid colours are exhibited only during the pairing-season.
The female does not possess even a rudiment of this appendage. In the
Anolis cristatellus, according to Mr. Austen, the throat pouch, which is
bright red marbled with yellow, is present in the female, though in a
rudimental condition. Again, in certain other lizards, both sexes are
equally well provided with throat pouches. Here we see with species
belonging to the same group, as in so many previous cases, the same
character either confined to the males, or more largely developed in them
than in the females, or again equally developed in both sexes. The little
lizards of the genus Draco, which glide through the air on their rib-
supported parachutes, and which in the beauty of their colours baffle
description, are furnished with skinny appendages to the throat "like the
wattles of gallinaceous birds." These become erected when the animal is
excited. They occur in both sexes, but are best developed when the male
arrives at maturity, at which age the middle appendage is sometimes twice
as long as the head. Most of the species likewise have a low crest running
along the neck; and this is much more developed in the full-grown males
than in the females or young males. (67. All the foregoing statements and
quotations, in regard to Cophotis, Sitana and Draco, as well as the
following facts in regard to Ceratophora and Chamaeleon, are from Dr.
Gunther himself, or from his magnificent work on the 'Reptiles of British
India,' Ray Soc., 1864, pp. 122, 130, 135.)
A Chinese species is said to live in pairs during the spring; "and if one
is caught, the other falls from the tree to the ground, and allows itself
to be captured with impunity"--I presume from despair. (68. Mr. Swinhoe,
'Proc. Zoolog. Soc.' 1870, p. 240.)
[Fig. 34. Ceratophora Stoddartii.
Upper figure;
lower figure, female.]
There are other and much more remarkable differences between the sexes of
certain lizards. The male of Ceratophora aspera bears on the extremity of
his snout an appendage half as long as the head. It is cylindrical,
covered with scales, flexible, and apparently capable of erection: in the
female it is quite rudimental. In a second species of the same genus a
terminal scale forms a minute horn on the summit of the flexible appendage;
and in a third species (C. Stoddartii, fig. 34) the whole appendage is
converted into a horn, which is usually of a white colour, but assumes a
purplish tint when the animal is excited. In the adult male of this latter
species the horn is half an inch in length, but it is of quite minute size
in the female and in the young. These appendages, as Dr. Gunther has
remarked to me, may be compared with the combs of gallinaceous birds, and
apparently serve as ornaments.
[Fig. 35. Chamaeleo bifurcus.
Upper figure, male;
lower figure, female.
Fig. 36. Chamaeleo Owenii.
Upper figure, male;
lower figure, female.]
In the genus Chamaeleon we come to the acme of difference between the
sexes. The upper part of the skull of the male C. bifurcus (Fig. 35), an
inhabitant of Madagascar, is produced into two great, solid, bony
projections, covered with scales like the rest of the head; and of this
wonderful modification of structure the female exhibits only a rudiment.
Again, in Chamaeleo Owenii (Fig. 36), from the West Coast of Africa, the
male bears on his snout and forehead three curious horns, of which the
female has not a trace. These horns consist of an excrescence of bone
covered with a smooth sheath, forming part of the general integuments of
the body, so that they are identical in structure with those of a bull,
goat, or other sheath-horned ruminant. Although the three horns differ so
much in appearance from the two great prolongations of the skull in C.
bifurcus, we can hardly doubt that they serve the same general purpose in
the economy of these two animals. The first conjecture, which will occur
to every one, is that they are used by the males for fighting together; and
as these animals are very quarrelsome (69. Dr. Buchholz, 'Monatsbericht K.
Preuss. Akad.' Jan. 1874, p. 78.), this is probably a correct view. Mr.
T.W. Wood also informs me that he once watched two individuals of C.
pumilus fighting violently on the branch of a tree; they flung their heads
about and tried to bite each other; they then rested for a time and
afterwards continued their battle.
With many lizards the sexes differ slightly in colour, the tints and
stripes of the males being brighter and more distinctly defined than in the
females. This, for instance, is the case with the above Cophotis and with
the Acanthodactylus capensis of S. Africa. In a Cordylus of the latter
country, the male is either much redder or greener than the female. In the
Indian Calotes nigrilabris there is a still greater difference; the lips
also of the male are black, whilst those of the female are green. In our
common little viviparous lizard (Zootoca vivipara) "the under side of the
body and base of the tail in the male are bright orange, spotted with
black; in the female these parts are pale-greyish-green without spots."
(70. Bell, 'History of British Reptiles,' 2nd ed., 1849, p. 40.) We have
seen that the males alone of Sitana possess a throat-pouch; and this is
splendidly tinted with blue, black, and red. In the Proctotretus tenuis of
Chile the male alone is marked with spots of blue, green, and coppery-red.
(71. For Proctotretus, see 'Zoology of the Voyage of the "Beagle";
Reptiles,' by Mr. Bell, p. 8. For the Lizards of S. Africa, see 'Zoology
of S. Africa: Reptiles,' by Sir Andrew Smith, pl. 25 and 39. For the
Indian Calotes, see 'Reptiles of British India,' by Dr. Gunther, p. 143.)
In many cases the males retain the same colours throughout the year, but in
others they become much brighter during the breeding-season; I may give as
an additional instance the Calotes maria, which at this season has a bright
red head, the rest of the body being green. (72. Gunther in 'Proceedings,
Zoological Society,' 1870, p. 778, with a coloured figure.)
Both sexes of many species are beautifully coloured exactly alike; and
there is no reason to suppose that such colours are protective. No doubt
with the bright green kinds which live in the midst of vegetation, this
colour serves to conceal them; and in N. Patagonia I saw a lizard
(Proctotretus multimaculatus) which, when frightened, flattened its body,
closed its eyes, and then from its mottled tints was hardly distinguishable
from the surrounding sand. But the bright colours with which so many
lizards are ornamented, as well as their various curious appendages, were
probably acquired by the males as an attraction, and then transmitted
either to their male offspring alone, or to both sexes. Sexual selection,
indeed, seems to have played almost as important a part with reptiles as
with birds; and the less conspicuous colours of the females in comparison
with the males cannot be accounted for, as Mr. Wallace believes to be the
case with birds, by the greater exposure of the females to danger during
incubation.
CHAPTER XIII.
SECONDARY SEXUAL CHARACTERS OF BIRDS.
Sexual differences--Law of battle--Special weapons--Vocal organs--
Instrumental music--Love-antics and dances--Decorations, permanent and
seasonal--Double and single annual moults--Display of ornaments by the
males.
Secondary sexual characters are more diversified and conspicuous in birds,
though not perhaps entailing more important changes of structure, than in
any other class of animals. I shall, therefore, treat the subject at
considerable length. Male birds sometimes, though rarely, possess special
weapons for fighting with each other. They charm the female by vocal or
instrumental music of the most varied kinds. They are ornamented by all
sorts of combs, wattles, protuberances, horns, air-distended sacks, top-
knots, naked shafts, plumes and lengthened feathers gracefully springing
from all parts of the body. The beak and naked skin about the head, and
the feathers, are often gorgeously coloured. The males sometimes pay their
court by dancing, or by fantastic antics performed either on the ground or
in the air. In one instance, at least, the male emits a musky odour, which
we may suppose serves to charm or excite the female; for that excellent
observer, Mr. Ramsay (1. 'Ibis,' vol. iii. (new series), 1867, p. 414.),
says of the Australian musk-duck (Biziura lobata) that "the smell which the
male emits during the summer months is confined to that sex, and in some
individuals is retained throughout the year; I have never, even in the
breeding-season, shot a female which had any smell of musk." So powerful
is this odour during the pairing-season, that it can be detected long
before the bird can be seen. (2. Gould, 'Handbook of the Birds of
Australia,' 1865, vol. ii. p. 383.) On the whole, birds appear to be the
most aesthetic of all animals, excepting of course man, and they have
nearly the same taste for the beautiful as we have. This is shewn by our
enjoyment of the singing of birds, and by our women, both civilised and
savage, decking their heads with borrowed plumes, and using gems which are
hardly more brilliantly coloured than the naked skin and wattles of certain
birds. In man, however, when cultivated, the sense of beauty is manifestly
a far more complex feeling, and is associated with various intellectual
ideas.
Before treating of the sexual characters with which we are here more
particularly concerned, I may just allude to certain differences between
the sexes which apparently depend on differences in their habits of life;
for such cases, though common in the lower, are rare in the higher classes.
Two humming-birds belonging to the genus Eustephanus, which inhabit the
island of Juan Fernandez, were long thought to be specifically distinct,
but are now known, as Mr. Gould informs me, to be the male and female of
the same species, and they differ slightly in the form of the beak. In
another genus of humming-birds (Grypus), the beak of the male is serrated
along the margin and hooked at the extremity, thus differing much from that
of the female. In the Neomorpha of New Zealand, there is, as we have seen,
a still wider difference in the form of the beak in relation to the manner
of feeding of the two sexes. Something of the same kind has been observed
with the goldfinch (Carduelis elegans), for I am assured by Mr. J. Jenner
Weir that the bird-catchers can distinguish the males by their slightly
longer beaks. The flocks of males are often found feeding on the seeds of
the teazle (Dipsacus), which they can reach with their elongated beaks,
whilst the females more commonly feed on the seeds of the betony or
Scrophularia. With a slight difference of this kind as a foundation, we
can see how the beaks of the two sexes might be made to differ greatly
through natural selection. In some of the above cases, however, it is
possible that the beaks of the males may have been first modified in
relation to their contests with other males; and that this afterwards led
to slightly changed habits of life.
LAW OF BATTLE.
Almost all male birds are extremely pugnacious, using their beaks, wings,
and legs for fighting together. We see this every spring with our robins
and sparrows. The smallest of all birds, namely the humming-bird, is one
of the most quarrelsome. Mr. Gosse (3. Quoted by Mr. Gould, 'Introduction
to the Trochilidae,' 1861, page 29.) describes a battle in which a pair
seized hold of each other's beaks, and whirled round and round, till they
almost fell to the ground; and M. Montes de Oca, in speaking or another
genus of humming-bird, says that two males rarely meet without a fierce
aerial encounter: when kept in cages "their fighting has mostly ended in
the splitting of the tongue of one of the two, which then surely dies from
being unable to feed." (4. Gould, ibid. p. 52.) With waders, the males
of the common water-hen (Gallinula chloropus) "when pairing, fight
violently for the females: they stand nearly upright in the water and
strike with their feet." Two were seen to be thus engaged for half an
hour, until one got hold of the head of the other, which would have been
killed had not the observer interfered; the female all the time looking on
as a quiet spectator. (5. W. Thompson, 'Natural History of Ireland:
Birds,' vol. ii. 1850, p. 327.) Mr. Blyth informs me that the males of an
allied bird (Gallicrex cristatus) are a third larger than the females, and
are so pugnacious during the breeding-season that they are kept by the
natives of Eastern Bengal for the sake of fighting. Various other birds
are kept in India for the same purpose, for instance, the bulbuls
(Pycnonotus hoemorrhous) which "fight with great spirit." (6. Jerdon,
'Birds of India,' 1863, vol. ii. p. 96.)
[Fig. 37. The Ruff or Machetes pugnax (from Brehm's 'Thierleben').]
The polygamous ruff (Machetes pugnax, Fig. 37) is notorious for his extreme
pugnacity; and in the spring, the males, which are considerably larger than
the females, congregate day after day at a particular spot, where the
females propose to lay their eggs. The fowlers discover these spots by the
turf being trampled somewhat bare. Here they fight very much like game-
cocks, seizing each other with their beaks and striking with their wings.
The great ruff of feathers round the neck is then erected, and according to
Col. Montagu "sweeps the ground as a shield to defend the more tender
parts"; and this is the only instance known to me in the case of birds of
any structure serving as a shield. The ruff of feathers, however, from its
varied and rich colours probably serves in chief part as an ornament. Like
most pugnacious birds, they seem always ready to fight, and when closely
confined, often kill each other; but Montagu observed that their pugnacity
becomes greater during the spring, when the long feathers on their necks
are fully developed; and at this period the least movement by any one bird
provokes a general battle. (7. Macgillivray, 'History of British Birds,'
vol. iv. 1852, pp. 177-181.) Of the pugnacity of web-footed birds, two
instances will suffice: in Guiana "bloody fights occur during the
breeding-season between the males of the wild musk-duck (Cairina moschata);
and where these fights have occurred the river is covered for some distance
with feathers." (8. Sir R. Schomburgk, in 'Journal of Royal Geographic
Society,' vol. xiii. 1843, p. 31.) Birds which seem ill-adapted for
fighting engage in fierce conflicts; thus the stronger males of the pelican
drive away the weaker ones, snapping with their huge beaks and giving heavy
blows with their wings. Male snipe fight together, "tugging and pushing
each other with their bills in the most curious manner imaginable." Some
few birds are believed never to fight; this is the case, according to
Audubon, with one of the woodpeckers of the United States (Picu sauratus),
although "the hens are followed by even half a dozen of their gay suitors."
(9. 'Ornithological Biography,' vol. i. p. 191. For pelicans and snipes,
see vol. iii. pp. 138, 477.)
The males of many birds are larger than the females, and this no doubt is
the result of the advantage gained by the larger and stronger males over
their rivals during many generations. The difference in size between the
two sexes is carried to an extreme point in several Australian species;
thus the male musk-duck (Biziura), and the male Cincloramphus cruralis
(allied to our pipits) are by measurement actually twice as large as their
respective females. (10. Gould, 'Handbook of Birds of Australia,' vol. i.
p. 395; vol. ii. p. 383.) With many other birds the females are larger
than the males; and, as formerly remarked, the explanation often given,
namely, that the females have most of the work in feeding their young, will
not suffice. In some few cases, as we shall hereafter see, the females
apparently have acquired their greater size and strength for the sake of
conquering other females and obtaining possession of the males.
The males of many gallinaceous birds, especially of the polygamous kinds,
are furnished with special weapons for fighting with their rivals, namely
spurs, which can be used with fearful effect. It has been recorded by a
trustworthy writer (11. Mr. Hewitt, in the 'Poultry Book' by Tegetmeier,
1866, p. 137.) that in Derbyshire a kite struck at a game-hen accompanied
by her chickens, when the cock rushed to the rescue, and drove his spur
right through the eye and skull of the aggressor. The spur was with
difficulty drawn from the skull, and as the kite, though dead, retained his
grasp, the two birds were firmly locked together; but the cock when
disentangled was very little injured. The invincible courage of the game-
cock is notorious: a gentleman who long ago witnessed the brutal scene,
told me that a bird had both its legs broken by some accident in the
cockpit, and the owner laid a wager that if the legs could be spliced so
that the bird could stand upright, he would continue fighting. This was
effected on the spot, and the bird fought with undaunted courage until he
received his death-stroke. In Ceylon a closely allied, wild species, the
Gallus Stanleyi, is known to fight desperately "in defence of his
seraglio," so that one of the combatants is frequently found dead. (12.
Layard, 'Annals and Magazine of Natural History,' vol. xiv. 1854, p. 63.)
An Indian partridge (Ortygornis gularis), the male of which is furnished
with strong and sharp spurs, is so quarrelsome "that the scars of former
fights disfigure the breast of almost every bird you kill." (13. Jerdon,
'Birds of India,' vol. iii. p. 574.)
The males of almost all gallinaceous birds, even those which are not
furnished with spurs, engage during the breeding-season in fierce
conflicts. The Capercailzie and Black-cock (Tetrao urogallus and T.
tetrix), which are both polygamists, have regular appointed places, where
during many weeks they congregate in numbers to fight together and to
display their charms before the females. Dr. W. Kovalevsky informs me that
in Russia he has seen the snow all bloody on the arenas where the
capercailzie have fought; and the black-cocks "make the feathers fly in
every direction," when several "engage in a battle royal." The elder Brehm
gives a curious account of the Balz, as the love-dances and love-songs of
the Black-cock are called in Germany. The bird utters almost continuously
the strangest noises: "he holds his tail up and spreads it out like a fan,
he lifts up his head and neck with all the feathers erect, and stretches
his wings from the body. Then he takes a few jumps in different
directions, sometimes in a circle, and presses the under part of his beak
so hard against the ground that the chin feathers are rubbed off. During
these movements he beats his wings and turns round and round. The more
ardent he grows the more lively he becomes, until at last the bird appears
like a frantic creature." At such times the black-cocks are so absorbed
that they become almost blind and deaf, but less so than the capercailzie:
hence bird after bird may be shot on the same spot, or even caught by the
hand. After performing these antics the males begin to fight: and the
same black-cock, in order to prove his strength over several antagonists,
will visit in the course of one morning several Balz-places, which remain
the same during successive years. (14. Brehm, 'Thierleben,' 1867, B. iv.
s. 351. Some of the foregoing statements are taken from L. Lloyd, 'The
Game Birds of Sweden,' etc., 1867, p. 79.)
The peacock with his long train appears more like a dandy than a warrior,
but he sometimes engages in fierce contests: the Rev. W. Darwin Fox
informs me that at some little distance from Chester two peacocks became so
excited whilst fighting, that they flew over the whole city, still engaged,
until they alighted on the top of St. John's tower.
The spur, in those gallinaceous birds which are thus provided, is generally
single; but Polyplectron (Fig. 51) has two or more on each leg; and one of
the Blood-pheasants (Ithaginis cruentus) has been seen with five spurs.
The spurs are generally confined to the male, being represented by mere
knobs or rudiments in the female; but the females of the Java peacock (Pavo
muticus) and, as I am informed by Mr. Blyth, of the small fire-backed
pheasant (Euplocamus erythrophthalmus) possess spurs. In Galloperdix it is
usual for the males to have two spurs, and for the females to have only one
on each leg. (15. Jerdon, 'Birds of India': on Ithaginis, vol. iii. p.
523; on Galloperdix, p. 541.) Hence spurs may be considered as a masculine
structure, which has been occasionally more or less transferred to the
females. Like most other secondary sexual characters, the spurs are highly
variable, both in number and development, in the same species.
[Fig.38. Palamedea cornuta (from Brehm), shewing the double wing-spurs,
and the filament on the head.]
Various birds have spurs on their wings. But the Egyptian goose
(Chenalopex aegyptiacus) has only "bare obtuse knobs," and these probably
shew us the first steps by which true spurs have been developed in other
species. In the spur-winged goose, Plectropterus gambensis, the males have
much larger spurs than the females; and they use them, as I am informed by
Mr. Bartlett, in fighting together, so that, in this case, the wing-spurs
serve as sexual weapons; but according to Livingstone, they are chiefly
used in the defence of the young. The Palamedea (Fig. 38) is armed with a
pair of spurs on each wing; and these are such formidable weapons that a
single blow has been known to drive a dog howling away. But it does not
appear that the spurs in this case, or in that of some of the spur-winged
rails, are larger in the male than in the female. (16. For the Egyptian
goose, see Macgillivray, 'British Birds,' vol. iv. p. 639. For
Plectropterus, Livingstone's 'Travels,' p. 254. For Palamedea, Brehm's
'Thierleben,' B. iv. s. 740. See also on this bird Azara, 'Voyages dans
l'Amerique merid.' tom. iv. 1809, pp. 179, 253.) In certain plovers,
however, the wing-spurs must be considered as a sexual character. Thus in
the male of our common peewit (Vanellus cristatus) the tubercle on the
shoulder of the wing becomes more prominent during the breeding-season, and
the males fight together. In some species of Lobivanellus a similar
tubercle becomes developed during the breeding-season "into a short horny
spur." In the Australian L. lobatus both sexes have spurs, but these are
much larger in the males than in the females. In an allied bird, the
Hoplopterus armatus, the spurs do not increase in size during the breeding-
season; but these birds have been seen in Egypt to fight together, in the
same manner as our peewits, by turning suddenly in the air and striking
sideways at each other, sometimes with fatal results. Thus also they drive
away other enemies. (17. See, on our peewit, Mr. R. Carr in 'Land and
Water,' Aug. 8th, 1868, p. 46. In regard to Lobivanellus, see Jerdon's
'Birds of India,' vol. iii. p. 647, and Gould's 'Handbook of Birds of
Australia,' vol. ii. p. 220. For the Hoplopterus, see Mr. Allen in the
'Ibis,' vol. v. 1863, p. 156.)
The season of love is that of battle; but the males of some birds, as of
the game-fowl and ruff, and even the young males of the wild turkey and
grouse (18. Audubon, 'Ornithological Biography,' vol. ii. p. 492; vol. i.
pp. 4-13.), are ready to fight whenever they meet. The presence of the
female is the teterrima belli causa. The Bengali baboos make the pretty
little males of the amadavat (Estrelda amandava) fight together by placing
three small cages in a row, with a female in the middle; after a little
time the two males are turned loose, and immediately a desperate battle
ensues. (19. Mr. Blyth, 'Land and Water,' 1867, p. 212.) When many males
congregate at the same appointed spot and fight together, as in the case of
grouse and various other birds, they are generally attended by the females
(20. Richardson on Tetrao umbellus, 'Fauna Bor. Amer.: Birds,' 1831, p.
343. L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 22, 79, on the
capercailzie and black-cock. Brehm, however, asserts ('Thierleben,' B. iv.
s. 352) that in Germany the grey-hens do not generally attend the Balzen of
the black-cocks, but this is an exception to the common rule; possibly the
hens may lie hidden in the surrounding bushes, as is known to be the case
with the gray-hens in Scandinavia, and with other species in N. America.),
which afterwards pair with the victorious combatants. But in some cases
the pairing precedes instead of succeeding the combat: thus according to
Audubon (21. 'Ornithological Biography,' vol. ii. p. 275.), several males
of the Virginian goat-sucker (Caprimulgus virgianus) "court, in a highly
entertaining manner the female, and no sooner has she made her choice, than
her approved gives chase to all intruders, and drives them beyond his
dominions." Generally the males try to drive away or kill their rivals
before they pair. It does not, however, appear that the females invariably
prefer the victorious males. I have indeed been assured by Dr. W.
Kovalevsky that the female capercailzie sometimes steals away with a young
male who has not dared to enter the arena with the older cocks, in the same
manner as occasionally happens with the does of the red-deer in Scotland.
When two males contend in presence of a single female, the victor, no
doubt, commonly gains his desire; but some of these battles are caused by
wandering males trying to distract the peace of an already mated pair.
(22. Brehm, 'Thierleben,' etc., B. iv. 1867, p. 990. Audubon,
'Ornithological Biography,' vol. ii. p. 492.)
Even with the most pugnacious species it is probable that the pairing does
not depend exclusively on the mere strength and courage of the male; for
such males are generally decorated with various ornaments, which often
become more brilliant during the breeding-season, and which are sedulously
displayed before the females. The males also endeavour to charm or excite
their mates by love-notes, songs, and antics; and the courtship is, in many
instances, a prolonged affair. Hence it is not probable that the females
are indifferent to the charms of the opposite sex, or that they are
invariably compelled to yield to the victorious males. It is more probable
that the females are excited, either before or after the conflict, by
certain males, and thus unconsciously prefer them. In the case of Tetrao
umbellus, a good observer (23. 'Land and Water,' July 25, 1868, p. 14.)
goes so far as to believe that the battles of the male "are all a sham,
performed to show themselves to the greatest advantage before the admiring
females who assemble around; for I have never been able to find a maimed
hero, and seldom more than a broken feather." I shall have to recur to
this subject, but I may here add that with the Tetrao cupido of the United
States, about a score of males assemble at a particular spot, and,
strutting about, make the whole air resound with their extraordinary
noises. At the first answer from a female the males begin to fight
furiously, and the weaker give way; but then, according to Audubon, both
the victors and vanquished search for the female, so that the females must
either then exert a choice, or the battle must be renewed. So, again, with
one of the field-starlings of the United States (Sturnella ludoviciana) the
males engage in fierce conflicts, "but at the sight of a female they all
fly after her as if mad." (24. Audubon's 'Ornithological Biography;' on
Tetrao cupido, vol. ii. p. 492; on the Sturnus, vol. ii. p. 219.)
VOCAL AND INSTRUMENTAL MUSIC.
With birds the voice serves to express various emotions, such as distress,
fear, anger, triumph, or mere happiness. It is apparently sometimes used
to excite terror, as in the case of the hissing noise made by some
nestling-birds. Audubon (25. 'Ornithological Biography,' vol. v. p.
601.), relates that a night-heron (Ardea nycticorax, Linn.), which he kept
tame, used to hide itself when a cat approached, and then "suddenly start
up uttering one of the most frightful cries, apparently enjoying the cat's
alarm and flight." The common domestic cock clucks to the hen, and the hen
to her chickens, when a dainty morsel is found. The hen, when she has laid
an egg, "repeats the same note very often, and concludes with the sixth
above, which she holds for a longer time" (26. The Hon. Daines Barrington,
'Philosophical Transactions,' 1773, p. 252.); and thus she expresses her
joy. Some social birds apparently call to each other for aid; and as they
flit from tree to tree, the flock is kept together by chirp answering
chirp. During the nocturnal migrations of geese and other water-fowl,
sonorous clangs from the van may be heard in the darkness overhead,
answered by clangs in the rear. Certain cries serve as danger signals,
which, as the sportsman knows to his cost, are understood by the same
species and by others. The domestic cock crows, and the humming-bird
chirps, in triumph over a defeated rival. The true song, however, of most
birds and various strange cries are chiefly uttered during the breeding-
season, and serve as a charm, or merely as a call-note, to the other sex.
Naturalists are much divided with respect to the object of the singing of
birds. Few more careful observers ever lived than Montagu, and he
maintained that the "males of song-birds and of many others do not in
general search for the female, but, on the contrary, their business in the
spring is to perch on some conspicuous spot, breathing out their full and
armorous notes, which, by instinct, the female knows, and repairs to the
spot to choose her mate." (27. 'Ornithological Dictionary,' 1833, p.
475.) Mr. Jenner Weir informs me that this is certainly the case with the
nightingale. Bechstein, who kept birds during his whole life, asserts,
"that the female canary always chooses the best singer, and that in a state
of nature the female finch selects that male out of a hundred whose notes
please her most." (28. 'Naturgeschichte der Stubenvogel,' 1840, s. 4.
Mr. Harrison Weir likewise writes to me:--"I am informed that the best
singing males generally get a mate first, when they are bred in the same
room.") There can be no doubt that birds closely attend to each other's
song. Mr. Weir has told me of the case of a bullfinch which had been
taught to pipe a German waltz, and who was so good a performer that he cost
ten guineas; when this bird was first introduced into a room where other
birds were kept and he began to sing, all the others, consisting of about
twenty linnets and canaries, ranged themselves on the nearest side of their
cages, and listened with the greatest interest to the new performer. Many
naturalists believe that the singing of birds is almost exclusively "the
effect of rivalry and emulation," and not for the sake of charming their
mates. This was the opinion of Daines Barrington and White of Selborne,
who both especially attended to this subject. (29. 'Philosophical
Transactions,' 1773, p. 263. White's 'Natural History of Selborne,' 1825,
vol. i. p. 246.) Barrington, however, admits that "superiority in song
gives to birds an amazing ascendancy over others, as is well known to bird-
catchers."
It is certain that there is an intense degree of rivalry between the males
in their singing. Bird-fanciers match their birds to see which will sing
longest; and I was told by Mr. Yarrell that a first-rate bird will
sometimes sing till he drops down almost dead, or according to Bechstein
(30. 'Naturgesch. der Stubenvogel,' 1840, s. 252.), quite dead from
rupturing a vessel in the lungs. Whatever the cause may be, male birds, as
I hear from Mr. Weir, often die suddenly during the season of song. That
the habit of singing is sometimes quite independent of love is clear, for a
sterile, hybrid canary-bird has been described (31. Mr. Bold, 'Zoologist,'
1843-44, p. 659.) as singing whilst viewing itself in a mirror, and then
dashing at its own image; it likewise attacked with fury a female canary,
when put into the same cage. The jealousy excited by the act of singing is
constantly taken advantage of by bird-catchers; a male, in good song, is
hidden and protected, whilst a stuffed bird, surrounded by limed twigs, is
exposed to view. In this manner, as Mr. Weir informs me, a man has in the
course of a single day caught fifty, and in one instance, seventy, male
chaffinches. The power and inclination to sing differ so greatly with
birds that although the price of an ordinary male chaffinch is only
sixpence, Mr. Weir saw one bird for which the bird-catcher asked three
pounds; the test of a really good singer being that it will continue to
sing whilst the cage is swung round the owner's head.
That male birds should sing from emulation as well as for charming the
female, is not at all incompatible; and it might have been expected that
these two habits would have concurred, like those of display and pugnacity.
Some authors, however, argue that the song of the male cannot serve to
charm the female, because the females of some few species, such as of the
canary, robin, lark, and bullfinch, especially when in a state of
widowhood, as Bechstein remarks, pour forth fairly melodious strains. In
some of these cases the habit of singing may be in part attributed to the
females having been highly fed and confined (32. D. Barrington,
'Philosophical Transactions,' 1773, p. 262. Bechstein, 'Stubenvogel,'
1840, s. 4.), for this disturbs all the functions connected with the
reproduction of the species. Many instances have already been given of the
partial transference of secondary masculine characters to the female, so
that it is not at all surprising that the females of some species should
possess the power of song. It has also been argued, that the song of the
male cannot serve as a charm, because the males of certain species, for
instance of the robin, sing during the autumn. (33. This is likewise the
case with the water-ouzel; see Mr. Hepburn in the 'Zoologist,' 1845-46, p.
1068.) But nothing is more common than for animals to take pleasure in
practising whatever instinct they follow at other times for some real good.
How often do we see birds which fly easily, gliding and sailing through the
air obviously for pleasure? The cat plays with the captured mouse, and the
cormorant with the captured fish. The weaver-bird (Ploceus), when confined
in a cage, amuses itself by neatly weaving blades of grass between the
wires of its cage. Birds which habitually fight during the breeding-season
are generally ready to fight at all times; and the males of the
capercailzie sometimes hold their Balzen or leks at the usual place of
assemblage during the autumn. (34. L. Lloyd, 'Game Birds of Sweden,'
1867, p. 25.) Hence it is not at all surprising that male birds should
continue singing for their own amusement after the season for courtship is
over.
As shewn in a previous chapter, singing is to a certain extent an art, and
is much improved by practice. Birds can be taught various tunes, and even
the unmelodious sparrow has learnt to sing like a linnet. They acquire the
song of their foster parents (35. Barrington, ibid. p. 264, Bechstein,
ibid. s. 5.), and sometimes that of their neighbours. (36. Dureau de la
Malle gives a curious instance ('Annales des Sc. Nat.' 3rd series, Zoolog.,
tom. x. p. 118) of some wild blackbirds in his garden in Paris, which
naturally learnt a republican air from a caged bird.) All the common
songsters belong to the Order of Insessores, and their vocal organs are
much more complex than those of most other birds; yet it is a singular fact
that some of the Insessores, such as ravens, crows, and magpies, possess
the proper apparatus (37. Bishop, in 'Todd's Cyclopaedia of Anatomy and
Physiology,' vol. iv. p. 1496.), though they never sing, and do not
naturally modulate their voices to any great extent. Hunter asserts (38.
As stated by Barrington in 'Philosophical Transactions,' 1773, p. 262.)
that with the true songsters the muscles of the larynx are stronger in the
males than in the females; but with this slight exception there is no
difference in the vocal organs of the two sexes, although the males of most
species sing so much better and more continuously than the females.
It is remarkable that only small birds properly sing. The Australian genus
Menura, however, must be excepted; for the Menura Alberti, which is about
the size of a half-grown turkey, not only mocks other birds, but "its own
whistle is exceedingly beautiful and varied." The males congregate and
form "corroborying places," where they sing, raising and spreading their
tails like peacocks, and drooping their wings. (39. Gould, 'Handbook to
the Birds of Australia,' vol. i. 1865, pp. 308-310. See also Mr. T.W. Wood
in the 'Student,' April 1870, p. 125.) It is also remarkable that birds
which sing well are rarely decorated with brilliant colours or other
ornaments. Of our British birds, excepting the bullfinch and goldfinch,
the best songsters are plain-coloured. The kingfisher, bee-eater, roller,
hoopoe, woodpeckers, etc., utter harsh cries; and the brilliant birds of
the tropics are hardly ever songsters. (40. See remarks to this effect in
Gould's 'Introduction to the Trochilidae,' 1861, p. 22.) Hence bright
colours and the power of song seem to replace each other. We can perceive
that if the plumage did not vary in brightness, or if bright colours were
dangerous to the species, other means would be employed to charm the
females; and melody of voice offers one such means.
[Fig. 39. Tetrao cupido: male. (T.W. Wood.)]
In some birds the vocal organs differ greatly in the two sexes. In the
Tetrao cupido (Fig. 39) the male has two bare, orange-coloured sacks, one
on each side of the neck; and these are largely inflated when the male,
during the breeding-season, makes his curious hollow sound, audible at a
great distance. Audubon proved that the sound was intimately connected
with this apparatus (which reminds us of the air-sacks on each side of the
mouth of certain male frogs), for he found that the sound was much
diminished when one of the sacks of a tame bird was pricked, and when both
were pricked it was altogether stopped. The female has "a somewhat
similar, though smaller naked space of skin on the neck; but this is not
capable of inflation." (41. 'The Sportsman and Naturalist in Canada,' by
Major W. Ross King, 1866, pp. 144-146. Mr. T.W. Wood gives in the
'Student' (April 1870, p. 116) an excellent account of the attitude and
habits of this bird during its courtship. He states that the ear-tufts or
neck-plumes are erected, so that they meet over the crown of the head. See
his drawing, Fig. 39.) The male of another kind of grouse (Tetrao
urophasianus), whilst courting the female, has his "bare yellow oesophagus
inflated to a prodigious size, fully half as large as the body"; and he
then utters various grating, deep, hollow tones. With his neck-feathers
erect, his wings lowered, and buzzing on the ground, and his long pointed
tail spread out like a fan, he displays a variety of grotesque attitudes.
The oesophagus of the female is not in any way remarkable. (42.
Richardson, 'Fauna Bor. American: Birds,' 1831, p. 359. Audubon, ibid.
vol. iv. p. 507.)
[Fig. 40. The Umbrella-bird or Cephalopterus ornatus, male (from Brehm).]
It seems now well made out that the great throat pouch of the European male
bustard (Otis tarda), and of at least four other species, does not, as was
formerly supposed, serve to hold water, but is connected with the utterance
during the breeding-season of a peculiar sound resembling "oak." (43. The
following papers have been lately written on this subject: Prof. A.
Newton, in the 'Ibis,' 1862, p. 107; Dr. Cullen, ibid. 1865, p. 145; Mr.
Flower, in 'Proc. Zool. Soc.' 1865, p. 747; and Dr. Murie, in 'Proc. Zool.
Soc.' 1868, p. 471. In this latter paper an excellent figure is given of
the male Australian Bustard in full display with the sack distended. It is
a singular fact that the sack is not developed in all the males of the same
species.) A crow-like bird inhabiting South America (see Cephalopterus
ornatus, Fig. 40) is called the umbrella-bird, from its immense top knot,
formed of bare white quills surmounted by dark-blue plumes, which it can
elevate into a great dome no less than five inches in diameter, covering
the whole head. This bird has on its neck a long, thin, cylindrical fleshy
appendage, which is thickly clothed with scale-like blue feathers. It
probably serves in part as an ornament, but likewise as a resounding
apparatus; for Mr. Bates found that it is connected "with an unusual
development of the trachea and vocal organs." It is dilated when the bird
utters its singularly deep, loud and long sustained fluty note. The head-
crest and neck-appendage are rudimentary in the female. (44. Bates, 'The
Naturalist on the Amazons,' 1863, vol. ii. p. 284; Wallace, in
'Proceedings, Zoological Society,' 1850, p. 206. A new species, with a
still larger neck-appendage (C. penduliger), has lately been discovered,
see 'Ibis,' vol. i. p. 457.)
The vocal organs of various web-footed and wading birds are extraordinarily
complex, and differ to a certain extent in the two sexes. In some cases
the trachea is convoluted, like a French horn, and is deeply embedded in
the sternum. In the wild swan (Cygnus ferus) it is more deeply embedded in
the adult male than in the adult female or young male. In the male
Merganser the enlarged portion of the trachea is furnished with an
additional pair of muscles. (45. Bishop, in Todd's 'Cyclopaedia of
Anatomy and Physiology,' vol. iv. p. 1499.) In one of the ducks, however,
namely Anas punctata, the bony enlargement is only a little more developed
in the male than in the female. (46. Prof. Newton, 'Proc. Zoolog. Soc.'
1871, p. 651.) But the meaning of these differences in the trachea of the
two sexes of the Anatidae is not understood; for the male is not always the
more vociferous; thus with the common duck, the male hisses, whilst the
female utters a loud quack. (47. The spoonbill (Platalea) has its trachea
convoluted into a figure of eight, and yet this bird (Jerdon, 'Birds of
India,' vol. iii. p. 763) is mute; but Mr. Blyth informs me that the
convolutions are not constantly present, so that perhaps they are now
tending towards abortion.) In both sexes of one of the cranes (Grus virgo)
the trachea penetrates the sternum, but presents "certain sexual
modifications." In the male of the black stork there is also a well-marked
sexual difference in the length and curvature of the bronchi. (48.
'Elements of Comparative Anatomy,' by R. Wagner, Eng. translat. 1845, p.
111. With respect to the swan, as given above, Yarrell's 'History of
British Birds,' 2nd edition, 1845, vol. iii. p. 193.) Highly important
structures have, therefore, in these cases been modified according to sex.
It is often difficult to conjecture whether the many strange cries and
notes uttered by male birds during the breeding-season serve as a charm or
merely as a call to the female. The soft cooing of the turtle-dove and of
many pigeons, it may be presumed, pleases the female. When the female of
the wild turkey utters her call in the morning, the male answers by a note
which differs from the gobbling noise made, when with erected feathers,
rustling wings and distended wattles, he puffs and struts before her. (49.
C.L. Bonaparte, quoted in the 'Naturalist Library: Birds,' vol. xiv. p.
126.) The spel of the black-cock certainly serves as a call to the female,
for it has been known to bring four or five females from a distance to a
male under confinement; but as the black-cock continues his spel for hours
during successive days, and in the case of the capercailzie "with an agony
of passion," we are led to suppose that the females which are present are
thus charmed. (50. L. Lloyd, 'The Game Birds of Sweden,' etc., 1867, pp.
22, 81.) The voice of the common rook is known to alter during the
breeding-season, and is therefore in some way sexual. (51. Jenner,
'Philosophical Transactions,' 1824, p. 20.) But what shall we say about
the harsh screams of, for instance, some kinds of macaws; have these birds
as bad taste for musical sounds as they apparently have for colour, judging
by the inharmonious contrast of their bright yellow and blue plumage? It
is indeed possible that without any advantage being thus gained, the loud
voices of many male birds may be the result of the inherited effects of the
continued use of their vocal organs when excited by the strong passions of
love, jealousy and rage; but to this point we shall recur when we treat of
quadrupeds.
We have as yet spoken only of the voice, but the males of various birds
practise, during their courtship, what may be called instrumental music.
Peacocks and Birds of Paradise rattle their quills together. Turkey-cocks
scrape their wings against the ground, and some kinds of grouse thus
produce a buzzing sound. Another North American grouse, the Tetrao
umbellus, when with his tail erect, his ruffs displayed, "he shows off his
finery to the females, who lie hid in the neighbourhood," drums by rapidly
striking his wings together above his back, according to Mr. R. Haymond,
and not, as Audubon thought, by striking them against his sides. The sound
thus produced is compared by some to distant thunder, and by others to the
quick roll of a drum. The female never drums, "but flies directly to the
place where the male is thus engaged." The male of the Kalij-pheasant, in
the Himalayas, often makes a singular drumming noise with his wings, not
unlike the sound produced by shaking a stiff piece of cloth." On the west
coast of Africa the little black-weavers (Ploceus?) congregate in a small
party on the bushes round a small open space, and sing and glide through
the air with quivering wings, "which make a rapid whirring sound like a
child's rattle." One bird after another thus performs for hours together,
but only during the courting-season. At this season, and at no other time,
the males of certain night-jars (Caprimulgus) make a strange booming noise
with their wings. The various species of woodpeckers strike a sonorous
branch with their beaks, with so rapid a vibratory movement that "the head
appears to be in two places at once." The sound thus produced is audible
at a considerable distance but cannot be described; and I feel sure that
its source would never be conjectured by any one hearing it for the first
time. As this jarring sound is made chiefly during the breeding-season, it
has been considered as a love-song; but it is perhaps more strictly a love-
call. The female, when driven from her nest, has been observed thus to
call her mate, who answered in the same manner and soon appeared. Lastly,
the male hoopoe (Upupa epops) combines vocal and instrumental music; for
during the breeding-season this bird, as Mr. Swinhoe observed, first draws
in air, and then taps the end of its beak perpendicularly down against a
stone or the trunk of a tree, "when the breath being forced down the
tubular bill produces the correct sound." If the beak is not thus struck
against some object, the sound is quite different. Air is at the same time
swallowed, and the oesophagus thus becomes much swollen; and this probably
acts as a resonator, not only with the hoopoe, but with pigeons and other
birds. (52. For the foregoing facts see, on Birds of Paradise, Brehm,
'Thierleben,' Band iii. s. 325. On Grouse, Richardson, 'Fauna Bor.
Americ.: Birds,' pp. 343 and 359; Major W. Ross King, 'The Sportsman in
Canada,' 1866, p. 156; Mr. Haymond, in Prof. Cox's 'Geol. Survey of
Indiana,' p. 227; Audubon, 'American Ornitholog. Biograph.' vol. i. p. 216.
On the Kalij-pheasant, Jerdon, 'Birds of India,' vol. iii. p. 533. On the
Weavers, Livingstone's 'Expedition to the Zambesi,' 1865, p. 425. On
Woodpeckers, Macgillivray, 'Hist. of British Birds,' vol. iii. 1840, pp.
84, 88, 89, and 95. On the Hoopoe, Mr. Swinhoe, in 'Proc. Zoolog. Soc.'
June 23, 1863 and 1871, p. 348. On the Night-jar, Audubon, ibid. vol. ii.
p. 255, and 'American Naturalist,' 1873, p. 672. The English Night-jar
likewise makes in the spring a curious noise during its rapid flight.)
[Fig. 41. Outer tail-feather of Scolopax gallinago (from 'Proc. Zool.
Soc.' 1858).
Fig. 42. Outer tail-feather of Scolopax frenata.
Fig. 43. Outer tail-feather of Scolopax javensis.]
In the foregoing cases sounds are made by the aid of structures already
present and otherwise necessary; but in the following cases certain
feathers have been specially modified for the express purpose of producing
sounds. The drumming, bleating, neighing, or thundering noise (as
expressed by different observers) made by the common snipe (Scolopax
gallinago) must have surprised every one who has ever heard it. This bird,
during the pairing-season, flies to "perhaps a thousand feet in height,"
and after zig-zagging about for a time descends to the earth in a curved
line, with outspread tail and quivering pinions, and surprising velocity.
The sound is emitted only during this rapid descent. No one was able to
explain the cause until M. Meves observed that on each side of the tail the
outer feathers are peculiarly formed (Fig. 41), having a stiff sabre-shaped
shaft with the oblique barbs of unusual length, the outer webs being
strongly bound together. He found that by blowing on these feathers, or by
fastening them to a long thin stick and waving them rapidly through the
air, he could reproduce the drumming noise made by the living bird. Both
sexes are furnished with these feathers, but they are generally larger in
the male than in the female, and emit a deeper note. In some species, as
in S. frenata (Fig. 42), four feathers, and in S. javensis (Fig. 43), no
less than eight on each side of the tail are greatly modified. Different
tones are emitted by the feathers of the different species when waved
through the air; and the Scolopax Wilsonii of the United States makes a
switching noise whilst descending rapidly to the earth. (53. See M.
Meves' interesting paper in 'Proc. Zool. Soc.' 1858, p. 199. For the
habits of the snipe, Macgillivray, 'History of British Birds,' vol. iv. p.
371. For the American snipe, Capt. Blakiston, 'Ibis,' vol. v. 1863, p.
131.)
[Fig. 44. Primary wing-feather of a Humming-bird, the Selasphorus
platycercus (from a sketch by Mr. Salvin).
Upper figure, that of male;
lower figure, corresponding feather of female.]
In the male of the Chamaepetes unicolor (a large gallinaceous bird of
America), the first primary wing-feather is arched towards the tip and is
much more attenuated than in the female. In an allied bird, the Penelope
nigra, Mr. Salvin observed a male, which, whilst it flew downwards "with
outstretched wings, gave forth a kind of crashing rushing noise," like the
falling of a tree. (54. Mr. Salvin, in 'Proceedings, Zoological Society,'
1867, p. 160. I am much indebted to this distinguished ornithologist for
sketches of the feathers of the Chamaepetes, and for other information.)
The male alone of one of the Indian bustards (Sypheotides auritus) has its
primary wing-feathers greatly acuminated; and the male of an allied species
is known to make a humming noise whilst courting the female. (55. Jerdon,
'Birds of India,' vol. iii. pp. 618, 621.) In a widely different group of
birds, namely Humming-birds, the males alone of certain kinds have either
the shafts of their primary wing-feathers broadly dilated, or the webs
abruptly excised towards the extremity. The male, for instance, of
Selasphorus platycercus, when adult, has the first primary wing-feather
(Fig. 44), thus excised. Whilst flying from flower to flower he makes "a
shrill, almost whistling noise" (56. Gould, 'Introduction to the
Trochilidae,' 1861, p. 49. Salvin, 'Proceedings, Zoological Society,'
1867, p. 160.); but it did not appear to Mr. Salvin that the noise was
intentionally made.
[Fig. 45. Secondary wing-feathers of Pipra deliciosa (from Mr. Sclater, in
'Proc. Zool. Soc.' 1860).
The three upper feathers, a, b, c, from the male;
the three lower corresponding feathers, d, e, f, from the female.
a and d, fifth secondary wing-feather of male and female, upper surface.
b and e, sixth secondary, upper surface.
c and f, seventh secondary, lower surface.]
Lastly, in several species of a sub-genus of Pipra or Manakin, the males,
as described by Mr. Sclater, have their SECONDARY wing-feathers modified in
a still more remarkable manner. In the brilliantly-coloured P. deliciosa
the first three secondaries are thick-stemmed and curved towards the body;
in the fourth and fifth (Fig. 45, a) the change is greater; and in the
sixth and seventh (b, c) the shaft "is thickened to an extraordinary
degree, forming a solid horny lump." The barbs also are greatly changed in
shape, in comparison with the corresponding feathers (d, e, f) in the
female. Even the bones of the wing, which support these singular feathers
in the male, are said by Mr. Fraser to be much thickened. These little
birds make an extraordinary noise, the first "sharp note being not unlike
the crack of a whip." (57. Sclater, in 'Proceedings, Zoological Society,'
1860, p. 90, and in 'Ibis,' vol. iv. 1862, p. 175. Also Salvin, in 'Ibis,'
1860, p. 37.)
The diversity of the sounds, both vocal and instrumental, made by the males
of many birds during the breeding-season, and the diversity of the means
for producing such sounds, are highly remarkable. We thus gain a high idea
of their importance for sexual purposes, and are reminded of the conclusion
arrived at as to insects. It is not difficult to imagine the steps by
which the notes of a bird, primarily used as a mere call or for some other
purpose, might have been improved into a melodious love song. In the case
of the modified feathers, by which the drumming, whistling, or roaring
noises are produced, we know that some birds during their courtship
flutter, shake, or rattle their unmodified feathers together; and if the
females were led to select the best performers, the males which possessed
the strongest or thickest, or most attenuated feathers, situated on any
part of the body, would be the most successful; and thus by slow degrees
the feathers might be modified to almost any extent. The females, of
course, would not notice each slight successive alteration in shape, but
only the sounds thus produced. It is a curious fact that in the same class
of animals, sounds so different as the drumming of the snipe's tail, the
tapping of the woodpecker's beak, the harsh trumpet-like cry of certain
water-fowl, the cooing of the turtle-dove, and the song of the nightingale,
should all be pleasing to the females of the several species. But we must
not judge of the tastes of distinct species by a uniform standard; nor must
we judge by the standard of man's taste. Even with man, we should remember
what discordant noises, the beating of tom-toms and the shrill notes of
reeds, please the ears of savages. Sir S. Baker remarks (58. 'The Nile
Tributaries of Abyssinia,' 1867, p. 203.), that "as the stomach of the Arab
prefers the raw meat and reeking liver taken hot from the animal, so does
his ear prefer his equally coarse and discordant music to all other."
LOVE ANTICS AND DANCES.
The curious love gestures of some birds have already been incidentally
noticed; so that little need here be added. In Northern America large
numbers of a grouse, the Tetrao phasianellus, meet every morning during the
breeding-season on a selected level spot, and here they run round and round
in a circle of about fifteen or twenty feet in diameter, so that the ground
is worn quite bare, like a fairy-ring. In these Partridge-dances, as they
are called by the hunters, the birds assume the strangest attitudes, and
run round, some to the left and some to the right. Audubon describes the
males of a heron (Ardea herodias) as walking about on their long legs with
great dignity before the females, bidding defiance to their rivals. With
one of the disgusting carrion-vultures (Cathartes jota) the same naturalist
states that "the gesticulations and parade of the males at the beginning of
the love-season are extremely ludicrous." Certain birds perform their
love-antics on the wing, as we have seen with the black African weaver,
instead of on the ground. During the spring our little white-throat
(Sylvia cinerea) often rises a few feet or yards in the air above some
bush, and "flutters with a fitful and fantastic motion, singing all the
while, and then drops to its perch." The great English bustard throws
himself into indescribably odd attitudes whilst courting the female, as has
been figured by Wolf. An allied Indian bustard (Otis bengalensis) at such
times "rises perpendicularly into the air with a hurried flapping of his
wings, raising his crest and puffing out the feathers of his neck and
breast, and then drops to the ground;" he repeats this manoeuvre several
times, at the same time humming in a peculiar tone. Such females as happen
to be near "obey this saltatory summons," and when they approach he trails
his wings and spreads his tail like a turkey-cock. (59. For Tetrao
phasianellus, see Richardson, 'Fauna, Bor. America,' p. 361, and for
further particulars Capt. Blakiston, 'Ibis,' 1863, p. 125. For the
Cathartes and Ardea, Audubon, 'Ornithological Biography,' vol. ii. p. 51,
and vol. iii. p. 89. On the White-throat, Macgillivray, 'History of
British Birds,' vol. ii. p. 354. On the Indian Bustard, Jerdon, 'Birds of
India,' vol. iii. p. 618.)
[Fig. 46. Bower-bird, Chlamydera maculata, with bower (from Brehm).]
But the most curious case is afforded by three allied genera of Australian
birds, the famous Bower-birds,--no doubt the co-descendants of some ancient
species which first acquired the strange instinct of constructing bowers
for performing their love-antics. The bowers (Fig. 46), which, as we shall
hereafter see, are decorated with feathers, shells, bones, and leaves, are
built on the ground for the sole purpose of courtship, for their nests are
formed in trees. Both sexes assist in the erection of the bowers, but the
male is the principal workman. So strong is this instinct that it is
practised under confinement, and Mr. Strange has described (60. Gould,
'Handbook to the Birds of Australia,' vol. i. pp. 444, 449, 455. The bower
of the Satin Bower-bird may be seen in the Zoological Society's Gardens,
Regent's Park.) the habits of some Satin Bower-birds which he kept in an
aviary in New South Wales. "At times the male will chase the female all
over the aviary, then go to the bower, pick up a gay feather or a large
leaf, utter a curious kind of note, set all his feathers erect, run round
the bower and become so excited that his eyes appear ready to start from
his bead; he continues opening first one wing then the other, uttering a
low, whistling note, and, like the domestic cock, seems to be picking up
something from the ground, until at last the female goes gently towards
him." Captain Stokes has described the habits and "play-houses" of another
species, the Great Bower-bird, which was seen "amusing itself by flying
backwards and forwards, taking a shell alternately from each side, and
carrying it through the archway in its mouth." These curious structures,
formed solely as halls of assemblage, where both sexes amuse themselves and
pay their court, must cost the birds much labour. The bower, for instance,
of the Fawn-breasted species, is nearly four feet in length, eighteen
inches in height, and is raised on a thick platform of sticks.
DECORATION.
I will first discuss the cases in which the males are ornamented either
exclusively or in a much higher degree than the females, and in a
succeeding chapter those in which both sexes are equally ornamented, and
finally the rare cases in which the female is somewhat more brightly-
coloured than the male. As with the artificial ornaments used by savage
and civilised men, so with the natural ornaments of birds, the head is the
chief seat of decoration. (61. See remarks to this effect, on the
'Feeling of Beauty among Animals,' by Mr. J. Shaw, in the 'Athenaeum,' Nov.
24th, 1866, p. 681.) The ornaments, as mentioned at the commencement of
this chapter, are wonderfully diversified. The plumes on the front or back
of the head consist of variously-shaped feathers, sometimes capable of
erection or expansion, by which their beautiful colours are fully
displayed. Elegant ear-tufts (Fig. 39) are occasionally present. The head
is sometimes covered with velvety down, as with the pheasant; or is naked
and vividly coloured. The throat, also, is sometimes ornamented with a
beard, wattles, or caruncles. Such appendages are generally brightly-
coloured, and no doubt serve as ornaments, though not always ornamental in
our eyes; for whilst the male is in the act of courting the female, they
often swell and assume vivid tints, as in the male turkey. At such times
the fleshy appendages about the head of the male Tragopan pheasant
(Ceriornis Temminckii) swell into a large lappet on the throat and into two
horns, one on each side of the splendid top-knot; and these are then
coloured of the most intense blue which I have ever beheld. (62. See Dr.
Murie's account with coloured figures in 'Proceedings, Zoological Society,'
1872, p. 730.) The African hornbill (Bucorax abyssinicus) inflates the
scarlet bladder-like wattle on its neck, and with its wings drooping and
tail expanded "makes quite a grand appearance." (63. Mr. Monteiro,
'Ibis,' vol. iv. 1862, p. 339.) Even the iris of the eye is sometimes more
brightly-coloured in the male than in the female; and this is frequently
the case with the beak, for instance, in our common blackbird. In Buceros
corrugatus, the whole beak and immense casque are coloured more
conspicuously in the male than in the female; and "the oblique grooves upon
the sides of the lower mandible are peculiar to the male sex." (64. 'Land
and Water,' 1868, p. 217.)
The head, again, often supports fleshy appendages, filaments, and solid
protuberances. These, if not common to both sexes, are always confined to
the males. The solid protuberances have been described in detail by Dr. W.
Marshall (65. 'Ueber die Schadelhocker,' etc., 'Niederland. Archiv. fur
Zoologie,' B. I. Heft 2, 1872.), who shews that they are formed either of
cancellated bone coated with skin, or of dermal and other tissues. With
mammals true horns are always supported on the frontal bones, but with
birds various bones have been modified for this purpose; and in species of
the same group the protuberances may have cores of bone, or be quite
destitute of them, with intermediate gradations connecting these two
extremes. Hence, as Dr. Marshall justly remarks, variations of the most
different kinds have served for the development through sexual selection of
these ornamental appendages. Elongated feathers or plumes spring from
almost every part of the body. The feathers on the throat and breast are
sometimes developed into beautiful ruffs and collars. The tail-feathers
are frequently increased in length; as we see in the tail-coverts of the
peacock, and in the tail itself of the Argus pheasant. With the peacock
even the bones of the tail have been modified to support the heavy tail-
coverts. (66. Dr. W. Marshall, 'Uber den Vogelschwanz,' ibid. B. I. Heft
2, 1872.) The body of the Argus is not larger than that of a fowl; yet the
length from the end of the beak to the extremity of the tail is no less
than five feet three inches (67. Jardine's 'Naturalist Library: Birds,'
vol. xiv. p. 166.), and that of the beautifully ocellated secondary wing-
feathers nearly three feet. In a small African night-jar (Cosmetornis
vexillarius) one of the primary wing-feathers, during the breeding-season,
attains a length of twenty-six inches, whilst the bird itself is only ten
inches in length. In another closely-allied genus of night-jars, the
shafts of the elongated wing-feathers are naked, except at the extremity,
where there is a disc. (68. Sclater, in the 'Ibis,' vol. vi. 1864, p.
114; Livingstone, 'Expedition to the Zambesi,' 1865, p. 66.) Again, in
another genus of night-jars, the tail-feathers are even still more
prodigiously developed. In general the feathers of the tail are more often
elongated than those of the wings, as any great elongation of the latter
impedes flight. We thus see that in closely-allied birds ornaments of the
same kind have been gained by the males through the development of widely
different feathers.
It is a curious fact that the feathers of species belonging to very
distinct groups have been modified in almost exactly the same peculiar
manner. Thus the wing-feathers in one of the above-mentioned night-jars
are bare along the shaft, and terminate in a disc; or are, as they are
sometimes called, spoon or racket-shaped. Feathers of this kind occur in
the tail of a motmot (Eumomota superciliaris), of a king-fisher, finch,
humming-bird, parrot, several Indian drongos (Dicrurus and Edolius, in one
of which the disc stands vertically), and in the tail of certain birds of
paradise. In these latter birds, similar feathers, beautifully ocellated,
ornament the head, as is likewise the case with some gallinaceous birds.
In an Indian bustard (Sypheotides auritus) the feathers forming the ear-
tufts, which are about four inches in length, also terminate in discs.
(69. Jerdon, 'Birds of India,' vol. iii. p. 620.) It is a most singular
fact that the motmots, as Mr. Salvin has clearly shewn (70. 'Proceedings,
Zoological Society,' 1873, p. 429.), give to their tail feathers the
racket-shape by biting off the barbs, and, further, that this continued
mutilation has produced a certain amount of inherited effect.
[Fig. 47. Paradisea Papuana (T.W. Wood).]
Again, the barbs of the feathers in various widely-distinct birds are
filamentous or plumose, as with some herons, ibises, birds of paradise, and
Gallinaceae. In other cases the barbs disappear, leaving the shafts bare
from end to end; and these in the tail of the Paradisea apoda attain a
length of thirty-four inches (71. Wallace, in 'Annals and Magazine of
Natural History,' vol. xx. 1857, p. 416, and in his 'Malay Archipelago,'
vol. ii. 1869, p. 390.): in P. Papuana (Fig. 47) they are much shorter and
thin. Smaller feathers when thus denuded appear like bristles, as on the
breast of the turkey-cock. As any fleeting fashion in dress comes to be
admired by man, so with birds a change of almost any kind in the structure
or colouring of the feathers in the male appears to have been admired by
the female. The fact of the feathers in widely distinct groups having been
modified in an analogous manner no doubt depends primarily on all the
feathers having nearly the same structure and manner of development, and
consequently tending to vary in the same manner. We often see a tendency
to analogous variability in the plumage of our domestic breeds belonging to
distinct species. Thus top-knots have appeared in several species. In an
extinct variety of the turkey, the top-knot consisted of bare quills
surmounted with plumes of down, so that they somewhat resembled the racket-
shaped feathers above described. In certain breeds of the pigeon and fowl
the feathers are plumose, with some tendency in the shafts to be naked. In
the Sebastopol goose the scapular feathers are greatly elongated, curled,
or even spirally twisted, with the margins plumose. (72. See my work on
'The Variation of Animals and Plants under Domestication,' vol. i. pp. 289,
293.)
In regard to colour, hardly anything need here be said, for every one knows
how splendid are the tints of many birds, and how harmoniously they are
combined. The colours are often metallic and iridescent. Circular spots
are sometimes surrounded by one or more differently shaded zones, and are
thus converted into ocelli. Nor need much be said on the wonderful
difference between the sexes of many birds. The common peacock offers a
striking instance. Female birds of paradise are obscurely coloured and
destitute of all ornaments, whilst the males are probably the most highly
decorated of all birds, and in so many different ways that they must be
seen to be appreciated. The elongated and golden-orange plumes which
spring from beneath the wings of the Paradisea apoda, when vertically
erected and made to vibrate, are described as forming a sort of halo, in
the centre of which the head "looks like a little emerald sun with its rays
formed by the two plumes." (73. Quoted from M. de Lafresnaye in 'Annals
and Mag. of Natural History,' vol. xiii. 1854, p. 157: see also Mr.
Wallace's much fuller account in vol. xx. 1857, p. 412, and in his 'Malay
Archipelago.'S) In another most beautiful species the head is bald, "and
of a rich cobalt blue, crossed by several lines of black velvety feathers."
(74. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 405.)
[Fig. 48. Lophornis ornatus, male and female (from Brehm).
Fig. 49. Spathura underwoodi, male and female (from Brehm).]
Male humming-birds (Figs. 48 and 49) almost vie with birds of paradise in
their beauty, as every one will admit who has seen Mr. Gould's splendid
volumes, or his rich collection. It is very remarkable in how many
different ways these birds are ornamented. Almost every part of their
plumage has been taken advantage of, and modified; and the modifications
have been carried, as Mr. Gould shewed me, to a wonderful extreme in some
species belonging to nearly every sub-group. Such cases are curiously like
those which we see in our fancy breeds, reared by man for the sake of
ornament; certain individuals originally varied in one character, and other
individuals of the same species in other characters; and these have been
seized on by man and much augmented--as shewn by the tail of the fantail-
pigeon, the hood of the jacobin, the beak and wattle of the carrier, and so
forth. The sole difference between these cases is that in the one, the
result is due to man's selection, whilst in the other, as with humming-
birds, birds of paradise, etc., it is due to the selection by the females
of the more beautiful males.
I will mention only one other bird, remarkable from the extreme contrast in
colour between the sexes, namely the famous bell-bird (Chasmorhynchus
niveus) of S. America, the note of which can be distinguished at the
distance of nearly three miles, and astonishes every one when first hearing
it. The male is pure white, whilst the female is dusky-green; and white is
a very rare colour in terrestrial species of moderate size and inoffensive
habits. The male, also, as described by Waterton, has a spiral tube,
nearly three inches in length, which rises from the base of the beak. It
is jet-black, dotted over with minute downy feathers. This tube can be
inflated with air, through a communication with the palate; and when not
inflated hangs down on one side. The genus consists of four species, the
males of which are very distinct, whilst the females, as described by Mr.
Sclater in a very interesting paper, closely resemble each other, thus
offering an excellent instance of the common rule that within the same
group the males differ much more from each other than do the females. In a
second species (C. nudicollis) the male is likewise snow-white, with the
exception of a large space of naked skin on the throat and round the eyes,
which during the breeding-season is of a fine green colour. In a third
species (C. tricarunculatus) the head and neck alone of the male are white,
the rest of the body being chestnut-brown, and the male of this species is
provided with three filamentous projections half as long as the body--one
rising from the base of the beak, and the two others from the corners of
the mouth. (75. Mr. Sclater, 'Intellectual Observer,' Jan. 1867.
Waterton's 'Wanderings,' p. 118. See also Mr. Salvin's interesting paper,
with a plate, in the 'Ibis,' 1865, p. 90.)
The coloured plumage and certain other ornaments of the adult males are
either retained for life, or are periodically renewed during the summer and
breeding-season. At this same season the beak and naked skin about the
head frequently change colour, as with some herons, ibises, gulls, one of
the bell-birds just noticed, etc. In the white ibis, the cheeks, the
inflatable skin of the throat, and the basal portion of the beak then
become crimson. (76. 'Land and Water,' 1867, p. 394.) In one of the
rails, Gallicrex cristatus, a large red caruncle is developed during this
period on the head of the male. So it is with a thin horny crest on the
beak of one of the pelicans, P. erythrorhynchus; for, after the breeding-
season, these horny crests are shed, like horns from the heads of stags,
and the shore of an island in a lake in Nevada was found covered with these
curious exuviae. (77. Mr. D.G. Elliot, in 'Proc. Zool. Soc.' 1869, p.
589.)
Changes of colour in the plumage according to the season depend, firstly on
a double annual moult, secondly on an actual change of colour in the
feathers themselves, and thirdly on their dull-coloured margins being
periodically shed, or on these three processes more or less combined. The
shedding of the deciduary margins may be compared with the shedding of
their down by very young birds; for the down in most cases arises from the
summits of the first true feathers. (78. Nitzsch's 'Pterylography,'
edited by P.L. Sclater, Ray Society, 1867, p. 14.)
With respect to the birds which annually undergo a double moult, there are,
firstly, some kinds, for instance snipes, swallow-plovers (Glareolae), and
curlews, in which the two sexes resemble each other, and do not change
colour at any season. I do not know whether the winter plumage is thicker
and warmer than the summer plumage, but warmth seems the most probable end
attained of a double moult, where there is no change of colour. Secondly,
there are birds, for instance, certain species of Totanus and other
Grallatores, the sexes of which resemble each other, but in which the
summer and winter plumage differ slightly in colour. The difference,
however, in these cases is so small that it can hardly be an advantage to
them; and it may, perhaps, be attributed to the direct action of the
different conditions to which the birds are exposed during the two seasons.
Thirdly, there are many other birds the sexes of which are alike, but which
are widely different in their summer and winter plumage. Fourthly, there
are birds the sexes of which differ from each other in colour; but the
females, though moulting twice, retain the same colours throughout the
year, whilst the males undergo a change of colour, sometimes a great one,
as with certain bustards. Fifthly and lastly, there are birds the sexes of
which differ from each other in both their summer and winter plumage; but
the male undergoes a greater amount of change at each recurrent season than
the female--of which the ruff (Machetes pugnax) offers a good instance.
With respect to the cause or purpose of the differences in colour between
the summer and winter plumage, this may in some instances, as with the
ptarmigan (79. The brown mottled summer plumage of the ptarmigan is of as
much importance to it, as a protection, as the white winter plumage; for in
Scandinavia during the spring, when the snow has disappeared, this bird is
known to suffer greatly from birds of prey, before it has acquired its
summer dress: see Wilhelm von Wright, in Lloyd, 'Game Birds of Sweden,'
1867, p. 125.), serve during both seasons as a protection. When the
difference between the two plumages is slight it may perhaps be attributed,
as already remarked, to the direct action of the conditions of life. But
with many birds there can hardly be a doubt that the summer plumage is
ornamental, even when both sexes are alike. We may conclude that this is
the case with many herons, egrets, etc., for they acquire their beautiful
plumes only during the breeding-season. Moreover, such plumes, top-knots,
etc., though possessed by both sexes, are occasionally a little more
developed in the male than in the female; and they resemble the plumes and
ornaments possessed by the males alone of other birds. It is also known
that confinement, by affecting the reproductive system of male birds,
frequently checks the development of their secondary sexual characters, but
has no immediate influence on any other characters; and I am informed by
Mr. Bartlett that eight or nine specimens of the Knot (Tringa canutus)
retained their unadorned winter plumage in the Zoological Gardens
throughout the year, from which fact we may infer that the summer plumage,
though common to both sexes, partakes of the nature of the exclusively
masculine plumage of many other birds. (80. In regard to the previous
statements on moulting, see, on snipes, etc., Macgillivray, 'Hist. Brit.
Birds,' vol. iv. p. 371; on Glareolae, curlews, and bustards, Jerdon,
'Birds of India,' vol. iii. pp. 615, 630, 683; on Totanus, ibid. p. 700; on
the plumes of herons, ibid. p. 738, and Macgillivray, vol. iv. pp. 435 and
444, and Mr. Stafford Allen, in the 'Ibis,' vol. v. 1863, p. 33.)
From the foregoing facts, more especially from neither sex of certain birds
changing colour during either annual moult, or changing so slightly that
the change can hardly be of any service to them, and from the females of
other species moulting twice yet retaining the same colours throughout the
year, we may conclude that the habit of annually moulting twice has not
been acquired in order that the male should assume an ornamental character
during the breeding-season; but that the double moult, having been
originally acquired for some distinct purpose, has subsequently been taken
advantage of in certain cases for gaining a nuptial plumage.
It appears at first sight a surprising circumstance that some closely-
allied species should regularly undergo a double annual moult, and others
only a single one. The ptarmigan, for instance, moults twice or even
thrice in the year, and the blackcock only once: some of the splendidly
coloured honey-suckers (Nectariniae) of India and some sub-genera of
obscurely coloured pipits (Anthus) have a double, whilst others have only a
single annual moult. (81. On the moulting of the ptarmigan, see Gould's
'Birds of Great Britain.' On the honey-suckers, Jerdon, 'Birds of India,'
vol. i. pp. 359, 365, 369. On the moulting of Anthus, see Blyth, in
'Ibis,' 1867, p. 32.) But the gradations in the manner of moulting, which
are known to occur with various birds, shew us how species, or whole
groups, might have originally acquired their double annual moult, or having
once gained the habit, have again lost it. With certain bustards and
plovers the vernal moult is far from complete, some feathers being renewed,
and some changed in colour. There is also reason to believe that with
certain bustards and rail-like birds, which properly undergo a double
moult, some of the older males retain their nuptial plumage throughout the
year. A few highly modified feathers may merely be added during the spring
to the plumage, as occurs with the disc-formed tail-feathers of certain
drongos (Bhringa) in India, and with the elongated feathers on the back,
neck, and crest of certain herons. By such steps as these, the vernal
moult might be rendered more and more complete, until a perfect double
moult was acquired. Some of the birds of paradise retain their nuptial
feathers throughout the year, and thus have only a single moult; others
cast them directly after the breeding-season, and thus have a double moult;
and others again cast them at this season during the first year, but not
afterwards; so that these latter species are intermediate in their manner
of moulting. There is also a great difference with many birds in the
length of time during which the two annual plumages are retained; so that
the one might come to be retained for the whole year, and the other
completely lost. Thus in the spring Machetes pugnax retains his ruff for
barely two months. In Natal the male widow-bird (Chera progne) acquires
his fine plumage and long tail-feathers in December or January, and loses
them in March; so that they are retained only for about three months. Most
species, which undergo a double moult, keep their ornamental feathers for
about six months. The male, however, of the wild Gallus bankiva retains
his neck-hackles for nine or ten months; and when these are cast off, the
underlying black feathers on the neck are fully exposed to view. But with
the domesticated descendant of this species, the neck-hackles of the male
are immediately replaced by new ones; so that we here see, as to part of
the plumage, a double moult changed under domestication into a single
moult. (82. For the foregoing statements in regard to partial moults, and
on old males retaining their nuptial plumage, see Jerdon, on bustards and
plovers, in 'Birds of India,' vol. iii. pp. 617, 637, 709, 711. Also Blyth
in 'Land and Water,' 1867, p. 84. On the moulting of Paradisea, see an
interesting article by Dr. W. Marshall, 'Archives Neerlandaises,' tom. vi.
1871. On the Vidua, 'Ibis,' vol. iii. 1861, p. 133. On the Drongo-
shrikes, Jerdon, ibid. vol. i. p. 435. On the vernal moult of the Herodias
bubulcus, Mr. S.S. Allen, in 'Ibis,' 1863, p. 33. On Gallus bankiva,
Blyth, in 'Annals and Mag. of Natural History,' vol. i. 1848, p. 455; see,
also, on this subject, my 'Variation of Animals under Domestication,' vol.
i. p. 236.)
The common drake (Anas boschas), after the breeding-season, is well known
to lose his male plumage for a period of three months, during which time he
assumes that of the female. The male pin-tail duck (Anas acuta) loses his
plumage for the shorter period of six weeks or two months; and Montagu
remarks that "this double moult within so short a time is a most
extraordinary circumstance, that seems to bid defiance to all human
reasoning." But the believer in the gradual modification of species will
be far from feeling surprise at finding gradations of all kinds. If the
male pin-tail were to acquire his new plumage within a still shorter
period, the new male feathers would almost necessarily be mingled with the
old, and both with some proper to the female; and this apparently is the
case with the male of a not distantly-allied bird, namely the Merganser
serrator, for the males are said to "undergo a change of plumage, which
assimilates them in some measure to the female." By a little further
acceleration in the process, the double moult would be completely lost.
(83. See Macgillivray, 'Hist. British Birds' (vol. v. pp. 34, 70, and
223), on the moulting of the Anatidae, with quotations from Waterton and
Montagu. Also Yarrell, 'History of British Birds,' vol. iii. p. 243.)
Some male birds, as before stated, become more brightly coloured in the
spring, not by a vernal moult, but either by an actual change of colour in
the feathers, or by their obscurely-coloured deciduary margins being shed.
Changes of colour thus caused may last for a longer or shorter time. In
the Pelecanus onocrotalus a beautiful rosy tint, with lemon-coloured marks
on the breast, overspreads the whole plumage in the spring; but these
tints, as Mr. Sclater states, "do not last long, disappearing generally in
about six weeks or two months after they have been attained." Certain
finches shed the margins of their feathers in the spring, and then become
brighter coloured, while other finches undergo no such change. Thus the
Fringilla tristis of the United States (as well as many other American
species) exhibits its bright colours only when the winter is past, whilst
our goldfinch, which exactly represents this bird in habits, and our
siskin, which represents it still more closely in structure, undergo no
such annual change. But a difference of this kind in the plumage of allied
species is not surprising, for with the common linnet, which belongs to the
same family, the crimson forehead and breast are displayed only during the
summer in England, whilst in Madeira these colours are retained throughout
the year. (84. On the pelican, see Sclater, in 'Proc. Zool. Soc.' 1868,
p. 265. On the American finches, see Audubon, 'Ornithological Biography,'
vol. i. pp. 174, 221, and Jerdon, 'Birds of India,' vol. ii. p. 383. On
the Fringilla cannabina of Madeira, Mr. E. Vernon Harcourt, 'Ibis,' vol. v.
1863, p. 230.)
DISPLAY BY MALE BIRDS OF THEIR PLUMAGE.
Ornaments of all kinds, whether permanently or temporarily gained, are
sedulously displayed by the males, and apparently serve to excite, attract,
or fascinate the females. But the males will sometimes display their
ornaments, when not in the presence of the females, as occasionally occurs
with grouse at their balz-places, and as may be noticed with the peacock;
this latter bird, however, evidently wishes for a spectator of some kind,
and, as I have often seen, will shew off his finery before poultry, or even
pigs. (85. See also 'Ornamental Poultry,' by Rev. E.S. Dixon, 1848, p.
8.) All naturalists who have closely attended to the habits of birds,
whether in a state of nature or under confinement, are unanimously of
opinion that the males take delight in displaying their beauty. Audubon
frequently speaks of the male as endeavouring in various ways to charm the
female. Mr. Gould, after describing some peculiarities in a male humming-
bird, says he has no doubt that it has the power of displaying them to the
greatest advantage before the female. Dr. Jerdon (86. 'Birds of India,'
introduct., vol. i. p. xxiv.; on the peacock, vol. iii. p. 507. See
Gould's 'Introduction to Trochilidae,' 1861, pp. 15 and 111.) insists that
the beautiful plumage of the male serves "to fascinate and attract the
female." Mr. Bartlett, at the Zoological Gardens, expressed himself to me
in the strongest terms to the same effect.
[Fig. 50. Rupicola crocea, male (T.W. Wood).]
It must be a grand sight in the forests of India "to come suddenly on
twenty or thirty pea-fowl, the males displaying their gorgeous trains, and
strutting about in all the pomp of pride before the gratified females."
The wild turkey-cock erects his glittering plumage, expands his finely-
zoned tail and barred wing-feathers, and altogether, with his crimson and
blue wattles, makes a superb, though, to our eyes, grotesque appearance.
Similar facts have already been given with respect to grouse of various
kinds. Turning to another Order: The male Rupicola crocea (Fig. 50) is
one of the most beautiful birds in the world, being of a splendid orange,
with some of the feathers curiously truncated and plumose. The female is
brownish-green, shaded with red, and has a much smaller crest. Sir R.
Schomburgk has described their courtship; he found one of their meeting-
places where ten males and two females were present. The space was from
four to five feet in diameter, and appeared to have been cleared of every
blade of grass and smoothed as if by human hands. A male "was capering, to
the apparent delight of several others. Now spreading its wings, throwing
up its head, or opening its tail like a fan; now strutting about with a
hopping gait until tired, when it gabbled some kind of note, and was
relieved by another. Thus three of them successively took the field, and
then, with self-approbation, withdrew to rest." The Indians, in order to
obtain their skins, wait at one of the meeting-places till the birds are
eagerly engaged in dancing, and then are able to kill with their poisoned
arrows four or five males, one after the other. (87. 'Journal of R.
Geograph. Soc.' vol. x. 1840, p. 236.) With birds of paradise a dozen or
more full-plumaged males congregate in a tree to hold a dancing-party, as
it is called by the natives: and here they fly about, raise their wings,
elevate their exquisite plumes, and make them vibrate, and the whole tree
seems, as Mr. Wallace remarks, to be filled with waving plumes. When thus
engaged, they become so absorbed that a skilful archer may shoot nearly the
whole party. These birds, when kept in confinement in the Malay
Archipelago, are said to take much care in keeping their feathers clean;
often spreading them out, examining them, and removing every speck of dirt.
One observer, who kept several pairs alive, did not doubt that the display
of the male was intended to please the female. (88. 'Annals and Mag. of
Nat. Hist.' vol. xiii. 1854, p. 157; also Wallace, ibid. vol. xx. 1857, p.
412, and 'The Malay Archipelago,' vol. ii. 1869, p. 252. Also Dr. Bennett,
as quoted by Brehm, 'Thierleben,' B. iii. s. 326.)
[Fig. 51. Polyplectron chinquis, male (T.W. Wood).]
The Gold and Amherst pheasants during their courtship not only expand and
raise their splendid frills, but twist them, as I have myself seen,
obliquely towards the female on whichever side she may be standing,
obviously in order that a large surface may be displayed before her. (89.
Mr. T.W. Wood has given ('The Student,' April 1870, p. 115) a full account
of this manner of display, by the Gold pheasant and by the Japanese
pheasant, Ph. versicolor; and he calls it the lateral or one-sided
display.) They likewise turn their beautiful tails and tail-coverts a
little towards the same side. Mr. Bartlett has observed a male
Polyplectron (Fig. 51) in the act of courtship, and has shewn me a specimen
stuffed in the attitude then assumed. The tail and wing-feathers of this
bird are ornamented with beautiful ocelli, like those on the peacock's
train. Now when the peacock displays himself, he expands and erects his
tail transversely to his body, for he stands in front of the female, and
has to shew off, at the same time, his rich blue throat and breast. But
the breast of the Polyplectron is obscurely coloured, and the ocelli are
not confined to the tail-feathers. Consequently the Polyplectron does not
stand in front of the female; but he erects and expands his tail-feathers a
little obliquely, lowering the expanded wing on the same side, and raising
that on the opposite side. In this attitude the ocelli over the whole body
are exposed at the same time before the eyes of the admiring female in one
grand bespangled expanse. To whichever side she may turn, the expanded
wings and the obliquely-held tail are turned towards her. The male
Tragopan pheasant acts in nearly the same manner, for he raises the
feathers of the body, though not the wing itself, on the side which is
opposite to the female, and which would otherwise be concealed, so that
nearly all the beautifully spotted feathers are exhibited at the same time.
[Fig. 52. Side view of male Argus pheasant, whilst displaying before the
female. Observed and sketched from nature by T.W. Wood.]
The Argus pheasant affords a much more remarkable case. The immensely
developed secondary wing-feathers are confined to the male; and each is
ornamented with a row of from twenty to twenty-three ocelli, above an inch
in diameter. These feathers are also elegantly marked with oblique stripes
and rows of spots of a dark colour, like those on the skin of a tiger and
leopard combined. These beautiful ornaments are hidden until the male
shows himself off before the female. He then erects his tail, and expands
his wing-feathers into a great, almost upright, circular fan or shield,
which is carried in front of the body. The neck and head are held on one
side, so that they are concealed by the fan; but the bird in order to see
the female, before whom he is displaying himself, sometimes pushes his head
between two of the long wing-feathers (as Mr. Bartlett has seen), and then
presents a grotesque appearance. This must be a frequent habit with the
bird in a state of nature, for Mr. Bartlett and his son on examining some
perfect skins sent from the East, found a place between two of the feathers
which was much frayed, as if the head had here frequently been pushed
through. Mr. Wood thinks that the male can also peep at the female on one
side, beyond the margin of the fan.
The ocelli on the wing-feathers are wonderful objects; for they are so
shaded that, as the Duke of Argyll remarks (90. 'The Reign of Law,' 1867,
p. 203.), they stand out like balls lying loosely within sockets. When I
looked at the specimen in the British Museum, which is mounted with the
wings expanded and trailing downwards, I was however greatly disappointed,
for the ocelli appeared flat, or even concave. But Mr. Gould soon made the
case clear to me, for he held the feathers erect, in the position in which
they would naturally be displayed, and now, from the light shining on them
from above, each ocellus at once resembled the ornament called a ball and
socket. These feathers have been shown to several artists, and all have
expressed their admiration at the perfect shading. It may well be asked,
could such artistically shaded ornaments have been formed by means of
sexual selection? But it will be convenient to defer giving an answer to
this question until we treat in the next chapter of the principle of
gradation.
The foregoing remarks relate to the secondary wing-feathers, but the
primary wing-feathers, which in most gallinaceous birds are uniformly
coloured, are in the Argus pheasant equally wonderful. They are of a soft
brown tint with numerous dark spots, each of which consists of two or three
black dots with a surrounding dark zone. But the chief ornament is a space
parallel to the dark-blue shaft, which in outline forms a perfect second
feather lying within the true feather. This inner part is coloured of a
lighter chestnut, and is thickly dotted with minute white points. I have
shewn this feather to several persons, and many have admired it even more
than the ball and socket feathers, and have declared that it was more like
a work of art than of nature. Now these feathers are quite hidden on all
ordinary occasions, but are fully displayed, together with the long
secondary feathers, when they are all expanded together so as to form the
great fan or shield.
The case of the male Argus pheasant is eminently interesting, because it
affords good evidence that the most refined beauty may serve as a sexual
charm, and for no other purpose. We must conclude that this is the case,
as the secondary and primary wing-feathers are not at all displayed, and
the ball and socket ornaments are not exhibited in full perfection until
the male assumes the attitude of courtship. The Argus pheasant does not
possess brilliant colours, so that his success in love appears to depend on
the great size of his plumes, and on the elaboration of the most elegant
patterns. Many will declare that it is utterly incredible that a female
bird should be able to appreciate fine shading and exquisite patterns. It
is undoubtedly a marvellous fact that she should possess this almost human
degree of taste. He who thinks that he can safely gauge the discrimination
and taste of the lower animals may deny that the female Argus pheasant can
appreciate such refined beauty; but he will then be compelled to admit that
the extraordinary attitudes assumed by the male during the act of
courtship, by which the wonderful beauty of his plumage is fully displayed,
are purposeless; and this is a conclusion which I for one will never admit.
Although so many pheasants and allied gallinaceous birds carefully display
their plumage before the females, it is remarkable, as Mr. Bartlett informs
me, that this is not the case with the dull-coloured Eared and Cheer
pheasants (Crossoptilon auritum and Phasianus wallichii); so that these
birds seem conscious that they have little beauty to display. Mr. Bartlett
has never seen the males of either of these species fighting together,
though he has not had such good opportunities for observing the Cheer as
the Eared pheasant. Mr. Jenner Weir, also, finds that all male birds with
rich or strongly-characterised plumage are more quarrelsome than the dull-
coloured species belonging to the same groups. The goldfinch, for
instance, is far more pugnacious than the linnet, and the blackbird than
the thrush. Those birds which undergo a seasonal change of plumage
likewise become much more pugnacious at the period when they are most gaily
ornamented. No doubt the males of some obscurely-coloured birds fight
desperately together, but it appears that when sexual selection has been
highly influential, and has given bright colours to the males of any
species, it has also very often given a strong tendency to pugnacity. We
shall meet with nearly analogous cases when we treat of mammals. On the
other hand, with birds the power of song and brilliant colours have rarely
been both acquired by the males of the same species; but in this case the
advantage gained would have been the same, namely success in charming the
female. Nevertheless it must be owned that the males of several
brilliantly coloured birds have had their feathers specially modified for
the sake of producing instrumental music, though the beauty of this cannot
be compared, at least according to our taste, with that of the vocal music
of many songsters.
We will now turn to male birds which are not ornamented in any high degree,
but which nevertheless display during their courtship whatever attractions
they may possess. These cases are in some respects more curious than the
foregoing, and have been but little noticed. I owe the following facts to
Mr. Weir, who has long kept confined birds of many kinds, including all the
British Fringillidae and Emberizidae. The facts have been selected from a
large body of valuable notes kindly sent me by him. The bullfinch makes
his advances in front of the female, and then puffs out his breast, so that
many more of the crimson feathers are seen at once than otherwise would be
the case. At the same time he twists and bows his black tail from side to
side in a ludicrous manner. The male chaffinch also stands in front of the
female, thus shewing his red breast and "blue bell," as the fanciers call
his head; the wings at the same time being slightly expanded, with the pure
white bands on the shoulders thus rendered conspicuous. The common linnet
distends his rosy breast, slightly expands his brown wings and tail, so as
to make the best of them by exhibiting their white edgings. We must,
however, be cautious in concluding that the wings are spread out solely for
display, as some birds do so whose wings are not beautiful. This is the
case with the domestic cock, but it is always the wing on the side opposite
to the female which is expanded, and at the same time scraped on the
ground. The male goldfinch behaves differently from all other finches:
his wings are beautiful, the shoulders being black, with the dark-tipped
wing-feathers spotted with white and edged with golden yellow. When he
courts the female, he sways his body from side to side, and quickly turns
his slightly expanded wings first to one side, then to the other, with a
golden flashing effect. Mr. Weir informs me that no other British finch
turns thus from side to side during his courtship, not even the closely-
allied male siskin, for he would not thus add to his beauty.
Most of the British Buntings are plain coloured birds; but in the spring
the feathers on the head of the male reed-bunting (Emberiza schoeniculus)
acquire a fine black colour by the abrasion of the dusky tips; and these
are erected during the act of courtship. Mr. Weir has kept two species of
Amadina from Australia: the A. castanotis is a very small and chastely
coloured finch, with a dark tail, white rump, and jet-black upper tail-
coverts, each of the latter being marked with three large conspicuous oval
spots of white. (91. For the description of these birds, see Gould's
'Handbook to the Birds of Australia,' vol. i. 1865, p. 417.) This species,
when courting the female, slightly spreads out and vibrates these parti-
coloured tail-coverts in a very peculiar manner. The male Amadina Lathami
behaves very differently, exhibiting before the female his brilliantly
spotted breast, scarlet rump, and scarlet upper tail-coverts. I may here
add from Dr. Jerdon that the Indian bulbul (Pycnonotus hoemorrhous) has its
under tail-coverts of a crimson colour, and these, it might be thought,
could never be well exhibited; but the bird "when excited often spreads
them out laterally, so that they can be seen even from above." (92.
'Birds of India,' vol. ii. p. 96.) The crimson under tail-coverts of some
other birds, as with one of the woodpeckers, Picus major, can be seen
without any such display. The common pigeon has iridescent feathers on the
breast, and every one must have seen how the male inflates his breast
whilst courting the female, thus shewing them off to the best advantage.
One of the beautiful bronze-winged pigeons of Australia (Ocyphaps lophotes)
behaves, as described to me by Mr. Weir, very differently: the male,
whilst standing before the female, lowers his head almost to the ground,
spreads out and raises his tail, and half expands his wings. He then
alternately and slowly raises and depresses his body, so that the
iridescent metallic feathers are all seen at once, and glitter in the sun.
Sufficient facts have now been given to shew with what care male birds
display their various charms, and this they do with the utmost skill.
Whilst preening their feathers, they have frequent opportunities for
admiring themselves, and of studying how best to exhibit their beauty. But
as all the males of the same species display themselves in exactly the same
manner, it appears that actions, at first perhaps intentional, have become
instinctive. If so, we ought not to accuse birds of conscious vanity; yet
when we see a peacock strutting about, with expanded and quivering tail-
feathers, he seems the very emblem of pride and vanity.
The various ornaments possessed by the males are certainly of the highest
importance to them, for in some cases they have been acquired at the
expense of greatly impeded powers of flight or of running. The African
night-jar (Cosmetornis), which during the pairing-season has one of its
primary wing-feathers developed into a streamer of very great length, is
thereby much retarded in its flight, although at other times remarkable for
its swiftness. The "unwieldy size" of the secondary wing-feathers of the
male Argus pheasant is said "almost entirely to deprive the bird of
flight." The fine plumes of male birds of paradise trouble them during a
high wind. The extremely long tail-feathers of the male widow-birds
(Vidua) of Southern Africa render "their flight heavy;" but as soon as
these are cast off they fly as well as the females. As birds always breed
when food is abundant, the males probably do not suffer much inconvenience
in searching for food from their impeded powers of movement; but there can
hardly be a doubt that they must be much more liable to be struck down by
birds of prey. Nor can we doubt that the long train of the peacock and the
long tail and wing-feathers of the Argus pheasant must render them an
easier prey to any prowling tiger-cat than would otherwise be the case.
Even the bright colours of many male birds cannot fail to make them
conspicuous to their enemies of all kinds. Hence, as Mr. Gould has
remarked, it probably is that such birds are generally of a shy
disposition, as if conscious that their beauty was a source of danger, and
are much more difficult to discover or approach, than the sombre coloured
and comparatively tame females or than the young and as yet unadorned
males. (93. On the Cosmetornis, see Livingstone's 'Expedition to the
Zambesi,' 1865, p. 66. On the Argus pheasant, Jardine's 'Nat. Hist. Lib.:
Birds,' vol. xiv. p. 167. On Birds of Paradise, Lesson, quoted by Brehm,
'Thierleben,' B. iii. s. 325. On the widow-bird, Barrow's 'Travels in
Africa,' vol. i. p. 243, and 'Ibis,' vol. iii. 1861 p. 133. Mr. Gould, on
the shyness of male birds, 'Handbook to Birds of Australia,' vol. i. 1865,
pp. 210, 457.)
It is a more curious fact that the males of some birds which are provided
with special weapons for battle, and which in a state of nature are so
pugnacious that they often kill each other, suffer from possessing certain
ornaments. Cock-fighters trim the hackles and cut off the combs and gills
of their cocks; and the birds are then said to be dubbed. An undubbed
bird, as Mr. Tegetmeier insists, "is at a fearful disadvantage; the comb
and gills offer an easy hold to his adversary's beak, and as a cock always
strikes where he holds, when once he has seized his foe, he has him
entirely in his power. Even supposing that the bird is not killed, the
loss of blood suffered by an undubbed cock is much greater than that
sustained by one that has been trimmed." (94. Tegetmeier, 'The Poultry
Book,' 1866, p. 139.) Young turkey-cocks in fighting always seize hold of
each other's wattles; and I presume that the old birds fight in the same
manner. It may perhaps be objected that the comb and wattles are not
ornamental, and cannot be of service to the birds in this way; but even to
our eyes, the beauty of the glossy black Spanish cock is much enhanced by
his white face and crimson comb; and no one who has ever seen the splendid
blue wattles of the male Tragopan pheasant distended in courtship can for a
moment doubt that beauty is the object gained. From the foregoing facts we
clearly see that the plumes and other ornaments of the males must be of the
highest importance to them; and we further see that beauty is even
sometimes more important than success in battle.
CHAPTER XIV.
BIRDS--continued.
Choice exerted by the female--Length of courtship--Unpaired birds--Mental
qualities and taste for the beautiful--Preference or antipathy shewn by the
female for particular males--Variability of birds--Variations sometimes
abrupt--Laws of variation--Formation of ocelli--Gradations of character--
Case of Peacock, Argus pheasant, and Urosticte.
When the sexes differ in beauty or in the power of singing, or in producing
what I have called instrumental music, it is almost invariably the male who
surpasses the female. These qualities, as we have just seen, are evidently
of high importance to the male. When they are gained for only a part of
the year it is always before the breeding-season. It is the male alone who
elaborately displays his varied attractions, and often performs strange
antics on the ground or in the air, in the presence of the female. Each
male drives away, or if he can, kills his rivals. Hence we may conclude
that it is the object of the male to induce the female to pair with him,
and for this purpose he tries to excite or charm her in various ways; and
this is the opinion of all those who have carefully studied the habits of
living birds. But there remains a question which has an all important
bearing on sexual selection, namely, does every male of the same species
excite and attract the female equally? Or does she exert a choice, and
prefer certain males? This latter question can be answered in the
affirmative by much direct and indirect evidence. It is far more difficult
to decide what qualities determine the choice of the females; but here
again we have some direct and indirect evidence that it is to a large
extent the external attractions of the male; though no doubt his vigour,
courage, and other mental qualities come into play. We will begin with the
indirect evidence.
LENGTH OF COURTSHIP.
The lengthened period during which both sexes of certain birds meet day
after day at an appointed place probably depends partly on the courtship
being a prolonged affair, and partly on reiteration in the act of pairing.
Thus in Germany and Scandinavia the balzen or leks of the black-cocks last
from the middle of March, all through April into May. As many as forty or
fifty, or even more birds congregate at the leks; and the same place is
often frequented during successive years. The lek of the capercailzie
lasts from the end of March to the middle or even end of May. In North
America "the partridge dances" of the Tetrao phasianellus "last for a month
or more." Other kinds of grouse, both in North America and Eastern Siberia
(1. Nordman describes ('Bull. Soc. Imp. des Nat. Moscou,' 1861, tom.
xxxiv. p. 264) the balzen of Tetrao urogalloides in Amur Land. He
estimated the number of birds assembled at above a hundred, not counting
the females, which lie hid in the surrounding bushes. The noises uttered
differ from those of T. urogallus.), follow nearly the same habits. The
fowlers discover the hillocks where the ruffs congregate by the grass being
trampled bare, and this shews that the same spot is long frequented. The
Indians of Guiana are well acquainted with the cleared arenas, where they
expect to find the beautiful cocks of the Rock; and the natives of New
Guinea know the trees where from ten to twenty male birds of paradise in
full plumage congregate. In this latter case it is not expressly stated
that the females meet on the same trees, but the hunters, if not specially
asked, would probably not mention their presence, as their skins are
valueless. Small parties of an African weaver (Ploceus) congregate, during
the breeding-season, and perform for hours their graceful evolutions.
Large numbers of the Solitary snipe (Scolopax major) assemble during dusk
in a morass; and the same place is frequented for the same purpose during
successive years; here they may be seen running about "like so many large
rats," puffing out their feathers, flapping their wings, and uttering the
strangest cries. (2. With respect to the assemblages of the above named
grouse, see Brehm, 'Thierleben,' B. iv. s. 350; also L. Lloyd, 'Game Birds
of Sweden,' 1867, pp. 19, 78. Richardson, 'Fauna Bor. Americana: Birds,'
p. 362. References in regard to the assemblages of other birds have
already been given. On Paradisea, see Wallace, in 'Annals and Mag. of Nat.
Hist.' vol. xx. 1857, p. 412. On the snipe, Lloyd, ibid. p. 221.)
Some of the above birds,--the black-cock, capercailzie, pheasant-grouse,
ruff, solitary snipe, and perhaps others,--are, as is believed,
polygamists. With such birds it might have been thought that the stronger
males would simply have driven away the weaker, and then at once have taken
possession of as many females as possible; but if it be indispensable for
the male to excite or please the female, we can understand the length of
the courtship and the congregation of so many individuals of both sexes at
the same spot. Certain strictly monogamous species likewise hold nuptial
assemblages; this seems to be the case in Scandinavia with one of the
ptarmigans, and their leks last from the middle of March to the middle of
May. In Australia the lyre-bird (Menura superba) forms "small round
hillocks," and the M. Alberti scratches for itself shallow holes, or, as
they are called by the natives, "corroborying places," where it is believed
both sexes assemble. The meetings of the M. superba are sometimes very
large; and an account has lately been published (3. Quoted by Mr. T.W.
Wood, in the 'Student,' April 1870, p. 125.) by a traveller, who heard in a
valley beneath him, thickly covered with scrub, "a din which completely
astonished" him; on crawling onwards he beheld, to his amazement, about one
hundred and fifty of the magnificent lyre-cocks, "ranged in order of
battle, and fighting with indescribable fury." The bowers of the Bower-
birds are the resort of both sexes during the breeding-season; and "here
the males meet and contend with each other for the favours of the female,
and here the latter assemble and coquet with the males." With two of the
genera, the same bower is resorted to during many years. (4. Gould,
'Handbook to the Birds of Australia,' vol. i. pp. 300, 308, 448, 451. On
the ptarmigan, above alluded to, see Lloyd, ibid. p. 129.)
The common magpie (Corvus pica, Linn.), as I have been informed by the Rev.
W. Darwin Fox, used to assemble from all parts of Delamere Forest, in order
to celebrate the "great magpie marriage." Some years ago these birds
abounded in extraordinary numbers, so that a gamekeeper killed in one
morning nineteen males, and another killed by a single shot seven birds at
roost together. They then had the habit of assembling very early in the
spring at particular spots, where they could be seen in flocks, chattering,
sometimes fighting, bustling and flying about the trees. The whole affair
was evidently considered by the birds as one of the highest importance.
Shortly after the meeting they all separated, and were then observed by Mr.
Fox and others to be paired for the season. In any district in which a
species does not exist in large numbers, great assemblages cannot, of
course, be held, and the same species may have different habits in
different countries. For instance, I have heard of only one instance, from
Mr. Wedderburn, of a regular assemblage of black game in Scotland, yet
these assemblages are so well known in Germany and Scandinavia that they
have received special names.
UNPAIRED BIRDS.
From the facts now given, we may conclude that the courtship of birds
belonging to widely different groups, is often a prolonged, delicate, and
troublesome affair. There is even reason to suspect, improbable as this
will at first appear, that some males and females of the same species,
inhabiting the same district, do not always please each other, and
consequently do not pair. Many accounts have been published of either the
male or female of a pair having been shot, and quickly replaced by another.
This has been observed more frequently with the magpie than with any other
bird, owing perhaps to its conspicuous appearance and nest. The
illustrious Jenner states that in Wiltshire one of a pair was daily shot no
less than seven times successively, "but all to no purpose, for the
remaining magpie soon found another mate"; and the last pair reared their
young. A new partner is generally found on the succeeding day; but Mr.
Thompson gives the case of one being replaced on the evening of the same
day. Even after the eggs are hatched, if one of the old birds is destroyed
a mate will often be found; this occurred after an interval of two days, in
a case recently observed by one of Sir J. Lubbock's keepers. (5. On
magpies, Jenner, in 'Philosophical Transactions,' 1824, p. 21.
Macgillivray, 'Hist. British Birds,' vol. i. p. 570. Thompson, in 'Annals
and Magazine of Natural History,' vol. viii. 1842, p. 494.) The first and
most obvious conjecture is that male magpies must be much more numerous
than females; and that in the above cases, as well as in many others which
could be given, the males alone had been killed. This apparently holds
good in some instances, for the gamekeepers in Delamere Forest assured Mr.
Fox that the magpies and carrion-crows which they formerly killed in
succession in large numbers near their nests, were all males; and they
accounted for this fact by the males being easily killed whilst bringing
food to the sitting females. Macgillivray, however, gives, on the
authority of an excellent observer, an instance of three magpies
successively killed on the same nest, which were all females; and another
case of six magpies successively killed whilst sitting on the same eggs,
which renders it probable that most of them were females; though, as I hear
from Mr. Fox, the male will sit on the eggs when the female is killed.
Sir J. Lubbock's gamekeeper has repeatedly shot, but how often he could not
say, one of a pair of jays (Garrulus glandarius), and has never failed
shortly afterwards to find the survivor re-matched. Mr. Fox, Mr. F. Bond,
and others have shot one of a pair of carrion-crows (Corvus corone), but
the nest was soon again tenanted by a pair. These birds are rather common;
but the peregrine-falcon (Falco peregrinus) is rare, yet Mr. Thompson
states that in Ireland "if either an old male or female be killed in the
breeding-season (not an uncommon circumstance), another mate is found
within a very few days, so that the eyries, notwithstanding such
casualties, are sure to turn out their complement of young." Mr. Jenner
Weir has known the same thing with the peregrine-falcons at Beachy Head.
The same observer informs me that three kestrels (Falco tinnunculus), all
males, were killed one after the other whilst attending the same nest; two
of these were in mature plumage, but the third was in the plumage of the
previous year. Even with the rare golden eagle (Aquila chrysaetos), Mr.
Birkbeck was assured by a trustworthy gamekeeper in Scotland, that if one
is killed, another is soon found. So with the white owl (Strix flammea),
"the survivor readily found a mate, and the mischief went on."
White of Selborne, who gives the case of the owl, adds that he knew a man,
who from believing that partridges when paired were disturbed by the males
fighting, used to shoot them; and though he had widowed the same female
several times, she always soon found a fresh partner. This same naturalist
ordered the sparrows, which deprived the house-martins of their nests, to
be shot; but the one which was left, "be it cock or hen, presently procured
a mate, and so for several times following." I could add analogous cases
relating to the chaffinch, nightingale, and redstart. With respect to the
latter bird (Phoenicura ruticilla), a writer expresses much surprise how
the sitting female could so soon have given effectual notice that she was a
widow, for the species was not common in the neighbourhood. Mr. Jenner
Weir has mentioned to me a nearly similar case; at Blackheath he never sees
or hears the note of the wild bullfinch, yet when one of his caged males
has died, a wild one in the course of a few days has generally come and
perched near the widowed female, whose call-note is not loud. I will give
only one other fact, on the authority of this same observer; one of a pair
of starlings (Sturnus vulgaris) was shot in the morning; by noon a new mate
was found; this was again shot, but before night the pair was complete; so
that the disconsolate widow or widower was thrice consoled during the same
day. Mr. Engleheart also informs me that he used during several years to
shoot one of a pair of starlings which built in a hole in a house at
Blackheath; but the loss was always immediately repaired. During one
season he kept an account, and found that he had shot thirty-five birds
from the same nest; these consisted of both males and females, but in what
proportion he could not say: nevertheless, after all this destruction, a
brood was reared. (6. On the peregrine falcon, see Thompson, 'Nat. Hist.
of Ireland: Birds,' vol. i. 1849, p. 39. On owls, sparrows, and
partridges, see White, 'Nat. Hist. of Selborne,' edit. of 1825, vol. i. p.
139. On the Phoenicura, see Loudon's 'Mag. of Nat. Hist.' vol. vii. 1834,
p. 245. Brehm ('Thierleben,' B. iv. s. 991) also alludes to cases of birds
thrice mated during the same day.)
These facts well deserve attention. How is it that there are birds enough
ready to replace immediately a lost mate of either sex? Magpies, jays,
carrion-crows, partridges, and some other birds, are always seen during the
spring in pairs, and never by themselves; and these offer at first sight
the most perplexing cases. But birds of the same sex, although of course
not truly paired, sometimes live in pairs or in small parties, as is known
to be the case with pigeons and partridges. Birds also sometimes live in
triplets, as has been observed with starlings, carrion-crows, parrots, and
partridges. With partridges two females have been known to live with one
male, and two males with one female. In all such cases it is probable that
the union would be easily broken; and one of the three would readily pair
with a widow or widower. The males of certain birds may occasionally be
heard pouring forth their love-song long after the proper time, shewing
that they have either lost or never gained a mate. Death from accident or
disease of one of a pair would leave the other free and single; and there
is reason to believe that female birds during the breeding-season are
especially liable to premature death. Again, birds which have had their
nests destroyed, or barren pairs, or retarded individuals, would easily be
induced to desert their mates, and would probably be glad to take what
share they could of the pleasures and duties of rearing offspring although
not their own. (7. See White ('Nat. Hist. of Selborne,' 1825, vol. i. p.
140) on the existence, early in the season, of small coveys of male
partridges, of which fact I have heard other instances. See Jenner, on the
retarded state of the generative organs in certain birds, in 'Phil.
Transact.' 1824. In regard to birds living in triplets, I owe to Mr.
Jenner Weir the cases of the starlings and parrots, and to Mr. Fox, of
partridges; on carrion-crows, see the 'Field,' 1868, p. 415. On various
male birds singing after the proper period, see Rev. L. Jenyns,
'Observations in Natural History,' 1846, p. 87.) Such contingencies as
these probably explain most of the foregoing cases. (8. The following
case has been given ('The Times,' Aug. 6, 1868) by the Rev. F.O. Morris, on
the authority of the Hon. and Rev. O.W. Forester. "The gamekeeper here
found a hawk's nest this year, with five young ones on it. He took four
and killed them, but left one with its wings clipped as a decoy to destroy
the old ones by. They were both shot next day, in the act of feeding the
young one, and the keeper thought it was done with. The next day he came
again and found two other charitable hawks, who had come with an adopted
feeling to succour the orphan. These two he killed, and then left the
nest. On returning afterwards he found two more charitable individuals on
the same errand of mercy. One of these he killed; the other he also shot,
but could not find. No more came on the like fruitless errand.")
Nevertheless, it is a strange fact that within the same district, during
the height of the breeding-season, there should be so many males and
females always ready to repair the loss of a mated bird. Why do not such
spare birds immediately pair together? Have we not some reason to suspect,
and the suspicion has occurred to Mr. Jenner Weir, that as the courtship of
birds appears to be in many cases prolonged and tedious, so it occasionally
happens that certain males and females do not succeed, during the proper
season, in exciting each other's love, and consequently do not pair? This
suspicion will appear somewhat less improbable after we have seen what
strong antipathies and preferences female birds occasionally evince towards
particular males.
MENTAL QUALITIES OF BIRDS, AND THEIR TASTE FOR THE BEAUTIFUL.
Before we further discuss the question whether the females select the more
attractive males or accept the first whom they may encounter, it will be
advisable briefly to consider the mental powers of birds. Their reason is
generally, and perhaps justly, ranked as low; yet some facts could be given
leading to an opposite conclusion. (9. I am indebted to Prof. Newton for
the following passage from Mr. Adam's 'Travels of a Naturalist,' 1870, p.
278. Speaking of Japanese nut-hatches in confinement, he says: "Instead
of the more yielding fruit of the yew, which is the usual food of the nut-
hatch of Japan, at one time I substituted hard hazel-nuts. As the bird was
unable to crack them, he placed them one by one in his water-glass,
evidently with the notion that they would in time become softer--an
interesting proof of intelligence on the part of these birds.") Low powers
of reasoning, however, are compatible, as we see with mankind, with strong
affections, acute perception, and a taste for the beautiful; and it is with
these latter qualities that we are here concerned. It has often been said
that parrots become so deeply attached to each other that when one dies the
other pines for a long time; but Mr. Jenner Weir thinks that with most
birds the strength of their affection has been much exaggerated.
Nevertheless when one of a pair in a state of nature has been shot, the
survivor has been heard for days afterwards uttering a plaintive call; and
Mr. St. John gives various facts proving the attachment of mated birds.
(10. 'A Tour in Sutherlandshire,' vol. i. 1849, p. 185. Dr. Buller says
('Birds of New Zealand,' 1872, p. 56) that a male King Lory was killed; and
the female "fretted and moped, refused her food, and died of a broken
heart.") Mr. Bennett relates (11. 'Wanderings in New South Wales,' vol.
ii. 1834, p. 62.) that in China after a drake of the beautiful mandarin
Teal had been stolen, the duck remained disconsolate, though sedulously
courted by another mandarin drake, who displayed before her all his charms.
After an interval of three weeks the stolen drake was recovered, and
instantly the pair recognised each other with extreme joy. On the other
hand, starlings, as we have seen, may be consoled thrice in the same day
for the loss of their mates. Pigeons have such excellent local memories,
that they have been known to return to their former homes after an interval
of nine months, yet, as I hear from Mr. Harrison Weir, if a pair which
naturally would remain mated for life be separated for a few weeks during
the winter, and afterwards matched with other birds, the two when brought
together again, rarely, if ever, recognise each other.
Birds sometimes exhibit benevolent feelings; they will feed the deserted
young ones even of distinct species, but this perhaps ought to be
considered as a mistaken instinct. They will feed, as shewn in an earlier
part of this work, adult birds of their own species which have become
blind. Mr. Buxton gives a curious account of a parrot which took care of a
frost-bitten and crippled bird of a distinct species, cleansed her
feathers, and defended her from the attacks of the other parrots which
roamed freely about his garden. It is a still more curious fact that these
birds apparently evince some sympathy for the pleasures of their fellows.
When a pair of cockatoos made a nest in an acacia tree, "it was ridiculous
to see the extravagant interest taken in the matter by the others of the
same species." These parrots, also, evinced unbounded curiosity, and
clearly had "the idea of property and possession." (12. 'Acclimatization
of Parrots,' by C. Buxton, M.P., 'Annals and Mag. of Nat. Hist.' Nov. 1868,
p. 381.) They have good memories, for in the Zoological Gardens they have
plainly recognised their former masters after an interval of some months.
Birds possess acute powers of observation. Every mated bird, of course,
recognises its fellow. Audubon states that a certain number of mocking-
thrushes (Mimus polyglottus) remain all the year round in Louisiana, whilst
others migrate to the Eastern States; these latter, on their return, are
instantly recognised, and always attacked, by their southern brethren.
Birds under confinement distinguish different persons, as is proved by the
strong and permanent antipathy or affection which they shew, without any
apparent cause, towards certain individuals. I have heard of numerous
instances with jays, partridges, canaries, and especially bullfinches. Mr.
Hussey has described in how extraordinary a manner a tamed partridge
recognised everybody: and its likes and dislikes were very strong. This
bird seemed "fond of gay colours, and no new gown or cap could be put on
without catching his attention." (13. The 'Zoologist,' 1847-48, p. 1602.)
Mr. Hewitt has described the habits of some ducks (recently descended from
wild birds), which, at the approach of a strange dog or cat, would rush
headlong into the water, and exhaust themselves in their attempts to
escape; but they knew Mr. Hewitt's own dogs and cats so well that they
would lie down and bask in the sun close to them. They always moved away
from a strange man, and so they would from the lady who attended them if
she made any great change in her dress. Audubon relates that he reared and
tamed a wild turkey which always ran away from any strange dog; this bird
escaped into the woods, and some days afterwards Audubon saw, as he
thought, a wild turkey, and made his dog chase it; but, to his
astonishment, the bird did not run away, and the dog, when he came up, did
not attack the bird, for they mutually recognised each other as old
friends. (14. Hewitt on wild ducks, 'Journal of Horticulture,' Jan. 13,
1863, p. 39. Audubon on the wild turkey, 'Ornithological Biography,' vol.
i. p. 14. On the mocking-thrush, ibid. vol. i. p. 110.)
Mr. Jenner Weir is convinced that birds pay particular attention to the
colours of other birds, sometimes out of jealousy, and sometimes as a sign
of kinship. Thus he turned a reed-bunting (Emberiza schoeniculus), which
had acquired its black head-dress, into his aviary, and the new-comer was
not noticed by any bird, except by a bullfinch, which is likewise black-
headed. This bullfinch was a very quiet bird, and had never before
quarrelled with any of its comrades, including another reed-bunting, which
had not as yet become black-headed: but the reed-bunting with a black head
was so unmercifully treated that it had to be removed. Spiza cyanea,
during the breeding-season, is of a bright blue colour; and though
generally peaceable, it attacked S. ciris, which has only the head blue,
and completely scalped the unfortunate bird. Mr. Weir was also obliged to
turn out a robin, as it fiercely attacked all the birds in his aviary with
any red in their plumage, but no other kinds; it actually killed a red-
breasted crossbill, and nearly killed a goldfinch. On the other band, he
has observed that some birds, when first introduced, fly towards the
species which resemble them most in colour, and settle by their sides.
As male birds display their fine plumage and other ornaments with so much
care before the females, it is obviously probable that these appreciate the
beauty of their suitors. It is, however, difficult to obtain direct
evidence of their capacity to appreciate beauty. When birds gaze at
themselves in a looking-glass (of which many instances have been recorded)
we cannot feel sure that it is not from jealousy of a supposed rival,
though this is not the conclusion of some observers. In other cases it is
difficult to distinguish between mere curiosity and admiration. It is
perhaps the former feeling which, as stated by Lord Lilford (15. The
'Ibis,' vol. ii. 1860, p. 344.), attracts the ruff towards any bright
object, so that, in the Ionian Islands, "it will dart down to a bright-
coloured handkerchief, regardless of repeated shots." The common lark is
drawn down from the sky, and is caught in large numbers, by a small mirror
made to move and glitter in the sun. Is it admiration or curiosity which
leads the magpie, raven, and some other birds to steal and secrete bright
objects, such as silver articles or jewels?
Mr. Gould states that certain humming-birds decorate the outsides of their
nests "with the utmost taste; they instinctively fasten thereon beautiful
pieces of flat lichen, the larger pieces in the middle, and the smaller on
the part attached to the branch. Now and then a pretty feather is
intertwined or fastened to the outer sides, the stem being always so placed
that the feather stands out beyond the surface." The best evidence,
however, of a taste for the beautiful is afforded by the three genera of
Australian bower-birds already mentioned. Their bowers (Fig. 46), where
the sexes congregate and play strange antics, are variously constructed,
but what most concerns us is, that they are decorated by the several
species in a different manner. The Satin bower-bird collects gaily-
coloured articles, such as the blue tail-feathers of parrakeets, bleached
bones and shells, which it sticks between the twigs or arranges at the
entrance. Mr. Gould found in one bower a neatly-worked stone tomahawk and
a slip of blue cotton, evidently procured from a native encampment. These
objects are continually re-arranged, and carried about by the birds whilst
at play. The bower of the Spotted bower-bird "is beautifully lined with
tall grasses, so disposed that the heads nearly meet, and the decorations
are very profuse." Round stones are used to keep the grass-stems in their
proper places, and to make divergent paths leading to the bower. The
stones and shells are often brought from a great distance. The Regent
bird, as described by Mr. Ramsay, ornaments its short bower with bleached
land-shells belonging to five or six species, and with "berries of various
colours, blue, red, and black, which give it when fresh a very pretty
appearance. Besides these there were several newly-picked leaves and young
shoots of a pinkish colour, the whole showing a decided taste for the
beautiful." Well may Mr. Gould say that "these highly decorated halls of
assembly must be regarded as the most wonderful instances of bird-
architecture yet discovered;" and the taste, as we see, of the several
species certainly differs. (16. On the ornamented nests of humming-birds,
Gould, 'Introduction to the Trochilidae,' 1861, p. 19. On the bower-birds,
Gould, 'Handbook to the Birds of Australia,' 1865, vol. i. pp. 444-461.
Ramsay, in the 'Ibis,' 1867, p. 456.)
PREFERENCE FOR PARTICULAR MALES BY THE FEMALES.
Having made these preliminary remarks on the discrimination and taste of
birds, I will give all the facts known to me which bear on the preference
shewn by the female for particular males. It is certain that distinct
species of birds occasionally pair in a state of nature and produce
hybrids. Many instances could be given: thus Macgillivray relates how a
male blackbird and female thrush "fell in love with each other," and
produced offspring. (17. 'History of Brit. Birds,' vol. ii. p. 92.)
Several years ago eighteen cases had been recorded of the occurrence in
Great Britain of hybrids between the black grouse and pheasant (18.
'Zoologist,' 1853-1854, p. 3946.); but most of these cases may perhaps be
accounted for by solitary birds not finding one of their own species to
pair with. With other birds, as Mr. Jenner Weir has reason to believe,
hybrids are sometimes the result of the casual intercourse of birds
building in close proximity. But these remarks do not apply to the many
recorded instances of tamed or domestic birds, belonging to distinct
species, which have become absolutely fascinated with each other, although
living with their own species. Thus Waterton (19. Waterton, 'Essays on
Nat. Hist.' 2nd series, pp. 42 and 117. For the following statements see
on the wigeon, 'Loudon's Mag. of Nat. Hist.' vol. ix. p. 616; L. Lloyd,
'Scandinavian Adventures,' vol. i. 1854, p. 452. Dixon, 'Ornamental and
Domestic Poultry,' p. 137; Hewitt, in 'Journal of Horticulture,' Jan. 13,
1863, p. 40; Bechstein, 'Stubenvogel,' 1840, s. 230. Mr. J. Jenner Weir
has lately given me an analogous case with ducks of two species.) states
that out of a flock of twenty-three Canada geese, a female paired with a
solitary Bernicle gander, although so different in appearance and size; and
they produced hybrid offspring. A male wigeon (Mareca penelope), living
with females of the same species, has been known to pair with a pintail
duck, Querquedula acuta. Lloyd describes the remarkable attachment between
a shield-drake (Tadorna vulpanser) and a common duck. Many additional
instances could be given; and the Rev. E.S. Dixon remarks that "those who
have kept many different species of geese together well know what
unaccountable attachments they are frequently forming, and that they are
quite as likely to pair and rear young with individuals of a race (species)
apparently the most alien to themselves as with their own stock."
The Rev. W.D. Fox informs me that he possessed at the same time a pair of
Chinese geese (Anser cygnoides), and a common gander with three geese. The
two lots kept quite separate, until the Chinese gander seduced one of the
common geese to live with him. Moreover, of the young birds hatched from
the eggs of the common geese, only four were pure, the other eighteen
proving hybrids; so that the Chinese gander seems to have had prepotent
charms over the common gander. I will give only one other case; Mr. Hewitt
states that a wild duck, reared in captivity, "after breeding a couple of
seasons with her own mallard, at once shook him off on my placing a male
Pintail on the water. It was evidently a case of love at first sight, for
she swam about the new-comer caressingly, though he appeared evidently
alarmed and averse to her overtures of affection. From that hour she
forgot her old partner. Winter passed by, and the next spring the pintail
seemed to have become a convert to her blandishments, for they nested and
produced seven or eight young ones."
What the charm may have been in these several cases, beyond mere novelty,
we cannot even conjecture. Colour, however, sometimes comes into play; for
in order to raise hybrids from the siskin (Fringilla spinus) and the
canary, it is much the best plan, according to Bechstein, to place birds of
the same tint together. Mr. Jenner Weir turned a female canary into his
aviary, where there were male linnets, goldfinches, siskins, greenfinches,
chaffinches, and other birds, in order to see which she would choose; but
there never was any doubt, and the greenfinch carried the day. They paired
and produced hybrid offspring.
The fact of the female preferring to pair with one male rather than with
another of the same species is not so likely to excite attention, as when
this occurs, as we have just seen, between distinct species. The former
cases can best be observed with domesticated or confined birds; but these
are often pampered by high feeding, and sometimes have their instincts
vitiated to an extreme degree. Of this latter fact I could give sufficient
proofs with pigeons, and especially with fowls, but they cannot be here
related. Vitiated instincts may also account for some of the hybrid unions
above mentioned; but in many of these cases the birds were allowed to range
freely over large ponds, and there is no reason to suppose that they were
unnaturally stimulated by high feeding.
With respect to birds in a state of nature, the first and most obvious
supposition which will occur to every one is that the female at the proper
season accepts the first male whom she may encounter; but she has at least
the opportunity for exerting a choice, as she is almost invariably pursued
by many males. Audubon--and we must remember that he spent a long life in
prowling about the forests of the United States and observing the birds--
does not doubt that the female deliberately chooses her mate; thus,
speaking of a woodpecker, he says the hen is followed by half-a-dozen gay
suitors, who continue performing strange antics, "until a marked preference
is shewn for one." The female of the red-winged starling (Agelaeus
phoeniceus) is likewise pursued by several males, "until, becoming
fatigued, she alights, receives their addresses, and soon makes a choice."
He describes also how several male night-jars repeatedly plunge through the
air with astonishing rapidity, suddenly turning, and thus making a singular
noise; "but no sooner has the female made her choice than the other males
are driven away." With one of the vultures (Cathartes aura) of the United
States, parties of eight, ten, or more males and females assemble on fallen
logs, "exhibiting the strongest desire to please mutually," and after many
caresses, each male leads off his partner on the wing. Audubon likewise
carefully observed the wild flocks of Canada geese (Anser canadensis), and
gives a graphic description of their love-antics; he says that the birds
which had been previously mated "renewed their courtship as early as the
month of January, while the others would be contending or coquetting for
hours every day, until all seemed satisfied with the choice they had made,
after which, although they remained together, any person could easily
perceive that they were careful to keep in pairs. I have observed also
that the older the birds the shorter were the preliminaries of their
courtship. The bachelors and old maids whether in regret, or not caring to
be disturbed by the bustle, quietly moved aside and lay down at some
distance from the rest." (20. Audubon, 'Ornithological Biography,' vol.
i. pp. 191, 349; vol. ii. pp. 42, 275; vol. iii. p. 2.) Many similar
statements with respect to other birds could be cited from this same
observer.
Turning now to domesticated and confined birds, I will commence by giving
what little I have learnt respecting the courtship of fowls. I have
received long letters on this subject from Messrs. Hewitt and Tegetmeier,
and almost an essay from the late Mr. Brent. It will be admitted by every
one that these gentlemen, so well known from their published works, are
careful and experienced observers. They do not believe that the females
prefer certain males on account of the beauty of their plumage; but some
allowance must be made for the artificial state under which these birds
have long been kept. Mr. Tegetmeier is convinced that a gamecock, though
disfigured by being dubbed and with his hackles trimmed, would be accepted
as readily as a male retaining all his natural ornaments. Mr. Brent,
however, admits that the beauty of the male probably aids in exciting the
female; and her acquiescence is necessary. Mr. Hewitt is convinced that
the union is by no means left to mere chance, for the female almost
invariably prefers the most vigorous, defiant, and mettlesome male; hence
it is almost useless, as he remarks, "to attempt true breeding if a game-
cock in good health and condition runs the locality, for almost every hen
on leaving the roosting-place will resort to the game-cock, even though
that bird may not actually drive away the male of her own variety." Under
ordinary circumstances the males and females of the fowl seem to come to a
mutual understanding by means of certain gestures, described to me by Mr.
Brent. But hens will often avoid the officious attentions of young males.
Old hens, and hens of a pugnacious disposition, as the same writer informs
me, dislike strange males, and will not yield until well beaten into
compliance. Ferguson, however, describes how a quarrelsome hen was subdued
by the gentle courtship of a Shanghai cock. (21. 'Rare and Prize
Poultry,' 1854, p. 27.)
There is reason to believe that pigeons of both sexes prefer pairing with
birds of the same breed; and dovecot-pigeons dislike all the highly
improved breeds. (22. 'Variation of Animals and Plants under
Domestication,' vol. ii. p. 103.) Mr. Harrison Weir has lately heard from
a trustworthy observer, who keeps blue pigeons, that these drive away all
other coloured varieties, such as white, red, and yellow; and from another
observer, that a female dun carrier could not, after repeated trials, be
matched with a black male, but immediately paired with a dun. Again, Mr.
Tegetmeier had a female blue turbit that obstinately refused to pair with
two males of the same breed, which were successively shut up with her for
weeks; but on being let out she would have immediately accepted the first
blue dragon that offered. As she was a valuable bird, she was then shut up
for many weeks with a silver (i.e., very pale blue) male, and at last mated
with him. Nevertheless, as a general rule, colour appears to have little
influence on the pairing of pigeons. Mr. Tegetmeier, at my request,
stained some of his birds with magenta, but they were not much noticed by
the others.
Female pigeons occasionally feel a strong antipathy towards certain males,
without any assignable cause. Thus MM. Boitard and Corbie, whose
experience extended over forty-five years, state: "Quand une femelle
eprouve de l'antipathie pour un male avec lequel on veut l'accoupler,
malgre tous les feux de l'amour, malgre l'alpiste et le chenevis dont on la
nourrit pour augmenter son ardeur, malgre un emprisonnement de six mois et
meme d'un an, elle refuse constamment ses caresses; les avances empressees,
les agaceries, les tournoiemens, les tendres roucoulemens, rien ne peut lui
plaire ni l'emouvoir; gonflee, boudeuse, blottie dans un coin de sa prison,
elle n'en sort que pour boire et manger, ou pour repousser avec une espece
de rage des caresses devenues trop pressantes." (23. Boitard and Corbie,
'Les Pigeons,' etc., 1824, p. 12. Prosper Lucas ('Traite de l'Hered. Nat.'
tom. ii. 1850, p. 296) has himself observed nearly similar facts with
pigeons.) On the other hand, Mr. Harrison Weir has himself observed, and
has heard from several breeders, that a female pigeon will occasionally
take a strong fancy for a particular male, and will desert her own mate for
him. Some females, according to another experienced observer, Riedel (24.
Die Taubenzucht, 1824, s. 86.), are of a profligate disposition, and prefer
almost any stranger to their own mate. Some amorous males, called by our
English fanciers "gay birds," are so successful in their gallantries, that,
as Mr. H. Weir informs me, they must be shut up on account of the mischief
which they cause.
Wild turkeys in the United States, according to Audubon, "sometimes pay
their addresses to the domesticated females, and are generally received by
them with great pleasure." So that these females apparently prefer the
wild to their own males. (25. 'Ornithological Biography,' vol. i. p. 13.
See to the same effect, Dr. Bryant, in Allen's 'Mammals and Birds of
Florida,' p. 344.)
Here is a more curious case. Sir R. Heron during many years kept an
account of the habits of the peafowl, which he bred in large numbers. He
states that "the hens have frequently great preference to a particular
peafowl. They were all so fond of an old pied cock, that one year, when he
was confined, though still in view, they were constantly assembled close to
the trellice-walls of his prison, and would not suffer a japanned peacock
to touch them. On his being let out in the autumn, the oldest of the hens
instantly courted him and was successful in her courtship. The next year
he was shut up in a stable, and then the hens all courted his rival." (26.
'Proceedings, Zoological Society,' 1835, p. 54. The japanned peacock is
considered by Mr. Sclater as a distinct species, and has been named Pavo
nigripennis; but the evidence seems to me to show that it is only a
variety.) This rival was a japanned or black-winged peacock, to our eyes a
more beautiful bird than the common kind.
Lichtenstein, who was a good observer and had excellent opportunities of
observation at the Cape of Good Hope, assured Rudolphi that the female
widow-bird (Chera progne) disowns the male when robbed of the long tail-
feathers with which he is ornamented during the breeding-season. I presume
that this observation must have been made on birds under confinement. (27.
Rudolphi, 'Beitrage zur Anthropologie,' 1812, s. 184.) Here is an
analogous case; Dr. Jaeger (28. 'Die Darwin'sche Theorie, und ihre
Stellung zu Moral und Religion,' 1869, s. 59.), director of the Zoological
Gardens of Vienna, states that a male silver-pheasant, who had been
triumphant over all other males and was the accepted lover of the females,
had his ornamental plumage spoiled. He was then immediately superseded by
a rival, who got the upper hand and afterwards led the flock.
It is a remarkable fact, as shewing how important colour is in the
courtship of birds, that Mr. Boardman, a well-known collector and observer
of birds for many years in the Northern United States, has never in his
large experience seen an albino paired with another bird; yet he has had
opportunities of observing many albinos belonging to several species. (29.
This statement is given by Mr. A. Leith Adams, in his 'Field and Forest
Rambles,' 1873, p. 76, and accords with his own experience.) It can hardly
be maintained that albinos in a state of nature are incapable of breeding,
as they can be raised with the greatest facility under confinement. It
appears, therefore, that we must attribute the fact that they do not pair
to their rejection by their normally coloured comrades.
Female birds not only exert a choice, but in some few cases they court the
male, or even fight together for his possession. Sir R. Heron states that
with peafowl, the first advances are always made by the female; something
of the same kind takes place, according to Audubon, with the older females
of the wild turkey. With the capercailzie, the females flit round the male
whilst he is parading at one of the places of assemblage, and solicit his
attention. (30. In regard to peafowl, see Sir R. Heron, 'Proc. Zoolog.
Soc.' 1835, p. 54, and the Rev. E.S. Dixon, 'Ornamental Poultry,' 1848, p.
8. For the turkey, Audubon, ibid. p. 4. For the capercailzie, Lloyd,
'Game Birds of Sweden,' 1867, p. 23.) We have seen that a tame wild-duck
seduced an unwilling pintail drake after a long courtship. Mr. Bartlett
believes that the Lophophorus, like many other gallinaceous birds, is
naturally polygamous, but two females cannot be placed in the same cage
with a male, as they fight so much together. The following instance of
rivalry is more surprising as it relates to bullfinches, which usually pair
for life. Mr. Jenner Weir introduced a dull-coloured and ugly female into
his aviary, and she immediately attacked another mated female so
unmercifully that the latter had to be separated. The new female did all
the courtship, and was at last successful, for she paired with the male;
but after a time she met with a just retribution, for, ceasing to be
pugnacious, she was replaced by the old female, and the male then deserted
his new and returned to his old love.
In all ordinary cases the male is so eager that he will accept any female,
and does not, as far as we can judge, prefer one to the other; but, as we
shall hereafter see, exceptions to this rule apparently occur in some few
groups. With domesticated birds, I have heard of only one case of males
shewing any preference for certain females, namely, that of the domestic
cock, who, according to the high authority of Mr. Hewitt, prefers the
younger to the older hens. On the other hand, in effecting hybrid unions
between the male pheasant and common hens, Mr. Hewitt is convinced that the
pheasant invariably prefers the older birds. He does not appear to be in
the least influenced by their colour; but "is most capricious in his
attachments" (31. Mr. Hewitt, quoted in Tegetmeier's 'Poultry Book,' 1866,
p. 165.): from some inexplicable cause he shews the most determined
aversion to certain hens, which no care on the part of the breeder can
overcome. Mr. Hewitt informs me that some hens are quite unattractive even
to the males of their own species, so that they may be kept with several
cocks during a whole season, and not one egg out of forty or fifty will
prove fertile. On the other hand, with the long-tailed duck (Harelda
glacialis), "it has been remarked," says M. Ekstrom, "that certain females
are much more courted than the rest. Frequently, indeed, one sees an
individual surrounded by six or eight amorous males." Whether this
statement is credible, I know not; but the native sportsmen shoot these
females in order to stuff them as decoys. (32. Quoted in Lloyd's 'Game
Birds of Sweden,' p. 345.)
With respect to female birds feeling a preference for particular males, we
must bear in mind that we can judge of choice being exerted only by
analogy. If an inhabitant of another planet were to behold a number of
young rustics at a fair courting a pretty girl, and quarrelling about her
like birds at one of their places of assemblage, he would, by the eagerness
of the wooers to please her and to display their finery, infer that she had
the power of choice. Now with birds the evidence stands thus: they have
acute powers of observation, and they seem to have some taste for the
beautiful both in colour and sound. It is certain that the females
occasionally exhibit, from unknown causes, the strongest antipathies and
preferences for particular males. When the sexes differ in colour or in
other ornaments the males with rare exceptions are the more decorated,
either permanently or temporarily during the breeding-season. They
sedulously display their various ornaments, exert their voices, and perform
strange antics in the presence of the females. Even well-armed males, who,
it might be thought, would altogether depend for success on the law of
battle, are in most cases highly ornamented; and their ornaments have been
acquired at the expense of some loss of power. In other cases ornaments
have been acquired, at the cost of increased risk from birds and beasts of
prey. With various species many individuals of both sexes congregate at
the same spot, and their courtship is a prolonged affair. There is even
reason to suspect that the males and females within the same district do
not always succeed in pleasing each other and pairing.
What then are we to conclude from these facts and considerations? Does the
male parade his charms with so much pomp and rivalry for no purpose? Are
we not justified in believing that the female exerts a choice, and that she
receives the addresses of the male who pleases her most? It is not
probable that she consciously deliberates; but she is most excited or
attracted by the most beautiful, or melodious, or gallant males. Nor need
it be supposed that the female studies each stripe or spot of colour; that
the peahen, for instance, admires each detail in the gorgeous train of the
peacock--she is probably struck only by the general effect. Nevertheless,
after hearing how carefully the male Argus pheasant displays his elegant
primary wing-feathers, and erects his ocellated plumes in the right
position for their full effect; or again, how the male goldfinch
alternately displays his gold-bespangled wings, we ought not to feel too
sure that the female does not attend to each detail of beauty. We can
judge, as already remarked, of choice being exerted, only from analogy; and
the mental powers of birds do not differ fundamentally from ours. From
these various considerations we may conclude that the pairing of birds is
not left to chance; but that those males, which are best able by their
various charms to please or excite the female, are under ordinary
circumstances accepted. If this be admitted, there is not much difficulty
in understanding how male birds have gradually acquired their ornamental
characters. All animals present individual differences, and as man can
modify his domesticated birds by selecting the individuals which appear to
him the most beautiful, so the habitual or even occasional preference by
the female of the more attractive males would almost certainly lead to
their modification; and such modifications might in the course of time be
augmented to almost any extent, compatible with the existence of the
species.
VARIABILITY OF BIRDS, AND ESPECIALLY OF THEIR SECONDARY SEXUAL CHARACTERS.
Variability and inheritance are the foundations for the work of selection.
That domesticated birds have varied greatly, their variations being
inherited, is certain. That birds in a state of nature have been modified
into distinct races is now universally admitted. (33. According to Dr.
Blasius ('Ibis,' vol. ii. 1860, p. 297), there are 425 indubitable species
of birds which breed in Europe, besides sixty forms, which are frequently
regarded as distinct species. Of the latter, Blasius thinks that only ten
are really doubtful, and that the other fifty ought to be united with their
nearest allies; but this shews that there must be a considerable amount of
variation with some of our European birds. It is also an unsettled point
with naturalists, whether several North American birds ought to be ranked
as specifically distinct from the corresponding European species. So again
many North American forms which until lately were named as distinct
species, are now considered to be local races.) Variations may be divided
into two classes; those which appear to our ignorance to arise
spontaneously, and those which are directly related to the surrounding
conditions, so that all or nearly all the individuals of the same species
are similarly modified. Cases of the latter kind have recently been
observed with care by Mr. J.A. Allen (34. 'Mammals and Birds of East
Florida,' also an 'Ornithological Reconnaissance of Kansas,' etc.
Notwithstanding the influence of climate on the colours of birds, it is
difficult to account for the dull or dark tints of almost all the species
inhabiting certain countries, for instance, the Galapagos Islands under the
equator, the wide temperate plains of Patagonia, and, as it appears, Egypt
(see Mr. Hartshorne in the 'American Naturalist,' 1873, p. 747). These
countries are open, and afford little shelter to birds; but it seems
doubtful whether the absence of brightly coloured species can be explained
on the principle of protection, for on the Pampas, which are equally open,
though covered by green grass, and where the birds would be equally exposed
to danger, many brilliant and conspicuously coloured species are common. I
have sometimes speculated whether the prevailing dull tints of the scenery
in the above named countries may not have affected the appreciation of
bright colours by the birds inhabiting them.), who shews that in the United
States many species of birds gradually become more strongly coloured in
proceeding southward, and more lightly coloured in proceeding westward to
the arid plains of the interior. Both sexes seem generally to be affected
in a like manner, but sometimes one sex more than the other. This result
is not incompatible with the belief that the colours of birds are mainly
due to the accumulation of successive variations through sexual selection;
for even after the sexes have been greatly differentiated, climate might
produce an equal effect on both sexes, or a greater effect on one sex than
on the other, owing to some constitutional difference.
Individual differences between the members of the same species are admitted
by every one to occur under a state of nature. Sudden and strongly marked
variations are rare; it is also doubtful whether if beneficial they would
often be preserved through selection and transmitted to succeeding
generations. (35. 'Origin of Species' fifth edit. 1869, p.104. I had
always perceived, that rare and strongly-marked deviations of structure,
deserving to be called monstrosities, could seldom be preserved through
natural selection, and that the preservation of even highly-beneficial
variations would depend to a certain extent on chance. I had also fully
appreciated the importance of mere individual differences, and this led me
to insist so strongly on the importance of that unconscious form of
selection by man, which follows from the preservation of the most valued
individuals of each breed, without any intention on his part to modify the
characters of the breed. But until I read an able article in the 'North
British Review' (March 1867, p. 289, et seq.), which has been of more use
to me than any other Review, I did not see how great the chances were
against the preservation of variations, whether slight or strongly
pronounced, occurring only in single individuals.) Nevertheless, it may be
worth while to give the few cases which I have been able to collect,
relating chiefly to colour,--simple albinism and melanism being excluded.
Mr. Gould is well known to admit the existence of few varieties, for he
esteems very slight differences as specific; yet he states (36.
'Introduction to the Trochlidae,' p. 102.) that near Bogota certain
humming-birds belonging to the genus Cynanthus are divided into two or
three races or varieties, which differ from each other in the colouring of
the tail--"some having the whole of the feathers blue, while others have
the eight central ones tipped with beautiful green." It does not appear
that intermediate gradations have been observed in this or the following
cases. In the males alone of one of the Australian parrakeets "the thighs
in some are scarlet, in others grass-green." In another parrakeet of the
same country "some individuals have the band across the wing-coverts
bright-yellow, while in others the same part is tinged with red. (37.
Gould, 'Handbook to Birds of Australia,' vol. ii. pp. 32 and 68.) In the
United States some few of the males of the scarlet tanager (Tanagra rubra)
have "a beautiful transverse band of glowing red on the smaller wing-
coverts" (38. Audubon, 'Ornithological Biography,' 1838, vol. iv. p.
389.); but this variation seems to be somewhat rare, so that its
preservation through sexual selection would follow only under usually
favourable circumstances. In Bengal the Honey buzzard (Pernis cristata)
has either a small rudimental crest on its head, or none at all: so slight
a difference, however, would not have been worth notice, had not this same
species possessed in Southern India a well-marked occipital crest formed of
several graduated feathers." (39. Jerdon, 'Birds of India,' vol. i. p.
108; and Mr. Blyth, in 'Land and Water,' 1868, p. 381.)
The following case is in some respects more interesting. A pied variety of
the raven, with the head, breast, abdomen, and parts of the wings and tail-
feathers white, is confined to the Feroe Islands. It is not very rare
there, for Graba saw during his visit from eight to ten living specimens.
Although the characters of this variety are not quite constant, yet it has
been named by several distinguished ornithologists as a distinct species.
The fact of the pied birds being pursued and persecuted with much clamour
by the other ravens of the island was the chief cause which led Brunnich to
conclude that they were specifically distinct; but this is now known to be
an error. (40. Graba, 'Tagebuch Reise nach Faro,' 1830, ss. 51-54.
Macgillivray, 'History of British Birds,' vol. iii. p. 745, 'Ibis,' vol. v.
1863, p. 469.) This case seems analogous to that lately given of albino
birds not pairing from being rejected by their comrades.
In various parts of the northern seas a remarkable variety of the common
Guillemot (Uria troile) is found; and in Feroe, one out of every five
birds, according to Graba's estimation, presents this variation. It is
characterised (41. Graba, ibid. s. 54. Macgillivray, ibid. vol. v. p.
327.) by a pure white ring round the eye, with a curved narrow white line,
an inch and a half in length, extending back from the ring. This
conspicuous character has caused the bird to be ranked by several
ornithologists as a distinct species under the name of U. lacrymans, but it
is now known to be merely a variety. It often pairs with the common kind,
yet intermediate gradations have never been seen; nor is this surprising,
for variations which appear suddenly, are often, as I have elsewhere shewn
(42. 'Variation of Animals and Plants under Domestication,' vol. ii. p.
92.), transmitted either unaltered or not at all. We thus see that two
distinct forms of the same species may co-exist in the same district, and
we cannot doubt that if the one had possessed any advantage over the other,
it would soon have been multiplied to the exclusion of the latter. If, for
instance, the male pied ravens, instead of being persecuted by their
comrades, had been highly attractive (like the above pied peacock) to the
black female ravens their numbers would have rapidly increased. And this
would have been a case of sexual selection.
With respect to the slight individual differences which are common, in a
greater or less degree, to all the members of the same species, we have
every reason to believe that they are by far the most important for the
work of selection. Secondary sexual characters are eminently liable to
vary, both with animals in a state of nature and under domestication. (43.
On these points see also 'Variation of Animals and Plants under
Domestication,' vol. i. p. 253; vol ii. pp. 73, 75.) There is also reason
to believe, as we have seen in our eighth chapter, that variations are more
apt to occur in the male than in the female sex. All these contingencies
are highly favourable for sexual selection. Whether characters thus
acquired are transmitted to one sex or to both sexes, depends, as we shall
see in the following chapter, on the form of inheritance which prevails.
It is sometimes difficult to form an opinion whether certain slight
differences between the sexes of birds are simply the result of variability
with sexually-limited inheritance, without the aid of sexual selection, or
whether they have been augmented through this latter process. I do not
here refer to the many instances where the male displays splendid colours
or other ornaments, of which the female partakes to a slight degree; for
these are almost certainly due to characters primarily acquired by the male
having been more or less transferred to the female. But what are we to
conclude with respect to certain birds in which, for instance, the eyes
differ slightly in colour in the two sexes? (44. See, for instance, on
the irides of a Podica and Gallicrex in 'Ibis,' vol. ii. 1860, p. 206; and
vol. v. 1863, p. 426.) In some cases the eyes differ conspicuously; thus
with the storks of the genus Xenorhynchus, those of the male are blackish-
hazel, whilst those of the females are gamboge-yellow; with many hornbills
(Buceros), as I hear from Mr. Blyth (45. See also Jerdon, 'Birds of
India,' vol. i. pp. 243-245.), the males have intense crimson eyes, and
those of the females are white. In the Buceros bicornis, the hind margin
of the casque and a stripe on the crest of the beak are black in the male,
but not so in the female. Are we to suppose that these black marks and the
crimson colour of the eyes have been preserved or augmented through sexual
selection in the males? This is very doubtful; for Mr. Bartlett shewed me
in the Zoological Gardens that the inside of the mouth of this Buceros is
black in the male and flesh-coloured in the female; and their external
appearance or beauty would not be thus affected. I observed in Chile (46.
'Zoology of the Voyage of H.M.S. "Beagle,"' 1841, p. 6.) that the iris in
the condor, when about a year old, is dark-brown, but changes at maturity
into yellowish-brown in the male, and into bright red in the female. The
male has also a small, longitudinal, leaden-coloured, fleshy crest or comb.
The comb of many gallinaceous birds is highly ornamental, and assumes vivid
colours during the act of courtship; but what are we to think of the dull-
coloured comb of the condor, which does not appear to us in the least
ornamental? The same question may be asked in regard to various other
characters, such as the knob on the base of the beak of the Chinese goose
(Anser cygnoides), which is much larger in the male than in the female. No
certain answer can be given to these questions; but we ought to be cautious
in assuming that knobs and various fleshy appendages cannot be attractive
to the female, when we remember that with savage races of man various
hideous deformities--deep scars on the face with the flesh raised into
protuberances, the septum of the nose pierced by sticks or bones, holes in
the ears and lips stretched widely open--are all admired as ornamental.
Whether or not unimportant differences between the sexes, such as those
just specified, have been preserved through sexual selection, these
differences, as well as all others, must primarily depend on the laws of
variation. On the principle of correlated development, the plumage often
varies on different parts of the body, or over the whole body, in the same
manner. We see this well illustrated in certain breeds of the fowl. In
all the breeds the feathers on the neck and loins of the males are
elongated, and are called hackles; now when both sexes acquire a top-knot,
which is a new character in the genus, the feathers on the head of the male
become hackle-shaped, evidently on the principle of correlation; whilst
those on the head of the female are of the ordinary shape. The colour also
of the hackles forming the top-knot of the male, is often correlated with
that of the hackles on the neck and loins, as may be seen by comparing
these feathers in the golden and silver-spangled Polish, the Houdans, and
Creve-coeur breeds. In some natural species we may observe exactly the
same correlation in the colours of these same feathers, as in the males of
the splendid Gold and Amherst pheasants.
The structure of each individual feather generally causes any change in its
colouring to be symmetrical; we see this in the various laced, spangled,
and pencilled breeds of the fowl; and on the principle of correlation the
feathers over the whole body are often coloured in the same manner. We are
thus enabled without much trouble to rear breeds with their plumage marked
almost as symmetrically as in natural species. In laced and spangled fowls
the coloured margins of the feathers are abruptly defined; but in a mongrel
raised by me from a black Spanish cock glossed with green, and a white
game-hen, all the feathers were greenish-black, excepting towards their
extremities, which were yellowish-white; but between the white extremities
and the black bases, there was on each feather a symmetrical, curved zone
of dark-brown. In some instances the shaft of the feather determines the
distribution of the tints; thus with the body-feathers of a mongrel from
the same black Spanish cock and a silver-spangled Polish hen, the shaft,
together with a narrow space on each side, was greenish-black, and this was
surrounded by a regular zone of dark-brown, edged with brownish-white. In
these cases we have feathers symmetrically shaded, like those which give so
much elegance to the plumage of many natural species. I have also noticed
a variety of the common pigeon with the wing-bars symmetrically zoned with
three bright shades, instead of being simply black on a slaty-blue ground,
as in the parent-species.
In many groups of birds the plumage is differently coloured in the several
species, yet certain spots, marks, or stripes are retained by all.
Analogous cases occur with the breeds of the pigeon, which usually retain
the two wing-bars, though they may be coloured red, yellow, white, black,
or blue, the rest of the plumage being of some wholly different tint. Here
is a more curious case, in which certain marks are retained, though
coloured in a manner almost exactly the opposite of what is natural; the
aboriginal pigeon has a blue tail, with the terminal halves of the outer
webs of the two outer tail feathers white; now there is a sub-variety
having a white instead of a blue tail, with precisely that part black which
is white in the parent-species. (47. Bechstein, 'Naturgeschichte
Deutschlands,' B. iv. 1795, s. 31, on a sub-variety of the Monck pigeon.)
FORMATION AND VARIABILITY OF THE OCELLI OR EYE-LIKE SPOTS ON THE PLUMAGE OF
BIRDS.
[Fig. 53. Cyllo leda, Linn., from a drawing by Mr. Trimen, shewing the
extreme range of variation in the ocelli.
A. Specimen, from Mauritius, upper surface of fore-wing.
A1. Specimen, from Natal, ditto.
B. Specimen, from Java, upper surface of hind-wing.
B1. Specimen, from Mauritius, ditto.]
As no ornaments are more beautiful than the ocelli on the feathers of
various birds, on the hairy coats of some mammals, on the scales of
reptiles and fishes, on the skin of amphibians, on the wings of many
Lepidoptera and other insects, they deserve to be especially noticed. An
ocellus consists of a spot within a ring of another colour, like the pupil
within the iris, but the central spot is often surrounded by additional
concentric zones. The ocelli on the tail-coverts of the peacock offer a
familiar example, as well as those on the wings of the peacock-butterfly
(Vanessa). Mr. Trimen has given me a description of a S. African moth
(Gynanisa isis), allied to our Emperor moth, in which a magnificent ocellus
occupies nearly the whole surface of each hinder wing; it consists of a
black centre, including a semi-transparent crescent-shaped mark, surrounded
by successive, ochre-yellow, black, ochre-yellow, pink, white, pink, brown,
and whitish zones. Although we do not know the steps by which these
wonderfully beautiful and complex ornaments have been developed, the
process has probably been a simple one, at least with insects; for, as Mr.
Trimen writes to me, "no characters of mere marking or coloration are so
unstable in the Lepidoptera as the ocelli, both in number and size." Mr.
Wallace, who first called my attention to this subject, shewed me a series
of specimens of our common meadow-brown butterfly (Hipparchia janira)
exhibiting numerous gradations from a simple minute black spot to an
elegantly-shaded ocellus. In a S. African butterfly (Cyllo leda, Linn.),
belonging to the same family, the ocelli are even still more variable. In
some specimens (A, Fig. 53) large spaces on the upper surface of the wings
are coloured black, and include irregular white marks; and from this state
a complete gradation can be traced into a tolerably perfect ocellus (A1),
and this results from the contraction of the irregular blotches of colour.
In another series of specimens a gradation can be followed from excessively
minute white dots, surrounded by a scarcely visible black line (B), into
perfectly symmetrical and large ocelli (B1). (48. This woodcut has been
engraved from a beautiful drawing, most kindly made for me by Mr. Trimen;
see also his description of the wonderful amount of variation in the
coloration and shape of the wings of this butterfly, in his 'Rhopalocera
Africae Australis,' p. 186.) In cases like these, the development of a
perfect ocellus does not require a long course of variation and selection.
With birds and many other animals, it seems to follow from the comparison
of allied species that circular spots are often generated by the breaking
up and contraction of stripes. In the Tragopan pheasant faint white lines
in the female represent the beautiful white spots in the male (49. Jerdon,
'Birds of India,' vol. iii. p. 517.); and something of the same kind may be
observed in the two sexes of the Argus pheasant. However this may be,
appearances strongly favour the belief that on the one hand, a dark spot is
often formed by the colouring matter being drawn towards a central point
from a surrounding zone, which latter is thus rendered lighter; and, on the
other hand, that a white spot is often formed by the colour being driven
away from a central point, so that it accumulates in a surrounding darker
zone. In either case an ocellus is the result. The colouring matter seems
to be a nearly constant quantity, but is redistributed, either
centripetally or centrifugally. The feathers of the common guinea-fowl
offer a good instance of white spots surrounded by darker zones; and
wherever the white spots are large and stand near each other, the
surrounding dark zones become confluent. In the same wing-feather of the
Argus pheasant dark spots may be seen surrounded by a pale zone, and white
spots by a dark zone. Thus the formation of an ocellus in its most
elementary state appears to be a simple affair. By what further steps the
more complex ocelli, which are surrounded by many successive zones of
colour, have been generated, I will not pretend to say. But the zoned
feathers of the mongrels from differently coloured fowls, and the
extraordinary variability of the ocelli on many Lepidoptera, lead us to
conclude that their formation is not a complex process, but depends on some
slight and graduated change in the nature of the adjoining tissues.
GRADATION OF SECONDARY SEXUAL CHARACTERS.
[Fig. 54. Feather of Peacock, about two-thirds of natural size, drawn by
Mr. Ford. The transparent zone is represented by the outermost white zone,
confined to the upper end of the disc.]
Cases of gradation are important, as shewing us that highly complex
ornaments may be acquired by small successive steps. In order to discover
the actual steps by which the male of any existing bird has acquired his
magnificent colours or other ornaments, we ought to behold the long line of
his extinct progenitors; but this is obviously impossible. We may,
however, generally gain a clue by comparing all the species of the same
group, if it be a large one; for some of them will probably retain, at
least partially, traces of their former characters. Instead of entering on
tedious details respecting various groups, in which striking instances of
gradation could be given, it seems the best plan to take one or two
strongly marked cases, for instance that of the peacock, in order to see if
light can be thrown on the steps by which this bird bas become so
splendidly decorated. The peacock is chiefly remarkable from the
extraordinary length of his tail-coverts; the tail itself not being much
elongated. The barbs along nearly the whole length of these feathers stand
separate or are decomposed; but this is the case with the feathers of many
species, and with some varieties of the domestic fowl and pigeon. The
barbs coalesce towards the extremity of the shaft forming the oval disc or
ocellus, which is certainly one of the most beautiful objects in the world.
It consists of an iridescent, intensely blue, indented centre, surrounded
by a rich green zone, this by a broad coppery-brown zone, and this by five
other narrow zones of slightly different iridescent shades. A trifling
character in the disc deserves notice; the barbs, for a space along one of
the concentric zones are more or less destitute of their barbules, so that
a part of the disc is surrounded by an almost transparent zone, which gives
it a highly finished aspect. But I have elsewhere described (50.
'Variation of Animals and Plants under Domestication,' vol. i. p. 254.) an
exactly analogous variation in the hackles of a sub-variety of the game-
cock, in which the tips, having a metallic lustre, "are separated from the
lower part of the feather by a symmetrically shaped transparent zone,
composed of the naked portions of the barbs." The lower margin or base of
the dark-blue centre of the ocellus is deeply indented on the line of the
shaft. The surrounding zones likewise shew traces, as may be seen in the
drawing (Fig. 54), of indentations, or rather breaks. These indentations
are common to the Indian and Javan peacocks (Pavo cristatus and P.
muticus); and they seem to deserve particular attention, as probably
connected with the development of the ocellus; but for a long time I could
not conjecture their meaning.
If we admit the principle of gradual evolution, there must formerly have
existed many species which presented every successive step between the
wonderfully elongated tail-coverts of the peacock and the short tail-
coverts of all ordinary birds; and again between the magnificent ocelli of
the former, and the simpler ocelli or mere coloured spots on other birds;
and so with all the other characters of the peacock. Let us look to the
allied Gallinaceae for any still-existing gradations. The species and sub-
species of Polyplectron inhabit countries adjacent to the native land of
the peacock; and they so far resemble this bird that they are sometimes
called peacock-pheasants. I am also informed by Mr. Bartlett that they
resemble the peacock in their voice and in some of their habits. During
the spring the males, as previously described, strut about before the
comparatively plain-coloured females, expanding and erecting their tail and
wing-feathers, which are ornamented with numerous ocelli. I request the
reader to turn back to the drawing (Fig. 51) of a Polyplectron; In P.
napoleonis the ocelli are confined to the tail, and the back is of a rich
metallic blue; in which respects this species approaches the Java peacock.
P. hardwickii possesses a peculiar top-knot, which is also somewhat like
that of the Java peacock. In all the species the ocelli on the wings and
tail are either circular or oval, and consist of a beautiful, iridescent,
greenish-blue or greenish-purple disc, with a black border. This border in
P. chinquis shades into brown, edged with cream colour, so that the ocellus
is here surrounded with variously shaded, though not bright, concentric
zones. The unusual length of the tail-coverts is another remarkable
character in Polyplectron; for in some of the species they are half, and in
others two-thirds as long as the true tail-feathers. The tail-coverts are
ocellated as in the peacock. Thus the several species of Polyplectron
manifestly make a graduated approach to the peacock in the length of their
tail-coverts, in the zoning of the ocelli, and in some other characters.
[Fig. 55. Part of a tail-covert of Polyplectron chinquis, with the two
ocelli of natural size.
Fig. 56. Part of a tail-covert of Polyplectron malaccense, with the two
ocelli, partially confluent, of natural size.]
Notwithstanding this approach, the first species of Polyplectron which I
examined almost made me give up the search; for I found not only that the
true tail-feathers, which in the peacock are quite plain, were ornamented
with ocelli, but that the ocelli on all the feathers differed fundamentally
from those of the peacock, in there being two on the same feather (Fig.
55), one on each side of the shaft. Hence I concluded that the early
progenitors of the peacock could not have resembled a Polyplectron. But on
continuing my search, I observed that in some of the species the two ocelli
stood very near each other; that in the tail-feathers of P. hardwickii they
touched each other; and, finally, that on the tail-coverts of this same
species as well as of P. malaccense (Fig. 56) they were actually confluent.
As the central part alone is confluent, an indentation is left at both the
upper and lower ends; and the surrounding coloured zones are likewise
indented. A single ocellus is thus formed on each tail-covert, though
still plainly betraying its double origin. These confluent ocelli differ
from the single ocelli of the peacock in having an indentation at both
ends, instead of only at the lower or basal end. The explanation, however,
of this difference is not difficult; in some species of Polyplectron the
two oval ocelli on the same feather stand parallel to each other; in other
species (as in P. chinquis) they converge towards one end; now the partial
confluence of two convergent ocelli would manifestly leave a much deeper
indentation at the divergent than at the convergent end. It is also
manifest that if the convergence were strongly pronounced and the
confluence complete, the indentation at the convergent end would tend to
disappear.
The tail-feathers in both species of the peacock are entirely destitute of
ocelli, and this apparently is related to their being covered up and
concealed by the long tail-coverts. In this respect they differ remarkably
from the tail-feathers of Polyplectron, which in most of the species are
ornamented with larger ocelli than those on the tail-coverts. Hence I was
led carefully to examine the tail-feathers of the several species, in order
to discover whether their ocelli shewed any tendency to disappear; and to
my great satisfaction, this appeared to be so. The central tail-feathers
of P. napoleonis have the two ocelli on each side of the shaft perfectly
developed; but the inner ocellus becomes less and less conspicuous on the
more exterior tail-feathers, until a mere shadow or rudiment is left on the
inner side of the outermost feather. Again, in P. malaccense, the ocelli
on the tail-coverts are, as we have seen, confluent; and these feathers are
of unusual length, being two-thirds of the length of the tail-feathers, so
that in both these respects they approach the tail-coverts of the peacock.
Now in P. malaccense, the two central tail-feathers alone are ornamented,
each with two brightly-coloured ocelli, the inner ocellus having completely
disappeared from all the other tail-feathers. Consequently the tail-
coverts and tail-feathers of this species of Polyplectron make a near
approach in structure and ornamentation to the corresponding feathers of
the peacock.
As far, then, as gradation throws light on the steps by which the
magnificent train of the peacock has been acquired, hardly anything more is
needed. If we picture to ourselves a progenitor of the peacock in an
almost exactly intermediate condition between the existing peacock, with
his enormously elongated tail-coverts, ornamented with single ocelli, and
an ordinary gallinaceous bird with short tail-coverts, merely spotted with
some colour, we shall see a bird allied to Polyplectron--that is, with
tail-coverts, capable of erection and expansion, ornamented with two
partially confluent ocelli, and long enough almost to conceal the tail-
feathers, the latter having already partially lost their ocelli. The
indentation of the central disc and of the surrounding zones of the
ocellus, in both species of peacock, speaks plainly in favour of this view,
and is otherwise inexplicable. The males of Polyplectron are no doubt
beautiful birds, but their beauty, when viewed from a little distance,
cannot be compared with that of the peacock. Many female progenitors of
the peacock must, during a long line of descent, have appreciated this
superiority; for they have unconsciously, by the continued preference for
the most beautiful males, rendered the peacock the most splendid of living
birds.
ARGUS PHEASANT.
Another excellent case for investigation is offered by the ocelli on the
wing-feathers of the Argus pheasant, which are shaded in so wonderful a
manner as to resemble balls lying loose within sockets, and consequently
differ from ordinary ocelli. No one, I presume, will attribute the
shading, which has excited the admiration of many experienced artists, to
chance--to the fortuitous concourse of atoms of colouring matter. That
these ornaments should have been formed through the selection of many
successive variations, not one of which was originally intended to produce
the ball-and-socket effect, seems as incredible as that one of Raphael's
Madonnas should have been formed by the selection of chance daubs of paint
made by a long succession of young artists, not one of whom intended at
first to draw the human figure. In order to discover how the ocelli have
been developed, we cannot look to a long line of progenitors, nor to many
closely-allied forms, for such do not now exist. But fortunately the
several feathers on the wing suffice to give us a clue to the problem, and
they prove to demonstration that a gradation is at least possible from a
mere spot to a finished ball-and-socket ocellus.
[Fig. 57. Part of secondary wing-feather of Argus pheasant, shewing two
perfect ocelli, a and b. A, B, C, D, etc., are dark stripes running
obliquely down, each to an ocellus.
[Much of the web on both sides, especially to the left of the shaft, has
been cut off.]
Fig.59. Portion of one of the secondary wing-feathers near to the body,
shewing the so-called elliptic ornaments. The right-hand figure is given
merely as a diagram for the sake of the letters of reference.
A, B, C, D, etc. Rows of spots running down to and forming the elliptic
ornaments.
b. Lowest spot or mark in row B.
c. The next succeeding spot or mark in the same row.
d. Apparently a broken prolongation of the spot c. in the same row B.]
The wing-feathers, bearing the ocelli, are covered with dark stripes (Fig.
57) or with rows of dark spots (Fig. 59), each stripe or row of spots
running obliquely down the outer side of the shaft to one of the ocelli.
The spots are generally elongated in a line transverse to the row in which
they stand. They often become confluent either in the line of the row--and
then they form a longitudinal stripe--or transversely, that is, with the
spots in the adjoining rows, and then they form transverse stripes. A spot
sometimes breaks up into smaller spots, which still stand in their proper
places.
It will be convenient first to describe a perfect ball-and-socket ocellus.
This consists of an intensely black circular ring, surrounding a space
shaded so as exactly to resemble a ball. The figure here given has been
admirably drawn by Mr. Ford and well engraved, but a woodcut cannot exhibit
the exquisite shading of the original. The ring is almost always slightly
broken or interrupted (Fig. 57) at a point in the upper half, a little to
the right of and above the white shade on the enclosed ball; it is also
sometimes broken towards the base on the right hand. These little breaks
have an important meaning. The ring is always much thickened, with the
edges ill-defined towards the left-hand upper corner, the feather being
held erect, in the position in which it is here drawn. Beneath this
thickened part there is on the surface of the ball an oblique almost pure-
white mark, which shades off downwards into a pale-leaden hue, and this
into yellowish and brown tints, which insensibly become darker and darker
towards the lower part of the ball. It is this shading which gives so
admirably the effect of light shining on a convex surface. If one of the
balls be examined, it will be seen that the lower part is of a brown tint
and is indistinctly separated by a curved oblique line from the upper part,
which is yellower and more leaden; this curved oblique line runs at right
angles to the longer axis of the white patch of light, and indeed of all
the shading; but this difference in colour, which cannot of course be shewn
in the woodcut, does not in the least interfere with the perfect shading of
the ball. It should be particularly observed that each ocellus stands in
obvious connection either with a dark stripe, or with a longitudinal row of
dark spots, for both occur indifferently on the same feather. Thus in Fig.
57 stripe A runs to ocellus a; B runs to ocellus b; stripe C is broken in
the upper part, and runs down to the next succeeding ocellus, not
represented in the woodcut; D to the next lower one, and so with the
stripes E and F. Lastly, the several ocelli are separated from each other
by a pale surface bearing irregular black marks.
[Fig. 58. Basal part of the secondary wing feather, nearest to the body.]
I will next describe the other extreme of the series, namely, the first
trace of an ocellus. The short secondary wing-feather (Fig. 58), nearest
to the body, is marked like the other feathers, with oblique, longitudinal,
rather irregular, rows of very dark spots. The basal spot, or that nearest
the shaft, in the five lower rows (excluding the lowest one) is a little
larger than the other spots of the same row, and a little more elongated in
a transverse direction. It differs also from the other spots by being
bordered on its upper side with some dull fulvous shading. But this spot
is not in any way more remarkable than those on the plumage of many birds,
and might easily be overlooked. The next higher spot does not differ at
all from the upper ones in the same row. The larger basal spots occupy
exactly the same relative position on these feathers as do the perfect
ocelli on the longer wing-feathers.
By looking to the next two or three succeeding wing-feathers, an absolutely
insensible gradation can be traced from one of the last-described basal
spots, together with the next higher one in the same row, to a curious
ornament, which cannot be called an ocellus, and which I will name, from
the want of a better term, an "elliptic ornament." These are shewn in the
accompanying figure (Fig. 59). We here see several oblique rows, A, B, C,
D, etc. (see the lettered diagram on the right hand), of dark spots of the
usual character. Each row of spots runs down to and is connected with one
of the elliptic ornaments, in exactly the same manner as each stripe in
Fig. 57 runs down to and is connected with one of the ball-and-socket
ocelli. Looking to any one row, for instance, B, in Fig. 59, the lowest
mark (b) is thicker and considerably longer than the upper spots, and has
its left extremity pointed and curved upwards. This black mark is abruptly
bordered on its upper side by a rather broad space of richly shaded tints,
beginning with a narrow brown zone, which passes into orange, and this into
a pale leaden tint, with the end towards the shaft much paler. These
shaded tints together fill up the whole inner space of the elliptic
ornament. The mark (b) corresponds in every respect with the basal shaded
spot of the simple feather described in the last paragraph (Fig. 58), but
is more highly developed and more brightly coloured. Above and to the
right of this spot (b, Fig. 59), with its bright shading, there is a long
narrow, black mark (c), belonging to the same row, and which is arched a
little downwards so as to face (b). This mark is sometimes broken into two
portions. It is also narrowly edged on the lower side with a fulvous tint.
To the left of and above c, in the same oblique direction, but always more
or less distinct from it, there is another black mark (d). This mark is
generally sub-triangular and irregular in shape, but in the one lettered in
the diagram it is unusually narrow, elongated, and regular. It apparently
consists of a lateral and broken prolongation of the mark (c), together
with its confluence with a broken and prolonged part of the next spot
above; but I do not feel sure of this. These three marks, b, c, and d,
with the intervening bright shades, form together the so-called elliptic
ornament. These ornaments placed parallel to the shaft, manifestly
correspond in position with the ball-and-socket ocelli. Their extremely
elegant appearance cannot be appreciated in the drawing, as the orange and
leaden tints, contrasting so well with the black marks, cannot be shewn.
[Fig. 60. An ocellus in an intermediate condition between the elliptic
ornament and the perfect ball-and-socket ocellus.]
Between one of the elliptic ornaments and a perfect ball-and-socket
ocellus, the gradation is so perfect that it is scarcely possible to decide
when the latter term ought to be used. The passage from the one into the
other is effected by the elongation and greater curvature in opposite
directions of the lower black mark (b, Fig. 59), and more especially of the
upper one (c), together with the contraction of the elongated sub-
triangular or narrow mark (d), so that at last these three marks become
confluent, forming an irregular elliptic ring. This ring is gradually
rendered more and more circular and regular, increasing at the same time in
diameter. I have here given a drawing (Fig. 60) of the natural size of an
ocellus not as yet quite perfect. The lower part of the black ring is much
more curved than is the lower mark in the elliptic ornament (b, Fig. 59).
The upper part of the ring consists of two or three separate portions; and
there is only a trace of the thickening of the portion which forms the
black mark above the white shade. This white shade itself is not as yet
much concentrated; and beneath it the surface is brighter coloured than in
a perfect ball-and-socket ocellus. Even in the most perfect ocelli traces
of the junction of three or four elongated black marks, by which the ring
has been formed, may often be detected. The irregular sub-triangular or
narrow mark (d, Fig. 59), manifestly forms, by its contraction and
equalisation, the thickened portion of the ring above the white shade on a
perfect ball-and-socket ocellus. The lower part of the ring is invariably
a little thicker than the other parts (Fig. 57), and this follows from the
lower black mark of the elliptic ornament (b, Fig. 59) having originally
been thicker than the upper mark (c). Every step can be followed in the
process of confluence and modification; and the black ring which surrounds
the ball of the ocellus is unquestionably formed by the union and
modification of the three black marks, b, c, d, of the elliptic ornament.
The irregular zigzag black marks between the successive ocelli (Fig. 57)
are plainly due to the breaking up of the somewhat more regular but similar
marks between the elliptic ornaments.
The successive steps in the shading of the ball-and-socket ocelli can be
followed out with equal clearness. The brown, orange, and pale-leadened
narrow zones, which border the lower black mark of the elliptic ornament,
can be seen gradually to become more and more softened and shaded into each
other, with the upper lighter part towards the left-hand corner rendered
still lighter, so as to become almost white, and at the same time more
contracted. But even in the most perfect ball-and-socket ocelli a slight
difference in the tints, though not in the shading, between the upper and
lower parts of the ball can be perceived, as before noticed; and the line
of separation is oblique, in the same direction as the bright coloured
shades of the elliptic ornaments. Thus almost every minute detail in the
shape and colouring of the ball-and-socket ocelli can be shewn to follow
from gradual changes in the elliptic ornaments; and the development of the
latter can be traced by equally small steps from the union of two almost
simple spots, the lower one (Fig. 58) having some dull fulvous shading on
its upper side.
[Fig. 61. Portion near summit of one of the secondary wing-feathers,
bearing perfect ball-and-socket ocelli.
a. Ornamented upper part.
b. Uppermost, imperfect ball-and-socket ocellus. (The shading above the
white mark on the summit of the ocellus is here a little too dark.)
c. Perfect ocellus.]
The extremities of the longer secondary feathers which bear the perfect
ball-and-socket ocelli, are peculiarly ornamented (Fig. 61). The oblique
longitudinal stripes suddenly cease upwards and become confused; and above
this limit the whole upper end of the feather (a) is covered with white
dots, surrounded by little black rings, standing on a dark ground. The
oblique stripe belonging to the uppermost ocellus (b) is barely represented
by a very short irregular black mark with the usual, curved, transverse
base. As this stripe is thus abruptly cut off, we can perhaps understand
from what has gone before, how it is that the upper thickened part of the
ring is here absent; for, as before stated, this thickened part apparently
stands in some relation with a broken prolongation from the next higher
spot. From the absence of the upper and thickened part of the ring, the
uppermost ocellus, though perfect in all other respects, appears as if its
top had been obliquely sliced off. It would, I think, perplex any one, who
believes that the plumage of the Argus pheasant was created as we now see
it, to account for the imperfect condition of the uppermost ocellus. I
should add that on the secondary wing-feather farthest from the body all
the ocelli are smaller and less perfect than on the other feathers, and
have the upper part of the ring deficient, as in the case just mentioned.
The imperfection here seems to be connected with the fact that the spots on
this feather shew less tendency than usual to become confluent into
stripes; they are, on the contrary, often broken up into smaller spots, so
that two or three rows run down to the same ocellus.
There still remains another very curious point, first observed by Mr. T.W.
Wood (51. The 'Field,' May 28, 1870.), which deserves attention. In a
photograph, given me by Mr. Ward, of a specimen mounted as in the act of
display, it may be seen that on the feathers which are held
perpendicularly, the white marks on the ocelli, representing light
reflected from a convex surface, are at the upper or further end, that is,
are directed upwards; and the bird whilst displaying himself on the ground
would naturally be illuminated from above. But here comes the curious
point; the outer feathers are held almost horizontally, and their ocelli
ought likewise to appear as if illuminated from above, and consequently the
white marks ought to be placed on the upper sides of the ocelli; and,
wonderful as is the fact, they are thus placed! Hence the ocelli on the
several feathers, though occupying very different positions with respect to
the light, all appear as if illuminated from above, just as an artist would
have shaded them. Nevertheless they are not illuminated from strictly the
same point as they ought to be; for the white marks on the ocelli of the
feathers which are held almost horizontally, are placed rather too much
towards the further end; that is, they are not sufficiently lateral. We
have, however, no right to expect absolute perfection in a part rendered
ornamental through sexual selection, any more than we have in a part
modified through natural selection for real use; for instance, in that
wondrous organ the human eye. And we know what Helmholtz, the highest
authority in Europe on the subject, has said about the human eye; that if
an optician had sold him an instrument so carelessly made, he would have
thought himself fully justified in returning it. (52. 'Popular Lectures
on Scientific Subjects,' Eng. trans. 1873, pp. 219, 227, 269, 390.)
We have now seen that a perfect series can be followed, from simple spots
to the wonderful ball-and-socket ornaments. Mr. Gould, who kindly gave me
some of these feathers, fully agrees with me in the completeness of the
gradation. It is obvious that the stages in development exhibited by the
feathers on the same bird do not at all necessarily shew us the steps
passed through by the extinct progenitors of the species; but they probably
give us the clue to the actual steps, and they at least prove to
demonstration that a gradation is possible. Bearing in mind how carefully
the male Argus pheasant displays his plumes before the female, as well as
the many facts rendering it probable that female birds prefer the more
attractive males, no one who admits the agency of sexual selection in any
case will deny that a simple dark spot with some fulvous shading might be
converted, through the approximation and modification of two adjoining
spots, together with some slight increase of colour, into one of the so-
called elliptic ornaments. These latter ornaments have been shewn to many
persons, and all have admitted that they are beautiful, some thinking them
even more so than the ball-and-socket ocelli. As the secondary plumes
became lengthened through sexual selection, and as the elliptic ornaments
increased in diameter, their colours apparently became less bright; and
then the ornamentation of the plumes had to be gained by an improvement in
the pattern and shading; and this process was carried on until the
wonderful ball-and-socket ocelli were finally developed. Thus we can
understand--and in no other way as it seems to me--the present condition
and origin of the ornaments on the wing-feathers of the Argus pheasant.
From the light afforded by the principle of gradation--from what we know of
the laws of variation--from the changes which have taken place in many of
our domesticated birds--and, lastly, from the character (as we shall
hereafter see more clearly) of the immature plumage of young birds--we can
sometimes indicate, with a certain amount of confidence, the probable steps
by which the males have acquired their brilliant plumage and various
ornaments; yet in many cases we are involved in complete darkness. Mr.
Gould several years ago pointed out to me a humming-bird, the Urosticte
benjamini, remarkable for the curious differences between the sexes. The
male, besides a splendid gorget, has greenish-black tail-feathers, with the
four CENTRAL ones tipped with white; in the female, as with most of the
allied species, the three OUTER tail-feathers on each side are tipped with
white, so that the male has the four central, whilst the female has the six
exterior feathers ornamented with white tips. What makes the case more
curious is that, although the colouring of the tail differs remarkably in
both sexes of many kinds of humming-birds, Mr. Gould does not know a single
species, besides the Urosticte, in which the male has the four central
feathers tipped with white.
The Duke of Argyll, in commenting on this case (53. 'The Reign of Law,'
1867, p. 247.), passes over sexual selection, and asks, "What explanation
does the law of natural selection give of such specific varieties as
these?" He answers "none whatever"; and I quite agree with him. But can
this be so confidently said of sexual selection? Seeing in how many ways
the tail-feathers of humming-birds differ, why should not the four central
feathers have varied in this one species alone, so as to have acquired
white tips? The variations may have been gradual, or somewhat abrupt as in
the case recently given of the humming-birds near Bogota, in which certain
individuals alone have the "central tail-feathers tipped with beautiful
green." In the female of the Urosticte I noticed extremely minute or
rudimental white tips to the two outer of the four central black tail-
feathers; so that here we have an indication of change of some kind in the
plumage of this species. If we grant the possibility of the central tail-
feathers of the male varying in whiteness, there is nothing strange in such
variations having been sexually selected. The white tips, together with
the small white ear-tufts, certainly add, as the Duke of Argyll admits, to
the beauty of the male; and whiteness is apparently appreciated by other
birds, as may be inferred from such cases as the snow-white male of the
Bell-bird. The statement made by Sir R. Heron should not be forgotten,
namely, that his peahens, when debarred from access to the pied peacock,
would not unite with any other male, and during that season produced no
offspring. Nor is it strange that variations in the tail-feathers of the
Urosticte should have been specially selected for the sake of ornament, for
the next succeeding genus in the family takes its name of Metallura from
the splendour of these feathers. We have, moreover, good evidence that
humming-birds take especial pains in displaying their tail-feathers; Mr.
Belt (54. 'The Naturalist in Nicaragua,' 1874, p. 112.), after describing
the beauty of the Florisuga mellivora, says, "I have seen the female
sitting on a branch, and two males displaying their charms in front of her.
One would shoot up like a rocket, then suddenly expanding the snow-white
tail, like an inverted parachute, slowly descend in front of her, turning
round gradually to shew off back and front...The expanded white tail
covered more space than all the rest of the bird, and was evidently the
grand feature in the performance. Whilst one male was descending, the
other would shoot up and come slowly down expanded. The entertainment
would end in a fight between the two performers; but whether the most
beautiful or the most pugnacious was the accepted suitor, I know not." Mr.
Gould, after describing the peculiar plumage of the Urosticte, adds, "that
ornament and variety is the sole object, I have myself but little doubt."
(55. 'Introduction to the Trochilidae,' 1861, p. 110.) If this be
admitted, we can perceive that the males which during former times were
decked in the most elegant and novel manner would have gained an advantage,
not in the ordinary struggle for life, but in rivalry with other males, and
would have left a larger number of offspring to inherit their newly-
acquired beauty.
CHAPTER XV.
Birds--continued.
Discussion as to why the males alone of some species, and both sexes of
others, are brightly coloured--On sexually-limited inheritance, as applied
to various structures and to brightly-coloured plumage--Nidification in
relation to colour--Loss of nuptial plumage during the winter.
We have in this chapter to consider why the females of many birds have not
acquired the same ornaments as the male; and why, on the other hand, both
sexes of many other birds are equally, or almost equally, ornamented? In
the following chapter we shall consider the few cases in which the female
is more conspicuously coloured than the male.
In my 'Origin of Species' (1. Fourth edition, 1866, p. 241.) I briefly
suggested that the long tail of the peacock would be inconvenient and the
conspicuous black colour of the male capercailzie dangerous, to the female
during the period of incubation: and consequently that the transmission of
these characters from the male to the female offspring had been checked
through natural selection. I still think that this may have occurred in
some few instances: but after mature reflection on all the facts which I
have been able to collect, I am now inclined to believe that when the sexes
differ, the successive variations have generally been from the first
limited in their transmission to the same sex in which they first arose.
Since my remarks appeared, the subject of sexual coloration has been
discussed in some very interesting papers by Mr. Wallace (2. 'Westminster
Review,' July 1867. 'Journal of Travel,' vol. i. 1868, p. 73.), who
believes that in almost all cases the successive variations tended at first
to be transmitted equally to both sexes; but that the female was saved,
through natural selection, from acquiring the conspicuous colours of the
male, owing to the danger which she would thus have incurred during
incubation.
This view necessitates a tedious discussion on a difficult point, namely,
whether the transmission of a character, which is at first inherited by
both sexes can be subsequently limited in its transmission to one sex alone
by means of natural selection. We must bear in mind, as shewn in the
preliminary chapter on sexual selection, that characters which are limited
in their development to one sex are always latent in the other. An
imaginary illustration will best aid us in seeing the difficulty of the
case; we may suppose that a fancier wished to make a breed of pigeons, in
which the males alone should be coloured of a pale blue, whilst the females
retained their former slaty tint. As with pigeons characters of all kinds
are usually transmitted to both sexes equally, the fancier would have to
try to convert this latter form of inheritance into sexually-limited
transmission. All that he could do would be to persevere in selecting
every male pigeon which was in the least degree of a paler blue; and the
natural result of this process, if steadily carried on for a long time, and
if the pale variations were strongly inherited or often recurred, would be
to make his whole stock of a lighter blue. But our fancier would be
compelled to match, generation after generation, his pale blue males with
slaty females, for he wishes to keep the latter of this colour. The result
would generally be the production either of a mongrel piebald lot, or more
probably the speedy and complete loss of the pale-blue tint; for the
primordial slaty colour would be transmitted with prepotent force.
Supposing, however, that some pale-blue males and slaty females were
produced during each successive generation, and were always crossed
together, then the slaty females would have, if I may use the expression,
much blue blood in their veins, for their fathers, grandfathers, etc., will
all have been blue birds. Under these circumstances it is conceivable
(though I know of no distinct facts rendering it probable) that the slaty
females might acquire so strong a latent tendency to pale-blueness, that
they would not destroy this colour in their male offspring, their female
offspring still inheriting the slaty tint. If so, the desired end of
making a breed with the two sexes permanently different in colour might be
gained.
The extreme importance, or rather necessity in the above case of the
desired character, namely, pale-blueness, being present though in a latent
state in the female, so that the male offspring should not be deteriorated,
will be best appreciated as follows: the male of Soemmerring's pheasant
has a tail thirty-seven inches in length, whilst that of the female is only
eight inches; the tail of the male common pheasant is about twenty inches,
and that of the female twelve inches long. Now if the female Soemmerring
pheasant with her SHORT tail were crossed with the male common pheasant,
there can be no doubt that the male hybrid offspring would have a much
LONGER tail than that of the pure offspring of the common pheasant. On the
other hand, if the female common pheasant, with a tail much longer than
that of the female Soemmerring pheasant, were crossed with the male of the
latter, the male hybrid offspring would have a much SHORTER tail than that
of the pure offspring of Soemmerring's pheasant. (3. Temminck says that
the tail of the female Phasianus Soemmerringii is only six inches long,
'Planches coloriees,' vol. v. 1838, pp. 487 and 488: the measurements
above given were made for me by Mr. Sclater. For the common pheasant, see
Macgillivray, 'History of British Birds,' vol. i. pp. 118-121.)
Our fancier, in order to make his new breed with the males of a pale-blue
tint, and the females unchanged, would have to continue selecting the males
during many generations; and each stage of paleness would have to be fixed
in the males, and rendered latent in the females. The task would be an
extremely difficult one, and has never been tried, but might possibly be
successfully carried out. The chief obstacle would be the early and
complete loss of the pale-blue tint, from the necessity of reiterated
crosses with the slaty female, the latter not having at first any LATENT
tendency to produce pale-blue offspring.
On the other hand, if one or two males were to vary ever so slightly in
paleness, and the variations were from the first limited in their
transmission to the male sex, the task of making a new breed of the desired
kind would be easy, for such males would simply have to be selected and
matched with ordinary females. An analogous case has actually occurred,
for there are breeds of the pigeon in Belgium (4. Dr. Chapuis, 'Le Pigeon
Voyageur Belge,' 1865, p. 87.) in which the males alone are marked with
black striae. So again Mr. Tegetmeier has recently shewn (5. The 'Field,'
Sept. 1872.) that dragons not rarely produce silver-coloured birds, which
are almost always hens; and he himself has bred ten such females. It is on
the other hand a very unusual event when a silver male is produced; so that
nothing would be easier, if desired, than to make a breed of dragons with
blue males and silver females. This tendency is indeed so strong that when
Mr. Tegetmeier at last got a silver male and matched him with one of the
silver females, he expected to get a breed with both sexes thus coloured;
he was however disappointed, for the young male reverted to the blue colour
of his grandfather, the young female alone being silver. No doubt with
patience this tendency to reversion in the males, reared from an occasional
silver male matched with a silver hen, might be eliminated, and then both
sexes would be coloured alike; and this very process has been followed with
success by Mr. Esquilant in the case of silver turbits.
With fowls, variations of colour, limited in their transmission to the male
sex, habitually occur. When this form of inheritance prevails, it might
well happen that some of the successive variations would be transferred to
the female, who would then slightly resemble the male, as actually occurs
in some breeds. Or again, the greater number, but not all, of the
successive steps might be transferred to both sexes, and the female would
then closely resemble the male. There can hardly be a doubt that this is
the cause of the male pouter pigeon having a somewhat larger crop, and of
the male carrier pigeon having somewhat larger wattles, than their
respective females; for fanciers have not selected one sex more than the
other, and have had no wish that these characters should be more strongly
displayed in the male than in the female, yet this is the case with both
breeds.
The same process would have to be followed, and the same difficulties
encountered, if it were desired to make a breed with the females alone of
some new colour.
Lastly, our fancier might wish to make a breed with the two sexes differing
from each other, and both from the parent species. Here the difficulty
would be extreme, unless the successive variations were from the first
sexually limited on both sides, and then there would be no difficulty. We
see this with the fowl; thus the two sexes of the pencilled Hamburghs
differ greatly from each other, and from the two sexes of the aboriginal
Gallus bankiva; and both are now kept constant to their standard of
excellence by continued selection, which would be impossible unless the
distinctive characters of both were limited in their transmission.
The Spanish fowl offers a more curious case; the male has an immense comb,
but some of the successive variations, by the accumulation of which it was
acquired, appear to have been transferred to the female; for she has a comb
many times larger than that of the females of the parent species. But the
comb of the female differs in one respect from that of the male, for it is
apt to lop over; and within a recent period it has been ordered by the
fancy that this should always be the case, and success has quickly followed
the order. Now the lopping of the comb must be sexually limited in its
transmission, otherwise it would prevent the comb of the male from being
perfectly upright, which would be abhorrent to every fancier. On the other
hand, the uprightness of the comb in the male must likewise be a sexually-
limited character, otherwise it would prevent the comb of the female from
lopping over.
From the foregoing illustrations, we see that even with almost unlimited
time at command, it would be an extremely difficult and complex, perhaps an
impossible process, to change one form of transmission into the other
through selection. Therefore, without distinct evidence in each case, I am
unwilling to admit that this has been effected in natural species. On the
other hand, by means of successive variations, which were from the first
sexually limited in their transmission, there would not be the least
difficulty in rendering a male bird widely different in colour or in any
other character from the female; the latter being left unaltered, or
slightly altered, or specially modified for the sake of protection.
As bright colours are of service to the males in their rivalry with other
males, such colours would be selected whether or not they were transmitted
exclusively to the same sex. Consequently the females might be expected
often to partake of the brightness of the males to a greater or less
degree; and this occurs with a host of species. If all the successive
variations were transmitted equally to both sexes, the females would be
indistinguishable from the males; and this likewise occurs with many birds.
If, however, dull colours were of high importance for the safety of the
female during incubation, as with many ground birds, the females which
varied in brightness, or which received through inheritance from the males
any marked accession of brightness, would sooner or later be destroyed.
But the tendency in the males to continue for an indefinite period
transmitting to their female offspring their own brightness, would have to
be eliminated by a change in the form of inheritance; and this, as shewn by
our previous illustration, would be extremely difficult. The more probable
result of the long-continued destruction of the more brightly-coloured
females, supposing the equal form of transmission to prevail, would be the
lessening or annihilation of the bright colours of the males, owing to
their continual crossing with the duller females. It would be tedious to
follow out all the other possible results; but I may remind the reader that
if sexually-limited variations in brightness occurred in the females, even
if they were not in the least injurious to them and consequently were not
eliminated, yet they would not be favoured or selected, for the male
usually accepts any female, and does not select the more attractive
individuals; consequently these variations would be liable to be lost, and
would have little influence on the character of the race; and this will aid
in accounting for the females being commonly duller-coloured than the
males.
In the eighth chapter instances were given, to which many might here be
added, of variations occurring at various ages, and inherited at the
corresponding age. It was also shewn that variations which occur late in
life are commonly transmitted to the same sex in which they first appear;
whilst variations occurring early in life are apt to be transmitted to both
sexes; not that all the cases of sexually-limited transmission can thus be
accounted for. It was further shewn that if a male bird varied by becoming
brighter whilst young, such variations would be of no service until the age
for reproduction had arrived, and there was competition between rival
males. But in the case of birds living on the ground and commonly in need
of the protection of dull colours, bright tints would be far more dangerous
to the young and inexperienced than to the adult males. Consequently the
males which varied in brightness whilst young would suffer much destruction
and be eliminated through natural selection; on the other hand, the males
which varied in this manner when nearly mature, notwithstanding that they
were exposed to some additional danger, might survive, and from being
favoured through sexual selection, would procreate their kind. As a
relation often exists between the period of variation and the form of
transmission, if the bright-coloured young males were destroyed and the
mature ones were successful in their courtship, the males alone would
acquire brilliant colours and would transmit them exclusively to their male
offspring. But I by no means wish to maintain that the influence of age on
the form of transmission, is the sole cause of the great difference in
brilliancy between the sexes of many birds.
When the sexes of birds differ in colour, it is interesting to determine
whether the males alone have been modified by sexual selection, the females
having been left unchanged, or only partially and indirectly thus changed;
or whether the females have been specially modified through natural
selection for the sake of protection. I will therefore discuss this
question at some length, even more fully than its intrinsic importance
deserves; for various curious collateral points may thus be conveniently
considered.
Before we enter on the subject of colour, more especially in reference to
Mr. Wallace's conclusions, it may be useful to discuss some other sexual
differences under a similar point of view. A breed of fowls formerly
existed in Germany (6. Bechstein, 'Naturgeschichte Deutschlands,' 1793, B.
iii. 339.) in which the hens were furnished with spurs; they were good
layers, but they so greatly disturbed their nests with their spurs that
they could not be allowed to sit on their own eggs. Hence at one time it
appeared to me probable that with the females of the wild Gallinaceae the
development of spurs had been checked through natural selection, from the
injury thus caused to their nests. This seemed all the more probable, as
wing-spurs, which would not be injurious during incubation, are often as
well-developed in the female as in the male; though in not a few cases they
are rather larger in the male. When the male is furnished with leg-spurs
the female almost always exhibits rudiments of them,--the rudiment
sometimes consisting of a mere scale, as in Gallus. Hence it might be
argued that the females had aboriginally been furnished with well-developed
spurs, but that these had subsequently been lost through disuse or natural
selection. But if this view be admitted, it would have to be extended to
innumerable other cases; and it implies that the female progenitors of the
existing spur-bearing species were once encumbered with an injurious
appendage.
In some few genera and species, as in Galloperdix, Acomus, and the Javan
peacock (Pavo muticus), the females, as well as the males, possess well-
developed leg-spurs. Are we to infer from this fact that they construct a
different sort of nest from that made by their nearest allies, and not
liable to be injured by their spurs; so that the spurs have not been
removed? Or are we to suppose that the females of these several species
especially require spurs for their defence? It is a more probable
conclusion that both the presence and absence of spurs in the females
result from different laws of inheritance having prevailed, independently
of natural selection. With the many females in which spurs appear as
rudiments, we may conclude that some few of the successive variations,
through which they were developed in the males, occurred very early in
life, and were consequently transferred to the females. In the other and
much rarer cases, in which the females possess fully developed spurs, we
may conclude that all the successive variations were transferred to them;
and that they gradually acquired and inherited the habit of not disturbing
their nests.
The vocal organs and the feathers variously modified for producing sound,
as well as the proper instincts for using them, often differ in the two
sexes, but are sometimes the same in both. Can such differences be
accounted for by the males having acquired these organs and instincts,
whilst the females have been saved from inheriting them, on account of the
danger to which they would have been exposed by attracting the attention of
birds or beasts of prey? This does not seem to me probable, when we think
of the multitude of birds which with impunity gladden the country with
their voices during the spring. (7. Daines Barrington, however, thought
it probable ('Philosophical Transactions,' 1773, p. 164) that few female
birds sing, because the talent would have been dangerous to them during
incubation. He adds, that a similar view may possibly account for the
inferiority of the female to the male in plumage.) It is a safer
conclusion that, as vocal and instrumental organs are of special service
only to the males during their courtship, these organs were developed
through sexual selection and their constant use in that sex alone--the
successive variations and the effects of use having been from the first
more or less limited in transmission to the male offspring.
Many analogous cases could be adduced; those for instance of the plumes on
the head being generally longer in the male than in the female, sometimes
of equal length in both sexes, and occasionally absent in the female,--
these several cases occurring in the same group of birds. It would be
difficult to account for such a difference between the sexes by the female
having been benefited by possessing a slightly shorter crest than the male,
and its consequent diminution or complete suppression through natural
selection. But I will take a more favourable case, namely the length of
the tail. The long train of the peacock would have been not only
inconvenient but dangerous to the peahen during the period of incubation
and whilst accompanying her young. Hence there is not the least a priori
improbability in the development of her tail having been checked through
natural selection. But the females of various pheasants, which apparently
are exposed on their open nests to as much danger as the peahen, have tails
of considerable length. The females as well as the males of the Menura
superba have long tails, and they build a domed nest, which is a great
anomaly in so large a bird. Naturalists have wondered how the female
Menura could manage her tail during incubation; but it is now known (8.
Mr. Ramsay, in 'Proc. Zoolog. Soc.' 1868, p. 50.) that she "enters the nest
head first, and then turns round with her tail sometimes over her back, but
more often bent round by her side. Thus in time the tail becomes quite
askew, and is a tolerable guide to the length of time the bird has been
sitting." Both sexes of an Australian kingfisher (Tanysiptera sylvia) have
the middle tail-feathers greatly lengthened, and the female makes her nest
in a hole; and as I am informed by Mr. R.B. Sharpe these feathers become
much crumpled during incubation.
In these two latter cases the great length of the tail-feathers must be in
some degree inconvenient to the female; and as in both species the tail-
feathers of the female are somewhat shorter than those of the male, it
might be argued that their full development had been prevented through
natural selection. But if the development of the tail of the peahen had
been checked only when it became inconveniently or dangerously great, she
would have retained a much longer tail than she actually possesses; for her
tail is not nearly so long, relatively to the size of her body, as that of
many female pheasants, nor longer than that of the female turkey. It must
also be borne in mind that, in accordance with this view, as soon as the
tail of the peahen became dangerously long, and its development was
consequently checked, she would have continually reacted on her male
progeny, and thus have prevented the peacock from acquiring his present
magnificent train. We may therefore infer that the length of the tail in
the peacock and its shortness in the peahen are the result of the requisite
variations in the male having been from the first transmitted to the male
offspring alone.
We are led to a nearly similar conclusion with respect to the length of the
tail in the various species of pheasants. In the Eared pheasant
(Crossoptilon auritum) the tail is of equal length in both sexes, namely
sixteen or seventeen inches; in the common pheasant it is about twenty
inches long in the male and twelve in the female; in Soemmerring's
pheasant, thirty-seven inches in the male and only eight in the female; and
lastly in Reeve's pheasant it is sometimes actually seventy-two inches long
in the male and sixteen in the female. Thus in the several species, the
tail of the female differs much in length, irrespectively of that of the
male; and this can be accounted for, as it seems to me, with much more
probability, by the laws of inheritance,--that is by the successive
variations having been from the first more or less closely limited in their
transmission to the male sex than by the agency of natural selection,
resulting from the length of tail being more or less injurious to the
females of these several allied species.
We may now consider Mr. Wallace's arguments in regard to the sexual
coloration of birds. He believes that the bright tints originally acquired
through sexual selection by the males would in all, or almost all cases,
have been transmitted to the females, unless the transference had been
checked through natural selection. I may here remind the reader that
various facts opposed to this view have already been given under reptiles,
amphibians, fishes and lepidoptera. Mr. Wallace rests his belief chiefly,
but not exclusively, as we shall see in the next chapter, on the following
statement (9. 'Journal of Travel,' edited by A. Murray, vol. i. 1868, p.
78.), that when both sexes are coloured in a very conspicuous manner, the
nest is of such a nature as to conceal the sitting bird; but when there is
a marked contrast of colour between the sexes, the male being gay and the
female dull-coloured, the nest is open and exposes the sitting bird to
view. This coincidence, as far as it goes, certainly seems to favour the
belief that the females which sit on open nests have been specially
modified for the sake of protection; but we shall presently see that there
is another and more probable explanation, namely, that conspicuous females
have acquired the instinct of building domed nests oftener than dull-
coloured birds. Mr. Wallace admits that there are, as might have been
expected, some exceptions to his two rules, but it is a question whether
the exceptions are not so numerous as seriously to invalidate them.
There is in the first place much truth in the Duke of Argyll's remark (10.
'Journal of Travel,' edited by A. Murray, vol. i. 1868, p. 281.) that a
large domed nest is more conspicuous to an enemy, especially to all tree-
haunting carnivorous animals, than a smaller open nest. Nor must we forget
that with many birds which build open nests, the male sits on the eggs and
aids the female in feeding the young: this is the case, for instance, with
Pyranga aestiva (11. Audubon, 'Ornithological Biography,' vol. i. p.
233.), one of the most splendid birds in the United States, the male being
vermilion, and the female light brownish-green. Now if brilliant colours
had been extremely dangerous to birds whilst sitting on their open nests,
the males in these cases would have suffered greatly. It might, however,
be of such paramount importance to the male to be brilliantly coloured, in
order to beat his rivals, that this may have more than compensated some
additional danger.
Mr. Wallace admits that with the King-crows (Dicrurus), Orioles, and
Pittidae, the females are conspicuously coloured, yet build open nests; but
he urges that the birds of the first group are highly pugnacious and could
defend themselves; that those of the second group take extreme care in
concealing their open nests, but this does not invariably hold good (12.
Jerdon, 'Birds of India,' vol. ii. p. 108. Gould's 'Handbook of the Birds
of Australia,' vol. i. p. 463.); and that with the birds of the third group
the females are brightly coloured chiefly on the under surface. Besides
these cases, pigeons which are sometimes brightly, and almost always
conspicuously coloured, and which are notoriously liable to the attacks of
birds of prey, offer a serious exception to the rule, for they almost
always build open and exposed nests. In another large family, that of the
humming-birds, all the species build open nests, yet with some of the most
gorgeous species the sexes are alike; and in the majority, the females,
though less brilliant than the males, are brightly coloured. Nor can it be
maintained that all female humming-birds, which are brightly coloured,
escape detection by their tints being green, for some display on their
upper surfaces red, blue, and other colours. (13. For instance, the
female Eupetomena macroura has the head and tail dark blue with reddish
loins; the female Lampornis porphyrurus is blackish-green on the upper
surface, with the lores and sides of the throat crimson; the female
Eulampis jugularis has the top of the head and back green, but the loins
and the tail are crimson. Many other instances of highly conspicuous
females could be given. See Mr. Gould's magnificent work on this family.)
In regard to birds which build in holes or construct domed nests, other
advantages, as Mr. Wallace remarks, besides concealment are gained, such as
shelter from the rain, greater warmth, and in hot countries protection from
the sun (14. Mr. Salvin noticed in Guatemala ('Ibis,' 1864, p. 375) that
humming-birds were much more unwilling to leave their nests during very hot
weather, when the sun was shining brightly, as if their eggs would be thus
injured, than during cool, cloudy, or rainy weather.); so that it is no
valid objection to his view that many birds having both sexes obscurely
coloured build concealed nests. (15. I may specify, as instances of dull-
coloured birds building concealed nests, the species belonging to eight
Australian genera described in Gould's 'Handbook of the Birds of
Australia,' vol. i. pp. 340, 362, 365, 383, 387, 389, 391, 414.) The
female Horn-bill (Buceros), for instance, of India and Africa is protected
during incubation with extraordinary care, for she plasters up with her own
excrement the orifice of the hole in which she sits on her eggs, leaving
only a small orifice through which the male feeds her; she is thus kept a
close prisoner during the whole period of incubation (16. Mr. C. Horne,
'Proc. Zoolog. Soc.' 1869. p. 243.); yet female horn-bills are not more
conspicuously coloured than many other birds of equal size which build open
nests. It is a more serious objection to Mr. Wallace's view, as is
admitted by him, that in some few groups the males are brilliantly coloured
and the females obscure, and yet the latter hatch their eggs in domed
nests. This is the case with the Grallinae of Australia, the Superb
Warblers (Maluridae) of the same country, the Sun-birds (Nectariniae), and
with several of the Australian Honey-suckers or Meliphagidae. (17. On the
nidification and colours of these latter species, see Gould's 'Handbook to
the Birds of Australia,' vol. i. pp. 504, 527.)
If we look to the birds of England we shall see that there is no close and
general relation between the colours of the female and the nature of the
nest which is constructed. About forty of our British birds (excluding
those of large size which could defend themselves) build in holes in banks,
rocks, or trees, or construct domed nests. If we take the colours of the
female goldfinch, bullfinch, or blackbird, as a standard of the degree of
conspicuousness, which is not highly dangerous to the sitting female, then
out of the above forty birds the females of only twelve can be considered
as conspicuous to a dangerous degree, the remaining twenty-eight being
inconspicuous. (18. I have consulted, on this subject, Macgillivray's
'British Birds,' and though doubts may be entertained in some cases in
regard to the degree of concealment of the nest, and to the degree of
conspicuousness of the female, yet the following birds, which all lay their
eggs in holes or in domed nests, can hardly be considered, by the above
standard, as conspicuous: Passer, 2 species; Sturnus, of which the female
is considerably less brilliant than the male; Cinclus; Motallica boarula
(?); Erithacus (?); Fruticola, 2 sp.; Saxicola; Ruticilla, 2 sp.; Sylvia, 3
sp.; Parus, 3 sp.; Mecistura; Anorthura; Certhia; Sitta; Yunx; Muscicapa, 2
sp.; Hirundo, 3 sp.; and Cypselus. The females of the following 12 birds
may be considered as conspicuous according to the same standard, viz.,
Pastor, Motacilla alba, Parus major and P. caeruleus, Upupa, Picus, 4 sp.,
Coracias, Alcedo, and Merops.) Nor is there any close relation within the
same genus between a well-pronounced difference in colour between the
sexes, and the nature of the nest constructed. Thus the male house sparrow
(Passer domesticus) differs much from the female, the male tree-sparrow (P.
montanus) hardly at all, and yet both build well-concealed nests. The two
sexes of the common fly-catcher (Muscicapa grisola) can hardly be
distinguished, whilst the sexes of the pied fly-catcher (M. luctuosa)
differ considerably, and both species build in holes or conceal their
nests. The female blackbird (Turdus merula) differs much, the female ring-
ouzel (T. torquatus) differs less, and the female common thrush (T.
musicus) hardly at all from their respective males; yet all build open
nests. On the other hand, the not very distantly-allied water-ouzel
(Cinclus aquaticus) builds a domed nest, and the sexes differ about as much
as in the ring-ouzel. The black and red grouse (Tetrao tetrix and T.
scoticus) build open nests in equally well-concealed spots, but in the one
species the sexes differ greatly, and in the other very little.
Notwithstanding the foregoing objections, I cannot doubt, after reading Mr.
Wallace's excellent essay, that looking to the birds of the world, a large
majority of the species in which the females are conspicuously coloured
(and in this case the males with rare exceptions are equally conspicuous),
build concealed nests for the sake of protection. Mr. Wallace enumerates
(19. 'Journal of Travel,' edited by A. Murray, vol. i. p. 78.) a long
series of groups in which this rule holds good; but it will suffice here to
give, as instances, the more familiar groups of kingfishers, toucans,
trogons, puff-birds (Capitonidae), plantain-eaters (Musophagae,
woodpeckers, and parrots. Mr. Wallace believes that in these groups, as
the males gradually acquired through sexual selection their brilliant
colours, these were transferred to the females and were not eliminated by
natural selection, owing to the protection which they already enjoyed from
their manner of nidification. According to this view, their present manner
of nesting was acquired before their present colours. But it seems to me
much more probable that in most cases, as the females were gradually
rendered more and more brilliant from partaking of the colours of the male,
they were gradually led to change their instincts (supposing that they
originally built open nests), and to seek protection by building domed or
concealed nests. No one who studies, for instance, Audubon's account of
the differences in the nests of the same species in the Northern and
Southern United States (20. See many statements in the 'Ornithological
Biography.' See also some curious observations on the nests of Italian
birds by Eugenio Bettoni, in the 'Atti della Societa Italiana,' vol. xi.
1869, p. 487.), will feel any great difficulty in admitting that birds,
either by a change (in the strict sense of the word) of their habits, or
through the natural selection of so-called spontaneous variations of
instinct, might readily be led to modify their manner of nesting.
This way of viewing the relation, as far as it holds good, between the
bright colours of female birds and their manner of nesting, receives some
support from certain cases occurring in the Sahara Desert. Here, as in
most other deserts, various birds, and many other animals, have had their
colours adapted in a wonderful manner to the tints of the surrounding
surface. Nevertheless there are, as I am informed by the Rev. Mr.
Tristram, some curious exceptions to the rule; thus the male of the
Monticola cyanea is conspicuous from his bright blue colour, and the female
almost equally conspicuous from her mottled brown and white plumage; both
sexes of two species of Dromolaea are of a lustrous black; so that these
three species are far from receiving protection from their colours, yet
they are able to survive, for they have acquired the habit of taking refuge
from danger in holes or crevices in the rocks.
With respect to the above groups in which the females are conspicuously
coloured and build concealed nests, it is not necessary to suppose that
each separate species had its nidifying instinct specially modified; but
only that the early progenitors of each group were gradually led to build
domed or concealed nests, and afterwards transmitted this instinct,
together with their bright colours, to their modified descendants. As far
as it can be trusted, the conclusion is interesting, that sexual selection
together with equal or nearly equal inheritance by both sexes, have
indirectly determined the manner of nidification of whole groups of birds.
According to Mr. Wallace, even in the groups in which the females, from
being protected in domed nests during incubation, have not had their bright
colours eliminated through natural selection, the males often differ in a
slight, and occasionally in a considerable degree from the females. This
is a significant fact, for such differences in colour must be accounted for
by some of the variations in the males having been from the first limited
in transmission to the same sex; as it can hardly be maintained that these
differences, especially when very slight, serve as a protection to the
female. Thus all the species in the splendid group of the Trogons build in
holes; and Mr. Gould gives figures (21. See his Monograph of the
Trogonidae, 1st edition.) of both sexes of twenty-five species, in all of
which, with one partial exception, the sexes differ sometimes slightly,
sometimes conspicuously, in colour,--the males being always finer than the
females, though the latter are likewise beautiful. All the species of
kingfishers build in holes, and with most of the species the sexes are
equally brilliant, and thus far Mr. Wallace's rule holds good; but in some
of the Australian species the colours of the females are rather less vivid
than those of the male; and in one splendidly-coloured species, the sexes
differ so much that they were at first thought to be specifically distinct.
(22. Namely, Cyanalcyon, Gould's 'Handbook to the Birds of Australia,'
vol. i. p. 133; see, also, pp. 130, 136.) Mr. R.B. Sharpe, who has
especially studied this group, has shewn me some American species (Ceryle)
in which the breast of the male is belted with black. Again, in
Carcineutes, the difference between the sexes is conspicuous: in the male
the upper surface is dull-blue banded with black, the lower surface being
partly fawn-coloured, and there is much red about the head; in the female
the upper surface is reddish-brown banded with black, and the lower surface
white with black markings. It is an interesting fact, as shewing how the
same peculiar style of sexual colouring often characterises allied forms,
that in three species of Dacelo the male differs from the female only in
the tail being dull-blue banded with black, whilst that of the female is
brown with blackish bars; so that here the tail differs in colour in the
two sexes in exactly the same manner as the whole upper surface in the two
sexes of Carcineutes.
With parrots, which likewise build in holes, we find analogous cases: in
most of the species, both sexes are brilliantly coloured and
indistinguishable, but in not a few species the males are coloured rather
more vividly than the females, or even very differently from them. Thus,
besides other strongly-marked differences, the whole under surface of the
male King Lory (Aprosmictus scapulatus) is scarlet, whilst the throat and
chest of the female is green tinged with red: in the Euphema splendida
there is a similar difference, the face and wing coverts moreover of the
female being of a paler blue than in the male. (23. Every gradation of
difference between the sexes may be followed in the parrots of Australia.
See Gould's 'Handbook,' etc., vol. ii. pp. 14-102.) In the family of the
tits (Parinae), which build concealed nests, the female of our common blue
tomtit (Parus caeruleus), is "much less brightly coloured" than the male:
and in the magnificent Sultan yellow tit of India the difference is
greater. (24. Macgillivray's 'British Birds,' vol. ii. p. 433. Jerdon,
'Birds of India,' vol. ii. p. 282.)
Again, in the great group of the woodpeckers (25. All the following facts
are taken from M. Malherbe's magnificent 'Monographie des Picidees,'
1861.), the sexes are generally nearly alike, but in the Megapicus validus
all those parts of the head, neck, and breast, which are crimson in the
male are pale brown in the female. As in several woodpeckers the head of
the male is bright crimson, whilst that of the female is plain, it occurred
to me that this colour might possibly make the female dangerously
conspicuous, whenever she put her head out of the hole containing her nest,
and consequently that this colour, in accordance with Mr. Wallace's belief,
had been eliminated. This view is strengthened by what Malherbe states
with respect to Indopicus carlotta; namely, that the young females, like
the young males, have some crimson about their heads, but that this colour
disappears in the adult female, whilst it is intensified in the adult male.
Nevertheless the following considerations render this view extremely
doubtful: the male takes a fair share in incubation (26. Audubon's
'Ornithological Biography,' vol. ii. p. 75; see also the 'Ibis,' vol. i. p.
268.), and would be thus almost equally exposed to danger; both sexes of
many species have their heads of an equally bright crimson; in other
species the difference between the sexes in the amount of scarlet is so
slight that it can hardly make any appreciable difference in the danger
incurred; and lastly, the colouring of the head in the two sexes often
differs slightly in other ways.
The cases, as yet given, of slight and graduated differences in colour
between the males and females in the groups, in which as a general rule the
sexes resemble each other, all relate to species which build domed or
concealed nests. But similar gradations may likewise be observed in groups
in which the sexes as a general rule resemble each other, but which build
open nests.
As I have before instanced the Australian parrots, so I may here instance,
without giving any details, the Australian pigeons. (27. Gould's
'Handbook to the Birds of Australia,' vol. ii. pp. 109-149.) It deserves
especial notice that in all these cases the slight differences in plumage
between the sexes are of the same general nature as the occasionally
greater differences. A good illustration of this fact has already been
afforded by those kingfishers in which either the tail alone or the whole
upper surface of the plumage differs in the same manner in the two sexes.
Similar cases may be observed with parrots and pigeons. The differences in
colour between the sexes of the same species are, also, of the same general
nature as the differences in colour between the distinct species of the
same group. For when in a group in which the sexes are usually alike, the
male differs considerably from the female, he is not coloured in a quite
new style. Hence we may infer that within the same group the special
colours of both sexes when they are alike, and the colours of the male,
when he differs slightly or even considerably from the female, have been in
most cases determined by the same general cause; this being sexual
selection.
It is not probable, as has already been remarked, that differences in
colour between the sexes, when very slight, can be of service to the female
as a protection. Assuming, however, that they are of service, they might
be thought to be cases of transition; but we have no reason to believe that
many species at any one time are undergoing change. Therefore we can
hardly admit that the numerous females which differ very slightly in colour
from their males are now all commencing to become obscure for the sake of
protection. Even if we consider somewhat more marked sexual differences,
is it probable, for instance, that the head of the female chaffinch,--the
crimson on the breast of the female bullfinch,--the green of the female
greenfinch,--the crest of the female golden-crested wren, have all been
rendered less bright by the slow process of selection for the sake of
protection? I cannot think so; and still less with the slight differences
between the sexes of those birds which build concealed nests. On the other
hand, the differences in colour between the sexes, whether great or small,
may to a large extent be explained on the principle of the successive
variations, acquired by the males through sexual selection, having been
from the first more or less limited in their transmission to the females.
That the degree of limitation should differ in different species of the
same group will not surprise any one who has studied the laws of
inheritance, for they are so complex that they appear to us in our
ignorance to be capricious in their action. (28. See remarks to this
effect in 'Variation of Animals and Plants under Domestication,' vol. ii.
chap. xii.)
As far as I can discover there are few large groups of birds in which all
the species have both sexes alike and brilliantly coloured, but I hear from
Mr. Sclater, that this appears to be the case with the Musophagae or
plantain-eaters. Nor do I believe that any large group exists in which the
sexes of all the species are widely dissimilar in colour: Mr. Wallace
informs me that the chatterers of S. America (Cotingidae) offer one of the
best instances; but with some of the species, in which the male has a
splendid red breast, the female exhibits some red on her breast; and the
females of other species shew traces of the green and other colours of the
males. Nevertheless we have a near approach to close sexual similarity or
dissimilarity throughout several groups: and this, from what has just been
said of the fluctuating nature of inheritance, is a somewhat surprising
circumstance. But that the same laws should largely prevail with allied
animals is not surprising. The domestic fowl has produced a great number
of breeds and sub-breeds, and in these the sexes generally differ in
plumage; so that it has been noticed as an unusual circumstance when in
certain sub-breeds they resemble each other. On the other hand, the
domestic pigeon has likewise produced a vast number of distinct breeds and
sub-breeds, and in these, with rare exceptions, the two sexes are
identically alike.
Therefore if other species of Gallus and Columba were domesticated and
varied, it would not be rash to predict that similar rules of sexual
similarity and dissimilarity, depending on the form of transmission, would
hold good in both cases. In like manner the same form of transmission has
generally prevailed under nature throughout the same groups, although
marked exceptions to this rule occur. Thus within the same family or even
genus, the sexes may be identically alike, or very different in colour.
Instances have already been given in the same genus, as with sparrows, fly-
catchers, thrushes and grouse. In the family of pheasants the sexes of
almost all the species are wonderfully dissimilar, but are quite alike in
the eared pheasant or Crossoptilon auritum. In two species of Chloephaga,
a genus of geese, the male cannot be distinguished from the females, except
by size; whilst in two others, the sexes are so unlike that they might
easily be mistaken for distinct species. (29. The 'Ibis,' vol. vi. 1864,
p. 122.)
The laws of inheritance can alone account for the following cases, in which
the female acquires, late in life, certain characters proper to the male,
and ultimately comes to resemble him more or less completely. Here
protection can hardly have come into play. Mr. Blyth informs me that the
females of Oriolus melanocephalus and of some allied species, when
sufficiently mature to breed, differ considerably in plumage from the adult
males; but after the second or third moults they differ only in their beaks
having a slight greenish tinge. In the dwarf bitterns (Ardetta), according
to the same authority, "the male acquires his final livery at the first
moult, the female not before the third or fourth moult; in the meanwhile
she presents an intermediate garb, which is ultimately exchanged for the
same livery as that of the male." So again the female Falco peregrinus
acquires her blue plumage more slowly than the male. Mr. Swinhoe states
that with one of the Drongo shrikes (Dicrurus macrocercus) the male, whilst
almost a nestling, moults his soft brown plumage and becomes of a uniform
glossy greenish-black; but the female retains for a long time the white
striae and spots on the axillary feathers; and does not completely assume
the uniform black colour of the male for three years. The same excellent
observer remarks that in the spring of the second year the female spoon-
bill (Platalea) of China resembles the male of the first year, and that
apparently it is not until the third spring that she acquires the same
adult plumage as that possessed by the male at a much earlier age. The
female Bombycilla carolinensis differs very little from the male, but the
appendages, which like beads of red sealing-wax ornament the wing-feathers
(30. When the male courts the female, these ornaments are vibrated, and
"are shewn off to great advantage," on the outstretched wings: A. Leith
Adams, 'Field and Forest Rambles,' 1873, p. 153.), are not developed in her
so early in life as in the male. In the male of an Indian parrakeet
(Palaeornis javanicus) the upper mandible is coral-red from his earliest
youth, but in the female, as Mr. Blyth has observed with caged and wild
birds, it is at first black and does not become red until the bird is at
least a year old, at which age the sexes resemble each other in all
respects. Both sexes of the wild turkey are ultimately furnished with a
tuft of bristles on the breast, but in two-year-old birds the tuft is about
four inches long in the male and hardly apparent in the female; when,
however, the latter has reached her fourth year, it is from four to five
inches in length. (31. On Ardetta, Translation of Cuvier's 'Regne
Animal,' by Mr. Blyth, footnote, p. 159. On the Peregrine Falcon, Mr.
Blyth, in Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304. On
Dicrurus, 'Ibis,' 1863, p. 44. On the Platalea, 'Ibis,' vol. vi. 1864, p.
366. On the Bombycilla, Audubon's 'Ornitholog. Biography,' vol. i. p.
229. On the Palaeornis, see, also, Jerdon, 'Birds of India,' vol. i. p.
263. On the wild turkey, Audubon, ibid. vol. i. p. 15; but I hear from
Judge Caton that in Illinois the female very rarely acquires a tuft.
Analogous cases with the females of Petrocossyphus are given by Mr. R.
Sharpe, 'Proceedings of the Zoological Society,' 1872, p. 496.)
These cases must not be confounded with those where diseased or old females
abnormally assume masculine characters, nor with those where fertile
females, whilst young, acquire the characters of the male, through
variation or some unknown cause. (32. Of these latter cases Mr. Blyth has
recorded (Translation of Cuvier's 'Regne Animal,' p. 158) various instances
with Lanius, Ruticilla, Linaria, and Anas. Audubon has also recorded a
similar case ('Ornitholog. Biography,' vol. v. p. 519) with Pyranga
aestiva.) But all these cases have so much in common that they depend,
according to the hypothesis of pangenesis, on gemmules derived from each
part of the male being present, though latent, in the female; their
development following on some slight change in the elective affinities of
her constituent tissues.
A few words must be added on changes of plumage in relation to the season
of the year. From reasons formerly assigned there can be little doubt that
the elegant plumes, long pendant feathers, crests, etc., of egrets, herons,
and many other birds, which are developed and retained only during the
summer, serve for ornamental and nuptial purposes, though common to both
sexes. The female is thus rendered more conspicuous during the period of
incubation than during the winter; but such birds as herons and egrets
would be able to defend themselves. As, however, plumes would probably be
inconvenient and certainly of no use during the winter, it is possible that
the habit of moulting twice in the year may have been gradually acquired
through natural selection for the sake of casting off inconvenient
ornaments during the winter. But this view cannot be extended to the many
waders, whose summer and winter plumages differ very little in colour.
With defenceless species, in which both sexes, or the males alone, become
extremely conspicuous during the breeding-season,--or when the males
acquire at this season such long wing or tail-feathers as to impede their
flight, as with Cosmetornis and Vidua,--it certainly at first appears
highly probable that the second moult has been gained for the special
purpose of throwing off these ornaments. We must, however, remember that
many birds, such as some of the Birds of Paradise, the Argus pheasant and
peacock, do not cast their plumes during the winter; and it can hardly be
maintained that the constitution of these birds, at least of the
Gallinaceae, renders a double moult impossible, for the ptarmigan moults
thrice in the year. (33. See Gould's 'Birds of Great Britain.') Hence it
must be considered as doubtful whether the many species which moult their
ornamental plumes or lose their bright colours during the winter, have
acquired this habit on account of the inconvenience or danger which they
would otherwise have suffered.
I conclude, therefore, that the habit of moulting twice in the year was in
most or all cases first acquired for some distinct purpose, perhaps for
gaining a warmer winter covering; and that variations in the plumage
occurring during the summer were accumulated through sexual selection, and
transmitted to the offspring at the same season of the year; that such
variations were inherited either by both sexes or by the males alone,
according to the form of inheritance which prevailed. This appears more
probable than that the species in all cases originally tended to retain
their ornamental plumage during the winter, but were saved from this
through natural selection, resulting from the inconvenience or danger thus
caused.
I have endeavoured in this chapter to shew that the arguments are not
trustworthy in favour of the view that weapons, bright colours, and various
ornaments, are now confined to the males owing to the conversion, by
natural selection, of the equal transmission of characters to both sexes,
into transmission to the male sex alone. It is also doubtful whether the
colours of many female birds are due to the preservation, for the sake of
protection, of variations which were from the first limited in their
transmission to the female sex. But it will be convenient to defer any
further discussion on this subject until I treat, in the following chapter,
of the differences in plumage between the young and old.
CHAPTER XVI.
BIRDS--concluded.
The immature plumage in relation to the character of the plumage in both
sexes when adult--Six classes of cases--Sexual differences between the
males of closely-allied or representative species--The female assuming the
characters of the male--Plumage of the young in relation to the summer and
winter plumage of the adults--On the increase of beauty in the birds of the
world--Protective colouring--Conspicuously coloured birds--Novelty
appreciated--Summary of the four chapters on Birds.
We must now consider the transmission of characters, as limited by age, in
reference to sexual selection. The truth and importance of the principle
of inheritance at corresponding ages need not here be discussed, as enough
has already been said on the subject. Before giving the several rather
complex rules or classes of cases, under which the differences in plumage
between the young and the old, as far as known to me, may be included, it
will be well to make a few preliminary remarks.
With animals of all kinds when the adults differ in colour from the young,
and the colours of the latter are not, as far as we can see, of any special
service, they may generally be attributed, like various embryological
structures, to the retention of a former character. But this view can be
maintained with confidence, only when the young of several species resemble
each other closely, and likewise resemble other adult species belonging to
the same group; for the latter are the living proofs that such a state of
things was formerly possible. Young lions and pumas are marked with feeble
stripes or rows of spots, and as many allied species both young and old are
similarly marked, no believer in evolution will doubt that the progenitor
of the lion and puma was a striped animal, and that the young have retained
vestiges of the stripes, like the kittens of black cats, which are not in
the least striped when grown up. Many species of deer, which when mature
are not spotted, are whilst young covered with white spots, as are likewise
some few species in the adult state. So again the young in the whole
family of pigs (Suidae), and in certain rather distantly allied animals,
such as the tapir, are marked with dark longitudinal stripes; but here we
have a character apparently derived from an extinct progenitor, and now
preserved by the young alone. In all such cases the old have had their
colours changed in the course of time, whilst the young have remained but
little altered, and this has been effected through the principle of
inheritance at corresponding ages.
This same principle applies to many birds belonging to various groups, in
which the young closely resemble each other, and differ much from their
respective adult parents. The young of almost all the Gallinaceae, and of
some distantly allied birds such as ostriches, are covered with
longitudinally striped down; but this character points back to a state of
things so remote that it hardly concerns us. Young cross-bills (Loxia)
have at first straight beaks like those of other finches, and in their
immature striated plumage they resemble the mature red-pole and female
siskin, as well as the young of the goldfinch, greenfinch, and some other
allied species. The young of many kinds of buntings (Emberiza) resemble
one another, and likewise the adult state of the common bunting, E.
miliaria. In almost the whole large group of thrushes the young have their
breasts spotted--a character which is retained throughout life by many
species, but is quite lost by others, as by the Turdus migratorius. So
again with many thrushes, the feathers on the back are mottled before they
are moulted for the first time, and this character is retained for life by
certain eastern species. The young of many species of shrikes (Lanius), of
some woodpeckers, and of an Indian pigeon (Chalcophaps indicus), are
transversely striped on the under surface; and certain allied species or
whole genera are similarly marked when adult. In some closely-allied and
resplendent Indian cuckoos (Chrysococcyx), the mature species differ
considerably from one another in colour, but the young cannot be
distinguished. The young of an Indian goose (Sarkidiornis melanonotus)
closely resemble in plumage an allied genus, Dendrocygna, when mature. (1.
In regard to thrushes, shrikes, and woodpeckers, see Mr. Blyth, in
Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304; also footnote to
his translation of Cuvier's 'Regne Animal,' p. 159. I give the case of
Loxia on Mr. Blyth's information. On thrushes, see also Audubon, 'Ornith.
Biog.' vol. ii. p. 195. On Chrysococcyx and Chalcophaps, Blyth, as quoted
in Jerdon's 'Birds of India,' vol. iii. p. 485. On Sarkidiornis, Blyth, in
'Ibis,' 1867, p. 175.) Similar facts will hereafter be given in regard to
certain herons. Young black-grouse (Tetrao tetrix) resemble the young as
well as the old of certain other species, for instance the red-grouse or T.
scoticus. Finally, as Mr. Blyth, who has attended closely to this subject,
has well remarked, the natural affinities of many species are best
exhibited in their immature plumage; and as the true affinities of all
organic beings depend on their descent from a common progenitor, this
remark strongly confirms the belief that the immature plumage approximately
shews us the former or ancestral condition of the species.
Although many young birds, belonging to various families, thus give us a
glimpse of the plumage of their remote progenitors, yet there are many
other birds, both dull-coloured and bright-coloured, in which the young
closely resemble their parents. In such cases the young of the different
species cannot resemble each other more closely than do the parents; nor
can they strikingly resemble allied forms when adult. They give us but
little insight into the plumage of their progenitors, excepting in so far
that, when the young and the old are coloured in the same general manner
throughout a whole group of species, it is probable that their progenitors
were similarly coloured.
We may now consider the classes of cases, under which the differences and
resemblances between the plumage of the young and the old, in both sexes or
in one sex alone, may be grouped. Rules of this kind were first enounced
by Cuvier; but with the progress of knowledge they require some
modification and amplification. This I have attempted to do, as far as the
extreme complexity of the subject permits, from information derived from
various sources; but a full essay on this subject by some competent
ornithologist is much needed. In order to ascertain to what extent each
rule prevails, I have tabulated the facts given in four great works,
namely, by Macgillivray on the birds of Britain, Audubon on those of North
America, Jerdon on those of India, and Gould on those of Australia. I may
here premise, first, that the several cases or rules graduate into each
other; and secondly, that when the young are said to resemble their
parents, it is not meant that they are identically alike, for their colours
are almost always less vivid, and the feathers are softer and often of a
different shape.
RULES OR CLASSES OF CASES.
I. When the adult male is more beautiful or conspicuous than the adult
female, the young of both sexes in their first plumage closely resemble the
adult female, as with the common fowl and peacock; or, as occasionally
occurs, they resemble her much more closely than they do the adult male.
II. When the adult female is more conspicuous than the adult male, as
sometimes though rarely occurs, the young of both sexes in their first
plumage resemble the adult male.
III. When the adult male resembles the adult female, the young of both
sexes have a peculiar first plumage of their own, as with the robin.
IV. When the adult male resembles the adult female, the young of both
sexes in their first plumage resemble the adults, as with the kingfisher,
many parrots, crows, hedge-warblers.
V. When the adults of both sexes have a distinct winter and summer
plumage, whether or not the male differs from the female, the young
resemble the adults of both sexes in their winter dress, or much more
rarely in their summer dress, or they resemble the females alone. Or the
young may have an intermediate character; or again they may differ greatly
from the adults in both their seasonal plumages.
VI. In some few cases the young in their first plumage differ from each
other according to sex; the young males resembling more or less closely the
adult males, and the young females more or less closely the adult females.
CLASS I.
In this class, the young of both sexes more or less closely resemble the
adult female, whilst the adult male differs from the adult female, often in
the most conspicuous manner. Innumerable instances in all Orders could be
given; it will suffice to call to mind the common pheasant, duck, and
house-sparrow. The cases under this class graduate into others. Thus the
two sexes when adult may differ so slightly, and the young so slightly from
the adults, that it is doubtful whether such cases ought to come under the
present, or under the third or fourth classes. So again the young of the
two sexes, instead of being quite alike, may differ in a slight degree from
each other, as in our sixth class. These transitional cases, however, are
few, or at least are not strongly pronounced, in comparison with those
which come strictly under the present class.
The force of the present law is well shewn in those groups, in which, as a
general rule, the two sexes and the young are all alike; for when in these
groups the male does differ from the female, as with certain parrots,
kingfishers, pigeons, etc., the young of both sexes resemble the adult
female. (2. See, for instance, Mr. Gould's account ('Handbook to the
Birds of Australia,' vol. i. p. 133) of Cyanalcyon (one of the
Kingfishers), in which, however, the young male, though resembling the
adult female, is less brilliantly coloured. In some species of Dacelo the
males have blue tails, and the females brown ones; and Mr. R.B. Sharpe
informs me that the tail of the young male of D. gaudichaudi is at first
brown. Mr. Gould has described (ibid. vol. ii. pp. 14, 20, 37) the sexes
and the young of certain black Cockatoos and of the King Lory, with which
the same rule prevails. Also Jerdon ('Birds of India,' vol. i. p. 260) on
the Palaeornis rosa, in which the young are more like the female than the
male. See Audubon ('Ornithological Biography,' vol. ii. p. 475) on the two
sexes and the young of Columba passerina.) We see the same fact exhibited
still more clearly in certain anomalous cases; thus the male of Heliothrix
auriculata (one of the humming-birds) differs conspicuously from the female
in having a splendid gorget and fine ear-tufts, but the female is
remarkable from having a much longer tail than that of the male; now the
young of both sexes resemble (with the exception of the breast being
spotted with bronze) the adult female in all other respects, including the
length of her tail, so that the tail of the male actually becomes shorter
as he reaches maturity, which is a most unusual circumstance. (3. I owe
this information to Mr. Gould, who shewed me the specimens; see also his
'Introduction to the Trochilidae,' 1861, p. 120.) Again, the plumage of
the male goosander (Mergus merganser) is more conspicuously coloured than
that of the female, with the scapular and secondary wing-feathers much
longer; but differently from what occurs, as far as I know, in any other
bird, the crest of the adult male, though broader than that of the female,
is considerably shorter, being only a little above an inch in length; the
crest of the female being two and a half inches long. Now the young of
both sexes entirely resemble the adult female, so that their crests are
actually of greater length, though narrower, than in the adult male. (4.
Macgillivray, 'Hist. Brit. Birds,' vol. v. pp. 207-214.)
When the young and the females closely resemble each other and both differ
from the males, the most obvious conclusion is that the males alone have
been modified. Even in the anomalous cases of the Heliothrix and Mergus,
it is probable that originally both adult sexes were furnished--the one
species with a much elongated tail, and the other with a much elongated
crest--these characters having since been partially lost by the adult males
from some unexplained cause, and transmitted in their diminished state to
their male offspring alone, when arrived at the corresponding age of
maturity. The belief that in the present class the male alone has been
modified, as far as the differences between the male and the female
together with her young are concerned, is strongly supported by some
remarkable facts recorded by Mr. Blyth (5. See his admirable paper in the
'Journal of the Asiatic Soc. of Bengal,' vol. xix. 1850, p. 223; see also
Jerdon, 'Birds of India,' vol. i. introduction, p. xxix. In regard to
Tanysiptera, Prof. Schlegel told Mr. Blyth that he could distinguish
several distinct races, solely by comparing the adult males.), with respect
to closely-allied species which represent each other in distinct countries.
For with several of these representative species the adult males have
undergone a certain amount of change and can be distinguished; the females
and the young from the distinct countries being indistinguishable, and
therefore absolutely unchanged. This is the case with certain Indian chats
(Thamnobia), with certain honey-suckers (Nectarinia), shrikes
(Tephrodornis), certain kingfishers (Tanysiptera), Kalij pheasants
(Gallophasis), and tree-partridges (Arboricola).
In some analogous cases, namely with birds having a different summer and
winter plumage, but with the two sexes nearly alike, certain closely-allied
species can easily be distinguished in their summer or nuptial plumage, yet
are indistinguishable in their winter as well as in their immature plumage.
This is the case with some of the closely-allied Indian wagtails or
Motacillae. Mr. Swinhoe (6. See also Mr. Swinhoe, in 'Ibis,' July 1863,
p. 131; and a previous paper, with an extract from a note by Mr. Blyth, in
'Ibis,' January, 1861, p. 25.) informs me that three species of Ardeola, a
genus of herons, which represent one another on separate continents, are
"most strikingly different" when ornamented with their summer plumes, but
are hardly, if at all, distinguishable during the winter. The young also
of these three species in their immature plumage closely resemble the
adults in their winter dress. This case is all the more interesting,
because with two other species of Ardeola both sexes retain, during the
winter and summer, nearly the same plumage as that possessed by the three
first species during the winter and in their immature state; and this
plumage, which is common to several distinct species at different ages and
seasons, probably shews us how the progenitors of the genus were coloured.
In all these cases, the nuptial plumage which we may assume was originally
acquired by the adult males during the breeding-season, and transmitted to
the adults of both sexes at the corresponding season, has been modified,
whilst the winter and immature plumages have been left unchanged.
The question naturally arises, how is it that in these latter cases the
winter plumage of both sexes, and in the former cases the plumage of the
adult females, as well as the immature plumage of the young, have not been
at all affected? The species which represent each other in distinct
countries will almost always have been exposed to somewhat different
conditions, but we can hardly attribute to this action the modification of
the plumage in the males alone, seeing that the females and the young,
though similarly exposed, have not been affected. Hardly any fact shews us
more clearly how subordinate in importance is the direct action of the
conditions of life, in comparison with the accumulation through selection
of indefinite variations, than the surprising difference between the sexes
of many birds; for both will have consumed the same food, and have been
exposed to the same climate. Nevertheless we are not precluded from
believing that in the course of time new conditions may produce some direct
effect either on both sexes, or from their constitutional differences
chiefly on one sex. We see only that this is subordinate in importance to
the accumulated results of selection. Judging, however, from a wide-spread
analogy, when a species migrates into a new country (and this must precede
the formation of representative species), the changed conditions to which
they will almost always have been exposed will cause them to undergo a
certain amount of fluctuating variability. In this case sexual selection,
which depends on an element liable to change--the taste or admiration of
the female--will have had new shades of colour or other differences to act
on and accumulate; and as sexual selection is always at work, it would
(from what we know of the results on domestic animals of man's
unintentional selection), be surprising if animals inhabiting separate
districts, which can never cross and thus blend their newly-acquired
characters, were not, after a sufficient lapse of time, differently
modified. These remarks likewise apply to the nuptial or summer plumage,
whether confined to the males, or common to both sexes.
Although the females of the above closely-allied or representative species,
together with their young, differ hardly at all from one another, so that
the males alone can be distinguished, yet the females of most species
within the same genus obviously differ from each other. The differences,
however, are rarely as great as between the males. We see this clearly in
the whole family of the Gallinaceae: the females, for instance, of the
common and Japan pheasant, and especially of the gold and Amherst pheasant
--of the silver pheasant and the wild fowl--resemble one another very
closely in colour, whilst the males differ to an extraordinary degree. So
it is with the females of most of the Cotingidae, Fringillidae, and many
other families. There can indeed be no doubt that, as a general rule, the
females have been less modified than the males. Some few birds, however,
offer a singular and inexplicable exception; thus the females of Paradisea
apoda and P. papuana differ from each other more than do their respective
males (7. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 394.); the
female of the latter species having the under surface pure white, whilst
the female P. apoda is deep brown beneath. So, again, as I hear from
Professor Newton, the males of two species of Oxynotus (shrikes), which
represent each other in the islands of Mauritius and Bourbon (8. These
species are described with coloured figures, by M. F. Pollen, in 'Ibis,'
1866, p. 275.), differ but little in colour, whilst the females differ
much. In the Bourbon species the female appears to have partially retained
an immature condition of plumage, for at first sight she "might be taken
for the young of the Mauritian species." These differences may be compared
with those inexplicable ones, which occur independently of man's selection
in certain sub-breeds of the game-fowl, in which the females are very
different, whilst the males can hardly be distinguished. (9. 'Variation
of Animals,' etc., vol. i. p. 251.)
As I account so largely by sexual selection for the differences between the
males of allied species, how can the differences between the females be
accounted for in all ordinary cases? We need not here consider the species
which belong to distinct genera; for with these, adaptation to different
habits of life, and other agencies, will have come into play. In regard to
the differences between the females within the same genus, it appears to me
almost certain, after looking through various large groups, that the chief
agent has been the greater or less transference to the female of the
characters acquired by the males through sexual selection. In the several
British finches, the two sexes differ either very slightly or considerably;
and if we compare the females of the greenfinch, chaffinch, goldfinch,
bullfinch, crossbill, sparrow, etc., we shall see that they differ from one
another chiefly in the points in which they partially resemble their
respective males; and the colours of the males may safely be attributed to
sexual selection. With many gallinaceous species the sexes differ to an
extreme degree, as with the peacock, pheasant, and fowl, whilst with other
species there has been a partial or even complete transference of character
from the male to the female. The females of the several species of
Polyplectron exhibit in a dim condition, and chiefly on the tail, the
splendid ocelli of their males. The female partridge differs from the male
only in the red mark on her breast being smaller; and the female wild
turkey only in her colours being much duller. In the guinea-fowl the two
sexes are indistinguishable. There is no improbability in the plain,
though peculiarly spotted plumage of this latter bird having been acquired
through sexual selection by the males, and then transmitted to both sexes;
for it is not essentially different from the much more beautifully spotted
plumage, characteristic of the males alone of the Tragopan pheasants.
It should be observed that, in some instances, the transference of
characters from the male to the female has been effected apparently at a
remote period, the male having subsequently undergone great changes,
without transferring to the female any of his later-gained characters. For
instance, the female and the young of the black-grouse (Tetrao tetrix)
resemble pretty closely both sexes and the young of the red-grouse (T.
scoticus); and we may consequently infer that the black-grouse is descended
from some ancient species, of which both sexes were coloured in nearly the
same manner as the red-grouse. As both sexes of this latter species are
more distinctly barred during the breeding-season than at any other time,
and as the male differs slightly from the female in his more strongly-
pronounced red and brown tints (10. Macgillivray, 'History of British
Birds,' vol. i. pp. 172-174.), we may conclude that his plumage has been
influenced by sexual selection, at least to a certain extent. If so, we
may further infer that nearly similar plumage of the female black-grouse
was similarly produced at some former period. But since this period the
male black-grouse has acquired his fine black plumage, with his forked and
outwardly-curled tail-feathers; but of these characters there has hardly
been any transference to the female, excepting that she shews in her tail a
trace of the curved fork.
We may therefore conclude that the females of distinct though allied
species have often had their plumage rendered more or less different by the
transference in various degrees of characters acquired by the males through
sexual selection, both during former and recent times. But it deserves
especial attention that brilliant colours have been transferred much more
rarely than other tints. For instance, the male of the red-throated blue-
breast (Cyanecula suecica) has a rich blue breast, including a sub-
triangular red mark; now marks of nearly the same shape have been
transferred to the female, but the central space is fulvous instead of red,
and is surrounded by mottled instead of blue feathers. The Gallinaceae
offer many analogous cases; for none of the species, such as partridges,
quails, guinea-fowls, etc., in which the colours of the plumage have been
largely transferred from the male to the female, are brilliantly coloured.
This is well exemplified with the pheasants, in which the male is generally
so much more brilliant than the female; but with the Eared and Cheer
pheasants (Crossoptilon auritum and Phasianus wallichii) the sexes closely
resemble each other and their colours are dull. We may go so far as to
believe that if any part of the plumage in the males of these two pheasants
had been brilliantly coloured, it would not have been transferred to the
females. These facts strongly support Mr. Wallace's view that with birds
which are exposed to much danger during incubation, the transference of
bright colours from the male to the female has been checked through natural
selection. We must not, however, forget that another explanation, before
given, is possible; namely, that the males which varied and became bright,
whilst they were young and inexperienced, would have been exposed to much
danger, and would generally have been destroyed; the older and more
cautious males, on the other hand, if they varied in a like manner, would
not only have been able to survive, but would have been favoured in their
rivalry with other males. Now variations occurring late in life tend to be
transmitted exclusively to the same sex, so that in this case extremely
bright tints would not have been transmitted to the females. On the other
hand, ornaments of a less conspicuous kind, such as those possessed by the
Eared and Cheer pheasants, would not have been dangerous, and if they
appeared during early youth, would generally have been transmitted to both
sexes.
In addition to the effects of the partial transference of characters from
the males to the females, some of the differences between the females of
closely allied species may be attributed to the direct or definite action
of the conditions of life. (11. See, on this subject, chap. xxiii. in the
'Variation of Animals and Plants under Domestication.') With the males,
any such action would generally have been masked by the brilliant colours
gained through sexual selection; but not so with the females. Each of the
endless diversities in plumage which we see in our domesticated birds is,
of course, the result of some definite cause; and under natural and more
uniform conditions, some one tint, assuming that it was in no way
injurious, would almost certainly sooner or later prevail. The free
intercrossing of the many individuals belonging to the same species would
ultimately tend to make any change of colour, thus induced, uniform in
character.
No one doubts that both sexes of many birds have had their colours adapted
for the sake of protection; and it is possible that the females alone of
some species may have been modified for this end. Although it would be a
difficult, perhaps an impossible process, as shewn in the last chapter, to
convert one form of transmission into another through selection, there
would not be the least difficulty in adapting the colours of the female,
independently of those of the male, to surrounding objects, through the
accumulation of variations which were from the first limited in their
transmission to the female sex. If the variations were not thus limited,
the bright tints of the male would be deteriorated or destroyed. Whether
the females alone of many species have been thus specially modified, is at
present very doubtful. I wish I could follow Mr. Wallace to the full
extent; for the admission would remove some difficulties. Any variations
which were of no service to the female as a protection would be at once
obliterated, instead of being lost simply by not being selected, or from
free intercrossing, or from being eliminated when transferred to the male
and in any way injurious to him. Thus the plumage of the female would be
kept constant in character. It would also be a relief if we could admit
that the obscure tints of both sexes of many birds had been acquired and
preserved for the sake of protection,--for example, of the hedge-warbler or
kitty-wren (Accentor modularis and Troglodytes vulgaris), with respect to
which we have no sufficient evidence of the action of sexual selection. We
ought, however, to be cautious in concluding that colours which appear to
us dull, are not attractive to the females of certain species; we should
bear in mind such cases as that of the common house-sparrow, in which the
male differs much from the female, but does not exhibit any bright tints.
No one probably will dispute that many gallinaceous birds which live on the
open ground, have acquired their present colours, at least in part, for the
sake of protection. We know how well they are thus concealed; we know that
ptarmigans, whilst changing from their winter to their summer plumage, both
of which are protective, suffer greatly from birds of prey. But can we
believe that the very slight differences in tints and markings between, for
instance, the female black-grouse and red-grouse serve as a protection?
Are partridges, as they are now coloured, better protected than if they had
resembled quails? Do the slight differences between the females of the
common pheasant, the Japan and gold pheasants, serve as a protection, or
might not their plumages have been interchanged with impunity? From what
Mr. Wallace has observed of the habits of certain gallinaceous birds in the
East, he thinks that such slight differences are beneficial. For myself, I
will only say that I am not convinced.
Formerly when I was inclined to lay much stress on protection as accounting
for the duller colours of female birds, it occurred to me that possibly
both sexes and the young might aboriginally have been equally bright
coloured; but that subsequently, the females from the danger incurred
during incubation, and the young from being inexperienced, had been
rendered dull as a protection. But this view is not supported by any
evidence, and is not probable; for we thus in imagination expose during
past times the females and the young to danger, from which it has
subsequently been necessary to shield their modified descendants. We have,
also, to reduce, through a gradual process of selection, the females and
the young to almost exactly the same tints and markings, and to transmit
them to the corresponding sex and period of life. On the supposition that
the females and the young have partaken during each stage of the process of
modification of a tendency to be as brightly coloured as the males, it is
also a somewhat strange fact that the females have never been rendered
dull-coloured without the young participating in the same change; for there
are no instances, as far as I can discover, of species with the females
dull and the young bright coloured. A partial exception, however, is
offered by the young of certain woodpeckers, for they have "the whole upper
part of the head tinged with red," which afterwards either decreases into a
mere circular red line in the adults of both sexes, or quite disappears in
the adult females. (12. Audubon, 'Ornith. Biography,' vol. i. p. 193.
Macgillivray, 'History of British Birds,' vol. iii. p. 85. See also the
case before given of Indopicus carlotta.)
Finally, with respect to our present class of cases, the most probable view
appears to be that successive variations in brightness or in other
ornamental characters, occurring in the males at a rather late period of
life have alone been preserved; and that most or all of these variations,
owing to the late period of life at which they appeared, have been from the
first transmitted only to the adult male offspring. Any variations in
brightness occurring in the females or in the young, would have been of no
service to them, and would not have been selected; and moreover, if
dangerous, would have been eliminated. Thus the females and the young will
either have been left unmodified, or (as is much more common) will have
been partially modified by receiving through transference from the males
some of his successive variations. Both sexes have perhaps been directly
acted on by the conditions of life to which they have long been exposed:
but the females from not being otherwise much modified, will best exhibit
any such effects. These changes and all others will have been kept uniform
by the free intercrossing of many individuals. In some cases, especially
with ground birds, the females and the young may possibly have been
modified, independently of the males, for the sake of protection, so as to
have acquired the same dull-coloured plumage.
CLASS II.
WHEN THE ADULT FEMALE IS MORE CONSPICUOUS THAN THE ADULT MALE, THE YOUNG OF
BOTH SEXES IN THEIR FIRST PLUMAGE RESEMBLE THE ADULT MALE.
This class is exactly the reverse of the last, for the females are here
brighter coloured or more conspicuous than the males; and the young, as far
as they are known, resemble the adult males instead of the adult females.
But the difference between the sexes is never nearly so great as with many
birds in the first class, and the cases are comparatively rare. Mr.
Wallace, who first called attention to the singular relation which exists
between the less bright colours of the males and their performing the
duties of incubation, lays great stress on this point (13. 'Westminster
Review,' July 1867, and A. Murray, 'Journal of Travel,' 1868, p. 83.), as a
crucial test that obscure colours have been acquired for the sake of
protection during the period of nesting. A different view seems to me more
probable. As the cases are curious and not numerous, I will briefly give
all that I have been able to find.
In one section of the genus Turnix, quail-like birds, the female is
invariably larger than the male (being nearly twice as large in one of the
Australian species), and this is an unusual circumstance with the
Gallinaceae. In most of the species the female is more distinctly coloured
and brighter than the male (14. For the Australian species, see Gould's
'Handbook,' etc., vol. ii. pp. 178, 180, 186, and 188. In the British
Museum specimens of the Australian Plain-wanderer (Pedionomus torquatus)
may be seen, shewing similar sexual differences.), but in some few species
the sexes are alike. In Turnix taigoor of India the male "wants the black
on the throat and neck, and the whole tone of the plumage is lighter and
less pronounced than that of the female." The female appears to be
noisier, and is certainly much more pugnacious than the male; so that the
females and not the males are often kept by the natives for fighting, like
game-cocks. As male birds are exposed by the English bird-catchers for a
decoy near a trap, in order to catch other males by exciting their rivalry,
so the females of this Turnix are employed in India. When thus exposed the
females soon begin their "loud purring call, which can be heard a long way
off, and any females within ear-shot run rapidly to the spot, and commence
fighting with the caged bird." In this way from twelve to twenty birds,
all breeding females, may be caught in the course of a single day. The
natives assert that the females after laying their eggs associate in
flocks, and leave the males to sit on them. There is no reason to doubt
the truth of this assertion, which is supported by some observations made
in China by Mr. Swinhoe. (15. Jerdon, 'Birds of India,' vol. iii. p. 596.
Mr. Swinhoe, in 'Ibis,' 1865, p. 542; 1866, pp. 131, 405.) Mr. Blyth
believes, that the young of both sexes resemble the adult male.
[Fig. 62. Rhynchaea capensis (from Brehm).]
The females of the three species of Painted Snipes (Rhynchaea, Fig. 62)
"are not only larger but much more richly coloured than the males." (16.
Jerdon, 'Birds of India,' vol. iii. p. 677.) With all other birds in which
the trachea differs in structure in the two sexes it is more developed and
complex in the male than in the female; but in the Rhynchaea australis it
is simple in the male, whilst in the female it makes four distinct
convolutions before entering the lungs. (17. Gould's 'Handbook to the
Birds of Australia,' vol. ii. p. 275.) The female therefore of this
species has acquired an eminently masculine character. Mr. Blyth
ascertained, by examining many specimens, that the trachea is not
convoluted in either sex of R. bengalensis, which species resembles R.
australis so closely, that it can hardly be distinguished except by its
shorter toes. This fact is another striking instance of the law that
secondary sexual characters are often widely different in closely-allied
forms, though it is a very rare circumstance when such differences relate
to the female sex. The young of both sexes of R. bengalensis in their
first plumage are said to resemble the mature male. (18. 'The Indian
Field,' Sept. 1858, p. 3.) There is also reason to believe that the male
undertakes the duty of incubation, for Mr. Swinhoe (19. 'Ibis,' 1866, p.
298.) found the females before the close of the summer associated in
flocks, as occurs with the females of the Turnix.
The females of Phalaropus fulicarius and P. hyperboreus are larger, and in
their summer plumage "more gaily attired than the males." But the
difference in colour between the sexes is far from conspicuous. According
to Professor Steenstrup, the male alone of P. fulicarius undertakes the
duty of incubation; this is likewise shewn by the state of his breast-
feathers during the breeding-season. The female of the dotterel plover
(Eudromias morinellus) is larger than the male, and has the red and black
tints on the lower surface, the white crescent on the breast, and the
stripes over the eyes, more strongly pronounced. The male also takes at
least a share in hatching the eggs; but the female likewise attends to the
young. (20. For these several statements, see Mr. Gould's 'Birds of Great
Britain.' Prof. Newton informs me that he has long been convinced, from
his own observations and from those of others, that the males of the above-
named species take either the whole or a large share of the duties of
incubation, and that they "shew much greater devotion towards their young,
when in danger, than do the females." So it is, as he informs me, with
Limosa lapponica and some few other Waders, in which the females are larger
and have more strongly contrasted colours than the males.) I have not been
able to discover whether with these species the young resemble the adult
males more closely than the adult females; for the comparison is somewhat
difficult to make on account of the double moult.
Turning now to the ostrich Order: the male of the common cassowary
(Casuarius galeatus) would be thought by any one to be the female, from his
smaller size and from the appendages and naked skin about his head being
much less brightly coloured; and I am informed by Mr. Bartlett that in the
Zoological Gardens, it is certainly the male alone who sits on the eggs and
takes care of the young. (21. The natives of Ceram (Wallace, 'Malay
Archipelago,' vol. ii. p. 150) assert that the male and female sit
alternately on the eggs; but this assertion, as Mr. Bartlett thinks, may be
accounted for by the female visiting the nest to lay her eggs.) The female
is said by Mr. T.W. Wood (22. The 'Student,' April 1870, p. 124.) to
exhibit during the breeding-season a most pugnacious disposition; and her
wattles then become enlarged and more brilliantly coloured. So again the
female of one of the emus (Dromoeus irroratus) is considerably larger than
the male, and she possesses a slight top-knot, but is otherwise
indistinguishable in plumage. She appears, however, "to have greater
power, when angry or otherwise excited, of erecting, like a turkey-cock,
the feathers of her neck and breast. She is usually the more courageous
and pugilistic. She makes a deep hollow guttural boom especially at night,
sounding like a small gong. The male has a slenderer frame and is more
docile, with no voice beyond a suppressed hiss when angry, or a croak." He
not only performs the whole duty of incubation, but has to defend the young
from their mother; "for as soon as she catches sight of her progeny she
becomes violently agitated, and notwithstanding the resistance of the
father appears to use her utmost endeavours to destroy them. For months
afterwards it is unsafe to put the parents together, violent quarrels being
the inevitable result, in which the female generally comes off conqueror."
(23. See the excellent account of the habits of this bird under
confinement, by Mr. A.W. Bennett, in 'Land and Water,' May 1868, p. 233.)
So that with this emu we have a complete reversal not only of the parental
and incubating instincts, but of the usual moral qualities of the two
sexes; the females being savage, quarrelsome, and noisy, the males gentle
and good. The case is very different with the African ostrich, for the
male is somewhat larger than the female and has finer plumes with more
strongly contrasted colours; nevertheless he undertakes the whole duty of
incubation. (24. Mr. Sclater, on the incubation of the Struthiones,
'Proc. Zool. Soc.' June 9, 1863. So it is with the Rhea darwinii: Captain
Musters says ('At Home with the Patagonians,' 1871, p. 128), that the male
is larger, stronger and swifter than the female, and of slightly darker
colours; yet he takes sole charge of the eggs and of the young, just as
does the male of the common species of Rhea.)
I will specify the few other cases known to me, in which the female is more
conspicuously coloured than the male, although nothing is known about the
manner of incubation. With the carrion-hawk of the Falkland Islands
(Milvago leucurus) I was much surprised to find by dissection that the
individuals, which had all their tints strongly pronounced, with the cere
and legs orange-coloured, were the adult females; whilst those with duller
plumage and grey legs were the males or the young. In an Australian tree-
creeper (Climacteris erythrops) the female differs from the male in "being
adorned with beautiful, radiated, rufous markings on the throat, the male
having this part quite plain." Lastly, in an Australian night-jar "the
female always exceeds the male in size and in the brilliance of her tints;
the males, on the other hand, have two white spots on the primaries more
conspicuous than in the female." (25. For the Milvago, see 'Zoology of
the Voyage of the "Beagle," Birds,' 1841, p. 16. For the Climacteris and
night-jar (Eurostopodus), see Gould's 'Handbook to the Birds of Australia,'
vol. i. pp. 602 and 97. The New Zealand shieldrake (Tadorna variegata)
offers a quite anomalous case; the head of the female is pure white, and
her back is redder than that of the male; the head of the male is of a rich
dark bronzed colour, and his back is clothed with finely pencilled slate-
coloured feathers, so that altogether he may be considered as the more
beautiful of the two. He is larger and more pugnacious than the female,
and does not sit on the eggs. So that in all these respects this species
comes under our first class of cases; but Mr. Sclater ('Proceedings of the
Zoological Society,' 1866, p. 150) was much surprised to observe that the
young of both sexes, when about three months old, resembled in their dark
heads and necks the adult males, instead of the adult females; so that it
would appear in this case that the females have been modified, whilst the
males and the young have retained a former state of plumage.)
We thus see that the cases in which female birds are more conspicuously
coloured than the males, with the young in their immature plumage
resembling the adult males instead of the adult females, as in the previous
class, are not numerous, though they are distributed in various Orders.
The amount of difference, also, between the sexes is incomparably less than
that which frequently occurs in the last class; so that the cause of the
difference, whatever it may have been, has here acted on the females either
less energetically or less persistently than on the males in the last
class. Mr. Wallace believes that the males have had their colours rendered
less conspicuous for the sake of protection during the period of
incubation; but the difference between the sexes in hardly any of the
foregoing cases appears sufficiently great for this view to be safely
accepted. In some of the cases, the brighter tints of the female are
almost confined to the lower surface, and the males, if thus coloured,
would not have been exposed to danger whilst sitting on the eggs. It
should also be borne in mind that the males are not only in a slight degree
less conspicuously coloured than the females, but are smaller and weaker.
They have, moreover, not only acquired the maternal instinct of incubation,
but are less pugnacious and vociferous than the females, and in one
instance have simpler vocal organs. Thus an almost complete transposition
of the instincts, habits, disposition, colour, size, and of some points of
structure, has been effected between the two sexes.
Now if we might assume that the males in the present class have lost some
of that ardour which is usual to their sex, so that they no longer search
eagerly for the females; or, if we might assume that the females have
become much more numerous than the males--and in the case of one Indian
Turnix the females are said to be "much more commonly met with than the
males" (26. Jerdon, 'Birds of India,' vol. iii. p. 598.)--then it is not
improbable that the females would have been led to court the males, instead
of being courted by them. This indeed is the case to a certain extent with
some birds, as we have seen with the peahen, wild turkey, and certain kinds
of grouse. Taking as our guide the habits of most male birds, the greater
size and strength as well as the extraordinary pugnacity of the females of
the Turnix and emu, must mean that they endeavour to drive away rival
females, in order to gain possession of the male; and on this view all the
facts become clear; for the males would probably be most charmed or excited
by the females which were the most attractive to them by their bright
colours, other ornaments, or vocal powers. Sexual selection would then do
its work, steadily adding to the attractions of the females; the males and
the young being left not at all, or but little modified.
CLASS III.
WHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES
HAVE A PECULIAR FIRST PLUMAGE OF THEIR OWN.
In this class the sexes when adult resemble each other, and differ from the
young. This occurs with many birds of many kinds. The male robin can
hardly be distinguished from the female, but the young are widely
different, with their mottled dusky-olive and brown plumage. The male and
female of the splendid scarlet ibis are alike, whilst the young are brown;
and the scarlet colour, though common to both sexes, is apparently a sexual
character, for it is not well developed in either sex under confinement;
and a loss of colour often occurs with brilliant males when they are
confined. With many species of herons the young differ greatly from the
adults; and the summer plumage of the latter, though common to both sexes,
clearly has a nuptial character. Young swans are slate-coloured, whilst
the mature birds are pure white; but it would be superfluous to give
additional instances. These differences between the young and the old
apparently depend, as in the last two classes, on the young having retained
a former or ancient state of plumage, whilst the old of both sexes have
acquired a new one. When the adults are bright coloured, we may conclude
from the remarks just made in relation to the scarlet ibis and to many
herons, and from the analogy of the species in the first class, that such
colours have been acquired through sexual selection by the nearly mature
males; but that, differently from what occurs in the first two classes, the
transmission, though limited to the same age, has not been limited to the
same sex. Consequently, the sexes when mature resemble each other and
differ from the young.
CLASS IV.
WHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES IN
THEIR FIRST PLUMAGE RESEMBLE THE ADULTS.
In this class the young and the adults of both sexes, whether brilliantly
or obscurely coloured, resemble each other. Such cases are, I think, more
common than those in the last class. We have in England instances in the
kingfisher, some woodpeckers, the jay, magpie, crow, and many small dull-
coloured birds, such as the hedge-warbler or kitty-wren. But the
similarity in plumage between the young and the old is never complete, and
graduates away into dissimilarity. Thus the young of some members of the
kingfisher family are not only less vividly coloured than the adults, but
many of the feathers on the lower surface are edged with brown (27.
Jerdon, 'Birds of India,' vol. i. pp. 222, 228. Gould's 'Handbook to the
Birds of Australia,' vol. i. pp. 124, 130.),--a vestige probably of a
former state of the plumage. Frequently in the same group of birds, even
within the same genus, for instance in an Australian genus of parrakeets
(Platycercus), the young of some species closely resemble, whilst the young
of other species differ considerably, from their parents of both sexes,
which are alike. (28. Gould, ibid. vol. ii. pp. 37, 46, 56.) Both sexes
and the young of the common jay are closely similar; but in the Canada jay
(Perisoreus canadensis) the young differ so much from their parents that
they were formerly described as distinct species. (29. Audubon, 'Ornith.
Biography,' vol. ii. p. 55.)
I may remark before proceeding that, under the present and next two classes
of cases, the facts are so complex and the conclusions so doubtful, that
any one who feels no especial interest in the subject had better pass them
over.
The brilliant or conspicuous colours which characterise many birds in the
present class, can rarely or never be of service to them as a protection;
so that they have probably been gained by the males through sexual
selection, and then transferred to the females and the young. It is,
however, possible that the males may have selected the more attractive
females; and if these transmitted their characters to their offspring of
both sexes, the same results would follow as from the selection of the more
attractive males by the females. But there is evidence that this
contingency has rarely, if ever, occurred in any of those groups of birds
in which the sexes are generally alike; for, if even a few of the
successive variations had failed to be transmitted to both sexes, the
females would have slightly exceeded the males in beauty. Exactly the
reverse occurs under nature; for, in almost every large group in which the
sexes generally resemble each other, the males of some few species are in a
slight degree more brightly coloured than the females. It is again
possible that the females may have selected the more beautiful males, these
males having reciprocally selected the more beautiful females; but it is
doubtful whether this double process of selection would be likely to occur,
owing to the greater eagerness of one sex than the other, and whether it
would be more efficient than selection on one side alone. It is,
therefore, the most probable view that sexual selection has acted, in the
present class, as far as ornamental characters are concerned, in accordance
with the general rule throughout the animal kingdom, that is, on the males;
and that these have transmitted their gradually-acquired colours, either
equally or almost equally, to their offspring of both sexes.
Another point is more doubtful, namely, whether the successive variations
first appeared in the males after had become nearly mature, or whilst quite
young. In either case sexual selection must have acted on the male when he
had to compete with rivals for the possession of the female; and in both
cases the characters thus acquired have been transmitted to both sexes and
all ages. But these characters if acquired by the males when adult, may
have been transmitted at first to the adults alone, and at some subsequent
period transferred to the young. For it is known that, when the law of
inheritance at corresponding ages fails, the offspring often inherit
characters at an earlier age than that at which they first appeared in
their parents. (30. 'Variation of Animals and Plants under
Domestication,' vol. ii. p. 79.) Cases apparently of this kind have been
observed with birds in a state of nature. For instance Mr. Blyth has seen
specimens of Lanius rufus and of Colymbus glacialis which had assumed
whilst young, in a quite anomalous manner, the adult plumage of their
parents. (31. 'Charlesworth's Magazine of Natural History,' vol. i. 1837,
pp. 305, 306.) Again, the young of the common swan (Cygnus olor) do not
cast off their dark feathers and become white until eighteen months or two
years old; but Dr. F. Forel has described the case of three vigorous young
birds, out of a brood of four, which were born pure white. These young
birds were not albinos, as shewn by the colour of their beaks and legs,
which nearly resembled the same parts in the adults. (32. 'Bulletin de la
Soc. Vaudoise des Sc. Nat.' vol. x. 1869, p. 132. The young of the Polish
swan, Cygnus immutabilis of Yarrell, are always white; but this species, as
Mr. Sclater informs me, is believed to be nothing more than a variety of
the domestic swan (Cygnus olor).)
It may be worth while to illustrate the above three modes by which, in the
present class, the two sexes and the young may have come to resemble each
other, by the curious case of the genus Passer. (33. I am indebted to Mr.
Blyth for information in regard to this genus. The sparrow of Palestine
belongs to the sub-genus Petronia.) In the house-sparrow (P. domesticus)
the male differs much from the female and from the young. The young and
the females are alike, and resemble to a large extent both sexes and the
young of the sparrow of Palestine (P. brachydactylus), as well as of some
allied species. We may therefore assume that the female and young of the
house-sparrow approximately shew us the plumage of the progenitor of the
genus. Now with the tree-sparrow (P. montanus) both sexes and the young
closely resemble the male of the house-sparrow; so that they have all been
modified in the same manner, and all depart from the typical colouring of
their early progenitor. This may have been effected by a male ancestor of
the tree-sparrow having varied, firstly, when nearly mature; or, secondly,
whilst quite young, and by having in either case transmitted his modified
plumage to the females and the young; or, thirdly, he may have varied when
adult and transmitted his plumage to both adult sexes, and, owing to the
failure of the law of inheritance at corresponding ages, at some subsequent
period to his young.
It is impossible to decide which of these three modes has generally
prevailed throughout the present class of cases. That the males varied
whilst young, and transmitted their variations to their offspring of both
sexes, is the most probable. I may here add that I have, with little
success, endeavoured, by consulting various works, to decide how far the
period of variation in birds has generally determined the transmission of
characters to one sex or to both. The two rules, often referred to
(namely, that variations occurring late in life are transmitted to one and
the same sex, whilst those which occur early in life are transmitted to
both sexes), apparently hold good in the first (34. For instance, the
males of Tanagra aestiva and Fringilla cyanea require three years, the male
of Fringilla ciris four years, to complete their beautiful plumage. (See
Audubon, 'Ornith. Biography,' vol. i. pp. 233, 280, 378). The Harlequin
duck takes three years (ibid. vol. iii. p. 614). The male of the Gold
pheasant, as I hear from Mr. Jenner Weir, can be distinguished from the
female when about three months old, but he does not acquire his full
splendour until the end of the September in the following year.), second,
and fourth classes of cases; but they fail in the third, often in the fifth
(35. Thus the Ibis tantalus and Grus americanus take four years, the
Flamingo several years, and the Ardea ludovicana two years, before they
acquire their perfect plumage. See Audubon, ibid. vol. i. p. 221; vol.
iii. pp. 133, 139, 211.), and in the sixth small class. They apply,
however, as far as I can judge, to a considerable majority of the species;
and we must not forget the striking generalisation by Dr. W. Marshall with
respect to the protuberances on the heads of birds. Whether or not the two
rules generally hold good, we may conclude from the facts given in the
eighth chapter, that the period of variation is one important element in
determining the form of transmission.
With birds it is difficult to decide by what standard we ought to judge of
the earliness or lateness of the period of variation, whether by the age in
reference to the duration of life, or to the power of reproduction, or to
the number of moults through which the species passes. The moulting of
birds, even within the same family, sometimes differs much without any
assignable cause. Some birds moult so early, that nearly all the body
feathers are cast off before the first wing-feathers are fully grown; and
we cannot believe that this was the primordial state of things. When the
period of moulting has been accelerated, the age at which the colours of
the adult plumage are first developed will falsely appear to us to be
earlier than it really is. This may be illustrated by the practice
followed by some bird-fanciers, who pull out a few feathers from the breast
of nestling bullfinches, and from the head or neck of young gold-pheasants,
in order to ascertain their sex; for in the males, these feathers are
immediately replaced by coloured ones. (36. Mr. Blyth, in Charlesworth's
'Magazine of Natural History,' vol. i. 1837, p. 300. Mr. Bartlett has
informed me in regard to gold pheasants.) The actual duration of life is
known in but few birds, so that we can hardly judge by this standard. And,
with reference to the period at which the power of reproduction is gained,
it is a remarkable fact that various birds occasionally breed whilst
retaining their immature plumage. (37. I have noticed the following cases
in Audubon's 'Ornith. Biography.' The redstart of America (Muscapica
ruticilla, vol. i. p. 203). The Ibis tantalus takes four years to come to
full maturity, but sometimes breeds in the second year (vol. iii. p. 133).
The Grus americanus takes the same time, but breeds before acquiring its
full plumage (vol. iii. p. 211). The adults of Ardea caerulea are blue,
and the young white; and white, mottled, and mature blue birds may all be
seen breeding together (vol. iv. p. 58): but Mr. Blyth informs me that
certain herons apparently are dimorphic, for white and coloured individuals
of the same age may be observed. The Harlequin duck (Anas histrionica,
Linn.) takes three years to acquire its full plumage, though many birds
breed in the second year (vol. iii. p. 614). The White-headed Eagle (Falco
leucocephalus, vol. iii. p. 210) is likewise known to breed in its immature
state. Some species of Oriolus (according to Mr. Blyth and Mr. Swinhoe, in
'Ibis,' July 1863, p. 68) likewise breed before they attain their full
plumage.)
The fact of birds breeding in their immature plumage seems opposed to the
belief that sexual selection has played as important a part, as I believe
it has, in giving ornamental colours, plumes, etc., to the males, and, by
means of equal transmission, to the females of many species. The objection
would be a valid one, if the younger and less ornamented males were as
successful in winning females and propagating their kind, as the older and
more beautiful males. But we have no reason to suppose that this is the
case. Audubon speaks of the breeding of the immature males of Ibis
tantalus as a rare event, as does Mr. Swinhoe, in regard to the immature
males of Oriolus. (38. See footnote 37 above.) If the young of any
species in their immature plumage were more successful in winning partners
than the adults, the adult plumage would probably soon be lost, as the
males would prevail, which retained their immature dress for the longest
period, and thus the character of the species would ultimately be modified.
(39. Other animals, belonging to quite distinct classes, are either
habitually or occasionally capable of breeding before they have fully
acquired their adult characters. This is the case with the young males of
the salmon. Several amphibians have been known to breed whilst retaining
their larval structure. Fritz Muller has shewn ('Facts and arguments for
Darwin,' Eng. trans. 1869, p. 79) that the males of several amphipod
crustaceans become sexually mature whilst young; and I infer that this is a
case of premature breeding, because they have not as yet acquired their
fully-developed claspers. All such facts are highly interesting, as
bearing on one means by which species may undergo great modifications of
character.) If, on the other hand, the young never succeeded in obtaining
a female, the habit of early reproduction would perhaps be sooner or later
eliminated, from being superfluous and entailing waste of power.
The plumage of certain birds goes on increasing in beauty during many years
after they are fully mature; this is the case with the train of the
peacock, with some of the birds of paradise, and with the crest and plumes
of certain herons, for instance, the Ardea ludovicana. (40. Jerdon,
'Birds of India,' vol. iii. p. 507, on the peacock. Dr. Marshall thinks
that the older and more brilliant males of birds of paradise, have an
advantage over the younger males; see 'Archives Neerlandaises,' tom. vi.
1871.--On Ardea, Audubon, ibid. vol. iii. p. 139.) But it is doubtful
whether the continued development of such feathers is the result of the
selection of successive beneficial variations (though this is the most
probable view with birds of paradise) or merely of continuous growth. Most
fishes continue increasing in size, as long as they are in good health and
have plenty of food; and a somewhat similar law may prevail with the plumes
of birds.
CLASS V.
WHEN THE ADULTS OF BOTH SEXES HAVE A DISTINCT WINTER AND SUMMER PLUMAGE,
WHETHER OR NOT THE MALE DIFFERS FROM THE FEMALE, THE YOUNG RESEMBLE THE
ADULTS OF BOTH SEXES IN THEIR WINTER DRESS, OR MUCH MORE RARELY IN THEIR
SUMMER DRESS, OR THEY RESEMBLE THE FEMALES ALONE. OR THE YOUNG MAY HAVE AN
INTERMEDIATE CHARACTER; OR, AGAIN, THEY MAY DIFFER GREATLY FROM THE ADULTS
IN BOTH THEIR SEASONAL PLUMAGES.
The cases in this class are singularly complex; nor is this surprising, as
they depend on inheritance, limited in a greater or less degree in three
different ways, namely, by sex, age, and the season of the year. In some
cases the individuals of the same species pass through at least five
distinct states of plumage. With the species, in which the male differs
from the female during the summer season alone, or, which is rarer, during
both seasons (41. For illustrative cases, see vol. iv. of Macgillivray's
'History of British Birds;' on Tringa, etc., pp. 229, 271; on the Machetes,
p. 172; on the Charadrius hiaticula, p. 118; on the Charadrius pluvialis,
p. 94.), the young generally resemble the females,--as with the so-called
goldfinch of North America, and apparently with the splendid Maluri of
Australia. (42. For the goldfinch of N. America, Fringilla tristis,
Linn., see Audubon, 'Ornithological Biography,' vol. i. p. 172. For the
Maluri, Gould's 'Handbook of the Birds of Australia,' vol. i. p. 318.)
With those species, the sexes of which are alike during both the summer and
winter, the young may resemble the adults, firstly, in their winter dress;
secondly, and this is of much rarer occurrence, in their summer dress;
thirdly, they may be intermediate between these two states; and, fourthly,
they may differ greatly from the adults at all seasons. We have an
instance of the first of these four cases in one of the egrets of India
(Buphus coromandus), in which the young and the adults of both sexes are
white during the winter, the adults becoming golden-buff during the summer.
With the gaper (Anastomus oscitans) of India we have a similar case, but
the colours are reversed: for the young and the adults of both sexes are
grey and black during the winter, the adults becoming white during the
summer. (43. I am indebted to Mr. Blyth for information as to the Buphus;
see also Jerdon, 'Birds of India,' vol. iii. p. 749. On the Anastomus, see
Blyth, in 'Ibis,' 1867, p. 173.) As an instance of the second case, the
young of the razor-bill (Alca torda, Linn.), in an early state of plumage,
are coloured like the adults during the summer; and the young of the white-
crowned sparrow of North America (Fringilla leucophrys), as soon as
fledged, have elegant white stripes on their heads, which are lost by the
young and the old during the winter. (44. On the Alca, see Macgillivray,
'Hist. Brit. Birds,' vol. v. p. 347. On the Fringilla leucophrys, Audubon,
ibid. vol. ii. p. 89. I shall have hereafter to refer to the young of
certain herons and egrets being white.) With respect to the third case,
namely, that of the young having an intermediate character between the
summer and winter adult plumages, Yarrell (45. 'History of British Birds,'
vol. i. 1839, p. 159.) insists that this occurs with many waders. Lastly,
in regard to the young differing greatly from both sexes in their adult
summer and winter plumages, this occurs with some herons and egrets of
North America and India,--the young alone being white.
I will make only a few remarks on these complicated cases. When the young
resemble the females in their summer dress, or the adults of both sexes in
their winter dress, the cases differ from those given under Classes I. and
III. only in the characters originally acquired by the males during the
breeding-season, having been limited in their transmission to the
corresponding season. When the adults have a distinct summer and winter
plumage, and the young differ from both, the case is more difficult to
understand. We may admit as probable that the young have retained an
ancient state of plumage; we can account by sexual selection for the summer
or nuptial plumage of the adults, but how are we to account for their
distinct winter plumage? If we could admit that this plumage serves in all
cases as a protection, its acquirement would be a simple affair; but there
seems no good reason for this admission. It may be suggested that the
widely different conditions of life during the winter and summer have acted
in a direct manner on the plumage; this may have had some effect, but I
have not much confidence in so great a difference as we sometimes see
between the two plumages, having been thus caused. A more probable
explanation is, that an ancient style of plumage, partially modified
through the transference of some characters from the summer plumage, has
been retained by the adults during the winter. Finally, all the cases in
our present class apparently depend on characters acquired by the adult
males, having been variously limited in their transmission according to
age, season, and sex; but it would not be worth while to attempt to follow
out these complex relations.
CLASS VI.
THE YOUNG IN THEIR FIRST PLUMAGE DIFFER FROM EACH OTHER ACCORDING TO SEX;
THE YOUNG MALES RESEMBLING MORE OR LESS CLOSELY THE ADULT MALES, AND THE
YOUNG FEMALES MORE OR LESS CLOSELY THE ADULT FEMALES.
The cases in the present class, though occurring in various groups, are not
numerous; yet it seems the most natural thing that the young should at
first somewhat resemble the adults of the same sex, and gradually become
more and more like them. The adult male blackcap (Sylvia atricapilla) has
a black head, that of the female being reddish-brown; and I am informed by
Mr. Blyth, that the young of both sexes can be distinguished by this
character even as nestlings. In the family of thrushes an unusual number
of similar cases have been noticed; thus, the male blackbird (Turdus
merula) can be distinguished in the nest from the female. The two sexes of
the mocking bird (Turdus polyglottus, Linn.) differ very little from each
other, yet the males can easily be distinguished at a very early age from
the females by showing more pure white. (46. Audubon, 'Ornith.
Biography,' vol. i. p. 113.) The males of a forest-thrush and of a rock-
thrush (Orocetes erythrogastra and Petrocincla cyanea) have much of their
plumage of a fine blue, whilst the females are brown; and the nestling
males of both species have their main wing and tail-feathers edged with
blue whilst those of the female are edged with brown. (47. Mr. C.A.
Wright, in 'Ibis,' vol. vi. 1864, p. 65. Jerdon, 'Birds of India,' vol. i.
p. 515. See also on the blackbird, Blyth in Charlesworth's 'Magazine of
Natural History,' vol. i. 1837, p. 113.) In the young blackbird the wing-
feathers assume their mature character and become black after the others;
on the other hand, in the two species just named the wing-feathers become
blue before the others. The most probable view with reference to the cases
in the present class is that the males, differently from what occurs in
Class I., have transmitted their colours to their male offspring at an
earlier age than that at which they were first acquired; for, if the males
had varied whilst quite young, their characters would probably have been
transmitted to both sexes. (48. The following additional cases may be
mentioned; the young males of Tanagra rubra can be distinguished from the
young females (Audubon, 'Ornith. Biography,' vol. iv. p. 392), and so it is
within the nestlings of a blue nuthatch, Dendrophila frontalis of India
(Jerdon, 'Birds of India,' vol. i. p. 389). Mr. Blyth also informs me that
the sexes of the stonechat, Saxicola rubicola, are distinguishable at a
very early age. Mr. Salvin gives ('Proc. Zoolog. Soc.' 1870, p. 206) the
case of a humming-bird, like the following one of Eustephanus.)
In Aithurus polytmus, a humming-bird, the male is splendidly coloured black
and green, and two of the tail-feathers are immensely lengthened; the
female has an ordinary tail and inconspicuous colours; now the young males,
instead of resembling the adult female, in accordance with the common rule,
begin from the first to assume the colours proper to their sex, and their
tail-feathers soon become elongated. I owe this information to Mr. Gould,
who has given me the following more striking and as yet unpublished case.
Two humming-birds belonging to the genus Eustephanus, both beautifully
coloured, inhabit the small island of Juan Fernandez, and have always been
ranked as specifically distinct. But it has lately been ascertained that
the one which is of a rich chestnut-brown colour with a golden-red head, is
the male, whilst the other which is elegantly variegated with green and
white with a metallic green head is the female. Now the young from the
first somewhat resemble the adults of the corresponding sex, the
resemblance gradually becoming more and more complete.
In considering this last case, if as before we take the plumage of the
young as our guide, it would appear that both sexes have been rendered
beautiful independently; and not that one sex has partially transferred its
beauty to the other. The male apparently has acquired his bright colours
through sexual selection in the same manner as, for instance, the peacock
or pheasant in our first class of cases; and the female in the same manner
as the female Rhynchaea or Turnix in our second class of cases. But there
is much difficulty in understanding how this could have been effected at
the same time with the two sexes of the same species. Mr. Salvin states,
as we have seen in the eighth chapter, that with certain humming-birds the
males greatly exceed the females in number, whilst with other species
inhabiting the same country the females greatly exceed the males. If,
then, we might assume that during some former lengthened period the males
of the Juan Fernandez species had greatly exceeded the females in number,
but that during another lengthened period the females had far exceeded the
males, we could understand how the males at one time, and the females at
another, might have been rendered beautiful by the selection of the
brighter coloured individuals of either sex; both sexes transmitting their
characters to their young at a rather earlier age than usual. Whether this
is the true explanation I will not pretend to say; but the case is too
remarkable to be passed over without notice.
We have now seen in all six classes, that an intimate relation exists
between the plumage of the young and the adults, either of one sex or both.
These relations are fairly well explained on the principle that one sex--
this being in the great majority of cases the male--first acquired through
variation and sexual selection bright colours or other ornaments, and
transmitted them in various ways, in accordance with the recognised laws of
inheritance. Why variations have occurred at different periods of life,
even sometimes with species of the same group, we do not know, but with
respect to the form of transmission, one important determining cause seems
to be the age at which the variations first appear.
From the principle of inheritance at corresponding ages, and from any
variations in colour which occurred in the males at an early age not being
then selected--on the contrary being often eliminated as dangerous--whilst
similar variations occurring at or near the period of reproduction have
been preserved, it follows that the plumage of the young will often have
been left unmodified, or but little modified. We thus get some insight
into the colouring of the progenitors of our existing species. In a vast
number of species in five out of our six classes of cases, the adults of
one sex or of both are bright coloured, at least during the breeding-
season, whilst the young are invariably less brightly coloured than the
adults, or are quite dull coloured; for no instance is known, as far as I
can discover, of the young of dull-coloured species displaying bright
colours, or of the young of bright-coloured species being more brilliant
than their parents. In the fourth class, however, in which the young and
the old resemble each other, there are many species (though by no means
all), of which the young are bright-coloured, and as these form old groups,
we may infer that their early progenitors were likewise bright. With this
exception, if we look to the birds of the world, it appears that their
beauty has been much increased since that period, of which their immature
plumage gives us a partial record.
ON THE COLOUR OF THE PLUMAGE IN RELATION TO PROTECTION.
It will have been seen that I cannot follow Mr. Wallace in the belief that
dull colours, when confined to the females, have been in most cases
specially gained for the sake of protection. There can, however, be no
doubt, as formerly remarked, that both sexes of many birds have had their
colours modified, so as to escape the notice of their enemies; or in some
instances, so as to approach their prey unobserved, just as owls have had
their plumage rendered soft, that their flight may not be overheard. Mr.
Wallace remarks (49. 'Westminster Review,' July 1867, p. 5.) that "it is
only in the tropics, among forests which never lose their foliage, that we
find whole groups of birds, whose chief colour is green." It will be
admitted by every one, who has ever tried, how difficult it is to
distinguish parrots in a leaf-covered tree. Nevertheless, we must remember
that many parrots are ornamented with crimson, blue, and orange tints,
which can hardly be protective. Woodpeckers are eminently arboreal, but
besides green species, there are many black, and black-and-white kinds--all
the species being apparently exposed to nearly the same dangers. It is
therefore probable that with tree-haunting birds, strongly-pronounced
colours have been acquired through sexual selection, but that a green tint
has been acquired oftener than any other, from the additional advantage of
protection.
In regard to birds which live on the ground, every one admits that they are
coloured so as to imitate the surrounding surface. How difficult it is to
see a partridge, snipe, woodcock, certain plovers, larks, and night-jars
when crouched on ground. Animals inhabiting deserts offer the most
striking cases, for the bare surface affords no concealment, and nearly all
the smaller quadrupeds, reptiles, and birds depend for safety on their
colours. Mr. Tristram has remarked in regard to the inhabitants of the
Sahara, that all are protected by their "isabelline or sand-colour." (50.
'Ibis,' 1859, vol. i. p. 429, et seq. Dr. Rohlfs, however, remarks to me
in a letter that according to his experience of the Sahara, this statement
is too strong.) Calling to my recollection the desert-birds of South
America, as well as most of the ground-birds of Great Britain, it appeared
to me that both sexes in such cases are generally coloured nearly alike.
Accordingly, I applied to Mr. Tristram with respect to the birds of the
Sahara, and he has kindly given me the following information. There are
twenty-six species belonging to fifteen genera, which manifestly have their
plumage coloured in a protective manner; and this colouring is all the more
striking, as with most of these birds it differs from that of their
congeners. Both sexes of thirteen out of the twenty-six species are
coloured in the same manner; but these belong to genera in which this rule
commonly prevails, so that they tell us nothing about the protective
colours being the same in both sexes of desert-birds. Of the other
thirteen species, three belong to genera in which the sexes usually differ
from each other, yet here they have the sexes alike. In the remaining ten
species, the male differs from the female; but the difference is confined
chiefly to the under surface of the plumage, which is concealed when the
bird crouches on the ground; the head and back being of the same sand-
coloured hue in the two sexes. So that in these ten species the upper
surfaces of both sexes have been acted on and rendered alike, through
natural selection, for the sake of protection; whilst the lower surfaces of
the males alone have been diversified, through sexual selection, for the
sake of ornament. Here, as both sexes are equally well protected, we
clearly see that the females have not been prevented by natural selection
from inheriting the colours of their male parents; so that we must look to
the law of sexually-limited transmission.
In all parts of the world both sexes of many soft-billed birds, especially
those which frequent reeds or sedges, are obscurely coloured. No doubt if
their colours had been brilliant, they would have been much more
conspicuous to their enemies; but whether their dull tints have been
specially gained for the sake of protection seems, as far as I can judge,
rather doubtful. It is still more doubtful whether such dull tints can
have been gained for the sake of ornament. We must, however, bear in mind
that male birds, though dull-coloured, often differ much from their females
(as with the common sparrow), and this leads to the belief that such
colours have been gained through sexual selection, from being attractive.
Many of the soft-billed birds are songsters; and a discussion in a former
chapter should not be forgotten, in which it was shewn that the best
songsters are rarely ornamented with bright tints. It would appear that
female birds, as a general rule, have selected their mates either for their
sweet voices or gay colours, but not for both charms combined. Some
species, which are manifestly coloured for the sake of protection, such as
the jack-snipe, woodcock, and night-jar, are likewise marked and shaded,
according to our standard of taste, with extreme elegance. In such cases
we may conclude that both natural and sexual selection have acted
conjointly for protection and ornament. Whether any bird exists which does
not possess some special attraction, by which to charm the opposite sex,
may be doubted. When both sexes are so obscurely coloured that it would be
rash to assume the agency of sexual selection, and when no direct evidence
can be advanced shewing that such colours serve as a protection, it is best
to own complete ignorance of the cause, or, which comes to nearly the same
thing, to attribute the result to the direct action of the conditions of
life.
Both sexes of many birds are conspicuously, though not brilliantly
coloured, such as the numerous black, white, or piebald species; and these
colours are probably the result of sexual selection. With the common
blackbird, capercailzie, blackcock, black scoter-duck (Oidemia), and even
with one of the birds of paradise (Lophorina atra), the males alone are
black, whilst the females are brown or mottled; and there can hardly be a
doubt that blackness in these cases has been a sexually selected character.
Therefore it is in some degree probable that the complete or partial
blackness of both sexes in such birds as crows, certain cockatoos, storks,
and swans, and many marine birds, is likewise the result of sexual
selection, accompanied by equal transmission to both sexes; for blackness
can hardly serve in any case as a protection. With several birds, in which
the male alone is black, and in others in which both sexes are black, the
beak or skin about the head is brightly coloured, and the contrast thus
afforded adds much to their beauty; we see this in the bright yellow beak
of the male blackbird, in the crimson skin over the eyes of the blackcock
and capercailzie, in the brightly and variously coloured beak of the
scoter-drake (Oidemia), in the red beak of the chough (Corvus graculus,
Linn.), of the black swan, and the black stork. This leads me to remark
that it is not incredible that toucans may owe the enormous size of their
beaks to sexual selection, for the sake of displaying the diversified and
vivid stripes of colour, with which these organs are ornamented. (51. No
satisfactory explanation has ever been offered of the immense size, and
still less of the bright colours, of the toucan's beak. Mr. Bates ('The
Naturalist on the Amazons,' vol. ii. 1863, p. 341) states that they use
their beaks for reaching fruit at the extreme tips of the branches; and
likewise, as stated by other authors, for extracting eggs and young birds
from the nests of other birds. But, as Mr. Bates admits, the beak "can
scarcely be considered a very perfectly-formed instrument for the end to
which it is applied." The great bulk of the beak, as shewn by its breadth,
depth, as well as length, is not intelligible on the view, that it serves
merely as an organ of prehension. Mr. Belt believes ('The Naturalist in
Nicaragua,' p. 197) that the principal use of the beak is as a defence
against enemies, especially to the female whilst nesting in a hole in a
tree.) The naked skin, also, at the base of the beak and round the eyes is
likewise often brilliantly coloured; and Mr. Gould, in speaking of one
species (52. Rhamphastos carinatus, Gould's 'Monograph of Ramphastidae.'),
says that the colours of the beak "are doubtless in the finest and most
brilliant state during the time of pairing." There is no greater
improbability that toucans should be encumbered with immense beaks, though
rendered as light as possible by their cancellated structure, for the
display of fine colours (an object falsely appearing to us unimportant),
than that the male Argus pheasant and some other birds should be encumbered
with plumes so long as to impede their flight.
In the same manner, as the males alone of various species are black, the
females being dull-coloured; so in a few cases the males alone are either
wholly or partially white, as with the several bell-birds of South America
(Chasmorhynchus), the Antarctic goose (Bernicla antarctica), the silver
pheasant, etc., whilst the females are brown or obscurely mottled.
Therefore, on the same principle as before, it is probable that both sexes
of many birds, such as white cockatoos, several egrets with their beautiful
plumes, certain ibises, gulls, terns, etc., have acquired their more or
less completely white plumage through sexual selection. In some of these
cases the plumage becomes white only at maturity. This is the case with
certain gannets, tropic-birds, etc., and with the snow-goose (Anser
hyperboreus). As the latter breeds on the "barren grounds," when not
covered with snow, and as it migrates southward during the winter, there is
no reason to suppose that its snow-white adult plumage serves as a
protection. In the Anastomus oscitans, we have still better evidence that
the white plumage is nuptial character, for it is developed only during the
summer; the young in their immature state, and the adults in their winter
dress, being grey and black. With many kinds of gulls (Larus), the head
and neck become pure white during the summer, being grey or mottled during
the winter and in the young state. On the other hand, with the smaller
gulls, or sea-mews (Gavia), and with some terns (Sterna), exactly the
reverse occurs; for the heads of the young birds during the first year, and
of the adults during the winter, are either pure white, or much paler
coloured than during the breeding-season. These latter cases offer another
instance of the capricious manner in which sexual selection appears often
to have acted. (53. On Larus, Gavia, and Sterna, see Macgillivray,
'History of British Birds,' vol. v. pp. 515, 584, 626. On the Anser
hyperboreus, Audubon, 'Ornithological Biography,' vol. iv. p. 562. On the
Anastomus, Mr. Blyth, in 'Ibis,' 1867, p. 173.)
That aquatic birds have acquired a white plumage so much oftener than
terrestrial birds, probably depends on their large size and strong powers
of flight, so that they can easily defend themselves or escape from birds
of prey, to which moreover they are not much exposed. Consequently, sexual
selection has not here been interfered with or guided for the sake of
protection. No doubt with birds which roam over the open ocean, the males
and females could find each other much more easily, when made conspicuous
either by being perfectly white or intensely black; so that these colours
may possible serve the same end as the call-notes of many land-birds. (54.
It may be noticed that with vultures, which roam far and wide high in the
air, like marine birds over the ocean, three or four species are almost
wholly or largely white, and that many others are black. So that here
again conspicuous colours may possibly aid the sexes in finding each other
during the breeding-season.) A white or black bird when it discovers and
flies down to a carcase floating on the sea or cast up on the beach, will
be seen from a great distance, and will guide other birds of the same and
other species, to the prey; but as this would be a disadvantage to the
first finders, the individuals which were the whitest or blackest would not
thus procure more food than the less strongly coloured individuals. Hence
conspicuous colours cannot have been gradually acquired for this purpose
through natural selection.
As sexual selection depends on so fluctuating an element as taste, we can
understand how it is that, within the same group of birds having nearly the
same habits, there should exist white or nearly white, as well as black, or
nearly black species,--for instance, both white and black cockatoos,
storks, ibises, swans, terns, and petrels. Piebald birds likewise
sometimes occur in the same groups together with black and white species;
for instance, the black-necked swan, certain terns, and the common magpie.
That a strong contrast in colour is agreeable to birds, we may conclude by
looking through any large collection, for the sexes often differ from each
other in the male having the pale parts of a purer white, and the variously
coloured dark parts of still darker tints than the female.
It would even appear that mere novelty, or slight changes for the sake of
change, have sometimes acted on female birds as a charm, like changes of
fashion with us. Thus the males of some parrots can hardly be said to be
more beautiful than the females, at least according to our taste, but they
differ in such points, as in having a rose-coloured collar instead of "a
bright emeraldine narrow green collar"; or in the male having a black
collar instead of "a yellow demi-collar in front," with a pale roseate
instead of a plum-blue head. (55. See Jerdon on the genus Palaeornis,
'Birds of India,' vol. i. pp. 258-260.) As so many male birds have
elongated tail-feathers or elongated crests for their chief ornament, the
shortened tail, formerly described in the male of a humming-bird, and the
shortened crest of the male goosander, seem like one of the many changes of
fashion which we admire in our own dresses.
Some members of the heron family offer a still more curious case of novelty
in colouring having, as it appears, been appreciated for the sake of
novelty. The young of the Ardea asha are white, the adults being dark
slate-coloured; and not only the young, but the adults in their winter
plumage, of the allied Buphus coromandus are white, this colour changing
into a rich golden-buff during the breeding-season. It is incredible that
the young of these two species, as well as of some other members of the
same family (56. The young of Ardea rufescens and A. caerulea of the
United States are likewise white, the adults being coloured in accordance
with their specific names. Audubon ('Ornithological Biography,' vol. iii.
p. 416; vol. iv. p. 58) seems rather pleased at the thought that this
remarkable change of plumage will greatly "disconcert the systematists."),
should for any special purpose have been rendered pure white and thus made
conspicuous to their enemies; or that the adults of one of these two
species should have been specially rendered white during the winter in a
country which is never covered with snow. On the other hand we have good
reason to believe that whiteness has been gained by many birds as a sexual
ornament. We may therefore conclude that some early progenitor of the
Ardea asha and the Buphus acquired a white plumage for nuptial purposes,
and transmitted this colour to their young; so that the young and the old
became white like certain existing egrets; and that the whiteness was
afterwards retained by the young, whilst it was exchanged by the adults for
more strongly-pronounced tints. But if we could look still further back to
the still earlier progenitors of these two species, we should probably see
the adults dark-coloured. I infer that this would be the case, from the
analogy of many other birds, which are dark whilst young, and when adult
are white; and more especially from the case of the Ardea gularis, the
colours of which are the reverse of those of A. asha, for the young are
dark-coloured and the adults white, the young having retained a former
state of plumage. It appears therefore that, during a long line of
descent, the adult progenitors of the Ardea asha, the Buphus, and of some
allies, have undergone the following changes of colour: first, a dark
shade; secondly, pure white; and thirdly, owing to another change of
fashion (if I may so express myself), their present slaty, reddish, or
golden-buff tints. These successive changes are intelligible only on the
principle of novelty having been admired by birds for its own sake.
Several writers have objected to the whole theory of sexual selection, by
assuming that with animals and savages the taste of the female for certain
colours or other ornaments would not remain constant for many generations;
that first one colour and then another would be admired, and consequently
that no permanent effect could be produced. We may admit that taste is
fluctuating, but it is not quite arbitrary. It depends much on habit, as
we see in mankind; and we may infer that this would hold good with birds
and other animals. Even in our own dress, the general character lasts
long, and the changes are to a certain extent graduated. Abundant evidence
will be given in two places in a future chapter, that savages of many races
have admired for many generations the same cicatrices on the skin, the same
hideously perforated lips, nostrils, or ears, distorted heads, etc.; and
these deformities present some analogy to the natural ornaments of various
animals. Nevertheless, with savages such fashions do not endure for ever,
as we may infer from the differences in this respect between allied tribes
on the same continent. So again the raisers of fancy animals certainly
have admired for many generations and still admire the same breeds; they
earnestly desire slight changes, which are considered as improvements, but
any great or sudden change is looked at as the greatest blemish. With
birds in a state of nature we have no reason to suppose that they would
admire an entirely new style of coloration, even if great and sudden
variations often occurred, which is far from being the case. We know that
dovecot pigeons do not willingly associate with the variously coloured
fancy breeds; that albino birds do not commonly get partners in marriage;
and that the black ravens of the Feroe Islands chase away their piebald
brethren. But this dislike of a sudden change would not preclude their
appreciating slight changes, any more than it does in the case of man.
Hence with respect to taste, which depends on many elements, but partly on
habit and partly on a love of novelty, there seems no improbability in
animals admiring for a very long period the same general style of
ornamentation or other attractions, and yet appreciating slight changes in
colours, form, or sound.
SUMMARY OF THE FOUR CHAPTERS ON BIRDS.
Most male birds are highly pugnacious during the breeding-season, and some
possess weapons adapted for fighting with their rivals. But the most
pugnacious and the best armed males rarely or never depend for success
solely on their power to drive away or kill their rivals, but have special
means for charming the female. With some it is the power of song, or of
giving forth strange cries, or instrumental music, and the males in
consequence differ from the females in their vocal organs, or in the
structure of certain feathers. From the curiously diversified means for
producing various sounds, we gain a high idea of the importance of this
means of courtship. Many birds endeavour to charm the females by love-
dances or antics, performed on the ground or in the air, and sometimes at
prepared places. But ornaments of many kinds, the most brilliant tints,
combs and wattles, beautiful plumes, elongated feathers, top-knots, and so
forth, are by far the commonest means. In some cases mere novelty appears
to have acted as a charm. The ornaments of the males must be highly
important to them, for they have been acquired in not a few cases at the
cost of increased danger from enemies, and even at some loss of power in
fighting with their rivals. The males of very many species do not assume
their ornamental dress until they arrive at maturity, or they assume it
only during the breeding-season, or the tints then become more vivid.
Certain ornamental appendages become enlarged, turgid, and brightly
coloured during the act of courtship. The males display their charms with
elaborate care and to the best effect; and this is done in the presence of
the females. The courtship is sometimes a prolonged affair, and many males
and females congregate at an appointed place. To suppose that the females
do not appreciate the beauty of the males, is to admit that their splendid
decorations, all their pomp and display, are useless; and this is
incredible. Birds have fine powers of discrimination, and in some few
instances it can be shewn that they have a taste for the beautiful. The
females, moreover, are known occasionally to exhibit a marked preference or
antipathy for certain individual males.
If it be admitted that the females prefer, or are unconsciously excited by
the more beautiful males, then the males would slowly but surely be
rendered more and more attractive through sexual selection. That it is
this sex which has been chiefly modified, we may infer from the fact that,
in almost every genus where the sexes differ, the males differ much more
from one another than do the females; this is well shewn in certain
closely-allied representative species, in which the females can hardly be
distinguished, whilst the males are quite distinct. Birds in a state of
nature offer individual differences which would amply suffice for the work
of sexual selection; but we have seen that they occasionally present more
strongly marked variations which recur so frequently that they would
immediately be fixed, if they served to allure the female. The laws of
variation must determine the nature of the initial changes, and will have
largely influenced the final result. The gradations, which may be observed
between the males of allied species, indicate the nature of the steps
through which they have passed. They explain also in the most interesting
manner how certain characters have originated, such as the indented ocelli
on the tail-feathers of the peacock, and the ball-and-socket ocelli on the
wing-feathers of the Argus pheasant. It is evident that the brilliant
colours, top-knots, fine plumes, etc., of many male birds cannot have been
acquired as a protection; indeed, they sometimes lead to danger. That they
are not due to the direct and definite action of the conditions of life, we
may feel assured, because the females have been exposed to the same
conditions, and yet often differ from the males to an extreme degree.
Although it is probable that changed conditions acting during a lengthened
period have in some cases produced a definite effect on both sexes, or
sometimes on one sex alone, the more important result will have been an
increased tendency to vary or to present more strongly-marked individual
differences; and such differences will have afforded an excellent ground-
work for the action of sexual selection.
The laws of inheritance, irrespectively of selection, appear to have
determined whether the characters acquired by the males for the sake of
ornament, for producing various sounds, and for fighting together, have
been transmitted to the males alone or to both sexes, either permanently,
or periodically during certain seasons of the year. Why various characters
should have been transmitted sometimes in one way and sometimes in another,
is not in most cases known; but the period of variability seems often to
have been the determining cause. When the two sexes have inherited all
characters in common they necessarily resemble each other; but as the
successive variations may be differently transmitted, every possible
gradation may be found, even within the same genus, from the closest
similarity to the widest dissimilarity between the sexes. With many
closely-allied species, following nearly the same habits of life, the males
have come to differ from each other chiefly through the action of sexual
selection; whilst the females have come to differ chiefly from partaking
more or less of the characters thus acquired by the males. The effects,
moreover, of the definite action of the conditions of life, will not have
been masked in the females, as in the males, by the accumulation through
sexual selection of strongly-pronounced colours and other ornaments. The
individuals of both sexes, however affected, will have been kept at each
successive period nearly uniform by the free intercrossing of many
individuals.
With species, in which the sexes differ in colour, it is possible or
probable that some of the successive variations often tended to be
transmitted equally to both sexes; but that when this occurred the females
were prevented from acquiring the bright colours of the males, by the
destruction which they suffered during incubation. There is no evidence
that it is possible by natural selection to convert one form of
transmission into another. But there would not be the least difficulty in
rendering a female dull-coloured, the male being still kept bright-
coloured, by the selection of successive variations, which were from the
first limited in their transmission to the same sex. Whether the females
of many species have actually been thus modified, must at present remain
doubtful. When, through the law of the equal transmission of characters to
both sexes, the females were rendered as conspicuously coloured as the
males, their instincts appear often to have been modified so that they were
led to build domed or concealed nests.
In one small and curious class of cases the characters and habits of the
two sexes have been completely transposed, for the females are larger,
stronger, more vociferous and brighter coloured than the males. They have,
also, become so quarrelsome that they often fight together for the
possession of the males, like the males of other pugnacious species for the
possession of the females. If, as seems probable, such females habitually
drive away their rivals, and by the display of their bright colours or
other charms endeavour to attract the males, we can understand how it is
that they have gradually been rendered, by sexual selection and sexually-
limited transmission, more beautiful than the males--the latter being left
unmodified or only slightly modified.
Whenever the law of inheritance at corresponding ages prevails but not that
of sexually-limited transmission, then if the parents vary late in life--
and we know that this constantly occurs with our poultry, and occasionally
with other birds--the young will be left unaffected, whilst the adults of
both sexes will be modified. If both these laws of inheritance prevail and
either sex varies late in life, that sex alone will be modified, the other
sex and the young being unaffected. When variations in brightness or in
other conspicuous characters occur early in life, as no doubt often
happens, they will not be acted on through sexual selection until the
period of reproduction arrives; consequently if dangerous to the young,
they will be eliminated through natural selection. Thus we can understand
how it is that variations arising late in life have so often been preserved
for the ornamentation of the males; the females and the young being left
almost unaffected, and therefore like each other. With species having a
distinct summer and winter plumage, the males of which either resemble or
differ from the females during both seasons or during the summer alone, the
degrees and kinds of resemblance between the young and the old are
exceedingly complex; and this complexity apparently depends on characters,
first acquired by the males, being transmitted in various ways and degrees,
as limited by age, sex, and season.
As the young of so many species have been but little modified in colour and
in other ornaments, we are enabled to form some judgment with respect to
the plumage of their early progenitors; and we may infer that the beauty of
our existing species, if we look to the whole class, has been largely
increased since that period, of which the immature plumage gives us an
indirect record. Many birds, especially those which live much on the
ground, have undoubtedly been obscurely coloured for the sake of
protection. In some instances the upper exposed surface of the plumage has
been thus coloured in both sexes, whilst the lower surface in the males
alone has been variously ornamented through sexual selection. Finally,
from the facts given in these four chapters, we may conclude that weapons
for battle, organs for producing sound, ornaments of many kinds, bright and
conspicuous colours, have generally been acquired by the males through
variation and sexual selection, and have been transmitted in various ways
according to the several laws of inheritance--the females and the young
being left comparatively but little modified. (57. I am greatly indebted
to the kindness of Mr. Sclater for having looked over these four chapters
on birds, and the two following ones on mammals. In this way I have been
saved from making mistakes about the names of the species, and from stating
anything as a fact which is known to this distinguished naturalist to be
erroneous. But, of course, he is not at all answerable for the accuracy of
the statements quoted by me from various authorities.)
CHAPTER XVII.
SECONDARY SEXUAL CHARACTERS OF MAMMALS.
The law of battle--Special weapons, confined to the males--Cause of absence
of weapons in the female--Weapons common to both sexes, yet primarily
acquired by the male--Other uses of such weapons--Their high importance--
Greater size of the male--Means of defence--On the preference shown by
either sex in the pairing of quadrupeds.
With mammals the male appears to win the female much more through the law
of battle than through the display of his charms. The most timid animals,
not provided with any special weapons for fighting, engage in desperate
conflicts during the season of love. Two male hares have been seen to
fight together until one was killed; male moles often fight, and sometimes
with fatal results; male squirrels engage in frequent contests, "and often
wound each other severely"; as do male beavers, so that "hardly a skin is
without scars." (1. See Waterton's account of two hares fighting,
'Zoologist,' vol. i. 1843, p. 211. On moles, Bell, 'Hist. of British
Quadrupeds,' 1st ed., p. 100. On squirrels, Audubon and Bachman,
Viviparous Quadrupeds of N. America, 1846, p. 269. On beavers, Mr. A.H.
Green, in 'Journal of Linnean Society, Zoology,' vol. x. 1869, p. 362.) I
observed the same fact with the hides of the guanacoes in Patagonia; and on
one occasion several were so absorbed in fighting that they fearlessly
rushed close by me. Livingstone speaks of the males of the many animals in
Southern Africa as almost invariably shewing the scars received in former
contests.
The law of battle prevails with aquatic as with terrestrial mammals. It is
notorious how desperately male seals fight, both with their teeth and
claws, during the breeding-season; and their hides are likewise often
covered with scars. Male sperm-whales are very jealous at this season; and
in their battles "they often lock their jaws together, and turn on their
sides and twist about"; so that their lower jaws often become distorted.
(2. On the battles of seals, see Capt. C. Abbott in 'Proc. Zool. Soc.'
1868, p. 191; Mr. R. Brown, ibid. 1868, p. 436; also L. Lloyd, 'Game Birds
of Sweden,' 1867, p. 412; also Pennant. On the sperm-whale see Mr. J.H.
Thompson, in 'Proc. Zool. Soc.' 1867, p. 246.)
All male animals which are furnished with special weapons for fighting, are
well known to engage in fierce battles. The courage and the desperate
conflicts of stags have often been described; their skeletons have been
found in various parts of the world, with the horns inextricably locked
together, shewing how miserably the victor and vanquished had perished.
(3. See Scrope ('Art of Deer-stalking,' p. 17) on the locking of the horns
with the Cervus elaphus. Richardson, in 'Fauna Bor. Americana,' 1829, p.
252, says that the wapiti, moose, and reindeer have been found thus locked
together. Sir. A. Smith found at the Cape of Good Hope the skeletons of
two gnus in the same condition.) No animal in the world is so dangerous as
an elephant in must. Lord Tankerville has given me a graphic description
of the battles between the wild bulls in Chillingham Park, the descendants,
degenerated in size but not in courage, of the gigantic Bos primigenius.
In 1861 several contended for mastery; and it was observed that two of the
younger bulls attacked in concert the old leader of the herd, overthrew and
disabled him, so that he was believed by the keepers to be lying mortally
wounded in a neighbouring wood. But a few days afterwards one of the young
bulls approached the wood alone; and then the "monarch of the chase," who
had been lashing himself up for vengeance, came out and, in a short time,
killed his antagonist. He then quietly joined the herd, and long held
undisputed sway. Admiral Sir B.J. Sulivan informs me that, when he lived
in the Falkland Islands, he imported a young English stallion, which
frequented the hills near Port William with eight mares. On these hills
there were two wild stallions, each with a small troop of mares; "and it is
certain that these stallions would never have approached each other without
fighting. Both had tried singly to fight the English horse and drive away
his mares, but had failed. One day they came in TOGETHER and attacked him.
This was seen by the capitan who had charge of the horses, and who, on
riding to the spot, found one of the two stallions engaged with the English
horse, whilst the other was driving away the mares, and had already
separated four from the rest. The capitan settled the matter by driving
the whole party into the corral, for the wild stallions would not leave the
mares."
Male animals which are provided with efficient cutting or tearing teeth for
the ordinary purposes of life, such as the carnivora, insectivora, and
rodents, are seldom furnished with weapons especially adapted for fighting
with their rivals. The case is very different with the males of many other
animals. We see this in the horns of stags and of certain kinds of
antelopes in which the females are hornless. With many animals the canine
teeth in the upper or lower jaw, or in both, are much larger in the males
than in the females, or are absent in the latter, with the exception
sometimes of a hidden rudiment. Certain antelopes, the musk-deer, camel,
horse, boar, various apes, seals, and the walrus, offer instances. In the
females of the walrus the tusks are sometimes quite absent. (4. Mr.
Lamont ('Seasons with the Sea-Horses,' 1861, p. 143) says that a good tusk
of the male walrus weighs 4 pounds, and is longer than that of the female,
which weighs about 3 pounds. The males are described as fighting
ferociously. On the occasional absence of the tusks in the female, see Mr.
R. Brown, 'Proceedings, Zoological Society,' 1868, p. 429.) In the male
elephant of India and in the male dugong (5. Owen, 'Anatomy of
Vertebrates,' vol. iii. p. 283.) the upper incisors form offensive weapons.
In the male narwhal the left canine alone is developed into the well-known,
spirally-twisted, so-called horn, which is sometimes from nine to ten feet
in length. It is believed that the males use these horns for fighting
together; for "an unbroken one can rarely be got, and occasionally one may
be found with the point of another jammed into the broken place." (6. Mr.
R. Brown, in 'Proc. Zool. Soc.' 1869, p. 553. See Prof. Turner, in
'Journal of Anat. and Phys.' 1872, p. 76, on the homological nature of
these tusks. Also Mr. J.W. Clarke on two tusks being developed in the
males, in 'Proceedings of the Zoological Society,' 1871, p. 42.) The tooth
on the opposite side of the head in the male consists of a rudiment about
ten inches in length, which is embedded in the jaw; but sometimes, though
rarely, both are equally developed on the two sides. In the female both
are always rudimentary. The male cachalot has a larger head than that of
the female, and it no doubt aids him in his aquatic battles. Lastly, the
adult male ornithorhynchus is provided with a remarkable apparatus, namely
a spur on the foreleg, closely resembling the poison-fang of a venomous
snake; but according to Harting, the secretion from the gland is not
poisonous; and on the leg of the female there is a hollow, apparently for
the reception of the spur. (7. Owen on the cachalot and Ornithorhynchus,
ibid. vol. iii. pp. 638, 641. Harting is quoted by Dr. Zouteveen in the
Dutch translation of this work, vol. ii. p. 292.)
When the males are provided with weapons which in the females are absent,
there can be hardly a doubt that these serve for fighting with other males;
and that they were acquired through sexual selection, and were transmitted
to the male sex alone. It is not probable, at least in most cases, that
the females have been prevented from acquiring such weapons, on account of
their being useless, superfluous, or in some way injurious. On the
contrary, as they are often used by the males for various purposes, more
especially as a defence against their enemies, it is a surprising fact that
they are so poorly developed, or quite absent, in the females of so many
animals. With female deer the development during each recurrent season of
great branching horns, and with female elephants the development of immense
tusks, would be a great waste of vital power, supposing that they were of
no use to the females. Consequently, they would have tended to be
eliminated in the female through natural selection; that is, if the
successive variations were limited in their transmission to the female sex,
for otherwise the weapons of the males would have been injuriously
affected, and this would have been a greater evil. On the whole, and from
the consideration of the following facts, it seems probable that when the
various weapons differ in the two sexes, this has generally depended on the
kind of transmission which has prevailed.
As the reindeer is the one species in the whole family of Deer, in which
the female is furnished with horns, though they are somewhat smaller,
thinner, and less branched than in the male, it might naturally be thought
that, at least in this case, they must be of some special service to her.
The female retains her horns from the time when they are fully developed,
namely, in September, throughout the winter until April or May, when she
brings forth her young. Mr. Crotch made particular enquiries for me in
Norway, and it appears that the females at this season conceal themselves
for about a fortnight in order to bring forth their young, and then
reappear, generally hornless. In Nova Scotia, however, as I hear from Mr.
H. Reeks, the female sometimes retains her horns longer. The male on the
other hand casts his horns much earlier, towards the end of November. As
both sexes have the same requirements and follow the same habits of life,
and as the male is destitute of horns during the winter, it is improbable
that they can be of any special service to the female during this season,
which includes the larger part of the time during which she is horned. Nor
is it probable that she can have inherited horns from some ancient
progenitor of the family of deer, for, from the fact of the females of so
many species in all quarters of the globe not having horns, we may conclude
that this was the primordial character of the group. (8. On the structure
and shedding of the horns of the reindeer, Hoffberg, 'Amoenitates Acad.'
vol. iv. 1788, p. 149. See Richardson, 'Fauna Bor. Americana,' p. 241, in
regard to the American variety or species: also Major W. Ross King, 'The
Sportsman in Canada,' 1866, p. 80.
The horns of the reindeer are developed at a most unusually early age; but
what the cause of this may be is not known. The effect has apparently been
the transference of the horns to both sexes. We should bear in mind that
horns are always transmitted through the female, and that she has a latent
capacity for their development, as we see in old or diseased females. (9.
Isidore Geoffroy St.-Hilaire, 'Essais de Zoolog. Generale,' 1841, p. 513.
Other masculine characters, besides the horns, are sometimes similarly
transferred to the female; thus Mr. Boner, in speaking of an old female
chamois ('Chamois Hunting in the Mountains of Bavaria,' 1860, 2nd ed., p.
363), says, "not only was the head very male-looking, but along the back
there was a ridge of long hair, usually to be found only in bucks.")
Moreover the females of some other species of deer exhibit, either normally
or occasionally, rudiments of horns; thus the female of Cervulus moschatus
has "bristly tufts, ending in a knob, instead of a horn"; and "in most
specimens of the female wapiti (Cervus canadensis) there is a sharp bony
protuberance in the place of the horn." (10. On the Cervulus, Dr. Gray,
'Catalogue of Mammalia in the British Museum,' part iii. p. 220. On the
Cervus canadensis or wapiti, see Hon. J.D. Caton, 'Ottawa Academy of Nat.
Sciences,' May 1868, p. 9.) From these several considerations we may
conclude that the possession of fairly well-developed horns by the female
reindeer, is due to the males having first acquired them as weapons for
fighting with other males; and secondarily to their development from some
unknown cause at an unusually early age in the males, and their consequent
transference to both sexes.
Turning to the sheath-horned ruminants: with antelopes a graduated series
can be formed, beginning with species, the females of which are completely
destitute of horns--passing on to those which have horns so small as to be
almost rudimentary (as with the Antilocapra americana, in which species
they are present in only one out of four or five females (11. I am
indebted to Dr. Canfield for this information; see also his paper in the
'Proceedings of the Zoological Society,' 1866, p. 105.))--to those which
have fairly developed horns, but manifestly smaller and thinner than in the
male and sometimes of a different shape (12. For instance the horns of the
female Ant. euchore resemble those of a distinct species, viz. the Ant.
dorcas var. Corine, see Desmarest, 'Mammalogie,' p. 455.),--and ending with
those in which both sexes have horns of equal size. As with the reindeer,
so with antelopes, there exists, as previously shewn, a relation between
the period of the development of the horns and their transmission to one or
both sexes; it is therefore probable that their presence or absence in the
females of some species, and their more or less perfect condition in the
females of other species, depends, not on their being of any special use,
but simply on inheritance. It accords with this view that even in the same
restricted genus both sexes of some species, and the males alone of others,
are thus provided. It is also a remarkable fact that, although the females
of Antilope bezoartica are normally destitute of horns, Mr. Blyth has seen
no less than three females thus furnished; and there was no reason to
suppose that they were old or diseased.
In all the wild species of goats and sheep the horns are larger in the male
than in the female, and are sometimes quite absent in the latter. (13.
Gray, 'Catalogue of Mammalia, the British Museum,' part iii. 1852, p. 160.)
In several domestic breeds of these two animals, the males alone are
furnished with horns; and in some breeds, for instance, in the sheep of
North Wales, though both sexes are properly horned, the ewes are very
liable to be hornless. I have been informed by a trustworthy witness, who
purposely inspected a flock of these same sheep during the lambing season,
that the horns at birth are generally more fully developed in the male than
in the female. Mr. J. Peel crossed his Lonk sheep, both sexes of which
always bear horns, with hornless Leicesters and hornless Shropshire Downs;
and the result was that the male offspring had their horns considerably
reduced, whilst the females were wholly destitute of them. These several
facts indicate that, with sheep, the horns are a much less firmly fixed
character in the females than in the males; and this leads us to look at
the horns as properly of masculine origin.
With the adult musk-ox (Ovibos moschatus) the horns of the male are larger
than those of the female, and in the latter the bases do not touch. (14.
Richardson, 'Fauna Bor. Americana,' p. 278.) In regard to ordinary cattle
Mr. Blyth remarks: "In most of the wild bovine animals the horns are both
longer and thicker in the bull than in the cow, and in the cow-banteng (Bos
sondaicus) the horns are remarkably small, and inclined much backwards. In
the domestic races of cattle, both of the humped and humpless types, the
horns are short and thick in the bull, longer and more slender in the cow
and ox; and in the Indian buffalo, they are shorter and thicker in the
bull, longer and more slender in the cow. In the wild gaour (B. gaurus)
the horns are mostly both longer and thicker in the bull than in the cow."
(15. 'Land and Water,' 1867, p. 346.) Dr. Forsyth Major also informs me
that a fossil skull, believed to be that of the female Bos etruscus, has
been found in Val d'Arno, which is wholly without horns. In the Rhinoceros
simus, as I may add, the horns of the female are generally longer but less
powerful than in the male; and in some other species of rhinoceros they are
said to be shorter in the female. (16. Sir Andrew Smith, 'Zoology of S.
Africa,' pl. xix. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 624.) From
these various facts we may infer as probable that horns of all kinds, even
when they are equally developed in the two sexes, were primarily acquired
by the male in order to conquer other males, and have been transferred more
or less completely to the female.
The effects of castration deserve notice, as throwing light on this same
point. Stags after the operation never renew their horns. The male
reindeer, however, must be excepted, as after castration he does renew
them. This fact, as well as the possession of horns by both sexes, seems
at first to prove that the horns in this species do not constitute a sexual
character (17. This is the conclusion of Seidlitz, 'Die Darwinsche
Theorie,' 1871, p. 47.); but as they are developed at a very early age,
before the sexes differ in constitution, it is not surprising that they
should be unaffected by castration, even if they were aboriginally acquired
by the male. With sheep both sexes properly bear horns; and I am informed
that with Welch sheep the horns of the males are considerably reduced by
castration; but the degree depends much on the age at which the operation
is performed, as is likewise the case with other animals. Merino rams have
large horns, whilst the ewes "generally speaking are without horns"; and in
this breed castration seems to produce a somewhat greater effect, so that
if performed at an early age the horns "remain almost undeveloped." (18.
I am much obliged to Prof. Victor Carus, for having made enquiries for me
in Saxony on this subject. H. von Nathusius ('Viehzucht,' 1872, p. 64)
says that the horns of sheep castrated at an early period, either
altogether disappear or remain as mere rudiments; but I do not know whether
he refers to merinos or to ordinary breeds.) On the Guinea coast there is
a breed in which the females never bear horns, and, as Mr. Winwood Reade
informs me, the rams after castration are quite destitute of them. With
cattle, the horns of the males are much altered by castration; for instead
of being short and thick, they become longer than those of the cow, but
otherwise resemble them. The Antilope bezoartica offers a somewhat
analogous case: the males have long straight spiral horns, nearly parallel
to each other, and directed backwards; the females occasionally bear horns,
but these when present are of a very different shape, for they are not
spiral, and spreading widely, bend round with the points forwards. Now it
is a remarkable fact that, in the castrated male, as Mr. Blyth informs me,
the horns are of the same peculiar shape as in the female, but longer and
thicker. If we may judge from analogy, the female probably shews us, in
these two cases of cattle and the antelope, the former condition of the
horns in some early progenitor of each species. But why castration should
lead to the reappearance of an early condition of the horns cannot be
explained with any certainty. Nevertheless, it seems probable, that in
nearly the same manner as the constitutional disturbance in the offspring,
caused by a cross between two distinct species or races, often leads to the
reappearance of long-lost characters (19. I have given various experiments
and other evidence proving that this is the case, in my 'Variation of
Animals and Plants under Domestication,' vol. ii. 1868, pp. 39-47.); so
here, the disturbance in the constitution of the individual, resulting from
castration, produces the same effect.
The tusks of the elephant, in the different species or races, differ
according to sex, nearly as do the horns of ruminants. In India and
Malacca the males alone are provided with well-developed tusks. The
elephant of Ceylon is considered by most naturalists as a distinct race,
but by some as a distinct species, and here "not one in a hundred is found
with tusks, the few that possess them being exclusively males." (20. Sir
J. Emerson Tennent, 'Ceylon,' 1859, vol. ii. p. 274. For Malacca, 'Journal
of Indian Archipelago,' vol. iv. p. 357.) The African elephant is
undoubtedly distinct, and the female has large well-developed tusks, though
not so large as those of the male.
These differences in the tusks of the several races and species of
elephants--the great variability of the horns of deer, as notably in the
wild reindeer--the occasional presence of horns in the female Antilope
Bezoartica, and their frequent absence in the female of Antilocapra
americana--the presence of two tusks in some few male narwhals--the
complete absence of tusks in some female walruses--are all instances of the
extreme variability of secondary sexual characters, and of their liability
to differ in closely-allied forms.
Although tusks and horns appear in all cases to have been primarily
developed as sexual weapons, they often serve other purposes. The elephant
uses his tusks in attacking the tiger; according to Bruce, he scores the
trunks of trees until they can be thrown down easily, and he likewise thus
extracts the farinaceous cores of palms; in Africa he often uses one tusk,
always the same, to probe the ground and thus ascertain whether it will
bear his weight. The common bull defends the herd with his horns; and the
elk in Sweden has been known, according to Lloyd, to strike a wolf dead
with a single blow of his great horns. Many similar facts could be given.
One of the most curious secondary uses to which the horns of an animal may
be occasionally put is that observed by Captain Hutton (21. 'Calcutta
Journal of Natural History,' vol. ii, 1843, p. 526.) with the wild goat
(Capra aegagrus) of the Himalayas and, as it is also said with the ibex,
namely that when the male accidentally falls from a height he bends inwards
his head, and by alighting on his massive horns, breaks the shock. The
female cannot thus use her horns, which are smaller, but from her more
quiet disposition she does not need this strange kind of shield so much.
Each male animal uses his weapons in his own peculiar fashion. The common
ram makes a charge and butts with such force with the bases of his horns,
that I have seen a powerful man knocked over like a child. Goats and
certain species of sheep, for instance the Ovis cycloceros of Afghanistan
(22. Mr. Blyth, in 'Land and Water,' March, 1867, p. 134, on the authority
of Capt. Hutton and others. For the wild Pembrokeshire goats, see the
'Field,' 1869, p. 150.), rear on their hind legs, and then not only butt,
but "make a cut down and a jerk up, with the ribbed front of their
scimitar-shaped horn, as with a sabre. When the O. cycloceros attacked a
large domestic ram, who was a noted bruiser, he conquered him by the sheer
novelty of his mode of fighting, always closing at once with his adversary,
and catching him across the face and nose with a sharp drawing jerk of the
head, and then bounding out of the way before the blow could be returned."
In Pembrokeshire a male goat, the master of a flock which during several
generations had run wild, was known to have killed several males in single
combat; this goat possessed enormous horns, measuring thirty-nine inches in
a straight line from tip to tip. The common bull, as every one knows,
gores and tosses his opponent; but the Italian buffalo is said never to use
his horns: he gives a tremendous blow with his convex forehead, and then
tramples on his fallen enemy with his knees--an instinct which the common
bull does not possess. (23. M. E.M. Bailly, "Sur l'usage des cornes,"
etc., .Annal des Sciences Nat.' tom. ii. 1824, p. 369.) Hence a dog who
pins a buffalo by the nose is immediately crushed. We must, however,
remember that the Italian buffalo has been long domesticated, and it is by
no means certain that the wild parent-form had similar horns. Mr. Bartlett
informs me that when a female Cape buffalo (Bubalus caffer) was turned into
an enclosure with a bull of the same species, she attacked him, and he in
return pushed her about with great violence. But it was manifest to Mr.
Bartlett that, had not the bull shewn dignified forbearance, he could
easily have killed her by a single lateral thrust with his immense horns.
The giraffe uses his short, hair-covered horns, which are rather longer in
the male than in the female, in a curious manner; for, with his long neck,
he swings his head to either side, almost upside down, with such force that
I have seen a hard plank deeply indented by a single blow.
[Fig. 63. Oryx leucoryx, male (from the Knowsley Menagerie).]
With antelopes it is sometimes difficult to imagine how they can possibly
use their curiously-shaped horns; thus the springboc (Ant. euchore) has
rather short upright horns, with the sharp points bent inwards almost at
right angles, so as to face each other; Mr. Bartlett does not know how they
are used, but suggests that they would inflict a fearful wound down each
side of the face of an antagonist. The slightly-curved horns of the Oryx
leucoryx (Fig. 63) are directed backwards, and are of such length that
their points reach beyond the middle of the back, over which they extend in
almost parallel lines. Thus they seem singularly ill-fitted for fighting;
but Mr. Bartlett informs me that when two of these animals prepare for
battle, they kneel down, with their beads between their fore legs, and in
this attitude the horns stand nearly parallel and close to the ground, with
the points directed forwards and a little upwards. The combatants then
gradually approach each other, and each endeavours to get the upturned
points under the body of the other; if one succeeds in doing this, he
suddenly springs up, throwing up his head at the same time, and can thus
wound or perhaps even transfix his antagonist. Both animals always kneel
down, so as to guard as far as possible against this manoeuvre. It has
been recorded that one of these antelopes has used his horn with effect
even against a lion; yet from being forced to place his head between the
forelegs in order to bring the points of the horns forward, he would
generally be under a great disadvantage when attacked by any other animal.
It is, therefore, not probable that the horns have been modified into their
present great length and peculiar position, as a protection against beasts
of prey. We can however see that, as soon as some ancient male progenitor
of the Oryx acquired moderately long horns, directed a little backwards, he
would be compelled, in his battles with rival males, to bend his head
somewhat inwards or downwards, as is now done by certain stags; and it is
not improbable that he might have acquired the habit of at first
occasionally and afterwards of regularly kneeling down. In this case it is
almost certain that the males which possessed the longest horns would have
had a great advantage over others with shorter horns; and then the horns
would gradually have been rendered longer and longer, through sexual
selection, until they acquired their present extraordinary length and
position.
With stags of many kinds the branches of the horns offer a curious case of
difficulty; for certainly a single straight point would inflict a much more
serious wound than several diverging ones. In Sir Philip Egerton's museum
there is a horn of the red-deer (Cervus elaphus), thirty inches in length,
with "not fewer than fifteen snags or branches"; and at Moritzburg there is
still preserved a pair of antlers of a red-deer, shot in 1699 by Frederick
I., one of which bears the astonishing number of thirty-three branches and
the other twenty-seven, making altogether sixty branches. Richardson
figures a pair of antlers of the wild reindeer with twenty-nine points.
(24. On the horns of red-deer, Owen, 'British Fossil Mammals,' 1846, p.
478; Richardson on the horns of the reindeer, 'Fauna Bor. Americana,' 1829,
p. 240. I am indebted to Prof. Victor Carus, for the Moritzburg case.)
From the manner in which the horns are branched, and more especially from
deer being known occasionally to fight together by kicking with their fore-
feet (25. Hon. J.D. Caton ('Ottawa Acad. of Nat. Science,' May 1868, p. 9)
says that the American deer fight with their fore-feet, after "the question
of superiority has been once settled and acknowledged in the herd."
Bailly, 'Sur l'Usage des cornes,' 'Annales des Sciences Nat.' tom. ii.
1824, p. 371.), M. Bailly actually comes to the conclusion that their horns
are more injurious than useful to them. But this author overlooks the
pitched battles between rival males. As I felt much perplexed about the
use or advantage of the branches, I applied to Mr. McNeill of Colonsay, who
has long and carefully observed the habits of red-deer, and he informs me
that he has never seen some of the branches brought into use, but that the
brow antlers, from inclining downwards, are a great protection to the
forehead, and their points are likewise used in attack. Sir Philip Egerton
also informs me both as to red-deer and fallow-deer that, in fighting, they
suddenly dash together, and getting their horns fixed against each other's
bodies, a desperate struggle ensues. When one is at last forced to yield
and turn round, the victor endeavours to plunge his brow antlers into his
defeated foe. It thus appears that the upper branches are used chiefly or
exclusively for pushing and fencing. Nevertheless in some species the
upper branches are used as weapons of offence; when a man was attacked by a
wapiti deer (Cervus canadensis) in Judge Caton's park in Ottawa, and
several men tried to rescue him, the stag "never raised his head from the
ground; in fact he kept his face almost flat on the ground, with his nose
nearly between his fore feet, except when he rolled his head to one side to
take a new observation preparatory to a plunge." In this position the ends
of the horns were directed against his adversaries. "In rolling his head
he necessarily raised it somewhat, because his antlers were so long that he
could not roll his head without raising them on one side, while, on the
other side they touched the ground." The stag by this procedure gradually
drove the party of rescuers backwards to a distance of 150 or 200 feet; and
the attacked man was killed. (26. See a most interesting account in the
Appendix to Hon. J.D. Caton's paper, as above quoted.)
[Fig. 64. Strepsiceros Kudu (from Sir Andrew Smith's 'Zoology of South
Africa.']
Although the horns of stags are efficient weapons, there can, I think be no
doubt that a single point would have been much more dangerous than a
branched antler; and Judge Caton, who has had large experience with deer,
fully concurs in this conclusion. Nor do the branching horns, though
highly important as a means of defence against rival stags, appear
perfectly well adapted for this purpose, as they are liable to become
interlocked. The suspicion has therefore crossed my mind that they may
serve in part as ornaments. That the branched antlers of stags as well as
the elegant lyrated horns of certain antelopes, with their graceful double
curvature (Fig. 64), are ornamental in our eyes, no one will dispute. If,
then, the horns, like the splendid accoutrements of the knights of old, add
to the noble appearance of stags and antelopes, they may have been modified
partly for this purpose, though mainly for actual service in battle; but I
have no evidence in favour of this belief.
An interesting case has lately been published, from which it appears that
the horns of a deer in one district in the United States are now being
modified through sexual and natural selection. A writer in an excellent
American Journal (27. The 'American Naturalist,' Dec. 1869, p. 552.) says,
that he has hunted for the last twenty-one years in the Adirondacks, where
the Cervus virginianus abounds. About fourteen years ago he first heard of
SPIKE-HORN BUCKS. These became from year to year more common; about five
years ago he shot one, and afterwards another, and now they are frequently
killed. "The spike-horn differs greatly from the common antler of the C.
virginianus. It consists of a single spike, more slender than the antler,
and scarcely half so long, projecting forward from the brow, and
terminating in a very sharp point. It gives a considerable advantage to
its possessor over the common buck. Besides enabling him to run more
swiftly through the thick woods and underbrush (every hunter knows that
does and yearling bucks run much more rapidly than the large bucks when
armed with their cumbrous antlers), the spike-horn is a more effective
weapon than the common antler. With this advantage the spike-horn bucks
are gaining upon the common bucks, and may, in time, entirely supersede
them in the Adirondacks. Undoubtedly, the first spike-horn buck was merely
an accidental freak of nature. But his spike-horns gave him an advantage,
and enabled him to propagate his peculiarity. His descendants having a
like advantage, have propagated the peculiarity in a constantly increasing
ratio, till they are slowly crowding the antlered deer from the region they
inhabit." A critic has well objected to this account by asking, why, if
the simple horns are now so advantageous, were the branched antlers of the
parent-form ever developed? To this I can only answer by remarking, that a
new mode of attack with new weapons might be a great advantage, as shewn by
the case of the Ovis cycloceros, who thus conquered a domestic ram famous
for his fighting power. Though the branched antlers of a stag are well
adapted for fighting with his rivals, and though it might be an advantage
to the prong-horned variety slowly to acquire long and branched horns, if
he had to fight only with others of the same kind, yet it by no means
follows that branched horns would be the best fitted for conquering a foe
differently armed. In the foregoing case of the Oryx leucoryx, it is
almost certain that the victory would rest with an antelope having short
horns, and who therefore did not need to kneel down, though an oryx might
profit by having still longer horns, if he fought only with his proper
rivals.
Male quadrupeds, which are furnished with tusks, use them in various ways,
as in the case of horns. The boar strikes laterally and upwards; the musk-
deer downwards with serious effect. (28. Pallas, 'Spicilegia Zoologica,'
fasc. xiii. 1779, p. 18.) The walrus, though having so short a neck and so
unwieldy a body, "can strike either upwards, or downwards, or sideways,
with equal dexterity." (29. Lamont, 'Seasons with the Sea-Horses,' 1861,
p. 141.) I was informed by the late Dr. Falconer, that the Indian elephant
fights in a different manner according to the position and curvature of his
tusks. When they are directed forwards and upwards he is able to fling a
tiger to a great distance--it is said to even thirty feet; when they are
short and turned downwards he endeavours suddenly to pin the tiger to the
ground and, in consequence, is dangerous to the rider, who is liable to be
jerked off the howdah. (30. See also Corse ('Philosophical Transactions,'
1799, p. 212) on the manner in which the short-tusked Mooknah variety
attacks other elephants.)
Very few male quadrupeds possess weapons of two distinct kinds specially
adapted for fighting with rival males. The male muntjac-deer (Cervulus),
however, offers an exception, as he is provided with horns and exserted
canine teeth. But we may infer from what follows that one form of weapon
has often been replaced in the course of ages by another. With ruminants
the development of horns generally stands in an inverse relation with that
of even moderately developed canine teeth. Thus camels, guanacoes,
chevrotains, and musk-deer, are hornless, and they have efficient canines;
these teeth being "always of smaller size in the females than in the
males." The Camelidae have, in addition to their true canines, a pair of
canine-shaped incisors in their upper jaws. (31. Owen, 'Anatomy of
Vertebrates,' vol. iii. p. 349.) Male deer and antelopes, on the other
hand, possess horns, and they rarely have canine teeth; and these, when
present, are always of small size, so that it is doubtful whether they are
of any service in their battles. In Antilope montana they exist only as
rudiments in the young male, disappearing as he grows old; and they are
absent in the female at all ages; but the females of certain other
antelopes and of certain deer have been known occasionally to exhibit
rudiments of these teeth. (32. See Ruppell (in 'Proc. Zoolog. Soc.' Jan.
12, 1836, p. 3) on the canines in deer and antelopes, with a note by Mr.
Martin on a female American deer. See also Falconer ('Palaeont. Memoirs
and Notes,' vol. i. 1868, p. 576) on canines in an adult female deer. In
old males of the musk-deer the canines (Pallas, 'Spic. Zoolog.' fasc. xiii.
1779, p. 18) sometimes grow to the length of three inches, whilst in old
females a rudiment projects scarcely half an inch above the gums.)
Stallions have small canine teeth, which are either quite absent or
rudimentary in the mare; but they do not appear to be used in fighting, for
stallions bite with their incisors, and do not open their mouths wide like
camels and guanacoes. Whenever the adult male possesses canines, now
inefficient, whilst the female has either none or mere rudiments, we may
conclude that the early male progenitor of the species was provided with
efficient canines, which have been partially transferred to the females.
The reduction of these teeth in the males seems to have followed from some
change in their manner of fighting, often (but not in the horse) caused by
the development of new weapons.
Tusks and horns are manifestly of high importance to their possessors, for
their development consumes much organised matter. A single tusk of the
Asiatic elephant--one of the extinct woolly species--and of the African
elephant, have been known to weigh respectively 150, 160, and 180 pounds;
and even greater weights have been given by some authors. (33. Emerson
Tennent, 'Ceylon,' 1859, vol. ii. p. 275; Owen, 'British Fossil Mammals,'
1846, p. 245.) With deer, in which the horns are periodically renewed, the
drain on the constitution must be greater; the horns, for instance, of the
moose weigh from fifty to sixty pounds, and those of the extinct Irish elk
from sixty to seventy pounds--the skull of the latter weighing on an
average only five pounds and a quarter. Although the horns are not
periodically renewed in sheep, yet their development, in the opinion of
many agriculturists, entails a sensible loss to the breeder. Stags,
moreover, in escaping from beasts of prey are loaded with an additional
weight for the race, and are greatly retarded in passing through a woody
country. The moose, for instance, with horns extending five and a half
feet from tip to tip, although so skilful in their use that he will not
touch or break a twig when walking quietly, cannot act so dexterously
whilst rushing away from a pack of wolves. "During his progress he holds
his nose up, so as to lay the horns horizontally back; and in this attitude
cannot see the ground distinctly." (34. Richardson, 'Fauna Bor.
Americana,' on the moose, Alces palmata, pp. 236, 237; on the expanse of
the horns, 'Land and Water,' 1869, p. 143. See also Owen, 'British Fossil
Mammals,' on the Irish elk, pp. 447, 455.) The tips of the horns of the
great Irish elk were actually eight feet apart! Whilst the horns are
covered with velvet, which lasts with red-deer for about twelve weeks, they
are extremely sensitive to a blow; so that in Germany the stags at this
time somewhat change their habits, and avoiding dense forests, frequent
young woods and low thickets. (35. 'Forest Creatures,' by C. Boner, 1861,
p. 60.) These facts remind us that male birds have acquired ornamental
plumes at the cost of retarded flight, and other ornaments at the cost of
some loss of power in their battles with rival males.
With mammals, when, as is often the case, the sexes differ in size, the
males are almost always larger and stronger. I am informed by Mr. Gould
that this holds good in a marked manner with the marsupials of Australia,
the males of which appear to continue growing until an unusually late age.
But the most extraordinary case is that of one of the seals (Callorhinus
ursinus), a full-grown female weighing less than one-sixth of a full-grown
male. (36. See the very interesting paper by Mr. J.A. Allen in 'Bull.
Mus. Comp. Zoology of Cambridge, United States,' vol. ii. No. 1, p. 82.
The weights were ascertained by a careful observer, Capt. Bryant. Dr. Gill
in 'The American Naturalist,' January, 1871, Prof. Shaler on the relative
size of the sexes of whales, 'American Naturalist,' January, 1873.) Dr.
Gill remarks that it is with the polygamous seals, the males of which are
well known to fight savagely together, that the sexes differ much in size;
the monogamous species differing but little. Whales also afford evidence
of the relation existing between the pugnacity of the males and their large
size compared with that of the female; the males of the right-whales do not
fight together, and they are not larger, but rather smaller, than their
females; on the other hand, male sperm-whales fight much together, and
their bodies are "often found scarred with the imprint of their rival's
teeth," and they are double the size of the females. The greater strength
of the male, as Hunter long ago remarked (37. 'Animal Economy,' p. 45.),
is invariably displayed in those parts of the body which are brought into
action in fighting with rival males--for instance, in the massive neck of
the bull. Male quadrupeds are also more courageous and pugnacious than the
females. There can be little doubt that these characters have been gained,
partly through sexual selection, owing to a long series of victories, by
the stronger and more courageous males over the weaker, and partly through
the inherited effects of use. It is probable that the successive
variations in strength, size, and courage, whether due to mere variability
or to the effects of use, by the accumulation of which male quadrupeds have
acquired these characteristic qualities, occurred rather late in life, and
were consequently to a large extent limited in their transmission to the
same sex.
From these considerations I was anxious to obtain information as to the
Scotch deer-hound, the sexes of which differ more in size than those of any
other breed (though blood-hounds differ considerably), or than in any wild
canine species known to me. Accordingly, I applied to Mr. Cupples, well
known for his success with this breed, who has weighed and measured many of
his own dogs, and who has with great kindness collected for me the
following facts from various sources. Fine male dogs, measured at the
shoulder, range from 28 inches, which is low, to 33 or even 34 inches in
height; and in weight from 80 pounds, which is light, to 120 pounds, or
even more. The females range in height from 23 to 27, or even to 28
inches; and in weight from 50 to 70, or even 80 pounds. (38. See also
Richardson's 'Manual on the Dog,' p. 59. Much valuable information on the
Scottish deer-hound is given by Mr. McNeill, who first called attention to
the inequality in size between the sexes, in Scrope's 'Art of Deer-
Stalking.' I hope that Mr. Cupples will keep to his intention of
publishing a full account and history of this famous breed.) Mr. Cupples
concludes that from 95 to 100 pounds for the male, and 70 for the female,
would be a safe average; but there is reason to believe that formerly both
sexes attained a greater weight. Mr. Cupples has weighed puppies when a
fortnight old; in one litter the average weight of four males exceeded that
of two females by six and a half ounces; in another litter the average
weight of four males exceeded that of one female by less than one ounce;
the same males when three weeks old, exceeded the female by seven and a
half ounces, and at the age of six weeks by nearly fourteen ounces. Mr.
Wright of Yeldersley House, in a letter to Mr. Cupples, says: "I have
taken notes on the sizes and weights of puppies of many litters, and as far
as my experience goes, dog-puppies as a rule differ very little from
bitches till they arrive at about five or six months old; and then the dogs
begin to increase, gaining upon the bitches both in weight and size. At
birth, and for several weeks afterwards, a bitch-puppy will occasionally be
larger than any of the dogs, but they are invariably beaten by them later."
Mr. McNeill, of Colonsay, concludes that "the males do not attain their
full growth till over two years old, though the females attain it sooner."
According to Mr. Cupples' experience, male dogs go on growing in stature
till they are from twelve to eighteen months old, and in weight till from
eighteen to twenty-four months old; whilst the females cease increasing in
stature at the age of from nine to fourteen or fifteen months, and in
weight at the age of from twelve to fifteen months. From these various
statements it is clear that the full difference in size between the male
and female Scotch deer-hound is not acquired until rather late in life.
The males almost exclusively are used for coursing, for, as Mr. McNeill
informs me, the females have not sufficient strength and weight to pull
down a full-grown deer. From the names used in old legends, it appears, as
I hear from Mr. Cupples, that, at a very ancient period, the males were the
most celebrated, the females being mentioned only as the mothers of famous
dogs. Hence, during many generations, it is the male which has been
chiefly tested for strength, size, speed, and courage, and the best will
have been bred from. As, however, the males do not attain their full
dimensions until rather late in life, they will have tended, in accordance
with the law often indicated, to transmit their characters to their male
offspring alone; and thus the great inequality in size between the sexes of
the Scotch deer-hound may probably be accounted for.
[Fig. 65. Head of Common wild boar, in prime of life (from Brehm).]
The males of some few quadrupeds possess organs or parts developed solely
as a means of defence against the attacks of other males. Some kinds of
deer use, as we have seen, the upper branches of their horns chiefly or
exclusively for defending themselves; and the Oryx antelope, as I am
informed by Mr. Bartlett, fences most skilfully with his long, gently
curved horns; but these are likewise used as organs of offence. The same
observer remarks that rhinoceroses in fighting, parry each other's sidelong
blows with their horns, which clatter loudly together, as do the tusks of
boars. Although wild boars fight desperately, they seldom, according to
Brehm, receive fatal wounds, as the blows fall on each other's tusks, or on
the layer of gristly skin covering the shoulder, called by the German
hunters, the shield; and here we have a part specially modified for
defence. With boars in the prime of life (Fig. 65) the tusks in the lower
jaw are used for fighting, but they become in old age, as Brehm states, so
much curved inwards and upwards over the snout that they can no longer be
used in this way. They may, however, still serve, and even more
effectively, as a means of defence. In compensation for the loss of the
lower tusks as weapons of offence, those in the upper jaw, which always
project a little laterally, increase in old age so much in length and curve
so much upwards that they can be used for attack. Nevertheless, an old
boar is not so dangerous to man as one at the age of six or seven years.
(39. Brehm, 'Thierleben,' B. ii. ss. 729-732.)
[Fig. 66. Skull of the Babirusa Pig (from Wallace's 'Malay Archipelago').]
In the full-grown male Babirusa pig of Celebes (Fig. 66), the lower tusks
are formidable weapons, like those of the European boar in the prime of
life, whilst the upper tusks are so long and have their points so much
curled inwards, sometimes even touching the forehead, that they are utterly
useless as weapons of attack. They more nearly resemble horns than teeth,
and are so manifestly useless as teeth that the animal was formerly
supposed to rest his head by hooking them on to a branch! Their convex
surfaces, however, if the head were held a little laterally, would serve as
an excellent guard; and hence, perhaps, it is that in old animals they "are
generally broken off, as if by fighting." (40. See Mr. Wallace's
interesting account of this animal, 'The Malay Archipelago,' 1869, vol. i.
p. 435.) Here, then, we have the curious case of the upper tusks of the
Babirusa regularly assuming during the prime of life a structure which
apparently renders them fitted only for defence; whilst in the European
boar the lower tusks assume in a less degree and only during old age nearly
the same form, and then serve in like manner solely for defence.
[Fig. 67. Head of female Aethopian wart-hog, from 'Proc. Zool. Soc.' 1869,
shewing the same characters as the male, though on a reduced scale.
N.B. When the engraving was first made, I was under the impression that it
represented the male.]
In the wart-hog (see Phacochoerus aethiopicus, Fig. 67) the tusks in the
upper jaw of the male curve upwards during the prime of life, and from
being pointed serve as formidable weapons. The tusks in the lower jaw are
sharper than those in the upper, but from their shortness it seems hardly
possible that they can be used as weapons of attack. They must, however,
greatly strengthen those in the upper jaw, from being ground so as to fit
closely against their bases. Neither the upper nor the lower tusks appear
to have been specially modified to act as guards, though no doubt they are
to a certain extent used for this purpose. But the wart-hog is not
destitute of other special means of protection, for it has, on each side of
the face, beneath the eyes, a rather stiff, yet flexible, cartilaginous,
oblong pad (Fig. 67), which projects two or three inches outwards; and it
appeared to Mr. Bartlett and myself, when viewing the living animal, that
these pads, when struck from beneath by the tusks of an opponent, would be
turned upwards, and would thus admirably protect the somewhat prominent
eyes. I may add, on the authority of Mr. Bartlett, that these boars when
fighting stand directly face to face.
Lastly, the African river-hog (Potomochoerus penicillatus) has a hard
cartilaginous knob on each side of the face beneath the eyes, which answers
to the flexible pad of the wart-hog; it has also two bony prominences on
the upper jaw above the nostrils. A boar of this species in the Zoological
Gardens recently broke into the cage of the wart-hog. They fought all
night long, and were found in the morning much exhausted, but not seriously
wounded. It is a significant fact, as shewing the purposes of the above-
described projections and excrescences, that these were covered with blood,
and were scored and abraded in an extraordinary manner.
Although the males of so many members of the pig family are provided with
weapons, and as we have just seen with means of defence, these weapons seem
to have been acquired within a rather late geological period. Dr. Forsyth
Major specifies (41. 'Atti della Soc. Italiana di Sc. Nat.' 1873, vol. xv.
fasc. iv.) several miocene species, in none of which do the tusks appear to
have been largely developed in the males; and Professor Rutimeyer was
formerly struck with this same fact.
The mane of the lion forms a good defence against the attacks of rival
lions, the one danger to which he is liable; for the males, as Sir A. Smith
informs me, engage in terrible battles, and a young lion dares not approach
an old one. In 1857 a tiger at Bromwich broke into the cage of a lion and
a fearful scene ensued: "the lion's mane saved his neck and head from
being much injured, but the tiger at last succeeded in ripping up his
belly, and in a few minutes he was dead." (42. 'The Times,' Nov. 10,
1857. In regard to the Canada lynx, see Audubon and Bachman, 'Quadrupeds
of North America,' 1846, p. 139.) The broad ruff round the throat and chin
of the Canadian lynx (Felis canadensis) is much longer in the male than in
the female; but whether it serves as a defence I do not know. Male seals
are well known to fight desperately together, and the males of certain
kinds (Otaria jubata) (43. Dr. Murie, on Otaria, 'Proc. Zoolog. Soc.'
1869, p. 109. Mr. J.A. Allen, in the paper above quoted (p. 75), doubts
whether the hair, which is longer on the neck in the male than in the
female, deserves to be called a mane.) have great manes, whilst the females
have small ones or none. The male baboon of the Cape of Good Hope
(Cynocephalus porcarius) has a much longer mane and larger canine teeth
than the female; and the mane probably serves as a protection, for, on
asking the keepers in the Zoological Gardens, without giving them any clue
to my object, whether any of the monkeys especially attacked each other by
the nape of the neck, I was answered that this was not the case, except
with the above baboon. In the Hamadryas baboon, Ehrenberg compares the
mane of the adult male to that of a young lion, whilst in the young of both
sexes and in the female the mane is almost absent.
It appeared to me probable that the immense woolly mane of the male
American bison, which reaches almost to the ground, and is much more
developed in the males than in the females, served as a protection to them
in their terrible battles; but an experienced hunter told Judge Caton that
he had never observed anything which favoured this belief. The stallion
has a thicker and fuller mane than the mare; and I have made particular
inquiries of two great trainers and breeders, who have had charge of many
entire horses, and am assured that they "invariably endeavour to seize one
another by the neck." It does not, however, follow from the foregoing
statements, that when the hair on the neck serves as a defence, that it was
originally developed for this purpose, though this is probable in some
cases, as in that of the lion. I am informed by Mr. McNeill that the long
hairs on the throat of the stag (Cervus elaphus) serve as a great
protection to him when hunted, for the dogs generally endeavour to seize
him by the throat; but it is not probable that these hairs were specially
developed for this purpose; otherwise the young and the females would have
been equally protected.
CHOICE IN PAIRING BY EITHER SEX OF QUADRUPEDS.
Before describing in the next chapter, the differences between the sexes in
voice, odours emitted, and ornaments, it will be convenient here to
consider whether the sexes exert any choice in their unions. Does the
female prefer any particular male, either before or after the males may
have fought together for supremacy; or does the male, when not a
polygamist, select any particular female? The general impression amongst
breeders seems to be that the male accepts any female; and this owing to
his eagerness, is, in most cases, probably the truth. Whether the female
as a general rule indifferently accepts any male is much more doubtful. In
the fourteenth chapter, on Birds, a considerable body of direct and
indirect evidence was advanced, shewing that the female selects her
partner; and it would be a strange anomaly if female quadrupeds, which
stand higher in the scale and have higher mental powers, did not generally,
or at least often, exert some choice. The female could in most cases
escape, if wooed by a male that did not please or excite her; and when
pursued by several males, as commonly occurs, she would often have the
opportunity, whilst they were fighting together, of escaping with some one
male, or at least of temporarily pairing with him. This latter contingency
has often been observed in Scotland with female red-deer, as I am informed
by Sir Philip Egerton and others. (44. Mr. Boner, in his excellent
description of the habits of the red-deer in Germany ('Forest Creatures,'
1861, p. 81) says, "while the stag is defending his rights against one
intruder, another invades the sanctuary of his harem, and carries off
trophy after trophy." Exactly the same thing occurs with seals; see Mr.
J.A. Allen, ibid. p. 100.)
It is scarcely possible that much should be known about female quadrupeds
in a state of nature making any choice in their marriage unions. The
following curious details on the courtship of one of the eared seals
(Callorhinus ursinus) are given (45. Mr. J.A. Allen in 'Bull. Mus. Comp.
Zoolog. of Cambridge, United States,' vol. ii. No. 1, p. 99.) on the
authority of Capt. Bryant, who had ample opportunities for observation. He
says, "Many of the females on their arrival at the island where they breed
appear desirous of returning to some particular male, and frequently climb
the outlying rocks to overlook the rookeries, calling out and listening as
if for a familiar voice. Then changing to another place they do the same
again...As soon as a female reaches the shore, the nearest male goes down
to meet her, making meanwhile a noise like the clucking of a hen to her
chickens. He bows to her and coaxes her until he gets between her and the
water so that she cannot escape him. Then his manner changes, and with a
harsh growl he drives her to a place in his harem. This continues until
the lower row of harems is nearly full. Then the males higher up select
the time when their more fortunate neighbours are off their guard to steal
their wives. This they do by taking them in their mouths and lifting them
over the heads of the other females, and carefully placing them in their
own harem, carrying them as cats do their kittens. Those still higher up
pursue the same method until the whole space is occupied. Frequently a
struggle ensues between two males for the possession of the same female,
and both seizing her at once pull her in two or terribly lacerate her with
their teeth. When the space is all filled, the old male walks around
complacently reviewing his family, scolding those who crowd or disturb the
others, and fiercely driving off all intruders. This surveillance always
keeps him actively occupied."
As so little is known about the courtship of animals in a state of nature,
I have endeavoured to discover how far our domesticated quadrupeds evince
any choice in their unions. Dogs offer the best opportunity for
observation, as they are carefully attended to and well understood. Many
breeders have expressed a strong opinion on this head. Thus, Mr. Mayhew
remarks, "The females are able to bestow their affections; and tender
recollections are as potent over them as they are known to be in other
cases, where higher animals are concerned. Bitches are not always prudent
in their loves, but are apt to fling themselves away on curs of low degree.
If reared with a companion of vulgar appearance, there often springs up
between the pair a devotion which no time can afterwards subdue. The
passion, for such it really is, becomes of a more than romantic endurance."
Mr. Mayhew, who attended chiefly to the smaller breeds, is convinced that
the females are strongly attracted by males of a large size. (46. 'Dogs:
their Management,' by E. Mayhew, M.R.C.V.S., 2nd ed., 1864, pp. 187-192.)
The well-known veterinary Blaine states (47. Quoted by Alex. Walker, 'On
Intermarriage,' 1838, p. 276; see also p. 244.) that his own female pug dog
became so attached to a spaniel, and a female setter to a cur, that in
neither case would they pair with a dog of their own breed until several
weeks had elapsed. Two similar and trustworthy accounts have been given me
in regard to a female retriever and a spaniel, both of which became
enamoured with terrier-dogs.
Mr. Cupples informs me that he can personally vouch for the accuracy of the
following more remarkable case, in which a valuable and wonderfully-
intelligent female terrier loved a retriever belonging to a neighbour to
such a degree, that she had often to be dragged away from him. After their
permanent separation, although repeatedly shewing milk in her teats, she
would never acknowledge the courtship of any other dog, and to the regret
of her owner never bore puppies. Mr. Cupples also states, that in 1868, a
female deerhound in his kennel thrice produced puppies, and on each
occasion shewed a marked preference for one of the largest and handsomest,
but not the most eager, of four deerhounds living with her, all in the
prime of life. Mr. Cupples has observed that the female generally favours a
dog whom she has associated with and knows; her shyness and timidity at
first incline her against a strange dog. The male, on the contrary, seems
rather inclined towards strange females. It appears to be rare when the
male refuses any particular female, but Mr. Wright, of Yeldersley House, a
great breeder of dogs, informs me that he has known some instances; he
cites the case of one of his own deerhounds, who would not take any notice
of a particular female mastiff, so that another deerhound had to be
employed. It would be superfluous to give, as I could, other instances,
and I will only add that Mr. Barr, who has carefully bred many bloodhounds,
states that in almost every instance particular individuals of opposite
sexes shew a decided preference for each other. Finally, Mr. Cupples,
after attending to this subject for another year, has written to me, "I
have had full confirmation of my former statement, that dogs in breeding
form decided preferences for each other, being often influenced by size,
bright colour, and individual characters, as well as by the degree of their
previous familiarity."
In regard to horses, Mr. Blenkiron, the greatest breeder of race-horses in
the world, informs me that stallions are so frequently capricious in their
choice, rejecting one mare and without any apparent cause taking to
another, that various artifices have to be habitually used. The famous
Monarque, for instance, would never consciously look at the dam of
Gladiateur, and a trick had to be practised. We can partly see the reason
why valuable race-horse stallions, which are in such demand as to be
exhausted, should be so particular in their choice. Mr. Blenkiron has
never known a mare reject a horse; but this has occurred in Mr. Wright's
stable, so that the mare had to be cheated. Prosper Lucas (48. 'Traite de
l'Hered. Nat.' tom. ii. 1850, p. 296.) quotes various statements from
French authorities, and remarks, "On voit des etalons qui s'eprennent d'une
jument, et negligent toutes les autres." He gives, on the authority of
Baelen, similar facts in regard to bulls; and Mr. H. Reeks assures me that
a famous short-horn bull belonging to his father "invariably refused to be
matched with a black cow." Hoffberg, in describing the domesticated
reindeer of Lapland says, "Foeminae majores et fortiores mares prae
caeteris admittunt, ad eos confugiunt, a junioribus agitatae, qui hos in
fugam conjiciunt." (49. 'Amoenitates Acad.' vol. iv. 1788, p. 160.) A
clergyman, who has bred many pigs, asserts that sows often reject one boar
and immediately accept another.
From these facts there can be no doubt that, with most of our domesticated
quadrupeds, strong individual antipathies and preferences are frequently
exhibited, and much more commonly by the female than by the male. This
being the case, it is improbable that the unions of quadrupeds in a state
of nature should be left to mere chance. It is much more probable that the
females are allured or excited by particular males, who possess certain
characters in a higher degree than other males; but what these characters
are, we can seldom or never discover with certainty.
CHAPTER XVIII.
SECONDARY SEXUAL CHARACTERS OF MAMMALS--continued.
Voice--Remarkable sexual peculiarities in seals--Odour--Development of the
hair--Colour of the hair and skin--Anomalous case of the female being more
ornamented than the male--Colour and ornaments due to sexual selection--
Colour acquired for the sake of protection--Colour, though common to both
sexes, often due to sexual selection--On the disappearance of spots and
stripes in adult quadrupeds--On the colours and ornaments of the
Quadrumana--Summary.
Quadrupeds use their voices for various purposes, as a signal of danger, as
a call from one member of a troop to another, or from the mother to her
lost offspring, or from the latter for protection to their mother; but such
uses need not here be considered. We are concerned only with the
difference between the voices of the sexes, for instance between that of
the lion and lioness, or of the bull and cow. Almost all male animals use
their voices much more during the rutting-season than at any other time;
and some, as the giraffe and porcupine (1. Owen, 'Anatomy of Vertebrates,'
vol. iii. p. 585.), are said to be completely mute excepting at this
season. As the throats (i.e. the larynx and thyroid bodies (2. Ibid. p.
595.)) of stags periodically become enlarged at the beginning of the
breeding-season, it might be thought that their powerful voices must be
somehow of high importance to them; but this is very doubtful. From
information given to me by two experienced observers, Mr. McNeill and Sir
P. Egerton, it seems that young stags under three years old do not roar or
bellow; and that the old ones begin bellowing at the commencement of the
breeding-season, at first only occasionally and moderately, whilst they
restlessly wander about in search of the females. Their battles are
prefaced by loud and prolonged bellowing, but during the actual conflict
they are silent. Animals of all kinds which habitually use their voices
utter various noises under any strong emotion, as when enraged and
preparing to fight; but this may merely be the result of nervous
excitement, which leads to the spasmodic contraction of almost all the
muscles of the body, as when a man grinds his teeth and clenches his fists
in rage or agony. No doubt stags challenge each other to mortal combat by
bellowing; but those with the more powerful voices, unless at the same time
the stronger, better-armed, and more courageous, would not gain any
advantage over their rivals.
It is possible that the roaring of the lion may be of some service to him
by striking terror into his adversary; for when enraged he likewise erects
his mane and thus instinctively tries to make himself appear as terrible as
possible. But it can hardly be supposed that the bellowing of the stag,
even if it be of service to him in this way, can have been important enough
to have led to the periodical enlargement of the throat. Some writers
suggest that the bellowing serves as a call to the female; but the
experienced observers above quoted inform me that female deer do not search
for the male, though the males search eagerly for the females, as indeed
might be expected from what we know of the habits of other male quadrupeds.
The voice of the female, on the other hand, quickly brings to her one or
more stags (3. See, for instance, Major W. Ross King ('The Sportsman in
Canada,' 1866, pp. 53, 131) on the habits of the moose and wild reindeer.),
as is well known to the hunters who in wild countries imitate her cry. If
we could believe that the male had the power to excite or allure the female
by his voice, the periodical enlargement of his vocal organs would be
intelligible on the principle of sexual selection, together with
inheritance limited to the same sex and season; but we have no evidence in
favour of this view. As the case stands, the loud voice of the stag during
the breeding-season does not seem to be of any special service to him,
either during his courtship or battles, or in any other way. But may we
not believe that the frequent use of the voice, under the strong excitement
of love, jealousy, and rage, continued during many generations, may at last
have produced an inherited effect on the vocal organs of the stag, as well
as of other male animals? This appears to me, in our present state of
knowledge, the most probable view.
The voice of the adult male gorilla is tremendous, and he is furnished with
a laryngeal sack, as is the adult male orang. (4. Owen 'Anatomy of
Vertebrates,' vol. iii. p. 600.) The gibbons rank among the noisiest of
monkeys, and the Sumatra species (Hylobates syndactylus) is also furnished
with an air sack; but Mr. Blyth, who has had opportunities for observation,
does not believe that the male is noisier than the female. Hence, these
latter monkeys probably use their voices as a mutual call; and this is
certainly the case with some quadrupeds, for instance the beaver. (5. Mr.
Green, in 'Journal of Linnean Society,' vol. x. 'Zoology,' 1869, note 362.)
Another gibbon, the H. agilis, is remarkable, from having the power of
giving a complete and correct octave of musical notes (6. C.L. Martin,
'General Introduction to the Natural History of Mamm. Animals,' 1841, p.
431.), which we may reasonably suspect serves as a sexual charm; but I
shall have to recur to this subject in the next chapter. The vocal organs
of the American Mycetes caraya are one-third larger in the male than in the
female, and are wonderfully powerful. These monkeys in warm weather make
the forests resound at morning and evening with their overwhelming voices.
The males begin the dreadful concert, and often continue it during many
hours, the females sometimes joining in with their less powerful voices.
An excellent observer, Rengger (7. 'Naturgeschichte der Saugethiere von
Paraguay,' 1830, ss. 15, 21.), could not perceive that they were excited to
begin by any special cause; he thinks that, like many birds, they delight
in their own music, and try to excel each other. Whether most of the
foregoing monkeys have acquired their powerful voices in order to beat
their rivals and charm the females--or whether the vocal organs have been
strengthened and enlarged through the inherited effects of long-continued
use without any particular good being thus gained--I will not pretend to
say; but the former view, at least in the case of the Hylobates agilis,
seems the most probable.
I may here mention two very curious sexual peculiarities occurring in
seals, because they have been supposed by some writers to affect the voice.
The nose of the male sea-elephant (Macrorhinus proboscideus) becomes
greatly elongated during the breeding-season, and can then be erected. In
this state it is sometimes a foot in length. The female is not thus
provided at any period of life. The male makes a wild, hoarse, gurgling
noise, which is audible at a great distance and is believed to be
strengthened by the proboscis; the voice of the female being different.
Lesson compares the erection of the proboscis, with the swelling of the
wattles of male gallinaceous birds whilst courting the females. In another
allied kind of seal, the bladder-nose (Cystophora cristata), the head is
covered by a great hood or bladder. This is supported by the septum of the
nose, which is produced far backwards and rises into an internal crest
seven inches in height. The hood is clothed with short hair, and is
muscular; can be inflated until it more than equals the whole head in size!
The males when rutting, fight furiously on the ice, and their roaring "is
said to be sometimes so loud as to be heard four miles off." When attacked
they likewise roar or bellow; and whenever irritated the bladder is
inflated and quivers. Some naturalists believe that the voice is thus
strengthened, but various other uses have been assigned to this
extraordinary structure. Mr. R. Brown thinks that it serves as a
protection against accidents of all kinds; but this is not probable, for,
as I am assured by Mr. Lamont who killed 600 of these animals, the hood is
rudimentary in the females, and it is not developed in the males during
youth. (8. On the sea-elephant, see an article by Lesson, in 'Dict.
Class. Hist. Nat.' tom. xiii. p. 418. For the Cystophora, or Stemmatopus,
see Dr. Dekay, 'Annals of Lyceum of Nat. Hist.' New York, vol. i. 1824, p.
94. Pennant has also collected information from the sealers on this
animal. The fullest account is given by Mr. Brown, in 'Proc. Zoolog. Soc.'
1868, p. 435.)
ODOUR.
With some animals, as with the notorious skunk of America, the overwhelming
odour which they emit appears to serve exclusively as a defence. With
shrew-mice (Sorex) both sexes possess abdominal scent-glands, and there can
be little doubt, from the rejection of their bodies by birds and beasts of
prey, that the odour is protective; nevertheless, the glands become
enlarged in the males during the breeding-season. In many other quadrupeds
the glands are of the same size in both sexes (9. As with the castoreum of
the beaver, see Mr. L.H. Morgan's most interesting work, 'The American
Beaver,' 1868, p. 300. Pallas ('Spic. Zoolog.' fasc. viii. 1779, p. 23)
has well discussed the odoriferous glands of mammals. Owen ('Anat. of
Vertebrates,' vol. iii. p. 634) also gives an account of these glands,
including those of the elephant, and (p. 763) those of shrew-mice. On
bats, Mr. Dobson in 'Proceedings of the Zoological Society' 1873, p. 241.),
but their uses are not known. In other species the glands are confined to
the males, or are more developed than in the females; and they almost
always become more active during the rutting-season. At this period the
glands on the sides of the face of the male elephant enlarge, and emit a
secretion having a strong musky odour. The males, and rarely the females,
of many kinds of bats have glands and protrudable sacks situated in various
parts; and it is believed that these are odoriferous.
The rank effluvium of the male goat is well known, and that of certain male
deer is wonderfully strong and persistent. On the banks of the Plata I
perceived the air tainted with the odour of the male Cervus campestris, at
half a mile to leeward of a herd; and a silk handkerchief, in which I
carried home a skin, though often used and washed, retained, when first
unfolded, traces of the odour for one year and seven months. This animal
does not emit its strong odour until more than a year old, and if castrated
whilst young never emits it. (10. Rengger, 'Naturgeschichte der
Saugethiere von Paraguay,' 1830, s. 355. This observer also gives some
curious particulars in regard to the odour.) Besides the general odour,
permeating the whole body of certain ruminants (for instance, Bos
moschatus) in the breeding-season, many deer, antelopes, sheep, and goats
possess odoriferous glands in various situations, more especially on their
faces. The so-called tear-sacks, or suborbital pits, come under this head.
These glands secrete a semi-fluid fetid matter which is sometimes so
copious as to stain the whole face, as I have myself seen in an antelope.
They are "usually larger in the male than in the female, and their
development is checked by castration." (11. Owen, 'Anatomy of
Vertebrates,' vol. iii. p. 632. See also Dr. Murie's observations on those
glands in the 'Proc. Zoolog. Soc.' 1870, p. 340. Desmarest, 'On the
Antilope subgutturosa, 'Mammalogie,' 1820, p. 455.) According to Desmarest
they are altogether absent in the female of Antilope subgutturosa. Hence,
there can be no doubt that they stand in close relation with the
reproductive functions. They are also sometimes present, and sometimes
absent, in nearly allied forms. In the adult male musk-deer (Moschus
moschiferus), a naked space round the tail is bedewed with an odoriferous
fluid, whilst in the adult female, and in the male until two years old,
this space is covered with hair and is not odoriferous. The proper musk-
sack of this deer is from its position necessarily confined to the male,
and forms an additional scent-organ. It is a singular fact that the matter
secreted by this latter gland, does not, according to Pallas, change in
consistence, or increase in quantity, during the rutting-season;
nevertheless this naturalist admits that its presence is in some way
connected with the act of reproduction. He gives, however, only a
conjectural and unsatisfactory explanation of its use. (12. Pallas,
'Spicilegia Zoolog.' fasc. xiii. 1799, p. 24; Desmoulins, 'Dict. Class.
d'Hist. Nat.' tom. iii. p. 586.)
In most cases, when only the male emits a strong odour during the breeding-
season, it probably serves to excite or allure the female. We must not
judge on this head by our own taste, for it is well known that rats are
enticed by certain essential oils, and cats by valerian, substances far
from agreeable to us; and that dogs, though they will not eat carrion,
sniff and roll on it. From the reasons given when discussing the voice of
the stag, we may reject the idea that the odour serves to bring the females
from a distance to the males. Active and long-continued use cannot here
have come into play, as in the case of the vocal organs. The odour emitted
must be of considerable importance to the male, inasmuch as large and
complex glands, furnished with muscles for everting the sack, and for
closing or opening the orifice, have in some cases been developed. The
development of these organs is intelligible through sexual selection, if
the most odoriferous males are the most successful in winning the females,
and in leaving offspring to inherit their gradually perfected glands and
odours.
DEVELOPMENT OF THE HAIR.
We have seen that male quadrupeds often have the hair on their necks and
shoulders much more developed than the females; and many additional
instances could be given. This sometimes serves as a defence to the male
during his battles; but whether the hair in most cases has been specially
developed for this purpose, is very doubtful. We may feel almost certain
that this is not the case, when only a thin and narrow crest runs along the
back; for a crest of this kind would afford scarcely any protection, and
the ridge of the back is not a place likely to be injured; nevertheless
such crests are sometimes confined to the males, or are much more developed
in them than in the females. Two antelopes, the Tragelaphus scriptus (13.
Dr. Gray, 'Gleanings from the Menagerie at Knowsley,' pl. 28.) (Fig. 70)
and Portax picta may be given as instances. When stags, and the males of
the wild goat, are enraged or terrified, these crests stand erect (14.
Judge Caton on the Wapiti, 'Transact. Ottawa Acad. Nat. Sciences,' 1868,
pp. 36, 40; Blyth, 'Land and Water,' on Capra aegagrus 1867, p. 37.); but
it cannot be supposed that they have been developed merely for the sake of
exciting fear in their enemies. One of the above-named antelopes, the
Portax picta, has a large well-defined brush of black hair on the throat,
and this is much larger in the male than in the female. In the Ammotragus
tragelaphus of North Africa, a member of the sheep-family, the fore-legs
are almost concealed by an extraordinary growth of hair, which depends from
the neck and upper halves of the legs; but Mr. Bartlett does not believe
that this mantle is of the least use to the male, in whom it is much more
developed than in the female.
[Fig. 68. Pithecia satanas, male (from Brehm).]
Male quadrupeds of many kinds differ from the females in having more hair,
or hair of a different character, on certain parts of their faces. Thus
the bull alone has curled hair on the forehead. (15. Hunter's 'Essays and
Observations,' edited by Owen, 1861. vol. i. p. 236.) In three closely-
allied sub-genera of the goat family, only the males possess beards,
sometimes of large size; in two other sub-genera both sexes have a beard,
but it disappears in some of the domestic breeds of the common goat; and
neither sex of the Hemitragus has a beard. In the ibex the beard is not
developed during the summer, and is so small at other times that it may be
called rudimentary. (16. See Dr. Gray's 'Catalogue of Mammalia in the
British Museum,' part iii. 1852, p. 144.) With some monkeys the beard is
confined to the male, as in the orang; or is much larger in the male than
in the female, as in the Mycetes caraya and Pithecia satanas (Fig. 68). So
it is with the whiskers of some species of Macacus (17. Rengger,
'Saugthiere,' etc., s. 14; Desmarest, 'Mammalogie,' p. 86.), and, as we
have seen, with the manes of some species of baboons. But with most kinds
of monkeys the various tufts of hair about the face and head are alike in
both sexes.
The males of various members of the ox family (Bovidae), and of certain
antelopes, are furnished with a dewlap, or great fold of skin on the neck,
which is much less developed in the female.
Now, what must we conclude with respect to such sexual differences as
these? No one will pretend that the beards of certain male goats, or the
dewlaps of the bull, or the crests of hair along the backs of certain male
antelopes, are of any use to them in their ordinary habits. It is possible
that the immense beard of the male Pithecia, and the large beard of the
male orang, may protect their throats when fighting; for the keepers in the
Zoological Gardens inform me that many monkeys attack each other by the
throat; but it is not probable that the beard has been developed for a
distinct purpose from that served by the whiskers, moustache, and other
tufts of hair on the face; and no one will suppose that these are useful as
a protection. Must we attribute all these appendages of hair or skin to
mere purposeless variability in the male? It cannot be denied that this is
possible; for in many domesticated quadrupeds, certain characters,
apparently not derived through reversion from any wild parent form, are
confined to the males, or are more developed in them than in the females--
for instance, the hump on the male zebu-cattle of India, the tail of fat-
tailed rams, the arched outline of the forehead in the males of several
breeds of sheep, and lastly, the mane, the long hairs on the hind legs, and
the dewlap of the male of the Berbura goat. (18. See the chapters on
these several animals in vol. i. of my 'Variation of Animals under
Domestication;' also vol. ii. p. 73; also chap. xx. on the practice of
selection by semi-civilised people. For the Berbura goat, see Dr. Gray,
'Catalogue,' ibid. p. 157.) The mane, which occurs only in the rams of an
African breed of sheep, is a true secondary sexual character, for, as I
hear from Mr. Winwood Reade, it is not developed if the animal be
castrated. Although we ought to be extremely cautious, as shewn in my work
on 'Variation under Domestication,' in concluding that any character, even
with animals kept by semi-civilised people, has not been subjected to
selection by man, and thus augmented, yet in the cases just specified this
is improbable; more especially as the characters are confined to the males,
or are more strongly developed in them than in the females. If it were
positively known that the above African ram is a descendant of the same
primitive stock as the other breeds of sheep, and if the Berbura male-goat
with his mane, dewlap, etc., is descended from the same stock as other
goats, then, assuming that selection has not been applied to these
characters, they must be due to simple variability, together with sexually-
limited inheritance.
Hence it appears reasonable to extend this same view to all analogous cases
with animals in a state of nature. Nevertheless I cannot persuade myself
that it generally holds good, as in the case of the extraordinary
development of hair on the throat and fore-legs of the male Ammotragus, or
in that of the immense beard of the male Pithecia. Such study as I have
been able to give to nature makes me believe that parts or organs which are
highly developed, were acquired at some period for a special purpose. With
those antelopes in which the adult male is more strongly-coloured than the
female, and with those monkeys in which the hair on the face is elegantly
arranged and coloured in a diversified manner, it seems probable that the
crests and tufts of hair were gained as ornaments; and this I know is the
opinion of some naturalists. If this be correct, there can be little doubt
that they were gained or at least modified through sexual selection; but
how far the same view may be extended to other mammals is doubtful.
COLOUR OF THE HAIR AND OF THE NAKED SKIN.
I will first give briefly all the cases known to me of male quadrupeds
differing in colour from the females. With Marsupials, as I am informed by
Mr. Gould, the sexes rarely differ in this respect; but the great red
kangaroo offers a striking exception, "delicate blue being the prevailing
tint in those parts of the female which in the male are red." (19.
Osphranter rufus, Gould, 'Mammals of Australia,' 1863, vol. ii. On the
Didelphis, Desmarest, 'Mammalogie,' p. 256.) In the Didelphis opossum of
Cayenne the female is said to be a little more red than the male. Of the
Rodents, Dr. Gray remarks: "African squirrels, especially those found in
the tropical regions, have the fur much brighter and more vivid at some
seasons of the year than at others, and the fur of the male is generally
brighter than that of the female." (20. 'Annals and Magazine of Natural
History,' Nov. 1867, p. 325. On the Mus minutus, Desmarest, 'Mammalogie,'
p. 304.) Dr. Gray informs me that he specified the African squirrels,
because, from their unusually bright colours, they best exhibit this
difference. The female of the Mus minutus of Russia is of a paler and
dirtier tint than the male. In a large number of bats the fur of the male
is lighter than in the female. (21. J.A. Allen, in 'Bulletin of Mus.
Comp. Zoolog. of Cambridge, United States,' 1869, p. 207. Mr. Dobson on
sexual characters in the Chiroptera, 'Proceedings of the Zoological
Society,' 1873, p. 241. Dr. Gray on Sloths, ibid. 1871, p. 436.) Mr.
Dobson also remarks, with respect to these animals: "Differences,
depending partly or entirely on the possession by the male of fur of a much
more brilliant hue, or distinguished by different markings or by the
greater length of certain portions, are met only, to any appreciable
extent, in the frugivorous bats in which the sense of sight is well
developed." This last remark deserves attention, as bearing on the
question whether bright colours are serviceable to male animals from being
ornamental. In one genus of sloths, it is now established, as Dr. Gray
states, "that the males are ornamented differently from the females--that
is to say, that they have a patch of soft short hair between the shoulders,
which is generally of a more or less orange colour, and in one species pure
white. The females, on the contrary, are destitute of this mark."
The terrestrial Carnivora and Insectivora rarely exhibit sexual differences
of any kind, including colour. The ocelot (Felis pardalis), however, is
exceptional, for the colours of the female, compared with those of the
male, are "moins apparentes, le fauve, etant plus terne, le blanc moins
pur, les raies ayant moins de largeur et les taches moins de diametre."
(22. Desmarest, 'Mammalogie,' 1820, p. 220. On Felis mitis, Rengger,
ibid. s. 194.) The sexes of the allied Felis mitis also differ, but in a
less degree; the general hues of the female being rather paler than in the
male, with the spots less black. The marine Carnivora or seals, on the
other hand, sometimes differ considerably in colour, and they present, as
we have already seen, other remarkable sexual differences. Thus the male
of the Otaria nigrescens of the southern hemisphere is of a rich brown
shade above; whilst the female, who acquires her adult tints earlier in
life than the male, is dark-grey above, the young of both sexes being of a
deep chocolate colour. The male of the northern Phoca groenlandica is
tawny grey, with a curious saddle-shaped dark mark on the back; the female
is much smaller, and has a very different appearance, being "dull white or
yellowish straw-colour, with a tawny hue on the back"; the young at first
are pure white, and can "hardly be distinguished among the icy hummocks and
snow, their colour thus acting as a protection." (23. Dr. Murie on the
Otaria, 'Proceedings Zoological Society,' 1869, p. 108. Mr. R. Brown on
the P. groenlandica, ibid. 1868, p. 417. See also on the colours of seals,
Desmarest, ibid. pp. 243, 249.)
With Ruminants sexual differences of colour occur more commonly than in any
other order. A difference of this kind is general in the Strepsicerene
antelopes; thus the male nilghau (Portax picta) is bluish-grey and much
darker than the female, with the square white patch on the throat, the
white marks on the fetlocks, and the black spots on the ears all much more
distinct. We have seen that in this species the crests and tufts of hair
are likewise more developed in the male than in the hornless female. I am
informed by Mr. Blyth that the male, without shedding his hair,
periodically becomes darker during the breeding-season. Young males cannot
be distinguished from young females until about twelve months old; and if
the male is emasculated before this period, he never, according to the same
authority, changes colour. The importance of this latter fact, as evidence
that the colouring of the Portax is of sexual origin, becomes obvious, when
we hear (24. Judge Caton, in 'Transactions of the Ottawa Academy of
Natural Sciences,' 1868, p. 4.) that neither the red summer-coat nor the
blue winter-coat of the Virginian deer is at all affected by emasculation.
With most or all of the highly-ornamented species of Tragelaphus the males
are darker than the hornless females, and their crests of hair are more
fully developed. In the male of that magnificent antelope, the Derbyan
eland, the body is redder, the whole neck much blacker, and the white band
which separates these colours broader than in the female. In the Cape
eland, also, the male is slightly darker than the female. (25. Dr. Gray,
'Cat. of Mamm. in Brit. Mus.' part iii. 1852, pp. 134-142; also Dr. Gray,
'Gleanings from the Menagerie of Knowsley,' in which there is a splendid
drawing of the Oreas derbianus: see the text on Tragelaphus. For the Cape
eland (Oreas canna), see Andrew Smith, 'Zoology of S. Africa,' pl. 41 and
42. There are also many of these Antelopes in the Zoological Gardens.)
In the Indian black-buck (A. bezoartica), which belongs to another tribe of
antelopes, the male is very dark, almost black; whilst the hornless female
is fawn-coloured. We meet in this species, as Mr. Blyth informs me, with
an exactly similar series of facts, as in the Portax picta, namely, in the
male periodically changing colour during the breeding-season, in the
effects of emasculation on this change, and in the young of both sexes
being indistinguishable from each other. In the Antilope niger the male is
black, the female, as well as the young of both sexes, being brown; in A.
sing-sing the male is much brighter coloured than the hornless female, and
his chest and belly are blacker; in the male A. caama, the marks and lines
which occur on various parts of the body are black, instead of brown as in
the female; in the brindled gnu (A. gorgon) "the colours of the male are
nearly the same as those of the female, only deeper and of a brighter hue."
(26. On the Ant. niger, see 'Proc. Zool. Soc.' 1850, p. 133. With respect
to an allied species, in which there is an equal sexual difference in
colour, see Sir S. Baker, 'The Albert Nyanza,' 1866, vol. ii. p. 627. For
the A. sing-sing, Gray, 'Cat. B. Mus.' p. 100. Desmarest, 'Mammalogie,' p.
468, on the A. caama. Andrew Smith, 'Zoology of S. Africa,' on the Gnu.)
Other analogous cases could be added.
The Banteng bull (Bos sondaicus) of the Malayan Archipelago is almost
black, with white legs and buttocks; the cow is of a bright dun, as are the
young males until about the age of three years, when they rapidly change
colour. The emasculated bull reverts to the colour of the female. The
female Kemas goat is paler, and both it and the female Capra aegagrus are
said to be more uniformly tinted than their males. Deer rarely present any
sexual differences in colour. Judge Caton, however, informs me that in the
males of the wapiti deer (Cervus canadensis) the neck, belly, and legs are
much darker than in the female; but during the winter the darker tints
gradually fade away and disappear. I may here mention that Judge Caton has
in his park three races of the Virginian deer, which differ slightly in
colour, but the differences are almost exclusively confined to the blue
winter or breeding-coat; so that this case may be compared with those given
in a previous chapter of closely-allied or representative species of birds,
which differ from each other only in their breeding plumage. (27. 'Ottawa
Academy of Sciences,' May 21, 1868, pp. 3, 5.) The females of Cervus
paludosus of S. America, as well as the young of both sexes, do not possess
the black stripes on the nose and the blackish-brown line on the breast,
which are characteristic of the adult males. (28. S. Muller, on the
Banteng, 'Zoog. Indischen Archipel.' 1839-1844, tab. 35; see also Raffles,
as quoted by Mr. Blyth, in 'Land and Water,' 1867, p. 476. On goats, Dr.
Gray, 'Catalogue of the British Museum,' p. 146; Desmarest, 'Mammalogie,'
p. 482. On the Cervus paludosus, Rengger, ibid. s. 345.) Lastly, as I am
informed by Mr. Blyth, the mature male of the beautifully coloured and
spotted axis deer is considerably darker than the female: and this hue the
castrated male never acquires.
The last Order which we need consider is that of the Primates. The male of
the Lemur macaco is generally coal-black, whilst the female is brown. (29.
Sclater, 'Proc. Zool. Soc.' 1866, p. i. The same fact has also been fully
ascertained by MM. Pollen and van Dam. See, also, Dr. Gray in 'Annals and
Magazine of Natural History,' May 1871, p. 340.) Of the Quadrumana of the
New World, the females and young of Mycetes caraya are greyish-yellow and
like each other; in the second year the young male becomes reddish-brown;
in the third, black, excepting the stomach, which, however, becomes quite
black in the fourth or fifth year. There is also a strongly-marked
difference in colour between the sexes of Mycetes seniculus and Cebus
capucinus; the young of the former, and I believe of the latter species,
resembling the females. With Pithecia leucocephala the young likewise
resemble the females, which are brownish-black above and light rusty-red
beneath, the adult males being black. The ruff of hair round the face of
Ateles marginatus is tinted yellow in the male and white in the female.
Turning to the Old World, the males of Hylobates hoolock are always black,
with the exception of a white band over the brows; the females vary from
whity-brown to a dark tint mixed with black, but are never wholly black.
(30. On Mycetes, Rengger, ibid. s. 14; and Brehm, 'Thierleben,' B. i. s.
96, 107. On Ateles Desmarest, 'Mammalogie,' p. 75. On Hylobates, Blyth,
'Land and Water,' 1867, p. 135. On the Semnopithecus, S. Muller, 'Zoog.
Indischen Archipel.' tab. x.) In the beautiful Cercopithecus diana, the
head of the adult male is of an intense black, whilst that of the female is
dark grey; in the former the fur between the thighs is of an elegant fawn-
colour, in the latter it is paler. In the beautiful and curious moustache
monkey (Cercopithecus cephus) the only difference between the sexes is that
the tail of the male is chestnut and that of the female grey; but Mr.
Bartlett informs me that all the hues become more pronounced in the male
when adult, whilst in the female they remain as they were during youth.
According to the coloured figures given by Solomon Muller, the male of
Semnopithecus chrysomelas is nearly black, the female being pale brown. In
the Cercopithecus cynosurus and griseo-viridis one part of the body, which
is confined to the male sex, is of the most brilliant blue or green, and
contrasts strikingly with the naked skin on the hinder part of the body,
which is vivid red.
[Fig. 69. Head of male Mandrill (from Gervais, 'Hist. Nat. des
Mammiferes').]
Lastly, in the baboon family, the adult male of Cynocephalus hamadryas
differs from the female not only by his immense mane, but slightly in the
colour of the hair and of the naked callosities. In the drill (C.
leucophaeus) the females and young are much paler-coloured, with less
green, than the adult males. No other member in the whole class of mammals
is coloured in so extraordinary a manner as the adult male mandrill (C.
mormon). The face at this age becomes of a fine blue, with the ridge and
tip of the nose of the most brilliant red. According to some authors, the
face is also marked with whitish stripes, and is shaded in parts with
black, but the colours appear to be variable. On the forehead there is a
crest of hair, and on the chin a yellow beard. "Toutes les parties
superieures de leurs cuisses et le grand espace nu de leurs fesses sont
egalement colores du rouge le plus vif, avec un melange de bleu qui ne
manque reellement pas d'elegance." (31. Gervais, 'Hist. Nat. des
Mammiferes,' 1854, p. 103. Figures are given of the skull of the male.
Also Desmarest, 'Mammalogie,' p. 70. Geoffroy St.-Hilaire and F. Cuvier,
'Hist. Nat. des Mammiferes,' 1824, tom. i.) When the animal is excited all
the naked parts become much more vividly tinted. Several authors have used
the strongest expressions in describing these resplendent colours, which
they compare with those of the most brilliant birds. Another remarkable
peculiarity is that when the great canine teeth are fully developed,
immense protuberances of bone are formed on each cheek, which are deeply
furrowed longitudinally, and the naked skin over them is brilliantly-
coloured, as just-described. (Fig. 69.) In the adult females and in the
young of both sexes these protuberances are scarcely perceptible; and the
naked parts are much less bright coloured, the face being almost black,
tinged with blue. In the adult female, however, the nose at certain
regular intervals of time becomes tinted with red.
In all the cases hitherto given the male is more strongly or brighter
coloured than the female, and differs from the young of both sexes. But as
with some few birds it is the female which is brighter coloured than the
male, so with the Rhesus monkey (Macacus rhesus), the female has a large
surface of naked skin round the tail, of a brilliant carmine red, which, as
I was assured by the keepers in the Zoological Gardens, periodically
becomes even yet more vivid, and her face also is pale red. On the other
hand, in the adult male and in the young of both sexes (as I saw in the
Gardens), neither the naked skin at the posterior end of the body, nor the
face, shew a trace of red. It appears, however, from some published
accounts, that the male does occasionally, or during certain seasons,
exhibit some traces of the red. Although he is thus less ornamented than
the female, yet in the larger size of his body larger canine teeth, more
developed whiskers, more prominent superciliary ridges, he follows the
common rule of the male excelling the female.
I have now given all the cases known to me of a difference in colour
between the sexes of mammals. Some of these may be the result of
variations confined to one sex and transmitted to the same sex, without any
good being gained, and therefore without the aid of selection. We have
instances of this with our domesticated animals, as in the males of certain
cats being rusty-red, whilst the females are tortoise-shell coloured.
Analogous cases occur in nature: Mr. Bartlett has seen many black
varieties of the jaguar, leopard, vulpine phalanger, and wombat; and he is
certain that all, or nearly all these animals, were males. On the other
hand, with wolves, foxes, and apparently American squirrels, both sexes are
occasionally born black. Hence it is quite possible that with some mammals
a difference in colour between the sexes, especially when this is
congenital, may simply be the result, without the aid of selection, of the
occurrence of one or more variations, which from the first were sexually
limited in their transmission. Nevertheless it is improbable that the
diversified, vivid, and contrasted colours of certain quadrupeds, for
instance, of the above monkeys and antelopes, can thus be accounted for.
We should bear in mind that these colours do not appear in the male at
birth, but only at or near maturity; and that unlike ordinary variations,
they are lost if the male be emasculated. It is on the whole probable that
the strongly-marked colours and other ornamental characters of male
quadrupeds are beneficial to them in their rivalry with other males, and
have consequently been acquired through sexual selection. This view is
strengthened by the differences in colour between the sexes occurring
almost exclusively, as may be collected from the previous details, in those
groups and sub-groups of mammals which present other and strongly-marked
secondary sexual characters; these being likewise due to sexual selection.
Quadrupeds manifestly take notice of colour. Sir S. Baker repeatedly
observed that the African elephant and rhinoceros attacked white or grey
horses with special fury. I have elsewhere shewn (32. The 'Variation of
Animals and Plants under Domestication,' 1868, vol. ii. pp. 102, 103.) that
half-wild horses apparently prefer to pair with those of the same colour,
and that herds of fallow-deer of different colours, though living together,
have long kept distinct. It is a more significant fact that a female zebra
would not admit the addresses of a male ass until he was painted so as to
resemble a zebra, and then, as John Hunter remarks, "she received him very
readily. In this curious fact, we have instinct excited by mere colour,
which had so strong an effect as to get the better of everything else. But
the male did not require this, the female being an animal somewhat similar
to himself, was sufficient to rouse him." (33. 'Essays and Observations,'
by J. Hunter, edited by Owen, 1861, vol. i. p. 194.)
In an earlier chapter we have seen that the mental powers of the higher
animals do not differ in kind, though greatly in degree, from the
corresponding powers of man, especially of the lower and barbarous races;
and it would appear that even their taste for the beautiful is not widely
different from that of the Quadrumana. As the negro of Africa raises the
flesh on his face into parallel ridges "or cicatrices, high above the
natural surface, which unsightly deformities are considered great personal
attractions" (34. Sir S. Baker, 'The Nile Tributaries of Abyssinia,'
1867.);--as negroes and savages in many parts of the world paint their
faces with red, blue, white, or black bars,--so the male mandrill of Africa
appears to have acquired his deeply-furrowed and gaudily-coloured face from
having been thus rendered attractive to the female. No doubt it is to us a
most grotesque notion that the posterior end of the body should be coloured
for the sake of ornament even more brilliantly than the face; but this is
not more strange than that the tails of many birds should be especially
decorated.
With mammals we do not at present possess any evidence that the males take
pains to display their charms before the female; and the elaborate manner
in which this is performed by male birds and other animals is the strongest
argument in favour of the belief that the females admire, or are excited
by, the ornaments and colours displayed before them. There is, however, a
striking parallelism between mammals and birds in all their secondary
sexual characters, namely in their weapons for fighting with rival males,
in their ornamental appendages, and in their colours. In both classes,
when the male differs from the female, the young of both sexes almost
always resemble each other, and in a large majority of cases resemble the
adult female. In both classes the male assumes the characters proper to
his sex shortly before the age of reproduction; and if emasculated at an
early period, loses them. In both classes the change of colour is
sometimes seasonal, and the tints of the naked parts sometimes become more
vivid during the act of courtship. In both classes the male is almost
always more vividly or strongly coloured than the female, and is ornamented
with larger crests of hair or feathers, or other such appendages. In a few
exceptional cases the female in both classes is more highly ornamented than
the male. With many mammals, and at least in the case of one bird, the
male is more odoriferous than the female. In both classes the voice of the
male is more powerful than that of the female. Considering this
parallelism, there can be little doubt that the same cause, whatever it may
be, has acted on mammals and birds; and the result, as far as ornamental
characters are concerned, may be attributed, as it appears to me, to the
long-continued preference of the individuals of one sex for certain
individuals of the opposite sex, combined with their success in leaving a
larger number of offspring to inherit their superior attractions.
EQUAL TRANSMISSION OF ORNAMENTAL CHARACTERS TO BOTH SEXES.
With many birds, ornaments, which analogy leads us to believe were
primarily acquired by the males, have been transmitted equally, or almost
equally, to both sexes; and we may now enquire how far this view applies to
mammals. With a considerable number of species, especially of the smaller
kinds, both sexes have been coloured, independently of sexual selection,
for the sake of protection; but not, as far as I can judge, in so many
cases, nor in so striking a manner, as in most of the lower classes.
Audubon remarks that he often mistook the musk-rat (35. Fiber zibethicus,
Audubon and Bachman, 'The Quadrupeds of North America,' 1846, p. 109.),
whilst sitting on the banks of a muddy stream, for a clod of earth, so
complete was the resemblance. The hare on her form is a familiar instance
of concealment through colour; yet this principle partly fails in a
closely-allied species, the rabbit, for when running to its burrow, it is
made conspicuous to the sportsman, and no doubt to all beasts of prey, by
its upturned white tail. No one doubts that the quadrupeds inhabiting
snow-clad regions have been rendered white to protect them from their
enemies, or to favour their stealing on their prey. In regions where snow
never lies for long, a white coat would be injurious; consequently, species
of this colour are extremely rare in the hotter parts of the world. It
deserves notice that many quadrupeds inhabiting moderately cold regions,
although they do not assume a white winter dress, become paler during this
season; and this apparently is the direct result of the conditions to which
they have long been exposed. Pallas (36. 'Novae species Quadrupedum e
Glirium ordine,' 1778, p. 7. What I have called the roe is the Capreolus
sibiricus subecaudatus of Pallas.) states that in Siberia a change of this
nature occurs with the wolf, two species of Mustela, the domestic horse,
the Equus hemionus, the domestic cow, two species of antelopes, the musk-
deer, the roe, elk, and reindeer. The roe, for instance, has a red summer
and a greyish-white winter coat; and the latter may perhaps serve as a
protection to the animal whilst wandering through the leafless thickets,
sprinkled with snow and hoar-frost. If the above-named animals were
gradually to extend their range into regions perpetually covered with snow,
their pale winter-coats would probably be rendered through natural
selection, whiter and whiter, until they became as white as snow.
Mr. Reeks has given me a curious instance of an animal profiting by being
peculiarly coloured. He raised from fifty to sixty white and brown piebald
rabbits in a large walled orchard; and he had at the same time some
similarly coloured cats in his house. Such cats, as I have often noticed,
are very conspicuous during day; but as they used to lie in watch during
the dusk at the mouths of the burrows, the rabbits apparently did not
distinguish them from their parti-coloured brethren. The result was that,
within eighteen months, every one of these parti-coloured rabbits was
destroyed; and there was evidence that this was effected by the cats.
Colour seems to be advantageous to another animal, the skunk, in a manner
of which we have had many instances in other classes. No animal will
voluntarily attack one of these creatures on account of the dreadful odour
which it emits when irritated; but during the dusk it would not easily be
recognised and might be attacked by a beast of prey. Hence it is, as Mr.
Belt believes (37. 'The Naturalist in Nicaragua,' p. 249.), that the skunk
is provided with a great white bushy tail, which serves as a conspicuous
warning.
[Fig. 70. Tragelaphus scriptus, male (from the Knowsley Menagerie).
Fig. 71. Damalis pygarga, male (from the Knowsley Menagerie).]
Although we must admit that many quadrupeds have received their present
tints either as a protection, or as an aid in procuring prey, yet with a
host of species, the colours are far too conspicuous and too singularly
arranged to allow us to suppose that they serve for these purposes. We may
take as an illustration certain antelopes; when we see the square white
patch on the throat, the white marks on the fetlocks, and the round black
spots on the ears, all more distinct in the male of the Portax picta, than
in the female;--when we see that the colours are more vivid, that the
narrow white lines on the flank and the broad white bar on the shoulder are
more distinct in the male Oreas derbyanus than in the female;--when we see
a similar difference between the sexes of the curiously-ornamented
Tragelaphus scriptus (Fig. 70),--we cannot believe that differences of this
kind are of any service to either sex in their daily habits of life. It
seems a much more probable conclusion that the various marks were first
acquired by the males and their colours intensified through sexual
selection, and then partially transferred to the females. If this view be
admitted, there can be little doubt that the equally singular colours and
marks of many other antelopes, though common to both sexes, have been
gained and transmitted in a like manner. Both sexes, for instance, of the
koodoo (Strepsiceros kudu) (Fig. 64) have narrow white vertical lines on
their hind flanks, and an elegant angular white mark on their foreheads.
Both sexes in the genus Damalis are very oddly coloured; in D. pygarga the
back and neck are purplish-red, shading on the flanks into black; and these
colours are abruptly separated from the white belly and from a large white
space on the buttocks; the head is still more oddly coloured, a large
oblong white mask, narrowly-edged with black, covers the face up to the
eyes (Fig. 71); there are three white stripes on the forehead, and the ears
are marked with white. The fawns of this species are of a uniform pale
yellowish-brown. In Damalis albifrons the colouring of the head differs
from that in the last species in a single white stripe replacing the three
stripes, and in the ears being almost wholly white. (38. See the fine
plates in A. Smith's 'Zoology of South Africa,' and Dr. Gray's 'Gleanings
from the Menagerie of Knowsley.') After having studied to the best of my
ability the sexual differences of animals belonging to all classes, I
cannot avoid the conclusion that the curiously-arranged colours of many
antelopes, though common to both sexes, are the result of sexual selection
primarily applied to the male.
The same conclusion may perhaps be extended to the tiger, one of the most
beautiful animals in the world, the sexes of which cannot be distinguished
by colour, even by the dealers in wild beasts. Mr. Wallace believes (39.
'Westminster Review,' July 1, 1867, p. 5.) that the striped coat of the
tiger "so assimilates with the vertical stems of the bamboo, as to assist
greatly in concealing him from his approaching prey." But this view does
not appear to me satisfactory. We have some slight evidence that his
beauty may be due to sexual selection, for in two species of Felis the
analogous marks and colours are rather brighter in the male than in the
female. The zebra is conspicuously striped, and stripes cannot afford any
protection in the open plains of South Africa. Burchell (40. 'Travels in
South Africa,' 1824, vol. ii. p. 315.) in describing a herd says, "their
sleek ribs glistened in the sun, and the brightness and regularity of their
striped coats presented a picture of extraordinary beauty, in which
probably they are not surpassed by any other quadruped." But as throughout
the whole group of the Equidae the sexes are identical in colour, we have
here no evidence of sexual selection. Nevertheless he who attributes the
white and dark vertical stripes on the flanks of various antelopes to this
process, will probably extend the same view to the Royal Tiger and
beautiful Zebra.
We have seen in a former chapter that when young animals belonging to any
class follow nearly the same habits of life as their parents, and yet are
coloured in a different manner, it may be inferred that they have retained
the colouring of some ancient and extinct progenitor. In the family of
pigs, and in the tapirs, the young are marked with longitudinal stripes,
and thus differ from all the existing adult species in these two groups.
With many kinds of deer the young are marked with elegant white spots, of
which their parents exhibit not a trace. A graduated series can be
followed from the axis deer, both sexes of which at all ages and during all
seasons are beautifully spotted (the male being rather more strongly
coloured than the female), to species in which neither the old nor the
young are spotted. I will specify some of the steps in this series. The
Mantchurian deer (Cervus mantchuricus) is spotted during the whole year,
but, as I have seen in the Zoological Gardens, the spots are much plainer
during the summer, when the general colour of the coat is lighter, than
during the winter, when the general colour is darker and the horns are
fully developed. In the hog-deer (Hyelaphus porcinus) the spots are
extremely conspicuous during the summer when the coat is reddish-brown, but
quite disappear during the winter when the coat is brown. (41. Dr. Gray,
'Gleanings from the Menagerie of Knowsley,' p. 64. Mr. Blyth, in speaking
('Land and Water,' 1869, p. 42) of the hog-deer of Ceylon, says it is more
brightly spotted with white than the common hog-deer, at the season when it
renews its horns.) In both these species the young are spotted. In the
Virginian deer the young are likewise spotted, and about five per cent. of
the adult animals living in Judge Caton's park, as I am informed by him,
temporarily exhibit at the period when the red summer coat is being
replaced by the bluish winter coat, a row of spots on each flank, which are
always the same in number, though very variable in distinctness. From this
condition there is but a very small step to the complete absence of spots
in the adults at all seasons; and, lastly, to their absence at all ages and
seasons, as occurs with certain species. From the existence of this
perfect series, and more especially from the fawns of so many species being
spotted, we may conclude that the now living members of the deer family are
the descendants of some ancient species which, like the axis deer, was
spotted at all ages and seasons. A still more ancient progenitor probably
somewhat resembled the Hyomoschus aquaticus--for this animal is spotted,
and the hornless males have large exserted canine teeth, of which some few
true deer still retain rudiments. Hyomoschus, also, offers one of those
interesting cases of a form linking together two groups, for it is
intermediate in certain osteological characters between the pachyderms and
ruminants, which were formerly thought to be quite distinct. (42.
Falconer and Cautley, 'Proc. Geolog. Soc.' 1843; and Falconer's 'Pal.
Memoirs,' vol. i. p. 196.)
A curious difficulty here arises. If we admit that coloured spots and
stripes were first acquired as ornaments, how comes it that so many
existing deer, the descendants of an aboriginally spotted animal, and all
the species of pigs and tapirs, the descendants of an aboriginally striped
animal, have lost in their adult state their former ornaments? I cannot
satisfactorily answer this question. We may feel almost sure that the
spots and stripes disappeared at or near maturity in the progenitors of our
existing species, so that they were still retained by the young; and, owing
to the law of inheritance at corresponding ages, were transmitted to the
young of all succeeding generations. It may have been a great advantage to
the lion and puma, from the open nature of their usual haunts, to have lost
their stripes, and to have been thus rendered less conspicuous to their
prey; and if the successive variations, by which this end was gained,
occurred rather late in life, the young would have retained their stripes,
as is now the case. As to deer, pigs, and tapirs, Fritz Muller has
suggested to me that these animals, by the removal of their spots or
stripes through natural selection, would have been less easily seen by
their enemies; and that they would have especially required this
protection, as soon as the carnivora increased in size and number during
the tertiary periods. This may be the true explanation, but it is rather
strange that the young should not have been thus protected, and still more
so that the adults of some species should have retained their spots, either
partially or completely, during part of the year. We know that, when the
domestic ass varies and becomes reddish-brown, grey, or black, the stripes
on the shoulders and even on the spine frequently disappear, though we
cannot explain the cause. Very few horses, except dun-coloured kinds, have
stripes on any part of their bodies, yet we have good reason to believe
that the aboriginal horse was striped on the legs and spine, and probably
on the shoulders. (43. The 'Variation of Animals and Plants under
Domestication,' 1868, vol. i. pp. 61-64.) Hence the disappearance of the
spots and stripes in our adult existing deer, pigs, and tapirs, may be due
to a change in the general colour of their coats; but whether this change
was effected through sexual or natural selection, or was due to the direct
action of the conditions of life, or to some other unknown cause, it is
impossible to decide. An observation made by Mr. Sclater well illustrates
our ignorance of the laws which regulate the appearance and disappearance
of stripes; the species of Asinus which inhabit the Asiatic continent are
destitute of stripes, not having even the cross shoulder-stripe, whilst
those which inhabit Africa are conspicuously striped, with the partial
exception of A. taeniopus, which has only the cross shoulder-stripe and
generally some faint bars on the legs; and this species inhabits the almost
intermediate region of Upper Egypt and Abyssinia. (44. 'Proc. Zool. Soc.'
1862, p. 164. See, also, Dr. Hartmann, 'Ann. d. Landw.' Bd. xliii. s.
222.)
QUADRUMANA.
[Fig. 72. Head of Semnopithecus rubicundus. This and the following
figures (from Prof. Gervais) are given to shew the odd arrangement and
development of the hair on the head.
Fig. 73. Head of Semnopithecus comatus.
Fig. 74. Head of Cebus capucinus.
Fig. 75. Head of Ateles marginatus.
Fig. 76. Head of Cebus vellerosus.]
Before we conclude, it will be well to add a few remarks on the ornaments
of monkeys. In most of the species the sexes resemble each other in
colour, but in some, as we have seen, the males differ from the females,
especially in the colour of the naked parts of the skin, in the development
of the beard, whiskers, and mane. Many species are coloured either in so
extraordinary or so beautiful a manner, and are furnished with such curious
and elegant crests of hair, that we can hardly avoid looking at these
characters as having been gained for the sake of ornament. The
accompanying figures (Figs. 72 to 76) serve to shew the arrangement of the
hair on the face and head in several species. It is scarcely conceivable
that these crests of hair, and the strongly contrasted colours of the fur
and skin, can be the result of mere variability without the aid of
selection; and it is inconceivable that they can be of use in any ordinary
way to these animals. If so, they have probably been gained through sexual
selection, though transmitted equally, or almost equally, to both sexes.
With many of the Quadrumana, we have additional evidence of the action of
sexual selection in the greater size and strength of the males, and in the
greater development of their canine teeth, in comparison with the females.
[Fig. 77. Cercopithecus petaurista (from Brehm).]
A few instances will suffice of the strange manner in which both sexes of
some species are coloured, and of the beauty of others. The face of the
Cercopithecus petaurista (Fig. 77) is black, the whiskers and beard being
white, with a defined, round, white spot on the nose, covered with short
white hair, which gives to the animal an almost ludicrous aspect. The
Semnopithecus frontatus likewise has a blackish face with a long black
beard, and a large naked spot on the forehead of a bluish-white colour.
The face of Macacus lasiotus is dirty flesh-coloured, with a defined red
spot on each cheek. The appearance of Cercocebus aethiops is grotesque,
with its black face, white whiskers and collar, chestnut head, and a large
naked white spot over each eyelid. In very many species, the beard,
whiskers, and crests of hair round the face are of a different colour from
the rest of the head, and when different, are always of a lighter tint (45.
I observed this fact in the Zoological Gardens; and many cases may be seen
in the coloured plates in Geoffroy St.-Hilaire and F. Cuvier, 'Histoire
Nat. des Mammiferes,' tom. i. 1824.), being often pure white, sometimes
bright yellow, or reddish. The whole face of the South American Brachyurus
calvus is of a "glowing scarlet hue"; but this colour does not appear until
the animal is nearly mature. (46. Bates, 'The Naturalist on the Amazons,'
1863, vol. ii. p. 310.) The naked skin of the face differs wonderfully in
colour in the various species. It is often brown or flesh-colour, with
parts perfectly white, and often as black as that of the most sooty negro.
In the Brachyurus the scarlet tint is brighter than that of the most
blushing Caucasian damsel. It is sometimes more distinctly orange than in
any Mongolian, and in several species it is blue, passing into violet or
grey. In all the species known to Mr. Bartlett, in which the adults of
both sexes have strongly-coloured faces, the colours are dull or absent
during early youth. This likewise holds good with the mandrill and Rhesus,
in which the face and the posterior parts of the body are brilliantly
coloured in one sex alone. In these latter cases we have reason to believe
that the colours were acquired through sexual selection; and we are
naturally led to extend the same view to the foregoing species, though both
sexes when adult have their faces coloured in the same manner.
[Fig. 78. Cercopithecus diana (from Brehm).]
Although many kinds of monkeys are far from beautiful according to our
taste, other species are universally admired for their elegant appearance
and bright colours. The Semnopithecus nemaeus, though peculiarly coloured,
is described as extremely pretty; the orange-tinted face is surrounded by
long whiskers of glossy whiteness, with a line of chestnut-red over the
eyebrows; the fur on the back is of a delicate grey, with a square patch on
the loins, the tail and the fore-arms being of a pure white; a gorget of
chestnut surmounts the chest; the thighs are black, with the legs chestnut-
red. I will mention only two other monkeys for their beauty; and I have
selected these as presenting slight sexual differences in colour, which
renders it in some degree probable that both sexes owe their elegant
appearance to sexual selection. In the moustache-monkey (Cercopithecus
cephus) the general colour of the fur is mottled-greenish with the throat
white; in the male the end of the tail is chestnut, but the face is the
most ornamented part, the skin being chiefly bluish-grey, shading into a
blackish tint beneath the eyes, with the upper lip of a delicate blue,
clothed on the lower edge with a thin black moustache; the whiskers are
orange-coloured, with the upper part black, forming a band which extends
backwards to the ears, the latter being clothed with whitish hairs. In the
Zoological Society's Gardens I have often overheard visitors admiring the
beauty of another monkey, deservedly called Cercopithecus diana (Fig. 78);
the general colour of the fur is grey; the chest and inner surface of the
forelegs are white; a large triangular defined space on the hinder part of
the back is rich chestnut; in the male the inner sides of the thighs and
the abdomen are delicate fawn-coloured, and the top of the head is black;
the face and ears are intensely black, contrasting finely with a white
transverse crest over the eyebrows and a long white peaked beard, of which
the basal portion is black. (47. I have seen most of the above monkeys in
the Zoological Society's Gardens. The description of the Semnopithecus
nemaeus is taken from Mr. W.C. Martin's 'Natural History of Mammalia,'
1841, p. 460; see also pp. 475, 523.)
In these and many other monkeys, the beauty and singular arrangement of
their colours, and still more the diversified and elegant arrangement of
the crests and tufts of hair on their heads, force the conviction on my
mind that these characters have been acquired through sexual selection
exclusively as ornaments.
SUMMARY.
The law of battle for the possession of the female appears to prevail
throughout the whole great class of mammals. Most naturalists will admit
that the greater size, strength, courage, and pugnacity of the male, his
special weapons of offence, as well as his special means of defence, have
been acquired or modified through that form of selection which I have
called sexual. This does not depend on any superiority in the general
struggle for life, but on certain individuals of one sex, generally the
male, being successful in conquering other males, and leaving a larger
number of offspring to inherit their superiority than do the less
successful males.
There is another and more peaceful kind of contest, in which the males
endeavour to excite or allure the females by various charms. This is
probably carried on in some cases by the powerful odours emitted by the
males during the breeding-season; the odoriferous glands having been
acquired through sexual selection. Whether the same view can be extended
to the voice is doubtful, for the vocal organs of the males must have been
strengthened by use during maturity, under the powerful excitements of
love, jealousy or rage, and will consequently have been transmitted to the
same sex. Various crests, tufts, and mantles of hair, which are either
confined to the male, or are more developed in this sex than in the female,
seem in most cases to be merely ornamental, though they sometimes serve as
a defence against rival males. There is even reason to suspect that the
branching horns of stags, and the elegant horns of certain antelopes,
though properly serving as weapons of offence or defence, have been partly
modified for ornament.
When the male differs in colour from the female, he generally exhibits
darker and more strongly-contrasted tints. We do not in this class meet
with the splendid red, blue, yellow, and green tints, so common with male
birds and many other animals. The naked parts, however, of certain
Quadrumana must be excepted; for such parts, often oddly situated, are
brilliantly coloured in some species. The colours of the male in other
cases may be due to simple variation, without the aid of selection. But
when the colours are diversified and strongly pronounced, when they are not
developed until near maturity, and when they are lost after emasculation,
we can hardly avoid the conclusion that they have been acquired through
sexual selection for the sake of ornament, and have been transmitted
exclusively, or almost exclusively, to the same sex. When both sexes are
coloured in the same manner, and the colours are conspicuous or curiously
arranged, without being of the least apparent use as a protection, and
especially when they are associated with various other ornamental
appendages, we are led by analogy to the same conclusion, namely, that they
have been acquired through sexual selection, although transmitted to both
sexes. That conspicuous and diversified colours, whether confined to the
males or common to both sexes, are as a general rule associated in the same
groups and sub-groups with other secondary sexual characters serving for
war or for ornament, will be found to hold good, if we look back to the
various cases given in this and the last chapter.
The law of the equal transmission of characters to both sexes, as far as
colour and other ornaments are concerned, has prevailed far more
extensively with mammals than with birds; but weapons, such as horns and
tusks, have often been transmitted either exclusively or much more
perfectly to the males than to the females. This is surprising, for, as
the males generally use their weapons for defence against enemies of all
kinds, their weapons would have been of service to the females. As far as
we can see, their absence in this sex can be accounted for only by the form
of inheritance which has prevailed. Finally, with quadrupeds the contest
between the individuals of the same sex, whether peaceful or bloody, has,
with the rarest exceptions, been confined to the males; so that the latter
have been modified through sexual selection, far more commonly than the
females, either for fighting with each other or for alluring the opposite
sex.
PART III.
SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION.
CHAPTER XIX.
SECONDARY SEXUAL CHARACTERS OF MAN.
Differences between man and woman--Causes of such differences and of
certain characters common to both sexes--Law of battle--Differences in
mental powers, and voice--On the influence of beauty in determining the
marriages of mankind--Attention paid by savages to ornaments--Their ideas
of beauty in woman--The tendency to exaggerate each natural peculiarity.
With mankind the differences between the sexes are greater than in most of
the Quadrumana, but not so great as in some, for instance, the mandrill.
Man on an average is considerably taller, heavier, and stronger than woman,
with squarer shoulders and more plainly-pronounced muscles. Owing to the
relation which exists between muscular development and the projection of
the brows (1. Schaaffhausen, translation in 'Anthropological Review,' Oct.
1868, pp. 419, 420, 427.), the superciliary ridge is generally more marked
in man than in woman. His body, and especially his face, is more hairy,
and his voice has a different and more powerful tone. In certain races the
women are said to differ slightly in tint from the men. For instance,
Schweinfurth, in speaking of a negress belonging to the Monbuttoos, who
inhabit the interior of Africa a few degrees north of the equator, says,
"Like all her race, she had a skin several shades lighter than her
husband's, being something of the colour of half-roasted coffee." (2. 'The
Heart of Africa,' English transl. 1873, vol i. p. 544.) As the women
labour in the fields and are quite unclothed, it is not likely that they
differ in colour from the men owing to less exposure to the weather.
European women are perhaps the brighter coloured of the two sexes, as may
be seen when both have been equally exposed.
Man is more courageous, pugnacious and energetic than woman, and has a more
inventive genius. His brain is absolutely larger, but whether or not
proportionately to his larger body, has not, I believe, been fully
ascertained. In woman the face is rounder; the jaws and the base of the
skull smaller; the outlines of the body rounder, in parts more prominent;
and her pelvis is broader than in man (3. Ecker, translation, in
'Anthropological Review,' Oct. 1868, pp. 351-356. The comparison of the
form of the skull in men and women has been followed out with much care by
Welcker.); but this latter character may perhaps be considered rather as a
primary than a secondary sexual character. She comes to maturity at an
earlier age than man.
As with animals of all classes, so with man, the distinctive characters of
the male sex are not fully developed until he is nearly mature; and if
emasculated they never appear. The beard, for instance, is a secondary
sexual character, and male children are beardless, though at an early age
they have abundant hair on the head. It is probably due to the rather late
appearance in life of the successive variations whereby man has acquired
his masculine characters, that they are transmitted to the male sex alone.
Male and female children resemble each other closely, like the young of so
many other animals in which the adult sexes differ widely; they likewise
resemble the mature female much more closely than the mature male. The
female, however, ultimately assumes certain distinctive characters, and in
the formation of her skull, is said to be intermediate between the child
and the man. (4. Ecker and Welcker, ibid. pp. 352, 355; Vogt, 'Lectures
on Man,' Eng. translat. p. 81.) Again, as the young of closely allied
though distinct species do not differ nearly so much from each other as do
the adults, so it is with the children of the different races of man. Some
have even maintained that race-differences cannot be detected in the
infantile skull. (5. Schaaffhausen, 'Anthropolog. Review,' ibid. p. 429.)
In regard to colour, the new-born negro child is reddish nut-brown, which
soon becomes slaty-grey; the black colour being fully developed within a
year in the Soudan, but not until three years in Egypt. The eyes of the
negro are at first blue, and the hair chestnut-brown rather than black,
being curled only at the ends. The children of the Australians immediately
after birth are yellowish-brown, and become dark at a later age. Those of
the Guaranys of Paraguay are whitish-yellow, but they acquire in the course
of a few weeks the yellowish-brown tint of their parents. Similar
observations have been made in other parts of America. (6. Pruner-Bey, on
negro infants as quoted by Vogt, 'Lectures on Man,' Eng. translat. 1864, p.
189: for further facts on negro infants, as quoted from Winterbottom and
Camper, see Lawrence, 'Lectures on Physiology,' etc. 1822, p. 451. For the
infants of the Guaranys, see Rengger, 'Saugethiere,' etc. s. 3. See also
Godron, 'De l'Espece,' tom. ii. 1859, p. 253. For the Australians, Waitz,
'Introduction to Anthropology,' Eng. translat. 1863, p. 99.)
I have specified the foregoing differences between the male and female sex
in mankind, because they are curiously like those of the Quadrumana. With
these animals the female is mature at an earlier age than the male; at
least this is certainly the case in Cebus azarae. (7. Rengger,
'Saugethiere,' etc., 1830, s. 49.) The males of most species are larger
and stronger than the females, of which fact the gorilla affords a well-
known instance. Even in so trifling a character as the greater prominence
of the superciliary ridge, the males of certain monkeys differ from the
females (8. As in Macacus cynomolgus (Desmarest, 'Mammalogie,' p. 65), and
in Hylobates agilis (Geoffroy St.-Hilaire and F. Cuvier, 'Histoire Nat. des
Mammiferes,' 1824, tom. i. p. 2).), and agree in this respect with mankind.
In the gorilla and certain other monkeys, the cranium of the adult male
presents a strongly-marked sagittal crest, which is absent in the female;
and Ecker found a trace of a similar difference between the two sexes in
the Australians. (9. 'Anthropological Review,' Oct. 1868, p. 353.) With
monkeys when there is any difference in the voice, that of the male is the
more powerful. We have seen that certain male monkeys have a well-
developed beard, which is quite deficient, or much less developed in the
female. No instance is known of the beard, whiskers, or moustache being
larger in the female than in the male monkey. Even in the colour of the
beard there is a curious parallelism between man and the Quadrumana, for
with man when the beard differs in colour from the hair of the head, as is
commonly the case, it is, I believe, almost always of a lighter tint, being
often reddish. I have repeatedly observed this fact in England; but two
gentlemen have lately written to me, saying that they form an exception to
the rule. One of these gentlemen accounts for the fact by the wide
difference in colour of the hair on the paternal and maternal sides of his
family. Both had been long aware of this peculiarity (one of them having
often been accused of dyeing his beard), and had been thus led to observe
other men, and were convinced that the exceptions were very rare. Dr.
Hooker attended to this little point for me in Russia, and found no
exception to the rule. In Calcutta, Mr. J. Scott, of the Botanic Gardens,
was so kind as to observe the many races of men to be seen there, as well
as in some other parts of India, namely, two races of Sikhim, the Bhoteas,
Hindoos, Burmese, and Chinese, most of which races have very little hair on
the face; and he always found that when there was any difference in colour
between the hair of the head and the beard, the latter was invariably
lighter. Now with monkeys, as has already been stated, the beard
frequently differs strikingly in colour from the hair of the head, and in
such cases it is always of a lighter hue, being often pure white, sometimes
yellow or reddish. (10. Mr. Blyth informs me that he has only seen one
instance of the beard, whiskers, etc., in a monkey becoming white with old
age, as is so commonly the case with us. This, however, occurred in an
aged Macacus cynomolgus, kept in confinement whose moustaches were
"remarkably long and human-like." Altogether this old monkey presented a
ludicrous resemblance to one of the reigning monarchs of Europe, after whom
he was universally nick-named. In certain races of man the hair on the
head hardly ever becomes grey; thus Mr. D. Forbes has never, as he informs
me, seen an instance with the Aymaras and Quichuas of South America.)
In regard to the general hairiness of the body, the women in all races are
less hairy than the men; and in some few Quadrumana the under side of the
body of the female is less hairy than that of the male. (11. This is the
case with the females of several species of Hylobates; see Geoffroy St.-
Hilaire and F. Cuvier, 'Hist. Nat. des Mamm.' tom. i. See also, on H. lar,
'Penny Cyclopedia,' vol. ii. pp. 149, 150.) Lastly, male monkeys, like
men, are bolder and fiercer than the females. They lead the troop, and
when there is danger, come to the front. We thus see how close is the
parallelism between the sexual differences of man and the Quadrumana. With
some few species, however, as with certain baboons, the orang and the
gorilla, there is a considerably greater difference between the sexes, as
in the size of the canine teeth, in the development and colour of the hair,
and especially in the colour of the naked parts of the skin, than in
mankind.
All the secondary sexual characters of man are highly variable, even within
the limits of the same race; and they differ much in the several races.
These two rules hold good generally throughout the animal kingdom. In the
excellent observations made on board the Novara (12. The results were
deduced by Dr. Weisbach from the measurements made by Drs. K. Scherzer and
Schwarz, see 'Reise der Novara: Anthropolog. Theil,' 1867, ss. 216, 231,
234, 236, 239, 269.), the male Australians were found to exceed the females
by only 65 millim. in height, whilst with the Javans the average excess was
218 millim.; so that in this latter race the difference in height between
the sexes is more than thrice as great as with the Australians. Numerous
measurements were carefully made of the stature, the circumference of the
neck and chest, the length of the back-bone and of the arms, in various
races; and nearly all these measurements shew that the males differ much
more from one another than do the females. This fact indicates that, as
far as these characters are concerned, it is the male which has been
chiefly modified, since the several races diverged from their common stock.
The development of the beard and the hairiness of the body differ
remarkably in the men of distinct races, and even in different tribes or
families of the same race. We Europeans see this amongst ourselves. In
the Island of St. Kilda, according to Martin (13. 'Voyage to St. Kilda'
(3rd ed. 1753), p. 37.), the men do not acquire beards until the age of
thirty or upwards, and even then the beards are very thin. On the
Europaeo-Asiatic continent, beards prevail until we pass beyond India;
though with the natives of Ceylon they are often absent, as was noticed in
ancient times by Diodorus. (14. Sir J.E. Tennent, 'Ceylon,' vol. ii.
1859, p. 107.) Eastward of India beards disappear, as with the Siamese,
Malays, Kalmucks, Chinese, and Japanese; nevertheless, the Ainos (15.
Quatrefages, 'Revue des Cours Scientifiques,' Aug. 29, 1868, p. 630; Vogt,
'Lectures on Man,' Eng. trans. p. 127.), who inhabit the northernmost
islands of the Japan Archipelago, are the hairiest men in the world. With
negroes the beard is scanty or wanting, and they rarely have whiskers; in
both sexes the body is frequently almost destitute of fine down. (16. On
the beards of negroes, Vogt, 'Lectures,' etc. p. 127; Waitz, 'Introduct. to
Anthropology,' Engl. translat. 1863, vol. i. p. 96. It is remarkable that
in the United States ('Investigations in Military and Anthropological
Statistics of American Soldiers,' 1869, p. 569) the pure negroes and their
crossed offspring seem to have bodies almost as hairy as Europeans.) On
the other hand, the Papuans of the Malay Archipelago, who are nearly as
black as negroes, possess well-developed beards. (17. Wallace, 'The Malay
Arch.' vol. ii. 1869, p. 178.) In the Pacific Ocean the inhabitants of the
Fiji Archipelago have large bushy beards, whilst those of the not distant
archipelagoes of Tonga and Samoa are beardless; but these men belong to
distinct races. In the Ellice group all the inhabitants belong to the same
race; yet on one island alone, namely Nunemaya, "the men have splendid
beards"; whilst on the other islands "they have, as a rule, a dozen
straggling hairs for a beard." (18. Dr. J. Barnard Davis on Oceanic
Races, in 'Anthropological Review,' April 1870, pp. 185, 191.)
Throughout the great American continent the men may be said to be
beardless; but in almost all the tribes a few short hairs are apt to appear
on the face, especially in old age. With the tribes of North America,
Catlin estimates that eighteen out of twenty men are completely destitute
by nature of a beard; but occasionally there may be seen a man, who has
neglected to pluck out the hairs at puberty, with a soft beard an inch or
two in length. The Guaranys of Paraguay differ from all the surrounding
tribes in having a small beard, and even some hair on the body, but no
whiskers. (19. Catlin, 'North American Indians,' 3rd. ed. 1842, vol. ii.
p. 227. On the Guaranys, see Azara, 'Voyages dans l'Amerique Merid.' tom.
ii. 1809, p. 85; also Rengger, 'Saugethiere von Paraguay,' s. 3.) I am
informed by Mr. D. Forbes, who particularly attended to this point, that
the Aymaras and Quichuas of the Cordillera are remarkably hairless, yet in
old age a few straggling hairs occasionally appear on the chin. The men of
these two tribes have very little hair on the various parts of the body
where hair grows abundantly in Europeans, and the women have none on the
corresponding parts. The hair on the head, however, attains an
extraordinary length in both sexes, often reaching almost to the ground;
and this is likewise the case with some of the N. American tribes. In the
amount of hair, and in the general shape of the body, the sexes of the
American aborigines do not differ so much from each other, as in most other
races. (20. Prof. and Mrs. Agassiz ('Journey in Brazil,' p. 530) remark
that the sexes of the American Indians differ less than those of the
negroes and of the higher races. See also Rengger, ibid. p. 3, on the
Guaranys.) This fact is analogous with what occurs with some closely
allied monkeys; thus the sexes of the chimpanzee are not as different as
those of the orang or gorilla. (21. Rutimeyer, 'Die Grenzen der
Thierwelt; eine Betrachtung zu Darwin's Lehre,' 1868, s. 54.)
In the previous chapters we have seen that with mammals, birds, fishes,
insects, etc., many characters, which there is every reason to believe were
primarily gained through sexual selection by one sex, have been transferred
to the other. As this same form of transmission has apparently prevailed
much with mankind, it will save useless repetition if we discuss the origin
of characters peculiar to the male sex together with certain other
characters common to both sexes.
LAW OF BATTLE.
With savages, for instance, the Australians, the women are the constant
cause of war both between members of the same tribe and between distinct
tribes. So no doubt it was in ancient times; "nam fuit ante Helenam mulier
teterrima belli causa." With some of the North American Indians, the
contest is reduced to a system. That excellent observer, Hearne (22. 'A
Journey from Prince of Wales Fort,' 8vo. ed. Dublin, 1796, p. 104. Sir J.
Lubbock ('Origin of Civilisation,' 1870, p. 69) gives other and similar
cases in North America. For the Guanas of South America see Azara,
'Voyages,' etc. tom. ii. p. 94.), says:--"It has ever been the custom among
these people for the men to wrestle for any woman to whom they are
attached; and, of course, the strongest party always carries off the prize.
A weak man, unless he be a good hunter, and well-beloved, is seldom
permitted to keep a wife that a stronger man thinks worth his notice. This
custom prevails throughout all the tribes, and causes a great spirit of
emulation among their youth, who are upon all occasions, from their
childhood, trying their strength and skill in wrestling." With the Guanas
of South America, Azara states that the men rarely marry till twenty years
old or more, as before that age they cannot conquer their rivals.
Other similar facts could be given; but even if we had no evidence on this
head, we might feel almost sure, from the analogy of the higher Quadrumana
(23. On the fighting of the male gorillas, see Dr. Savage, in 'Boston
Journal of Natural History,' vol. v. 1847, p. 423. On Presbytis entellus,
see the 'Indian Field,' 1859, p. 146.), that the law of battle had
prevailed with man during the early stages of his development. The
occasional appearance at the present day of canine teeth which project
above the others, with traces of a diastema or open space for the reception
of the opposite canines, is in all probability a case of reversion to a
former state, when the progenitors of man were provided with these weapons,
like so many existing male Quadrumana. It was remarked in a former chapter
that as man gradually became erect, and continually used his hands and arms
for fighting with sticks and stones, as well as for the other purposes of
life, he would have used his jaws and teeth less and less. The jaws,
together with their muscles, would then have been reduced through disuse,
as would the teeth through the not well understood principles of
correlation and economy of growth; for we everywhere see that parts, which
are no longer of service, are reduced in size. By such steps the original
inequality between the jaws and teeth in the two sexes of mankind would
ultimately have been obliterated. The case is almost parallel with that of
many male Ruminants, in which the canine teeth have been reduced to mere
rudiments, or have disappeared, apparently in consequence of the
development of horns. As the prodigious difference between the skulls of
the two sexes in the orang and gorilla stands in close relation with the
development of the immense canine teeth in the males, we may infer that the
reduction of the jaws and teeth in the early male progenitors of man must
have led to a most striking and favourable change in his appearance.
There can be little doubt that the greater size and strength of man, in
comparison with woman, together with his broader shoulders, more developed
muscles, rugged outline of body, his greater courage and pugnacity, are all
due in chief part to inheritance from his half-human male ancestors. These
characters would, however, have been preserved or even augmented during the
long ages of man's savagery, by the success of the strongest and boldest
men, both in the general struggle for life and in their contests for wives;
a success which would have ensured their leaving a more numerous progeny
than their less favoured brethren. It is not probable that the greater
strength of man was primarily acquired through the inherited effects of his
having worked harder than woman for his own subsistence and that of his
family; for the women in all barbarous nations are compelled to work at
least as hard as the men. With civilised people the arbitrament of battle
for the possession of the women has long ceased; on the other hand, the
men, as a general rule, have to work harder than the women for their joint
subsistence, and thus their greater strength will have been kept up.
DIFFERENCE IN THE MENTAL POWERS OF THE TWO SEXES.
With respect to differences of this nature between man and woman, it is
probable that sexual selection has played a highly important part. I am
aware that some writers doubt whether there is any such inherent
difference; but this is at least probable from the analogy of the lower
animals which present other secondary sexual characters. No one disputes
that the bull differs in disposition from the cow, the wild-boar from the
sow, the stallion from the mare, and, as is well known to the keepers of
menageries, the males of the larger apes from the females. Woman seems to
differ from man in mental disposition, chiefly in her greater tenderness
and less selfishness; and this holds good even with savages, as shewn by a
well-known passage in Mungo Park's Travels, and by statements made by many
other travellers. Woman, owing to her maternal instincts, displays these
qualities towards her infants in an eminent degree; therefore it is likely
that she would often extend them towards her fellow-creatures. Man is the
rival of other men; he delights in competition, and this leads to ambition
which passes too easily into selfishness. These latter qualities seem to
be his natural and unfortunate birthright. It is generally admitted that
with woman the powers of intuition, of rapid perception, and perhaps of
imitation, are more strongly marked than in man; but some, at least, of
these faculties are characteristic of the lower races, and therefore of a
past and lower state of civilisation.
The chief distinction in the intellectual powers of the two sexes is shewn
by man's attaining to a higher eminence, in whatever he takes up, than can
woman--whether requiring deep thought, reason, or imagination, or merely
the use of the senses and hands. If two lists were made of the most
eminent men and women in poetry, painting, sculpture, music (inclusive both
of composition and performance), history, science, and philosophy, with
half-a-dozen names under each subject, the two lists would not bear
comparison. We may also infer, from the law of the deviation from
averages, so well illustrated by Mr. Galton, in his work on 'Hereditary
Genius,' that if men are capable of a decided pre-eminence over women in
many subjects, the average of mental power in man must be above that of
woman.
Amongst the half-human progenitors of man, and amongst savages, there have
been struggles between the males during many generations for the possession
of the females. But mere bodily strength and size would do little for
victory, unless associated with courage, perseverance, and determined
energy. With social animals, the young males have to pass through many a
contest before they win a female, and the older males have to retain their
females by renewed battles. They have, also, in the case of mankind, to
defend their females, as well as their young, from enemies of all kinds,
and to hunt for their joint subsistence. But to avoid enemies or to attack
them with success, to capture wild animals, and to fashion weapons,
requires the aid of the higher mental faculties, namely, observation,
reason, invention, or imagination. These various faculties will thus have
been continually put to the test and selected during manhood; they will,
moreover, have been strengthened by use during this same period of life.
Consequently in accordance with the principle often alluded to, we might
expect that they would at least tend to be transmitted chiefly to the male
offspring at the corresponding period of manhood.
Now, when two men are put into competition, or a man with a woman, both
possessed of every mental quality in equal perfection, save that one has
higher energy, perseverance, and courage, the latter will generally become
more eminent in every pursuit, and will gain the ascendancy. (24. J.
Stuart Mill remarks ('The Subjection of Women,' 1869, p. 122), "The things
in which man most excels woman are those which require most plodding, and
long hammering at single thoughts." What is this but energy and
perseverance?) He may be said to possess genius--for genius has been
declared by a great authority to be patience; and patience, in this sense,
means unflinching, undaunted perseverance. But this view of genius is
perhaps deficient; for without the higher powers of the imagination and
reason, no eminent success can be gained in many subjects. These latter
faculties, as well as the former, will have been developed in man, partly
through sexual selection,--that is, through the contest of rival males, and
partly through natural selection, that is, from success in the general
struggle for life; and as in both cases the struggle will have been during
maturity, the characters gained will have been transmitted more fully to
the male than to the female offspring. It accords in a striking manner
with this view of the modification and re-inforcement of many of our mental
faculties by sexual selection, that, firstly, they notoriously undergo a
considerable change at puberty (25. Maudsley, 'Mind and Body,' p. 31.),
and, secondly, that eunuchs remain throughout life inferior in these same
qualities. Thus, man has ultimately become superior to woman. It is,
indeed, fortunate that the law of the equal transmission of characters to
both sexes prevails with mammals; otherwise, it is probable that man would
have become as superior in mental endowment to woman, as the peacock is in
ornamental plumage to the peahen.
It must be borne in mind that the tendency in characters acquired by either
sex late in life, to be transmitted to the same sex at the same age, and of
early acquired characters to be transmitted to both sexes, are rules which,
though general, do not always hold. If they always held good, we might
conclude (but I here exceed my proper bounds) that the inherited effects of
the early education of boys and girls would be transmitted equally to both
sexes; so that the present inequality in mental power between the sexes
would not be effaced by a similar course of early training; nor can it have
been caused by their dissimilar early training. In order that woman should
reach the same standard as man, she ought, when nearly adult, to be trained
to energy and perseverance, and to have her reason and imagination
exercised to the highest point; and then she would probably transmit these
qualities chiefly to her adult daughters. All women, however, could not be
thus raised, unless during many generations those who excelled in the above
robust virtues were married, and produced offspring in larger numbers than
other women. As before remarked of bodily strength, although men do not
now fight for their wives, and this form of selection has passed away, yet
during manhood, they generally undergo a severe struggle in order to
maintain themselves and their families; and this will tend to keep up or
even increase their mental powers, and, as a consequence, the present
inequality between the sexes. (26. An observation by Vogt bears on this
subject: he says, "It is a remarkable circumstance, that the difference
between the sexes, as regards the cranial cavity, increases with the
development of the race, so that the male European excels much more the
female, than the negro the negress. Welcker confirms this statement of
Huschke from his measurements of negro and German skulls." But Vogt admits
('Lectures on Man,' Eng. translat. 1864, p. 81) that more observations are
requisite on this point.
VOICE AND MUSICAL POWERS.
In some species of Quadrumana there is a great difference between the adult
sexes, in the power of their voices and in the development of the vocal
organs; and man appears to have inherited this difference from his early
progenitors. His vocal cords are about one-third longer than in woman, or
than in boys; and emasculation produces the same effect on him as on the
lower animals, for it "arrests that prominent growth of the thyroid, etc.,
which accompanies the elongation of the cords." (27. Owen, 'Anatomy of
Vertebrates,' vol. iii. p. 603.) With respect to the cause of this
difference between the sexes, I have nothing to add to the remarks in the
last chapter on the probable effects of the long-continued use of the vocal
organs by the male under the excitement of love, rage and jealousy.
According to Sir Duncan Gibb (28. 'Journal of the Anthropological
Society,' April 1869, p. lvii. and lxvi.), the voice and the form of the
larynx differ in the different races of mankind; but with the Tartars,
Chinese, etc., the voice of the male is said not to differ so much from
that of the female, as in most other races.
The capacity and love for singing or music, though not a sexual character
in man, must not here be passed over. Although the sounds emitted by
animals of all kinds serve many purposes, a strong case can be made out,
that the vocal organs were primarily used and perfected in relation to the
propagation of the species. Insects and some few spiders are the lowest
animals which voluntarily produce any sound; and this is generally effected
by the aid of beautifully constructed stridulating organs, which are often
confined to the males. The sounds thus produced consist, I believe in all
cases, of the same note, repeated rhythmically (29. Dr. Scudder, 'Notes on
Stridulation,' in 'Proc. Boston Soc. of Nat. Hist.' vol. xi. April 1868.);
and this is sometimes pleasing even to the ears of man. The chief and, in
some cases, exclusive purpose appears to be either to call or charm the
opposite sex.
The sounds produced by fishes are said in some cases to be made only by the
males during the breeding-season. All the air-breathing Vertebrata
necessarily possess an apparatus for inhaling and expelling air, with a
pipe capable of being closed at one end. Hence when the primeval members
of this class were strongly excited and their muscles violently contracted,
purposeless sounds would almost certainly have been produced; and these, if
they proved in any way serviceable, might readily have been modified or
intensified by the preservation of properly adapted variations. The lowest
Vertebrates which breathe air are Amphibians; and of these, frogs and toads
possess vocal organs, which are incessantly used during the breeding-
season, and which are often more highly developed in the male than in the
female. The male alone of the tortoise utters a noise, and this only
during the season of love. Male alligators roar or bellow during the same
season. Every one knows how much birds use their vocal organs as a means
of courtship; and some species likewise perform what may be called
instrumental music.
In the class of Mammals, with which we are here more particularly
concerned, the males of almost all the species use their voices during the
breeding-season much more than at any other time; and some are absolutely
mute excepting at this season. With other species both sexes, or only the
females, use their voices as a love-call. Considering these facts, and
that the vocal organs of some quadrupeds are much more largely developed in
the male than in the female, either permanently or temporarily during the
breeding-season; and considering that in most of the lower classes the
sounds produced by the males, serve not only to call but to excite or
allure the female, it is a surprising fact that we have not as yet any good
evidence that these organs are used by male mammals to charm the females.
The American Mycetes caraya perhaps forms an exception, as does the
Hylobates agilis, an ape allied to man. This gibbon has an extremely loud
but musical voice. Mr. Waterhouse states (30. Given in W.C.L. Martin's
'General Introduction to Natural History of Mamm. Animals,' 1841, p. 432;
Owen, 'Anatomy of Vertebrates,' vol. iii, p. 600.), "It appeared to me that
in ascending and descending the scale, the intervals were always exactly
half-tones; and I am sure that the highest note was the exact octave to the
lowest. The quality of the notes is very musical; and I do not doubt that
a good violinist would be able to give a correct idea of the gibbon's
composition, excepting as regards its loudness." Mr. Waterhouse then gives
the notes. Professor Owen, who is a musician, confirms the foregoing
statement, and remarks, though erroneously, that this gibbon "alone of
brute mammals may be said to sing." It appears to be much excited after
its performance. Unfortunately, its habits have never been closely
observed in a state of nature; but from the analogy of other animals, it is
probable that it uses its musical powers more especially during the season
of courtship.
This gibbon is not the only species in the genus which sings, for my son,
Francis Darwin, attentively listened in the Zoological Gardens to H.
leuciscus whilst singing a cadence of three notes, in true musical
intervals and with a clear musical tone. It is a more surprising fact that
certain rodents utter musical sounds. Singing mice have often been
mentioned and exhibited, but imposture has commonly been suspected. We
have, however, at last a clear account by a well-known observer, the Rev.
S. Lockwood (31. The 'American Naturalist,' 1871, p. 761.), of the musical
powers of an American species, the Hesperomys cognatus, belonging to a
genus distinct from that of the English mouse. This little animal was kept
in confinement, and the performance was repeatedly heard. In one of the
two chief songs, "the last bar would frequently be prolonged to two or
three; and she would sometimes change from C sharp and D, to C natural and
D, then warble on these two notes awhile, and wind up with a quick chirp on
C sharp and D. The distinctness between the semitones was very marked, and
easily appreciable to a good ear." Mr. Lockwood gives both songs in
musical notation; and adds that though this little mouse "had no ear for
time, yet she would keep to the key of B (two flats) and strictly in a
major key."..."Her soft clear voice falls an octave with all the precision
possible; then at the wind up, it rises again into a very quick trill on C
sharp and D."
A critic has asked how the ears of man, and he ought to have added of other
animals, could have been adapted by selection so as to distinguish musical
notes. But this question shews some confusion on the subject; a noise is
the sensation resulting from the co-existence of several aerial "simple
vibrations" of various periods, each of which intermits so frequently that
its separate existence cannot be perceived. It is only in the want of
continuity of such vibrations, and in their want of harmony inter se, that
a noise differs from a musical note. Thus an ear to be capable of
discriminating noises--and the high importance of this power to all animals
is admitted by every one--must be sensitive to musical notes. We have
evidence of this capacity even low down in the animal scale: thus
Crustaceans are provided with auditory hairs of different lengths, which
have been seen to vibrate when the proper musical notes are struck. (32.
Helmholtz, 'Theorie Phys. de la Musique,' 1868, p. 187.) As stated in a
previous chapter, similar observations have been made on the hairs of the
antennae of gnats. It has been positively asserted by good observers that
spiders are attracted by music. It is also well known that some dogs howl
when hearing particular tones. (33. Several accounts have been published
to this effect. Mr. Peach writes to me that an old dog of his howls when B
flat is sounded on the flute, and to no other note. I may add another
instance of a dog always whining, when one note on a concertina, which was
out of tune, was played.) Seals apparently appreciate music, and their
fondness for it "was well known to the ancients, and is often taken
advantage of by the hunters at the present day." (34. Mr. R. Brown, in
'Proc. Zool. Soc.' 1868, p. 410.)
Therefore, as far as the mere perception of musical notes is concerned,
there seems no special difficulty in the case of man or of any other
animal. Helmholtz has explained on physiological principles why concords
are agreeable, and discords disagreeable to the human ear; but we are
little concerned with these, as music in harmony is a late invention. We
are more concerned with melody, and here again, according to Helmholtz, it
is intelligible why the notes of our musical scale are used. The ear
analyses all sounds into their component "simple vibrations," although we
are not conscious of this analysis. In a musical note the lowest in pitch
of these is generally predominant, and the others which are less marked are
the octave, the twelfth, the second octave, etc., all harmonies of the
fundamental predominant note; any two notes of our scale have many of these
harmonic over-tones in common. It seems pretty clear then, that if an
animal always wished to sing precisely the same song, he would guide
himself by sounding those notes in succession, which possess many over-
tones in common--that is, he would choose for his song, notes which belong
to our musical scale.
But if it be further asked why musical tones in a certain order and rhythm
give man and other animals pleasure, we can no more give the reason than
for the pleasantness of certain tastes and smells. That they do give
pleasure of some kind to animals, we may infer from their being produced
during the season of courtship by many insects, spiders, fishes,
amphibians, and birds; for unless the females were able to appreciate such
sounds and were excited or charmed by them, the persevering efforts of the
males, and the complex structures often possessed by them alone, would be
useless; and this it is impossible to believe.
Human song is generally admitted to be the basis or origin of instrumental
music. As neither the enjoyment nor the capacity of producing musical
notes are faculties of the least use to man in reference to his daily
habits of life, they must be ranked amongst the most mysterious with which
he is endowed. They are present, though in a very rude condition, in men
of all races, even the most savage; but so different is the taste of the
several races, that our music gives no pleasure to savages, and their music
is to us in most cases hideous and unmeaning. Dr. Seemann, in some
interesting remarks on this subject (35. 'Journal of Anthropological
Society,' Oct. 1870, p. clv. See also the several later chapters in Sir
John Lubbock's 'Prehistoric Times,' 2nd ed. 1869, which contain an
admirable account of the habits of savages.), "doubts whether even amongst
the nations of Western Europe, intimately connected as they are by close
and frequent intercourse, the music of the one is interpreted in the same
sense by the others. By travelling eastwards we find that there is
certainly a different language of music. Songs of joy and dance-
accompaniments are no longer, as with us, in the major keys, but always in
the minor." Whether or not the half-human progenitors of man possessed,
like the singing gibbons, the capacity of producing, and therefore no doubt
of appreciating, musical notes, we know that man possessed these faculties
at a very remote period. M. Lartet has described two flutes made out of
the bones and horns of the reindeer, found in caves together with flint
tools and the remains of extinct animals. The arts of singing and of
dancing are also very ancient, and are now practised by all or nearly all
the lowest races of man. Poetry, which may be considered as the offspring
of song, is likewise so ancient, that many persons have felt astonished
that it should have arisen during the earliest ages of which we have any
record.
We see that the musical faculties, which are not wholly deficient in any
race, are capable of prompt and high development, for Hottentots and
Negroes have become excellent musicians, although in their native countries
they rarely practise anything that we should consider music. Schweinfurth,
however, was pleased with some of the simple melodies which he heard in the
interior of Africa. But there is nothing anomalous in the musical
faculties lying dormant in man: some species of birds which never
naturally sing, can without much difficulty be taught to do so; thus a
house-sparrow has learnt the song of a linnet. As these two species are
closely allied, and belong to the order of Insessores, which includes
nearly all the singing-birds in the world, it is possible that a progenitor
of the sparrow may have been a songster. It is more remarkable that
parrots, belonging to a group distinct from the Insessores, and having
differently constructed vocal organs, can be taught not only to speak, but
to pipe or whistle tunes invented by man, so that they must have some
musical capacity. Nevertheless it would be very rash to assume that
parrots are descended from some ancient form which was a songster. Many
cases could be advanced of organs and instincts originally adapted for one
purpose, having been utilised for some distinct purpose. (36. Since this
chapter was printed, I have seen a valuable article by Mr. Chauncey Wright
('North American Review,' Oct. 1870, page 293), who, in discussing the
above subject, remarks, "There are many consequences of the ultimate laws
or uniformities of nature, through which the acquisition of one useful
power will bring with it many resulting advantages as well as limiting
disadvantages, actual or possible, which the principle of utility may not
have comprehended in its action." As I have attempted to shew in an early
chapter of this work, this principle has an important bearing on the
acquisition by man of some of his mental characteristics.) Hence the
capacity for high musical development which the savage races of man
possess, may be due either to the practice by our semi-human progenitors of
some rude form of music, or simply to their having acquired the proper
vocal organs for a different purpose. But in this latter case we must
assume, as in the above instance of parrots, and as seems to occur with
many animals, that they already possessed some sense of melody.
Music arouses in us various emotions, but not the more terrible ones of
horror, fear, rage, etc. It awakens the gentler feelings of tenderness and
love, which readily pass into devotion. In the Chinese annals it is said,
"Music hath the power of making heaven descend upon earth." It likewise
stirs up in us the sense of triumph and the glorious ardour for war. These
powerful and mingled feelings may well give rise to the sense of sublimity.
We can concentrate, as Dr. Seemann observes, greater intensity of feeling
in a single musical note than in pages of writing. It is probable that
nearly the same emotions, but much weaker and far less complex, are felt by
birds when the male pours forth his full volume of song, in rivalry with
other males, to captivate the female. Love is still the commonest theme of
our songs. As Herbert Spencer remarks, "music arouses dormant sentiments
of which we had not conceived the possibility, and do not know the meaning;
or, as Richter says, tells us of things we have not seen and shall not
see." Conversely, when vivid emotions are felt and expressed by the
orator, or even in common speech, musical cadences and rhythm are
instinctively used. The negro in Africa when excited often bursts forth in
song; "another will reply in song, whilst the company, as if touched by a
musical wave, murmur a chorus in perfect unison." (37. Winwood Reade,
'The Martyrdom of Man,' 1872, p. 441, and 'African Sketch Book,' 1873, vol.
ii. p. 313.) Even monkeys express strong feelings in different tones--
anger and impatience by low,--fear and pain by high notes. (38. Rengger,
'Saugethiere von Paraguay,' s. 49.) The sensations and ideas thus excited
in us by music, or expressed by the cadences of oratory, appear from their
vagueness, yet depth, like mental reversions to the emotions and thoughts
of a long-past age.
All these facts with respect to music and impassioned speech become
intelligible to a certain extent, if we may assume that musical tones and
rhythm were used by our half-human ancestors, during the season of
courtship, when animals of all kinds are excited not only by love, but by
the strong passions of jealousy, rivalry, and triumph. From the deeply-
laid principle of inherited associations, musical tones in this case would
be likely to call up vaguely and indefinitely the strong emotions of a
long-past age. As we have every reason to suppose that articulate speech
is one of the latest, as it certainly is the highest, of the arts acquired
by man, and as the instinctive power of producing musical notes and rhythms
is developed low down in the animal series, it would be altogether opposed
to the principle of evolution, if we were to admit that man's musical
capacity has been developed from the tones used in impassioned speech. We
must suppose that the rhythms and cadences of oratory are derived from
previously developed musical powers. (39. See the very interesting
discussion on the 'Origin and Function of Music,' by Mr. Herbert Spencer,
in his collected 'Essays,' 1858, p. 359. Mr. Spencer comes to an exactly
opposite conclusion to that at which I have arrived. He concludes, as did
Diderot formerly, that the cadences used in emotional speech afford the
foundation from which music has been developed; whilst I conclude that
musical notes and rhythm were first acquired by the male or female
progenitors of mankind for the sake of charming the opposite sex. Thus
musical tones became firmly associated with some of the strongest passions
an animal is capable of feeling, and are consequently used instinctively,
or through association when strong emotions are expressed in speech. Mr.
Spencer does not offer any satisfactory explanation, nor can I, why high or
deep notes should be expressive, both with man and the lower animals, of
certain emotions. Mr. Spencer gives also an interesting discussion on the
relations between poetry, recitative and song.) We can thus understand how
it is that music, dancing, song, and poetry are such very ancient arts. We
may go even further than this, and, as remarked in a former chapter,
believe that musical sounds afforded one of the bases for the development
of language. (40. I find in Lord Monboddo's 'Origin of Language,' vol. i.
1774, p. 469, that Dr. Blacklock likewise thought "that the first language
among men was music, and that before our ideas were expressed by articulate
sounds, they were communicated by tones varied according to different
degrees of gravity and acuteness.")
As the males of several quadrumanous animals have their vocal organs much
more developed than in the females, and as a gibbon, one of the
anthropomorphous apes, pours forth a whole octave of musical notes and may
be said to sing, it appears probable that the progenitors of man, either
the males or females or both sexes, before acquiring the power of
expressing their mutual love in articulate language, endeavoured to charm
each other with musical notes and rhythm. So little is known about the use
of the voice by the Quadrumana during the season of love, that we have no
means of judging whether the habit of singing was first acquired by our
male or female ancestors. Women are generally thought to possess sweeter
voices than men, and as far as this serves as any guide, we may infer that
they first acquired musical powers in order to attract the other sex. (41.
See an interesting discussion on this subject by Haeckel, 'Generelle
Morphologie,' B. ii. 1866, s. 246.) But if so, this must have occurred
long ago, before our ancestors had become sufficiently human to treat and
value their women merely as useful slaves. The impassioned orator, bard,
or musician, when with his varied tones and cadences he excites the
strongest emotions in his hearers, little suspects that he uses the same
means by which his half-human ancestors long ago aroused each other's
ardent passions, during their courtship and rivalry.
THE INFLUENCE OF BEAUTY IN DETERMINING THE MARRIAGES OF MANKIND.
In civilised life man is largely, but by no means exclusively, influenced
in the choice of his wife by external appearance; but we are chiefly
concerned with primeval times, and our only means of forming a judgment on
this subject is to study the habits of existing semi-civilised and savage
nations. If it can be shewn that the men of different races prefer women
having various characteristics, or conversely with the women, we have then
to enquire whether such choice, continued during many generations, would
produce any sensible effect on the race, either on one sex or both
according to the form of inheritance which has prevailed.
It will be well first to shew in some detail that savages pay the greatest
attention to their personal appearance. (42. A full and excellent account
of the manner in which savages in all parts of the world ornament
themselves, is given by the Italian traveller, Professor Mantegazza, 'Rio
de la Plata, Viaggi e Studi,' 1867, pp. 525-545; all the following
statements, when other references are not given, are taken from this work.
See, also, Waitz, 'Introduction to Anthropology,' Eng. translat. vol. i.
1863, p. 275, et passim. Lawrence also gives very full details in his
'Lectures on Physiology,' 1822. Since this chapter was written Sir J.
Lubbock has published his 'Origin of Civilisation,' 1870, in which there is
an interesting chapter on the present subject, and from which (pp. 42, 48)
I have taken some facts about savages dyeing their teeth and hair, and
piercing their teeth.) That they have a passion for ornament is notorious;
and an English philosopher goes so far as to maintain, that clothes were
first made for ornament and not for warmth. As Professor Waitz remarks,
"however poor and miserable man is, he finds a pleasure in adorning
himself." The extravagance of the naked Indians of South America in
decorating themselves is shewn "by a man of large stature gaining with
difficulty enough by the labour of a fortnight to procure in exchange the
chica necessary to paint himself red." (43. Humboldt, 'Personal
Narrative,' Eng. translat. vol. iv. p. 515; on the imagination shewn in
painting the body, p. 522; on modifying the form of the calf of the leg, p.
466.) The ancient barbarians of Europe during the Reindeer period brought
to their caves any brilliant or singular objects which they happened to
find. Savages at the present day everywhere deck themselves with plumes,
necklaces, armlets, ear-rings, etc. They paint themselves in the most
diversified manner. "If painted nations," as Humboldt observes, "had been
examined with the same attention as clothed nations, it would have been
perceived that the most fertile imagination and the most mutable caprice
have created the fashions of painting, as well as those of garments."
In one part of Africa the eyelids are coloured black; in another the nails
are coloured yellow or purple. In many places the hair is dyed of various
tints. In different countries the teeth are stained black, red, blue,
etc., and in the Malay Archipelago it is thought shameful to have white
teeth "like those of a dog." Not one great country can be named, from the
polar regions in the north to New Zealand in the south, in which the
aborigines do not tattoo themselves. This practice was followed by the
Jews of old, and by the ancient Britons. In Africa some of the natives
tattoo themselves, but it is a much more common practice to raise
protuberances by rubbing salt into incisions made in various parts of the
body; and these are considered by the inhabitants of Kordofan and Darfur
"to be great personal attractions." In the Arab countries no beauty can be
perfect until the cheeks "or temples have been gashed." (44. 'The Nile
Tributaries,' 1867; 'The Albert N'yanza,' 1866, vol. i. p. 218.) In South
America, as Humboldt remarks, "a mother would be accused of culpable
indifference towards her children, if she did not employ artificial means
to shape the calf of the leg after the fashion of the country." In the Old
and New Worlds the shape of the skull was formerly modified during infancy
in the most extraordinary manner, as is still the case in many places, and
such deformities are considered ornamental. For instance, the savages of
Colombia (45. Quoted by Prichard, 'Physical History of Mankind,' 4th ed.
vol. i. 1851, p. 321.) deem a much flattened head "an essential point of
beauty."
The hair is treated with especial care in various countries; it is allowed
to grow to full length, so as to reach to the ground, or is combed into "a
compact frizzled mop, which is the Papuan's pride and glory." (46. On the
Papuans, Wallace, 'The Malay Archipelago,' vol. ii. p. 445. On the
coiffure of the Africans, Sir S. Baker, 'The Albert N'yanza,' vol. i. p.
210.) In northern Africa "a man requires a period of from eight to ten
years to perfect his coiffure." With other nations the head is shaved, and
in parts of South America and Africa even the eyebrows and eyelashes are
eradicated. The natives of the Upper Nile knock out the four front teeth,
saying that they do not wish to resemble brutes. Further south, the
Batokas knock out only the two upper incisors, which, as Livingstone (47.
'Travels,' p. 533.) remarks, gives the face a hideous appearance, owing to
the prominence of the lower jaw; but these people think the presence of the
incisors most unsightly, and on beholding some Europeans, cried out, "Look
at the great teeth!" The chief Sebituani tried in vain to alter this
fashion. In various parts of Africa and in the Malay Archipelago the
natives file the incisors into points like those of a saw, or pierce them
with holes, into which they insert studs.
As the face with us is chiefly admired for its beauty, so with savages it
is the chief seat of mutilation. In all quarters of the world the septum,
and more rarely the wings of the nose are pierced; rings, sticks, feathers,
and other ornaments being inserted into the holes. The ears are everywhere
pierced and similarly ornamented, and with the Botocudos and Lenguas of
South America the hole is gradually so much enlarged that the lower edge
touches the shoulder. In North and South America and in Africa either the
upper or lower lip is pierced; and with the Botocudos the hole in the lower
lip is so large that a disc of wood, four inches in diameter, is placed in
it. Mantegazza gives a curious account of the shame felt by a South
American native, and of the ridicule which he excited, when he sold his
tembeta,--the large coloured piece of wood which is passed through the
hole. In Central Africa the women perforate the lower lip and wear a
crystal, which, from the movement of the tongue, has "a wriggling motion,
indescribably ludicrous during conversation." The wife of the chief of
Latooka told Sir S. Baker (49. 'The Albert N'yanza,' 1866, vol. i. p.
217.) that Lady Baker "would be much improved if she would extract her four
front teeth from the lower jaw, and wear the long pointed polished crystal
in her under lip." Further south with the Makalolo, the upper lip is
perforated, and a large metal and bamboo ring, called a pelele, is worn in
the hole. "This caused the lip in one case to project two inches beyond
the tip of the nose; and when the lady smiled, the contraction of the
muscles elevated it over the eyes. 'Why do the women wear these things?'
the venerable chief, Chinsurdi, was asked. Evidently surprised at such a
stupid question, he replied, 'For beauty! They are the only beautiful
things women have; men have beards, women have none. What kind of a person
would she be without the pelele? She would not be a woman at all with a
mouth like a man, but no beard.'" (49. Livingstone, 'British
Association,' 1860; report given in the 'Athenaeum,' July 7, 1860, p. 29.)
Hardly any part of the body, which can be unnaturally modified, has
escaped. The amount of suffering thus caused must have been extreme, for
many of the operations require several years for their completion, so that
the idea of their necessity must be imperative. The motives are various;
the men paint their bodies to make themselves appear terrible in battle;
certain mutilations are connected with religious rites, or they mark the
age of puberty, or the rank of the man, or they serve to distinguish the
tribes. Amongst savages the same fashions prevail for long periods (50.
Sir S. Baker (ibid. vol. i. p. 210) speaking of the natives of Central
Africa says, "every tribe has a distinct and unchanging fashion for
dressing the hair." See Agassiz ('Journey in Brazil,' 1868, p. 318) on
invariability of the tattooing of Amazonian Indians.), and thus
mutilations, from whatever cause first made, soon come to be valued as
distinctive marks. But self-adornment, vanity, and the admiration of
others, seem to be the commonest motives. In regard to tattooing, I was
told by the missionaries in New Zealand that when they tried to persuade
some girls to give up the practice, they answered, "We must just have a few
lines on our lips; else when we grow old we shall be so very ugly." With
the men of New Zealand, a most capable judge (51. Rev. R. Taylor, 'New
Zealand and its Inhabitants,' 1855, p. 152.) says, "to have fine tattooed
faces was the great ambition of the young, both to render themselves
attractive to the ladies, and conspicuous in war." A star tattooed on the
forehead and a spot on the chin are thought by the women in one part of
Africa to be irresistible attractions. (52. Mantegazza, 'Viaggi e Studi,'
p. 542.) In most, but not all parts of the world, the men are more
ornamented than the women, and often in a different manner; sometimes,
though rarely, the women are hardly at all ornamented. As the women are
made by savages to perform the greatest share of the work, and as they are
not allowed to eat the best kinds of food, so it accords with the
characteristic selfishness of man that they should not be allowed to
obtain, or use the finest ornaments. Lastly, it is a remarkable fact, as
proved by the foregoing quotations, that the same fashions in modifying the
shape of the head, in ornamenting the hair, in painting, tattooing, in
perforating the nose, lips, or ears, in removing or filing the teeth, etc.,
now prevail, and have long prevailed, in the most distant quarters of the
world. It is extremely improbable that these practices, followed by so
many distinct nations, should be due to tradition from any common source.
They indicate the close similarity of the mind of man, to whatever race he
may belong, just as do the almost universal habits of dancing,
masquerading, and making rude pictures.
Having made these preliminary remarks on the admiration felt by savages for
various ornaments, and for deformities most unsightly in our eyes, let us
see how far the men are attracted by the appearance of their women, and
what are their ideas of beauty. I have heard it maintained that savages
are quite indifferent about the beauty of their women, valuing them solely
as slaves; it may therefore be well to observe that this conclusion does
not at all agree with the care which the women take in ornamenting
themselves, or with their vanity. Burchell (53. 'Travels in South
Africa,' 1824, vol. i. p. 414.) gives an amusing account of a Bush-woman
who used as much grease, red ochre, and shining powder "as would have
ruined any but a very rich husband." She displayed also "much vanity and
too evident a consciousness of her superiority." Mr. Winwood Reade informs
me that the negroes of the West Coast often discuss the beauty of their
women. Some competent observers have attributed the fearfully common
practice of infanticide partly to the desire felt by the women to retain
their good looks. (54. See, for references, Gerland, 'Ueber das
Aussterben der Naturvolker,' 1868, ss. 51, 53, 55; also Azara, 'Voyages,'
etc., tom. ii. p. 116.) In several regions the women wear charms and use
love-philters to gain the affections of the men; and Mr. Brown enumerates
four plants used for this purpose by the women of North-Western America.
(55. On the vegetable productions used by the North-Western American
Indians, see 'Pharmaceutical Journal,' vol. x.)
Hearne (56. 'A Journey from Prince of Wales Fort,' 8vo. ed. 1796, p. 89.),
an excellent observer, who lived many years with the American Indians,
says, in speaking of the women, "Ask a Northern Indian what is beauty, and
he will answer, a broad flat face, small eyes, high cheek-bones, three or
four broad black lines across each cheek, a low forehead, a large broad
chin, a clumsy hook nose, a tawny hide, and breasts hanging down to the
belt." Pallas, who visited the northern parts of the Chinese empire, says,
"those women are preferred who have the Mandschu form; that is to say, a
broad face, high cheek-bones, very broad noses, and enormous ears"(57.
Quoted by Prichard, 'Physical History of Mankind,' 3rd ed. vol. iv. 1844,
p. 519; Vogt, 'Lectures on Man,' Eng. translat. p. 129. On the opinion of
the Chinese on the Cingalese, E. Tennent, 'Ceylon,' 1859, vol. ii. p.
107.); and Vogt remarks that the obliquity of the eye, which is proper to
the Chinese and Japanese, is exaggerated in their pictures for the purpose,
as it "seems, of exhibiting its beauty, as contrasted with the eye of the
red-haired barbarians." It is well known, as Huc repeatedly remarks, that
the Chinese of the interior think Europeans hideous, with their white skins
and prominent noses. The nose is far from being too prominent, according
to our ideas, in the natives of Ceylon; yet "the Chinese in the seventh
century, accustomed to the flat features of the Mongol races, were
surprised at the prominent noses of the Cingalese; and Thsang described
them as having 'the beak of a bird, with the body of a man.'"
Finlayson, after minutely describing the people of Cochin China, says that
their rounded heads and faces are their chief characteristics; and, he
adds, "the roundness of the whole countenance is more striking in the
women, who are reckoned beautiful in proportion as they display this form
of face." The Siamese have small noses with divergent nostrils, a wide
mouth, rather thick lips, a remarkably large face, with very high and broad
cheek-bones. It is, therefore, not wonderful that "beauty, according to
our notion, is a stranger to them. Yet they consider their own females to
be much more beautiful than those of Europe." (58. Prichard, as taken
from Crawfurd and Finlayson, 'Phys. Hist. of Mankind,' vol. iv. pp. 534,
535.)
It is well known that with many Hottentot women the posterior part of the
body projects in a wonderful manner; they are steatopygous; and Sir Andrew
Smith is certain that this peculiarity is greatly admired by the men. (59.
Idem illustrissimus viator dixit mihi praecinctorium vel tabulam foeminae,
quod nobis teterrimum est, quondam permagno aestimari ab hominibus in hac
gente. Nunc res mutata est, et censent talem conformationem minime
optandam esse.) He once saw a woman who was considered a beauty, and she
was so immensely developed behind, that when seated on level ground she
could not rise, and had to push herself along until she came to a slope.
Some of the women in various negro tribes have the same peculiarity; and,
according to Burton, the Somal men are said to choose their wives by
ranging them in a line, and by picking her out who projects farthest a
tergo. Nothing can be more hateful to a negro than the opposite form."
(60. The 'Anthropological Review,' November 1864, p. 237. For additional
references, see Waitz, 'Introduction to Anthropology,' Eng. translat.,
1863, vol. i. p. 105.)
With respect to colour, the negroes rallied Mungo Park on the whiteness of
his skin and the prominence of his nose, both of which they considered as
"unsightly and unnatural conformations." He in return praised the glossy
jet of their skins and the lovely depression of their noses; this they said
was "honeymouth," nevertheless they gave him food. The African Moors,
also, "knitted their brows and seemed to shudder" at the whiteness of his
skin. On the eastern coast, the negro boys when they saw Burton, cried
out, "Look at the white man; does he not look like a white ape?" On the
western coast, as Mr. Winwood Reade informs me, the negroes admire a very
black skin more than one of a lighter tint. But their horror of whiteness
may be attributed, according to this same traveller, partly to the belief
held by most negroes that demons and spirits are white, and partly to their
thinking it a sign of ill-health.
The Banyai of the more southern part of the continent are negroes, but "a
great many of them are of a light coffee-and-milk colour, and, indeed, this
colour is considered handsome throughout the whole country"; so that here
we have a different standard of taste. With the Kaffirs, who differ much
from negroes, "the skin, except among the tribes near Delagoa Bay, is not
usually black, the prevailing colour being a mixture of black and red, the
most common shade being chocolate. Dark complexions, as being most common,
are naturally held in the highest esteem. To be told that he is light-
coloured, or like a white man, would be deemed a very poor compliment by a
Kaffir. I have heard of one unfortunate man who was so very fair that no
girl would marry him." One of the titles of the Zulu king is, "You who are
black." (61. Mungo Park's 'Travels in Africa,' 4to. 1816, pp. 53, 131.
Burton's statement is quoted by Schaaffhausen, 'Archiv. fur Anthropologie,'
1866, s. 163. On the Banyai, Livingstone, 'Travels,' p. 64. On the
Kaffirs, the Rev. J. Shooter, 'The Kafirs of Natal and the Zulu Country,'
1857, p. 1.) Mr. Galton, in speaking to me about the natives of S. Africa,
remarked that their ideas of beauty seem very different from ours; for in
one tribe two slim, slight, and pretty girls were not admired by the
natives.
Turning to other quarters of the world; in Java, a yellow, not a white
girl, is considered, according to Madame Pfeiffer, a beauty. A man of
Cochin China "spoke with contempt of the wife of the English Ambassador,
that she had white teeth like a dog, and a rosy colour like that of potato-
flowers." We have seen that the Chinese dislike our white skin, and that
the N. Americans admire "a tawny hide." In S. America, the Yuracaras, who
inhabit the wooded, damp slopes of the eastern Cordillera, are remarkably
pale-coloured, as their name in their own language expresses; nevertheless
they consider European women as very inferior to their own. (62. For the
Javans and Cochin-Chinese, see Waitz, 'Introduct. to Anthropology,' Eng.
translat. vol. i. p. 305. On the Yuracaras, A. d'Orbigny, as quoted in
Prichard, 'Physical History of Mankind,' vol. v. 3rd ed. p. 476.)
In several of the tribes of North America the hair on the head grows to a
wonderful length; and Catlin gives a curious proof how much this is
esteemed, for the chief of the Crows was elected to this office from having
the longest hair of any man in the tribe, namely ten feet and seven inches.
The Aymaras and Quichuas of S. America, likewise have very long hair; and
this, as Mr. D. Forbes informs me, is so much valued as a beauty, that
cutting it off was the severest punishment which he could inflict on them.
In both the Northern and Southern halves of the continent the natives
sometimes increase the apparent length of their hair by weaving into it
fibrous substances. Although the hair on the head is thus cherished, that
on the face is considered by the North American Indians "as very vulgar,"
and every hair is carefully eradicated. This practice prevails throughout
the American continent from Vancouver's Island in the north to Tierra del
Fuego in the south. When York Minster, a Fuegian on board the "Beagle,"
was taken back to his country, the natives told him be ought to pull out
the few short hairs on his face. They also threatened a young missionary,
who was left for a time with them, to strip him naked, and pluck the hair
from his face and body, yet he was far from being a hairy man. This
fashion is carried so far that the Indians of Paraguay eradicate their
eyebrows and eyelashes, saying that they do not wish to be like horses.
(63. 'North American Indians,' by G. Catlin, 3rd ed., 1842, vol. i. p. 49;
vol. ii, p. 227. On the natives of Vancouver's Island, see Sproat, 'Scenes
and Studies of Savage Life,' 1868, p. 25. On the Indians of Paraguay,
Azara, 'Voyages,' tom. ii. p. 105.)
It is remarkable that throughout the world the races which are almost
completely destitute of a beard dislike hairs on the face and body, and
take pains to eradicate them. The Kalmucks are beardless, and they are
well known, like the Americans, to pluck out all straggling hairs; and so
it is with the Polynesians, some of the Malays, and the Siamese. Mr.
Veitch states that the Japanese ladies "all objected to our whiskers,
considering them very ugly, and told us to cut them off, and be like
Japanese men." The New Zealanders have short, curled beards; yet they
formerly plucked out the hairs on the face. They had a saying that "there
is no woman for a hairy man;" but it would appear that the fashion has
changed in New Zealand, perhaps owing to the presence of Europeans, and I
am assured that beards are now admired by the Maories. (64. On the
Siamese, Prichard, ibid. vol. iv. p. 533. On the Japanese, Veitch in
'Gardeners' Chronicle,' 1860, p. 1104. On the New Zealanders, Mantegazza,
'Viaggi e Studi,' 1867, p. 526. For the other nations mentioned, see
references in Lawrence, 'Lectures on Physiology,' etc., 1822, p. 272.)
On the other hand, bearded races admire and greatly value their beards;
among the Anglo-Saxons every part of the body had a recognised value; "the
loss of the beard being estimated at twenty shillings, while the breaking
of a thigh was fixed at only twelve." (65. Lubbock, 'Origin of
Civilisation,' 1870, p. 321.) In the East men swear solemnly by their
beards. We have seen that Chinsurdi, the chief of the Makalolo in Africa,
thought that beards were a great ornament. In the Pacific the Fijian's
beard is "profuse and bushy, and is his greatest pride"; whilst the
inhabitants of the adjacent archipelagoes of Tonga and Samoa are
"beardless, and abhor a rough chin." In one island alone of the Ellice
group "the men are heavily bearded, and not a little proud thereof." (66.
Dr. Barnard Davis quotes Mr. Prichard and others for these facts in regard
to the Polynesians, in 'Anthropolog. Review,' April 1870, pp. 185, 191.)
We thus see how widely the different races of man differ in their taste for
the beautiful. In every nation sufficiently advanced to have made effigies
of their gods or of their deified rulers, the sculptors no doubt have
endeavoured to express their highest ideal of beauty and grandeur. (67.
Ch. Comte has remarks to this effect in his 'Traite de Legislation,' 3rd
ed. 1837, p. 136.) Under this point of view it is well to compare in our
mind the Jupiter or Apollo of the Greeks with the Egyptian or Assyrian
statues; and these with the hideous bas-reliefs on the ruined buildings of
Central America.
I have met with very few statements opposed to this conclusion. Mr.
Winwood Reade, however, who has had ample opportunities for observation,
not only with the negroes of the West Coast of Africa, but with those of
the interior who have never associated with Europeans, is convinced that
their ideas of beauty are ON THE WHOLE the same as ours; and Dr. Rohlfs
writes to me to the same effect with respect to Bornu and the countries
inhabited by the Pullo tribes. Mr. Reade found that he agreed with the
negroes in their estimation of the beauty of the native girls; and that
their appreciation of the beauty of European women corresponded with ours.
They admire long hair, and use artificial means to make it appear abundant;
they admire also a beard, though themselves very scantily provided. Mr.
Reade feels doubtful what kind of nose is most appreciated; a girl has been
heard to say, "I do not want to marry him, he has got no nose"; and this
shews that a very flat nose is not admired. We should, however, bear in
mind that the depressed, broad noses and projecting jaws of the negroes of
the West Coast are exceptional types with the inhabitants of Africa.
Notwithstanding the foregoing statements, Mr. Reade admits that negroes "do
not like the colour of our skin; they look on blue eyes with aversion, and
they think our noses too long and our lips too thin." He does not think it
probable that negroes would ever prefer the most beautiful European woman,
on the mere grounds of physical admiration, to a good-looking negress.
(68. The 'African Sketch Book,' vol. ii. 1873, pp. 253, 394, 521. The
Fuegians, as I have been informed by a missionary who long resided with
them, consider European women as extremely beautiful; but from what we have
seen of the judgment of the other aborigines of America, I cannot but think
that this must be a mistake, unless indeed the statement refers to the few
Fuegians who have lived for some time with Europeans, and who must consider
us as superior beings. I should add that a most experienced observer,
Capt. Burton, believes that a woman whom we consider beautiful is admired
throughout the world. 'Anthropological Review,' March, 1864, p. 245.)
The general truth of the principle, long ago insisted on by Humboldt (69.
'Personal Narrative,' Eng. translat. vol. iv. p. 518, and elsewhere.
Mantegazza, in his 'Viaggi e Studi,' strongly insists on this same
principle.), that man admires and often tries to exaggerate whatever
characters nature may have given him, is shewn in many ways. The practice
of beardless races extirpating every trace of a beard, and often all the
hairs on the body affords one illustration. The skull has been greatly
modified during ancient and modern times by many nations; and there can be
little doubt that this has been practised, especially in N. and S. America,
in order to exaggerate some natural and admired peculiarity. Many American
Indians are known to admire a head so extremely flattened as to appear to
us idiotic. The natives on the north-western coast compress the head into
a pointed cone; and it is their constant practice to gather the hair into a
knot on the top of the head, for the sake, as Dr. Wilson remarks, "of
increasing the apparent elevation of the favourite conoid form." The
inhabitants of Arakhan admire a broad, smooth forehead, and in order to
produce it, they fasten a plate of lead on the heads of the new-born
children. On the other hand, "a broad, well-rounded occiput is considered
a great beauty" by the natives of the Fiji Islands. (70. On the skulls of
the American tribes, see Nott and Gliddon, 'Types of Mankind,' 1854, p.
440; Prichard, 'Physical History of Mankind,' vol. i. 3rd ed. p. 321; on
the natives of Arakhan, ibid. vol. iv. p. 537. Wilson, 'Physical
Ethnology,' Smithsonian Institution, 1863, p. 288; on the Fijians, p. 290.
Sir J. Lubbock ('Prehistoric Times,' 2nd ed. 1869, p. 506) gives an
excellent resume on this subject.)
As with the skull, so with the nose; the ancient Huns during the age of
Attila were accustomed to flatten the noses of their infants with bandages,
"for the sake of exaggerating a natural conformation." With the Tahitians,
to be called LONG-NOSE is considered as an insult, and they compress the
noses and foreheads of their children for the sake of beauty. The same
holds with the Malays of Sumatra, the Hottentots, certain Negroes, and the
natives of Brazil. (71. On the Huns, Godron, 'De l'Espece,' tom. ii.
1859, p. 300. On the Tahitians, Waitz, 'Anthropology,' Eng. translat. vol.
i. p. 305. Marsden, quoted by Prichard, 'Phys. Hist. of Mankind,' 3rd
edit. vol. v. p. 67. Lawrence, 'Lectures on Physiology,' p. 337.) The
Chinese have by nature unusually small feet (72. This fact was ascertained
in the 'Reise der Novara: Anthropolog. Theil.' Dr. Weisbach, 1867, s.
265.); and it is well known that the women of the upper classes distort
their feet to make them still smaller. Lastly, Humboldt thinks that the
American Indians prefer colouring their bodies with red paint in order to
exaggerate their natural tint; and until recently European women added to
their naturally bright colours by rouge and white cosmetics; but it may be
doubted whether barbarous nations have generally had any such intention in
painting themselves.
In the fashions of our own dress we see exactly the same principle and the
same desire to carry every point to an extreme; we exhibit, also, the same
spirit of emulation. But the fashions of savages are far more permanent
than ours; and whenever their bodies are artificially modified, this is
necessarily the case. The Arab women of the Upper Nile occupy about three
days in dressing their hair; they never imitate other tribes, "but simply
vie with each other in the superlativeness of their own style." Dr.
Wilson, in speaking of the compressed skulls of various American races,
adds, "such usages are among the least eradicable, and long survive the
shock of revolutions that change dynasties and efface more important
national peculiarities." (73. 'Smithsonian Institution,' 1863, p. 289.
On the fashions of Arab women, Sir S. Baker, 'The Nile Tributaries,' 1867,
p. 121.) The same principle comes into play in the art of breeding; and we
can thus understand, as I have elsewhere explained (74. The 'Variation of
Animals and Plants under Domestication,' vol. i. p. 214; vol. ii. p. 240.),
the wonderful development of the many races of animals and plants, which
have been kept merely for ornament. Fanciers always wish each character to
be somewhat increased; they do not admire a medium standard; they certainly
do not desire any great and abrupt change in the character of their breeds;
they admire solely what they are accustomed to, but they ardently desire to
see each characteristic feature a little more developed.
The senses of man and of the lower animals seem to be so constituted that
brilliant colours and certain forms, as well as harmonious and rhythmical
sounds, give pleasure and are called beautiful; but why this should be so
we know not. It is certainly not true that there is in the mind of man any
universal standard of beauty with respect to the human body. It is,
however, possible that certain tastes may in the course of time become
inherited, though there is no evidence in favour of this belief: and if
so, each race would possess its own innate ideal standard of beauty. It
has been argued (75. Schaaffhausen, 'Archiv. fur Anthropologie,' 1866, s.
164.) that ugliness consists in an approach to the structure of the lower
animals, and no doubt this is partly true with the more civilised nations,
in which intellect is highly appreciated; but this explanation will hardly
apply to all forms of ugliness. The men of each race prefer what they are
accustomed to; they cannot endure any great change; but they like variety,
and admire each characteristic carried to a moderate extreme. (76. Mr.
Bain has collected ('Mental and Moral Science,' 1868, pp. 304-314) about a
dozen more or less different theories of the idea of beauty; but none is
quite the same as that here given.) Men accustomed to a nearly oval face,
to straight and regular features, and to bright colours, admire, as we
Europeans know, these points when strongly developed. On the other hand,
men accustomed to a broad face, with high cheek-bones, a depressed nose,
and a black skin, admire these peculiarities when strongly marked. No
doubt characters of all kinds may be too much developed for beauty. Hence
a perfect beauty, which implies many characters modified in a particular
manner, will be in every race a prodigy. As the great anatomist Bichat
long ago said, if every one were cast in the same mould, there would be no
such thing as beauty. If all our women were to become as beautiful as the
Venus de' Medici, we should for a time be charmed; but we should soon wish
for variety; and as soon as we had obtained variety, we should wish to see
certain characters a little exaggerated beyond the then existing common
standard.
CHAPTER XX.
SECONDARY SEXUAL CHARACTERS OF MAN--continued.
On the effects of the continued selection of women according to a different
standard of beauty in each race--On the causes which interfere with sexual
selection in civilised and savage nations--Conditions favourable to sexual
selection during primeval times--On the manner of action of sexual
selection with mankind--On the women in savage tribes having some power to
choose their husbands--Absence of hair on the body, and development of the
beard--Colour of the skin--Summary.
We have seen in the last chapter that with all barbarous races ornaments,
dress, and external appearance are highly valued; and that the men judge of
the beauty of their women by widely different standards. We must next
inquire whether this preference and the consequent selection during many
generations of those women, which appear to the men of each race the most
attractive, has altered the character either of the females alone, or of
both sexes. With mammals the general rule appears to be that characters of
all kinds are inherited equally by the males and females; we might
therefore expect that with mankind any characters gained by the females or
by the males through sexual selection would commonly be transferred to the
offspring of both sexes. If any change has thus been effected, it is
almost certain that the different races would be differently modified, as
each has its own standard of beauty.
With mankind, especially with savages, many causes interfere with the
action of sexual selection as far as the bodily frame is concerned.
Civilised men are largely attracted by the mental charms of women, by their
wealth, and especially by their social position; for men rarely marry into
a much lower rank. The men who succeed in obtaining the more beautiful
women will not have a better chance of leaving a long line of descendants
than other men with plainer wives, save the few who bequeath their fortunes
according to primogeniture. With respect to the opposite form of
selection, namely, of the more attractive men by the women, although in
civilised nations women have free or almost free choice, which is not the
case with barbarous races, yet their choice is largely influenced by the
social position and wealth of the men; and the success of the latter in
life depends much on their intellectual powers and energy, or on the fruits
of these same powers in their forefathers. No excuse is needed for
treating this subject in some detail; for, as the German philosopher
Schopenhauer remarks, "the final aim of all love intrigues, be they comic
or tragic, is really of more importance than all other ends in human life.
What it all turns upon is nothing less than the composition of the next
generation...It is not the weal or woe of any one individual, but that of
the human race to come, which is here at stake." (1. 'Schopenhauer and
Darwinism,' in 'Journal of Anthropology,' Jan. 1871, p. 323.
There is, however, reason to believe that in certain civilised and semi-
civilised nations sexual selection has effected something in modifying the
bodily frame of some of the members. Many persons are convinced, as it
appears to me with justice, that our aristocracy, including under this term
all wealthy families in which primogeniture has long prevailed, from having
chosen during many generations from all classes the more beautiful women as
their wives, have become handsomer, according to the European standard,
than the middle classes; yet the middle classes are placed under equally
favourable conditions of life for the perfect development of the body.
Cook remarks that the superiority in personal appearance "which is
observable in the erees or nobles in all the other islands (of the Pacific)
is found in the Sandwich Islands"; but this may be chiefly due to their
better food and manner of life.
The old traveller Chardin, in describing the Persians, says their "blood is
now highly refined by frequent intermixtures with the Georgians and
Circassians, two nations which surpass all the world in personal beauty.
There is hardly a man of rank in Persia who is not born of a Georgian or
Circassian mother." He adds that they inherit their beauty, "not from
their ancestors, for without the above mixture, the men of rank in Persia,
who are descendants of the Tartars, would be extremely ugly." (2. These
quotations are taken from Lawrence ('Lectures on Physiology,' etc., 1822,
p. 393), who attributes the beauty of the upper classes in England to the
men having long selected the more beautiful women.) Here is a more curious
case; the priestesses who attended the temple of Venus Erycina at San-
Giuliano in Sicily, were selected for their beauty out of the whole of
Greece; they were not vestal virgins, and Quatrefages (3. 'Anthropologie,'
'Revue des Cours Scientifiques,' Oct. 1868, p. 721.), who states the
foregoing fact, says that the women of San-Giuliano are now famous as the
most beautiful in the island, and are sought by artists as models. But it
is obvious that the evidence in all the above cases is doubtful.
The following case, though relating to savages, is well worth giving for
its curiosity. Mr. Winwood Reade informs me that the Jollofs, a tribe of
negroes on the west coast of Africa, "are remarkable for their uniformly
fine appearance." A friend of his asked one of these men, "How is it that
every one whom I meet is so fine looking, not only your men but your
women?" The Jollof answered, "It is very easily explained: it has always
been our custom to pick out our worst-looking slaves and to sell them." It
need hardly be added that with all savages, female slaves serve as
concubines. That this negro should have attributed, whether rightly or
wrongly, the fine appearance of his tribe to the long-continued elimination
of the ugly women is not so surprising as it may at first appear; for I
have elsewhere shewn (4. 'Variation of Animals and Plants under
Domestication,' vol. i. p. 207.) that negroes fully appreciate the
importance of selection in the breeding of their domestic animals, and I
could give from Mr. Reade additional evidence on this head.
THE CAUSES WHICH PREVENT OR CHECK THE ACTION OF SEXUAL SELECTION WITH
SAVAGES.
The chief causes are, first, so-called communal marriages or promiscuous
intercourse; secondly, the consequences of female infanticide; thirdly,
early betrothals; and lastly, the low estimation in which women are held,
as mere slaves. These four points must be considered in some detail.
It is obvious that as long as the pairing of man, or of any other animal,
is left to mere chance, with no choice exerted by either sex, there can be
no sexual selection; and no effect will be produced on the offspring by
certain individuals having had an advantage over others in their courtship.
Now it is asserted that there exist at the present day tribes which
practise what Sir J. Lubbock by courtesy calls communal marriages; that is,
all the men and women in the tribe are husbands and wives to one another.
The licentiousness of many savages is no doubt astonishing, but it seems to
me that more evidence is requisite, before we fully admit that their
intercourse is in any case promiscuous. Nevertheless all those who have
most closely studied the subject (5. Sir J. Lubbock, 'The Origin of
Civilisation,' 1870, chap. iii. especially pp. 60-67. Mr. M'Lennan, in his
extremely valuable work on 'Primitive Marriage,' 1865, p. 163, speaks of
the union of the sexes "in the earliest times as loose, transitory, and in
some degree promiscuous." Mr. M'Lennan and Sir J. Lubbock have collected
much evidence on the extreme licentiousness of savages at the present time.
Mr. L.H. Morgan, in his interesting memoir of the classificatory system of
relationship. ('Proceedings of the American Academy of Sciences,' vol.
vii. Feb. 1868, p. 475), concludes that polygamy and all forms of marriage
during primeval times were essentially unknown. It appears also, from Sir
J. Lubbock's work, that Bachofen likewise believes that communal
intercourse originally prevailed.), and whose judgment is worth much more
than mine, believe that communal marriage (this expression being variously
guarded) was the original and universal form throughout the world,
including therein the intermarriage of brothers and sisters. The late Sir
A. Smith, who had travelled widely in S. Africa, and knew much about the
habits of savages there and elsewhere, expressed to me the strongest
opinion that no race exists in which woman is considered as the property of
the community. I believe that his judgment was largely determined by what
is implied by the term marriage. Throughout the following discussion I use
the term in the same sense as when naturalists speak of animals as
monogamous, meaning thereby that the male is accepted by or chooses a
single female, and lives with her either during the breeding-season or for
the whole year, keeping possession of her by the law of might; or, as when
they speak of a polygamous species, meaning that the male lives with
several females. This kind of marriage is all that concerns us here, as it
suffices for the work of sexual selection. But I know that some of the
writers above referred to imply by the term marriage a recognised right
protected by the tribe.
The indirect evidence in favour of the belief of the former prevalence of
communal marriages is strong, and rests chiefly on the terms of
relationship which are employed between the members of the same tribe,
implying a connection with the tribe, and not with either parent. But the
subject is too large and complex for even an abstract to be here given, and
I will confine myself to a few remarks. It is evident in the case of such
marriages, or where the marriage tie is very loose, that the relationship
of the child to its father cannot be known. But it seems almost incredible
that the relationship of the child to its mother should ever be completely
ignored, especially as the women in most savage tribes nurse their infants
for a long time. Accordingly, in many cases the lines of descent are
traced through the mother alone, to the exclusion of the father. But in
other cases the terms employed express a connection with the tribe alone,
to the exclusion even of the mother. It seems possible that the connection
between the related members of the same barbarous tribe, exposed to all
sorts of danger, might be so much more important, owing to the need of
mutual protection and aid, than that between the mother and her child, as
to lead to the sole use of terms expressive of the former relationships;
but Mr. Morgan is convinced that this view is by no means sufficient.
The terms of relationship used in different parts of the world may be
divided, according to the author just quoted, into two great classes, the
classificatory and descriptive, the latter being employed by us. It is the
classificatory system which so strongly leads to the belief that communal
and other extremely loose forms of marriage were originally universal. But
as far as I can see, there is no necessity on this ground for believing in
absolutely promiscuous intercourse; and I am glad to find that this is Sir
J. Lubbock's view. Men and women, like many of the lower animals, might
formerly have entered into strict though temporary unions for each birth,
and in this case nearly as much confusion would have arisen in the terms of
relationship as in the case of promiscuous intercourse. As far as sexual
selection is concerned, all that is required is that choice should be
exerted before the parents unite, and it signifies little whether the
unions last for life or only for a season.
Besides the evidence derived from the terms of relationship, other lines of
reasoning indicate the former wide prevalence of communal marriage. Sir J.
Lubbock accounts for the strange and widely-extended habit of exogamy--that
is, the men of one tribe taking wives from a distinct tribe,--by communism
having been the original form of intercourse; so that a man never obtained
a wife for himself unless he captured her from a neighbouring and hostile
tribe, and then she would naturally have become his sole and valuable
property. Thus the practice of capturing wives might have arisen; and from
the honour so gained it might ultimately have become the universal habit.
According to Sir J. Lubbock (6. 'Address to British Association On the
Social and Religious Condition of the Lower Races of Man,' 1870, p. 20.),
we can also thus understand "the necessity of expiation for marriage as an
infringement of tribal rites, since according to old ideas, a man had no
right to appropriate to himself that which belonged to the whole tribe."
Sir J. Lubbock further gives a curious body of facts shewing that in old
times high honour was bestowed on women who were utterly licentious; and
this, as he explains, is intelligible, if we admit that promiscuous
intercourse was the aboriginal, and therefore long revered custom of the
tribe. (7. 'Origin of Civilisation,' 1870, p. 86. In the several works
above quoted, there will be found copious evidence on relationship through
the females alone, or with the tribe alone.)
Although the manner of development of the marriage tie is an obscure
subject, as we may infer from the divergent opinions on several points
between the three authors who have studied it most closely, namely, Mr.
Morgan, Mr. M'Lennan, and Sir J. Lubbock, yet from the foregoing and
several other lines of evidence it seems probable (8. Mr. C. Staniland
Wake argues strongly ('Anthropologia,' March, 1874, p. 197) against the
views held by these three writers on the former prevalence of almost
promiscuous intercourse; and he thinks that the classificatory system of
relationship can be otherwise explained.) that the habit of marriage, in
any strict sense of the word, has been gradually developed; and that almost
promiscuous or very loose intercourse was once extremely common throughout
the world. Nevertheless, from the strength of the feeling of jealousy all
through the animal kingdom, as well as from the analogy of the lower
animals, more particularly of those which come nearest to man, I cannot
believe that absolutely promiscuous intercourse prevailed in times past,
shortly before man attained to his present rank in the zoological scale.
Man, as I have attempted to shew, is certainly descended from some ape-like
creature. With the existing Quadrumana, as far as their habits are known,
the males of some species are monogamous, but live during only a part of
the year with the females: of this the orang seems to afford an instance.
Several kinds, for example some of the Indian and American monkeys, are
strictly monogamous, and associate all the year round with their wives.
Others are polygamous, for example the gorilla and several American
species, and each family lives separate. Even when this occurs, the
families inhabiting the same district are probably somewhat social; the
chimpanzee, for instance, is occasionally met with in large bands. Again,
other species are polygamous, but several males, each with his own females,
live associated in a body, as with several species of baboons. (9. Brehm
('Thierleben,' B. i. p. 77) says Cynocephalus hamadryas lives in great
troops containing twice as many adult females as adult males. See Rengger
on American polygamous species, and Owen ('Anatomy of Vertebrates,' vol.
iii. p. 746) on American monogamous species. Other references might be
added.) We may indeed conclude from what we know of the jealousy of all
male quadrupeds, armed, as many of them are, with special weapons for
battling with their rivals, that promiscuous intercourse in a state of
nature is extremely improbable. The pairing may not last for life, but
only for each birth; yet if the males which are the strongest and best able
to defend or otherwise assist their females and young, were to select the
more attractive females, this would suffice for sexual selection.
Therefore, looking far enough back in the stream of time, and judging from
the social habits of man as he now exists, the most probable view is that
he aboriginally lived in small communities, each with a single wife, or if
powerful with several, whom he jealously guarded against all other men. Or
he may not have been a social animal, and yet have lived with several
wives, like the gorilla; for all the natives "agree that but one adult male
is seen in a band; when the young male grows up, a contest takes place for
mastery, and the strongest, by killing and driving out the others,
establishes himself as the head of the community." (10. Dr. Savage, in
'Boston Journal of Natural History,' vol. v. 1845-47, p. 423.) The younger
males, being thus expelled and wandering about, would, when at last
successful in finding a partner, prevent too close interbreeding within the
limits of the same family.
Although savages are now extremely licentious, and although communal
marriages may formerly have largely prevailed, yet many tribes practise
some form of marriage, but of a far more lax nature than that of civilised
nations. Polygamy, as just stated, is almost universally followed by the
leading men in every tribe. Nevertheless there are tribes, standing almost
at the bottom of the scale, which are strictly monogamous. This is the
case with the Veddahs of Ceylon: they have a saying, according to Sir J.
Lubbock (11. 'Prehistoric Times,' 1869, p. 424.), "that death alone can
separate husband and wife." An intelligent Kandyan chief, of course a
polygamist, "was perfectly scandalised at the utter barbarism of living
with only one wife, and never parting until separated by death." It was,
he said, "just like the Wanderoo monkeys." Whether savages who now enter
into some form of marriage, either polygamous or monogamous, have retained
this habit from primeval times, or whether they have returned to some form
of marriage, after passing through a stage of promiscuous intercourse, I
will not pretend to conjecture.
INFANTICIDE.
This practice is now very common throughout the world, and there is reason
to believe that it prevailed much more extensively during former times.
(12. Mr. M'Lennan, 'Primitive Marriage,' 1865. See especially on exogamy
and infanticide, pp. 130, 138, 165.) Barbarians find it difficult to
support themselves and their children, and it is a simple plan to kill
their infants. In South America some tribes, according to Azara, formerly
destroyed so many infants of both sexes that they were on the point of
extinction. In the Polynesian Islands women have been known to kill from
four or five, to even ten of their children; and Ellis could not find a
single woman who had not killed at least one. In a village on the eastern
frontier of India Colonel MacCulloch found not a single female child.
Wherever infanticide (13. Dr. Gerland ('Ueber das Aussterben der
Naturvolker,' 1868) has collected much information on infanticide, see
especially ss. 27, 51, 54. Azara ('Voyages,' etc., tom. ii. pp. 94, 116)
enters in detail on the motives. See also M'Lennan (ibid. p. 139) for
cases in India. In the former reprints of the 2nd edition of this book an
incorrect quotation from Sir G. Grey was unfortunately given in the above
passage and has now been removed from the text.) prevails the struggle for
existence will be in so far less severe, and all the members of the tribe
will have an almost equally good chance of rearing their few surviving
children. In most cases a larger number of female than of male infants are
destroyed, for it is obvious that the latter are of more value to the
tribe, as they will, when grown up, aid in defending it, and can support
themselves. But the trouble experienced by the women in rearing children,
their consequent loss of beauty, the higher estimation set on them when
few, and their happier fate, are assigned by the women themselves, and by
various observers, as additional motives for infanticide.
When, owing to female infanticide, the women of a tribe were few, the habit
of capturing wives from neighbouring tribes would naturally arise. Sir J.
Lubbock, however, as we have seen, attributes the practice in chief part to
the former existence of communal marriage, and to the men having
consequently captured women from other tribes to hold as their sole
property. Additional causes might be assigned, such as the communities
being very small, in which case, marriageable women would often be
deficient. That the habit was most extensively practised during former
times, even by the ancestors of civilised nations, is clearly shewn by the
preservation of many curious customs and ceremonies, of which Mr. M'Lennan
has given an interesting account. In our own marriages the "best man"
seems originally to have been the chief abettor of the bridegroom in the
act of capture. Now as long as men habitually procured their wives through
violence and craft, they would have been glad to seize on any woman, and
would not have selected the more attractive ones. But as soon as the
practice of procuring wives from a distinct tribe was effected through
barter, as now occurs in many places, the more attractive women would
generally have been purchased. The incessant crossing, however, between
tribe and tribe, which necessarily follows from any form of this habit,
would tend to keep all the people inhabiting the same country nearly
uniform in character; and this would interfere with the power of sexual
selection in differentiating the tribes.
The scarcity of women, consequent on female infanticide, leads, also, to
another practice, that of polyandry, still common in several parts of the
world, and which formerly, as Mr. M'Lennan believes, prevailed almost
universally: but this latter conclusion is doubted by Mr. Morgan and Sir
J. Lubbock. (14. 'Primitive Marriage,' p. 208; Sir J. Lubbock, 'Origin of
Civilisation,' p. 100. See also Mr. Morgan, loc. cit., on the former
prevalence of polyandry.) Whenever two or more men are compelled to marry
one woman, it is certain that all the women of the tribe will get married,
and there will be no selection by the men of the more attractive women.
But under these circumstances the women no doubt will have the power of
choice, and will prefer the more attractive men. Azara, for instance,
describes how carefully a Guana woman bargains for all sorts of privileges,
before accepting some one or more husbands; and the men in consequence take
unusual care of their personal appearance. So amongst the Todas of India,
who practise polyandry, the girls can accept or refuse any man. (15.
Azara, 'Voyages,' etc., tom. ii. pp. 92-95; Colonel Marshall, 'Amongst the
Todas,' p. 212.) A very ugly man in these cases would perhaps altogether
fail in getting a wife, or get one later in life; but the handsomer men,
although more successful in obtaining wives, would not, as far as we can
see, leave more offspring to inherit their beauty than the less handsome
husbands of the same women.
EARLY BETROTHALS AND SLAVERY OF WOMEN.
With many savages it is the custom to betroth the females whilst mere
infants; and this would effectually prevent preference being exerted on
either side according to personal appearance. But it would not prevent the
more attractive women from being afterwards stolen or taken by force from
their husbands by the more powerful men; and this often happens in
Australia, America, and elsewhere. The same consequences with reference to
sexual selection would to a certain extent follow, when women are valued
almost solely as slaves or beasts of burden, as is the case with many
savages. The men, however, at all times would prefer the handsomest slaves
according to their standard of beauty.
We thus see that several customs prevail with savages which must greatly
interfere with, or completely stop, the action of sexual selection. On the
other hand, the conditions of life to which savages are exposed, and some
of their habits, are favourable to natural selection; and this comes into
play at the same time with sexual selection. Savages are known to suffer
severely from recurrent famines; they do not increase their food by
artificial means; they rarely refrain from marriage (16. Burchell says
('Travels in S. Africa,' vol. ii. 1824, p. 58), that among the wild nations
of Southern Africa, neither men nor women ever pass their lives in a state
of celibacy. Azara ('Voyages dans l'Amerique Merid.' tom. ii. 1809, p. 21)
makes precisely the same remark in regard to the wild Indians of South
America.), and generally marry whilst young. Consequently they must be
subjected to occasional hard struggles for existence, and the favoured
individuals will alone survive.
At a very early period, before man attained to his present rank in the
scale, many of his conditions would be different from what now obtains
amongst savages. Judging from the analogy of the lower animals, he would
then either live with a single female, or be a polygamist. The most
powerful and able males would succeed best in obtaining attractive females.
They would also succeed best in the general struggle for life, and in
defending their females, as well as their offspring, from enemies of all
kinds. At this early period the ancestors of man would not be sufficiently
advanced in intellect to look forward to distant contingencies; they would
not foresee that the rearing of all their children, especially their female
children, would make the struggle for life severer for the tribe. They
would be governed more by their instincts and less by their reason than are
savages at the present day. They would not at that period have partially
lost one of the strongest of all instincts, common to all the lower
animals, namely the love of their young offspring; and consequently they
would not have practised female infanticide. Women would not have been
thus rendered scarce, and polyandry would not have been practised; for
hardly any other cause, except the scarcity of women seems sufficient to
break down the natural and widely prevalent feeling of jealousy, and the
desire of each male to possess a female for himself. Polyandry would be a
natural stepping-stone to communal marriages or almost promiscuous
intercourse; though the best authorities believe that this latter habit
preceded polyandry. During primordial times there would be no early
betrothals, for this implies foresight. Nor would women be valued merely
as useful slaves or beasts of burthen. Both sexes, if the females as well
as the males were permitted to exert any choice, would choose their
partners not for mental charms, or property, or social position, but almost
solely from external appearance. All the adults would marry or pair, and
all the offspring, as far as that was possible, would be reared; so that
the struggle for existence would be periodically excessively severe. Thus
during these times all the conditions for sexual selection would have been
more favourable than at a later period, when man had advanced in his
intellectual powers but had retrograded in his instincts. Therefore,
whatever influence sexual selection may have had in producing the
differences between the races of man, and between man and the higher
Quadrumana, this influence would have been more powerful at a remote period
than at the present day, though probably not yet wholly lost.
THE MANNER OF ACTION OF SEXUAL SELECTION WITH MANKIND.
With primeval man under the favourable conditions just stated, and with
those savages who at the present time enter into any marriage tie, sexual
selection has probably acted in the following manner, subject to greater or
less interference from female infanticide, early betrothals, etc. The
strongest and most vigorous men--those who could best defend and hunt for
their families, who were provided with the best weapons and possessed the
most property, such as a large number of dogs or other animals,--would
succeed in rearing a greater average number of offspring than the weaker
and poorer members of the same tribes. There can, also, be no doubt that
such men would generally be able to select the more attractive women. At
present the chiefs of nearly every tribe throughout the world succeed in
obtaining more than one wife. I hear from Mr. Mantell that, until
recently, almost every girl in New Zealand who was pretty, or promised to
be pretty, was tapu to some chief. With the Kafirs, as Mr. C. Hamilton
states (17. 'Anthropological Review,' Jan. 1870, p. xvi.), "the chiefs
generally have the pick of the women for many miles round, and are most
persevering in establishing or confirming their privilege." We have seen
that each race has its own style of beauty, and we know that it is natural
to man to admire each characteristic point in his domestic animals, dress,
ornaments, and personal appearance, when carried a little beyond the
average. If then the several foregoing propositions be admitted, and I
cannot see that they are doubtful, it would be an inexplicable circumstance
if the selection of the more attractive women by the more powerful men of
each tribe, who would rear on an average a greater number of children, did
not after the lapse of many generations somewhat modify the character of
the tribe.
When a foreign breed of our domestic animals is introduced into a new
country, or when a native breed is long and carefully attended to, either
for use or ornament, it is found after several generations to have
undergone a greater or less amount of change whenever the means of
comparison exist. This follows from unconscious selection during a long
series of generations--that is, the preservation of the most approved
individuals--without any wish or expectation of such a result on the part
of the breeder. So again, if during many years two careful breeders rear
animals of the same family, and do not compare them together or with a
common standard, the animals are found to have become, to the surprise of
their owners, slightly different. (18. The 'Variation of Animals and
Plants under Domestication,' vol. ii. pp. 210-217.) Each breeder has
impressed, as von Nathusius well expresses it, the character of his own
mind--his own taste and judgment--on his animals. What reason, then, can
be assigned why similar results should not follow from the long-continued
selection of the most admired women by those men of each tribe who were
able to rear the greatest number of children? This would be unconscious
selection, for an effect would be produced, independently of any wish or
expectation on the part of the men who preferred certain women to others.
Let us suppose the members of a tribe, practising some form of marriage, to
spread over an unoccupied continent, they would soon split up into distinct
hordes, separated from each other by various barriers, and still more
effectually by the incessant wars between all barbarous nations. The
hordes would thus be exposed to slightly different conditions and habits of
life, and would sooner or later come to differ in some small degree. As
soon as this occurred, each isolated tribe would form for itself a slightly
different standard of beauty (19. An ingenious writer argues, from a
comparison of the pictures of Raphael, Rubens, and modern French artists,
that the idea of beauty is not absolutely the same even throughout Europe:
see the 'Lives of Haydn and Mozart,' by Bombet (otherwise M. Beyle),
English translation, p. 278.); and then unconscious selection would come
into action through the more powerful and leading men preferring certain
women to others. Thus the differences between the tribes, at first very
slight, would gradually and inevitably be more or less increased.
With animals in a state of nature, many characters proper to the males,
such as size, strength, special weapons, courage and pugnacity, have been
acquired through the law of battle. The semi-human progenitors of man,
like their allies the Quadrumana, will almost certainly have been thus
modified; and, as savages still fight for the possession of their women, a
similar process of selection has probably gone on in a greater or less
degree to the present day. Other characters proper to the males of the
lower animals, such as bright colours and various ornaments, have been
acquired by the more attractive males having been preferred by the females.
There are, however, exceptional cases in which the males are the selectors,
instead of having been the selected. We recognise such cases by the
females being more highly ornamented than the males,--their ornamental
characters having been transmitted exclusively or chiefly to their female
offspring. One such case has been described in the order to which man
belongs, that of the Rhesus monkey.
Man is more powerful in body and mind than woman, and in the savage state
he keeps her in a far more abject state of bondage than does the male of
any other animal; therefore it is not surprising that he should have gained
the power of selection. Women are everywhere conscious of the value of
their own beauty; and when they have the means, they take more delight in
decorating themselves with all sorts of ornaments than do men. They borrow
the plumes of male birds, with which nature has decked this sex, in order
to charm the females. As women have long been selected for beauty, it is
not surprising that some of their successive variations should have been
transmitted exclusively to the same sex; consequently that they should have
transmitted beauty in a somewhat higher degree to their female than to
their male offspring, and thus have become more beautiful, according to
general opinion, than men. Women, however, certainly transmit most of
their characters, including some beauty, to their offspring of both sexes;
so that the continued preference by the men of each race for the more
attractive women, according to their standard of taste, will have tended to
modify in the same manner all the individuals of both sexes belonging to
the race.
With respect to the other form of sexual selection (which with the lower
animals is much the more common), namely, when the females are the
selectors, and accept only those males which excite or charm them most, we
have reason to believe that it formerly acted on our progenitors. Man in
all probability owes his beard, and perhaps some other characters, to
inheritance from an ancient progenitor who thus gained his ornaments. But
this form of selection may have occasionally acted during later times; for
in utterly barbarous tribes the women have more power in choosing,
rejecting, and tempting their lovers, or of afterwards changing their
husbands, than might have been expected. As this is a point of some
importance, I will give in detail such evidence as I have been able to
collect.
Hearne describes how a woman in one of the tribes of Arctic America
repeatedly ran away from her husband and joined her lover; and with the
Charruas of S. America, according to Azara, divorce is quite optional.
Amongst the Abipones, a man on choosing a wife bargains with the parents
about the price. But "it frequently happens that the girl rescinds what
has been agreed upon between the parents and the bridegroom, obstinately
rejecting the very mention of marriage." She often runs away, hides
herself, and thus eludes the bridegroom. Captain Musters who lived with
the Patagonians, says that their marriages are always settled by
inclination; "if the parents make a match contrary to the daughter's will,
she refuses and is never compelled to comply." In Tierra del Fuego a young
man first obtains the consent of the parents by doing them some service,
and then he attempts to carry off the girl; "but if she is unwilling, she
hides herself in the woods until her admirer is heartily tired of looking
for her, and gives up the pursuit; but this seldom happens." In the Fiji
Islands the man seizes on the woman whom he wishes for his wife by actual
or pretended force; but "on reaching the home of her abductor, should she
not approve of the match, she runs to some one who can protect her; if,
however, she is satisfied, the matter is settled forthwith." With the
Kalmucks there is a regular race between the bride and bridegroom, the
former having a fair start; and Clarke "was assured that no instance occurs
of a girl being caught, unless she has a partiality to the pursuer."
Amongst the wild tribes of the Malay Archipelago there is also a racing
match; and it appears from M. Bourien's account, as Sir J. Lubbock remarks,
that "the race, 'is not to the swift, nor the battle to the strong,' but to
the young man who has the good fortune to please his intended bride." A
similar custom, with the same result, prevails with the Koraks of North-
Eastern Asia.
Turning to Africa: the Kafirs buy their wives, and girls are severely
beaten by their fathers if they will not accept a chosen husband; but it is
manifest from many facts given by the Rev. Mr. Shooter, that they have
considerable power of choice. Thus very ugly, though rich men, have been
known to fail in getting wives. The girls, before consenting to be
betrothed, compel the men to shew themselves off first in front and then
behind, and "exhibit their paces." They have been known to propose to a
man, and they not rarely run away with a favoured lover. So again, Mr.
Leslie, who was intimately acquainted with the Kafirs, says, "it is a
mistake to imagine that a girl is sold by her father in the same manner,
and with the same authority, with which he would dispose of a cow."
Amongst the degraded Bushmen of S. Africa, "when a girl has grown up to
womanhood without having been betrothed, which, however, does not often
happen, her lover must gain her approbation, as well as that of the
parents." (20. Azara, 'Voyages,' etc., tom. ii. p. 23. Dobrizhoffer, 'An
Account of the Abipones,' vol. ii. 1822, p. 207. Capt. Musters, in 'Proc.
R. Geograph. Soc.' vol. xv. p. 47. Williams on the Fiji Islanders, as
quoted by Lubbock, 'Origin of Civilisation,' 1870, p. 79. On the Fuegians,
King and Fitzroy, 'Voyages of the "Adventure" and "Beagle,"' vol. ii. 1839,
p. 182. On the Kalmucks, quoted by M'Lennan, 'Primitive Marriage,' 1865,
p. 32. On the Malays, Lubbock, ibid. p. 76. The Rev. J. Shooter, 'On the
Kafirs of Natal,' 1857, pp. 52-60. Mr. D. Leslie, 'Kafir Character and
Customs,' 1871, p. 4. On the Bush-men, Burchell, 'Travels in S. Africa,'
ii. 1824, p. 59. On the Koraks by McKennan, as quoted by Mr. Wake, in
'Anthropologia,' Oct. 1873, p. 75.) Mr. Winwood Reade made inquiries for
me with respect to the negroes of Western Africa, and he informs me that
"the women, at least among the more intelligent Pagan tribes, have no
difficulty in getting the husbands whom they may desire, although it is
considered unwomanly to ask a man to marry them. They are quite capable of
falling in love, and of forming tender, passionate, and faithful
attachments." Additional cases could be given.
We thus see that with savages the women are not in quite so abject a state
in relation to marriage as has often been supposed. They can tempt the men
whom they prefer, and can sometimes reject those whom they dislike, either
before or after marriage. Preference on the part of the women, steadily
acting in any one direction, would ultimately affect the character of the
tribe; for the women would generally choose not merely the handsomest men,
according to their standard of taste, but those who were at the same time
best able to defend and support them. Such well-endowed pairs would
commonly rear a larger number of offspring than the less favoured. The
same result would obviously follow in a still more marked manner if there
was selection on both sides; that is, if the more attractive, and at the
same time more powerful men were to prefer, and were preferred by, the more
attractive women. And this double form of selection seems actually to have
occurred, especially during the earlier periods of our long history.
We will now examine a little more closely some of the characters which
distinguish the several races of man from one another and from the lower
animals, namely, the greater or less deficiency of hair on the body, and
the colour of the skin. We need say nothing about the great diversity in
the shape of the features and of the skull between the different races, as
we have seen in the last chapter how different is the standard of beauty in
these respects. These characters will therefore probably have been acted
on through sexual selection; but we have no means of judging whether they
have been acted on chiefly from the male or female side. The musical
faculties of man have likewise been already discussed.
ABSENCE OF HAIR ON THE BODY, AND ITS DEVELOPMENT ON THE FACE AND HEAD.
From the presence of the woolly hair or lanugo on the human foetus, and of
rudimentary hairs scattered over the body during maturity, we may infer
that man is descended from some animal which was born hairy and remained so
during life. The loss of hair is an inconvenience and probably an injury
to man, even in a hot climate, for he is thus exposed to the scorching of
the sun, and to sudden chills, especially during wet weather. As Mr.
Wallace remarks, the natives in all countries are glad to protect their
naked backs and shoulders with some slight covering. No one supposes that
the nakedness of the skin is any direct advantage to man; his body
therefore cannot have been divested of hair through natural selection.
(21. 'Contributions to the Theory of Natural Selection,' 1870, p. 346.
Mr. Wallace believes (p. 350) "that some intelligent power has guided or
determined the development of man"; and he considers the hairless condition
of the skin as coming under this head. The Rev. T.R. Stebbing, in
commenting on this view ('Transactions of Devonshire Association for
Science,' 1870) remarks, that had Mr. Wallace "employed his usual ingenuity
on the question of man's hairless skin, he might have seen the possibility
of its selection through its superior beauty or the health attaching to
superior cleanliness.") Nor, as shewn in a former chapter, have we any
evidence that this can be due to the direct action of climate, or that it
is the result of correlated development.
The absence of hair on the body is to a certain extent a secondary sexual
character; for in all parts of the world women are less hairy than men.
Therefore we may reasonably suspect that this character has been gained
through sexual selection. We know that the faces of several species of
monkeys, and large surfaces at the posterior end of the body of other
species, have been denuded of hair; and this we may safely attribute to
sexual selection, for these surfaces are not only vividly coloured, but
sometimes, as with the male mandrill and female rhesus, much more vividly
in the one sex than in the other, especially during the breeding-season. I
am informed by Mr. Bartlett that, as these animals gradually reach
maturity, the naked surfaces grow larger compared with the size of their
bodies. The hair, however, appears to have been removed, not for the sake
of nudity, but that the colour of the skin may be more fully displayed. So
again with many birds, it appears as if the head and neck had been divested
of feathers through sexual selection, to exhibit the brightly-coloured
skin.
As the body in woman is less hairy than in man, and as this character is
common to all races, we may conclude that it was our female semi-human
ancestors who were first divested of hair, and that this occurred at an
extremely remote period before the several races had diverged from a common
stock. Whilst our female ancestors were gradually acquiring this new
character of nudity, they must have transmitted it almost equally to their
offspring of both sexes whilst young; so that its transmission, as with the
ornaments of many mammals and birds, has not been limited either by sex or
age. There is nothing surprising in a partial loss of hair having been
esteemed as an ornament by our ape-like progenitors, for we have seen that
innumerable strange characters have been thus esteemed by animals of all
kinds, and have consequently been gained through sexual selection. Nor is
it surprising that a slightly injurious character should have been thus
acquired; for we know that this is the case with the plumes of certain
birds, and with the horns of certain stags.
The females of some of the anthropoid apes, as stated in a former chapter,
are somewhat less hairy on the under surface than the males; and here we
have what might have afforded a commencement for the process of denudation.
With respect to the completion of the process through sexual selection, it
is well to bear in mind the New Zealand proverb, "There is no woman for a
hairy man." All who have seen photographs of the Siamese hairy family will
admit how ludicrously hideous is the opposite extreme of excessive
hairiness. And the king of Siam had to bribe a man to marry the first
hairy woman in the family; and she transmitted this character to her young
offspring of both sexes. (22. The 'Variation of Animals and Plants under
Domestication,' vol. ii. 1868, p. 237.)
Some races are much more hairy than others, especially the males; but it
must not be assumed that the more hairy races, such as the European, have
retained their primordial condition more completely than the naked races,
such as the Kalmucks or Americans. It is more probable that the hairiness
of the former is due to partial reversion; for characters which have been
at some former period long inherited are always apt to return. We have
seen that idiots are often very hairy, and they are apt to revert in other
characters to a lower animal type. It does not appear that a cold climate
has been influential in leading to this kind of reversion; excepting
perhaps with the negroes, who have been reared during several generations
in the United States (23. 'Investigations into Military and
Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p.
568:--Observations were carefully made on the hairiness of 2129 black and
coloured soldiers, whilst they were bathing; and by looking to the
published table, "it is manifest at a glance that there is but little, if
any, difference between the white and the black races in this respect." It
is, however, certain that negroes in their native and much hotter land of
Africa, have remarkably smooth bodies. It should be particularly observed,
that both pure blacks and mulattoes were included in the above enumeration;
and this is an unfortunate circumstance, as in accordance with a principle,
the truth of which I have elsewhere proved, crossed races of man would be
eminently liable to revert to the primordial hairy character of their early
ape-like progenitors.), and possibly with the Ainos, who inhabit the
northern islands of the Japan archipelago. But the laws of inheritance are
so complex that we can seldom understand their action. If the greater
hairiness of certain races be the result of reversion, unchecked by any
form of selection, its extreme variability, even within the limits of the
same race, ceases to be remarkable. (24. Hardly any view advanced in this
work has met with so much disfavour (see for instance, Sprengel, 'Die
Fortschritte des Darwinismus,' 1874, p. 80) as the above explanation of the
loss of hair in mankind through sexual selection; but none of the opposed
arguments seem to me of much weight, in comparison with the facts shewing
that the nudity of the skin is to a certain extent a secondary sexual
character in man and in some of the Quadrumana.)
With respect to the beard in man, if we turn to our best guide, the
Quadrumana, we find beards equally developed in both sexes of many species,
but in some, either confined to the males, or more developed in them than
in the females. From this fact and from the curious arrangement, as well
as the bright colours of the hair about the heads of many monkeys, it is
highly probable, as before explained, that the males first acquired their
beards through sexual selection as an ornament, transmitting them in most
cases, equally or nearly so, to their offspring of both sexes. We know
from Eschricht (25. 'Ueber die Richtung der Haare am Menschlichen Korper,'
in Muller's 'Archiv. fur Anat. und Phys.' 1837, s. 40.) that with mankind
the female as well as the male foetus is furnished with much hair on the
face, especially round the mouth; and this indicates that we are descended
from progenitors of whom both sexes were bearded. It appears therefore at
first sight probable that man has retained his beard from a very early
period, whilst woman lost her beard at the same time that her body became
almost completely divested of hair. Even the colour of our beards seems to
have been inherited from an ape-like progenitor; for when there is any
difference in tint between the hair of the head and the beard, the latter
is lighter coloured in all monkeys and in man. In those Quadrumana in
which the male has a larger beard than that of the female, it is fully
developed only at maturity, just as with mankind; and it is possible that
only the later stages of development have been retained by man. In
opposition to this view of the retention of the beard from an early period
is the fact of its great variability in different races, and even within
the same race; for this indicates reversion,--long lost characters being
very apt to vary on re-appearance.
Nor must we overlook the part which sexual selection may have played in
later times; for we know that with savages the men of the beardless races
take infinite pains in eradicating every hair from their faces as something
odious, whilst the men of the bearded races feel the greatest pride in
their beards. The women, no doubt, participate in these feelings, and if
so sexual selection can hardly have failed to have effected something in
the course of later times. It is also possible that the long-continued
habit of eradicating the hair may have produced an inherited effect. Dr.
Brown-Sequard has shewn that if certain animals are operated on in a
particular manner, their offspring are affected. Further evidence could be
given of the inheritance of the effects of mutilations; but a fact lately
ascertained by Mr. Salvin (26. On the tail-feathers of Motmots,
'Proceedings of the Zoological Society,' 1873, p. 429.) has a more direct
bearing on the present question; for he has shewn that the motmots, which
are known habitually to bite off the barbs of the two central tail-
feathers, have the barbs of these feathers naturally somewhat reduced.
(27. Mr. Sproat has suggested ('Scenes and Studies of Savage Life,' 1868,
p. 25) this same view. Some distinguished ethnologists, amongst others M.
Gosse of Geneva, believe that artificial modifications of the skull tend to
be inherited.) Nevertheless, with mankind the habit of eradicating the
beard and the hairs on the body would probably not have arisen until these
had already become by some means reduced.
It is difficult to form any judgment as to how the hair on the head became
developed to its present great length in many races. Eschricht (28.
'Ueber die Richtung,' ibid. s. 40.) states that in the human foetus the
hair on the face during the fifth month is longer than that on the head;
and this indicates that our semi-human progenitors were not furnished with
long tresses, which must therefore have been a late acquisition. This is
likewise indicated by the extraordinary difference in the length of the
hair in the different races; in the negro the hair forms a mere curly mat;
with us it is of great length, and with the American natives it not rarely
reaches to the ground. Some species of Semnopithecus have their heads
covered with moderately long hair, and this probably serves as an ornament
and was acquired through sexual selection. The same view may perhaps be
extended to mankind, for we know that long tresses are now and were
formerly much admired, as may be observed in the works of almost every
poet; St. Paul says, "if a woman have long hair, it is a glory to her;" and
we have seen that in North America a chief was elected solely from the
length of his hair.
COLOUR OF THE SKIN.
The best kind of evidence that in man the colour of the skin has been
modified through sexual selection is scanty; for in most races the sexes do
not differ in this respect, and only slightly, as we have seen, in others.
We know, however, from the many facts already given that the colour of the
skin is regarded by the men of all races as a highly important element in
their beauty; so that it is a character which would be likely to have been
modified through selection, as has occurred in innumerable instances with
the lower animals. It seems at first sight a monstrous supposition that
the jet-blackness of the negro should have been gained through sexual
selection; but this view is supported by various analogies, and we know
that negroes admire their own colour. With mammals, when the sexes differ
in colour, the male is often black or much darker than the female; and it
depends merely on the form of inheritance whether this or any other tint is
transmitted to both sexes or to one alone. The resemblance to a negro in
miniature of Pithecia satanas with his jet black skin, white rolling
eyeballs, and hair parted on the top of the head, is almost ludicrous.
The colour of the face differs much more widely in the various kinds of
monkeys than it does in the races of man; and we have some reason to
believe that the red, blue, orange, almost white and black tints of their
skin, even when common to both sexes, as well as the bright colours of
their fur, and the ornamental tufts about the head, have all been acquired
through sexual selection. As the order of development during growth,
generally indicates the order in which the characters of a species have
been developed and modified during previous generations; and as the newly-
born infants of the various races of man do not differ nearly as much in
colour as do the adults, although their bodies are as completely destitute
of hair, we have some slight evidence that the tints of the different races
were acquired at a period subsequent to the removal of the hair, which must
have occurred at a very early period in the history of man.
SUMMARY.
We may conclude that the greater size, strength, courage, pugnacity, and
energy of man, in comparison with woman, were acquired during primeval
times, and have subsequently been augmented, chiefly through the contests
of rival males for the possession of the females. The greater intellectual
vigour and power of invention in man is probably due to natural selection,
combined with the inherited effects of habit, for the most able men will
have succeeded best in defending and providing for themselves and for their
wives and offspring. As far as the extreme intricacy of the subject
permits us to judge, it appears that our male ape-like progenitors acquired
their beards as an ornament to charm or excite the opposite sex, and
transmitted them only to their male offspring. The females apparently
first had their bodies denuded of hair, also as a sexual ornament; but they
transmitted this character almost equally to both sexes. It is not
improbable that the females were modified in other respects for the same
purpose and by the same means; so that women have acquired sweeter voices
and become more beautiful than men.
It deserves attention that with mankind the conditions were in many
respects much more favourable for sexual selection, during a very early
period, when man had only just attained to the rank of manhood, than during
later times. For he would then, as we may safely conclude, have been
guided more by his instinctive passions, and less by foresight or reason.
He would have jealously guarded his wife or wives. He would not have
practised infanticide; nor valued his wives merely as useful slaves; nor
have been betrothed to them during infancy. Hence we may infer that the
races of men were differentiated, as far as sexual selection is concerned,
in chief part at a very remote epoch; and this conclusion throws light on
the remarkable fact that at the most ancient period, of which we have not
as yet any record, the races of man had already come to differ nearly or
quite as much as they do at the present day.
The views here advanced, on the part which sexual selection has played in
the history of man, want scientific precision. He who does not admit this
agency in the case of the lower animals, will disregard all that I have
written in the later chapters on man. We cannot positively say that this
character, but not that, has been thus modified; it has, however, been
shewn that the races of man differ from each other and from their nearest
allies, in certain characters which are of no service to them in their
daily habits of life, and which it is extremely probable would have been
modified through sexual selection. We have seen that with the lowest
savages the people of each tribe admire their own characteristic
qualities,--the shape of the head and face, the squareness of the cheek-
bones, the prominence or depression of the nose, the colour of the skin,
the length of the hair on the head, the absence of hair on the face and
body, or the presence of a great beard, and so forth. Hence these and
other such points could hardly fail to be slowly and gradually exaggerated,
from the more powerful and able men in each tribe, who would succeed in
rearing the largest number of offspring, having selected during many
generations for their wives the most strongly characterised and therefore
most attractive women. For my own part I conclude that of all the causes
which have led to the differences in external appearance between the races
of man, and to a certain extent between man and the lower animals, sexual
selection has been the most efficient.
CHAPTER XXI.
GENERAL SUMMARY AND CONCLUSION.
Main conclusion that man is descended from some lower form--Manner of
development--Genealogy of man--Intellectual and moral faculties--Sexual
Selection--Concluding remarks.
A brief summary will be sufficient to recall to the reader's mind the more
salient points in this work. Many of the views which have been advanced
are highly speculative, and some no doubt will prove erroneous; but I have
in every case given the reasons which have led me to one view rather than
to another. It seemed worth while to try how far the principle of
evolution would throw light on some of the more complex problems in the
natural history of man. False facts are highly injurious to the progress
of science, for they often endure long; but false views, if supported by
some evidence, do little harm, for every one takes a salutary pleasure in
proving their falseness: and when this is done, one path towards error is
closed and the road to truth is often at the same time opened.
The main conclusion here arrived at, and now held by many naturalists who
are well competent to form a sound judgment, is that man is descended from
some less highly organised form. The grounds upon which this conclusion
rests will never be shaken, for the close similarity between man and the
lower animals in embryonic development, as well as in innumerable points of
structure and constitution, both of high and of the most trifling
importance,--the rudiments which he retains, and the abnormal reversions to
which he is occasionally liable,--are facts which cannot be disputed. They
have long been known, but until recently they told us nothing with respect
to the origin of man. Now when viewed by the light of our knowledge of the
whole organic world, their meaning is unmistakable. The great principle of
evolution stands up clear and firm, when these groups or facts are
considered in connection with others, such as the mutual affinities of the
members of the same group, their geographical distribution in past and
present times, and their geological succession. It is incredible that all
these facts should speak falsely. He who is not content to look, like a
savage, at the phenomena of nature as disconnected, cannot any longer
believe that man is the work of a separate act of creation. He will be
forced to admit that the close resemblance of the embryo of man to that,
for instance, of a dog--the construction of his skull, limbs and whole
frame on the same plan with that of other mammals, independently of the
uses to which the parts may be put--the occasional re-appearance of various
structures, for instance of several muscles, which man does not normally
possess, but which are common to the Quadrumana--and a crowd of analogous
facts--all point in the plainest manner to the conclusion that man is the
co-descendant with other mammals of a common progenitor.
We have seen that man incessantly presents individual differences in all
parts of his body and in his mental faculties. These differences or
variations seem to be induced by the same general causes, and to obey the
same laws as with the lower animals. In both cases similar laws of
inheritance prevail. Man tends to increase at a greater rate than his
means of subsistence; consequently he is occasionally subjected to a severe
struggle for existence, and natural selection will have effected whatever
lies within its scope. A succession of strongly-marked variations of a
similar nature is by no means requisite; slight fluctuating differences in
the individual suffice for the work of natural selection; not that we have
any reason to suppose that in the same species, all parts of the
organisation tend to vary to the same degree. We may feel assured that the
inherited effects of the long-continued use or disuse of parts will have
done much in the same direction with natural selection. Modifications
formerly of importance, though no longer of any special use, are long-
inherited. When one part is modified, other parts change through the
principle of correlation, of which we have instances in many curious cases
of correlated monstrosities. Something may be attributed to the direct and
definite action of the surrounding conditions of life, such as abundant
food, heat or moisture; and lastly, many characters of slight physiological
importance, some indeed of considerable importance, have been gained
through sexual selection.
No doubt man, as well as every other animal, presents structures, which
seem to our limited knowledge, not to be now of any service to him, nor to
have been so formerly, either for the general conditions of life, or in the
relations of one sex to the other. Such structures cannot be accounted for
by any form of selection, or by the inherited effects of the use and disuse
of parts. We know, however, that many strange and strongly-marked
peculiarities of structure occasionally appear in our domesticated
productions, and if their unknown causes were to act more uniformly, they
would probably become common to all the individuals of the species. We may
hope hereafter to understand something about the causes of such occasional
modifications, especially through the study of monstrosities: hence the
labours of experimentalists, such as those of M. Camille Dareste, are full
of promise for the future. In general we can only say that the cause of
each slight variation and of each monstrosity lies much more in the
constitution of the organism, than in the nature of the surrounding
conditions; though new and changed conditions certainly play an important
part in exciting organic changes of many kinds.
Through the means just specified, aided perhaps by others as yet
undiscovered, man has been raised to his present state. But since he
attained to the rank of manhood, he has diverged into distinct races, or as
they may be more fitly called, sub-species. Some of these, such as the
Negro and European, are so distinct that, if specimens had been brought to
a naturalist without any further information, they would undoubtedly have
been considered by him as good and true species. Nevertheless all the
races agree in so many unimportant details of structure and in so many
mental peculiarities that these can be accounted for only by inheritance
from a common progenitor; and a progenitor thus characterised would
probably deserve to rank as man.
It must not be supposed that the divergence of each race from the other
races, and of all from a common stock, can be traced back to any one pair
of progenitors. On the contrary, at every stage in the process of
modification, all the individuals which were in any way better fitted for
their conditions of life, though in different degrees, would have survived
in greater numbers than the less well-fitted. The process would have been
like that followed by man, when he does not intentionally select particular
individuals, but breeds from all the superior individuals, and neglects the
inferior. He thus slowly but surely modifies his stock, and unconsciously
forms a new strain. So with respect to modifications acquired
independently of selection, and due to variations arising from the nature
of the organism and the action of the surrounding conditions, or from
changed habits of life, no single pair will have been modified much more
than the other pairs inhabiting the same country, for all will have been
continually blended through free intercrossing.
By considering the embryological structure of man,--the homologies which he
presents with the lower animals,--the rudiments which he retains,--and the
reversions to which he is liable, we can partly recall in imagination the
former condition of our early progenitors; and can approximately place them
in their proper place in the zoological series. We thus learn that man is
descended from a hairy, tailed quadruped, probably arboreal in its habits,
and an inhabitant of the Old World. This creature, if its whole structure
had been examined by a naturalist, would have been classed amongst the
Quadrumana, as surely as the still more ancient progenitor of the Old and
New World monkeys. The Quadrumana and all the higher mammals are probably
derived from an ancient marsupial animal, and this through a long line of
diversified forms, from some amphibian-like creature, and this again from
some fish-like animal. In the dim obscurity of the past we can see that
the early progenitor of all the Vertebrata must have been an aquatic
animal, provided with branchiae, with the two sexes united in the same
individual, and with the most important organs of the body (such as the
brain and heart) imperfectly or not at all developed. This animal seems to
have been more like the larvae of the existing marine Ascidians than any
other known form.
The high standard of our intellectual powers and moral disposition is the
greatest difficulty which presents itself, after we have been driven to
this conclusion on the origin of man. But every one who admits the
principle of evolution, must see that the mental powers of the higher
animals, which are the same in kind with those of man, though so different
in degree, are capable of advancement. Thus the interval between the
mental powers of one of the higher apes and of a fish, or between those of
an ant and scale-insect, is immense; yet their development does not offer
any special difficulty; for with our domesticated animals, the mental
faculties are certainly variable, and the variations are inherited. No one
doubts that they are of the utmost importance to animals in a state of
nature. Therefore the conditions are favourable for their development
through natural selection. The same conclusion may be extended to man; the
intellect must have been all-important to him, even at a very remote
period, as enabling him to invent and use language, to make weapons, tools,
traps, etc., whereby with the aid of his social habits, he long ago became
the most dominant of all living creatures.
A great stride in the development of the intellect will have followed, as
soon as the half-art and half-instinct of language came into use; for the
continued use of language will have reacted on the brain and produced an
inherited effect; and this again will have reacted on the improvement of
language. As Mr. Chauncey Wright (1. 'On the Limits of Natural
Selection,' in the 'North American Review,' Oct. 1870, p. 295.) has well
remarked, the largeness of the brain in man relatively to his body,
compared with the lower animals, may be attributed in chief part to the
early use of some simple form of language,--that wonderful engine which
affixes signs to all sorts of objects and qualities, and excites trains of
thought which would never arise from the mere impression of the senses, or
if they did arise could not be followed out. The higher intellectual
powers of man, such as those of ratiocination, abstraction, self-
consciousness, etc., probably follow from the continued improvement and
exercise of the other mental faculties.
The development of the moral qualities is a more interesting problem. The
foundation lies in the social instincts, including under this term the
family ties. These instincts are highly complex, and in the case of the
lower animals give special tendencies towards certain definite actions; but
the more important elements are love, and the distinct emotion of sympathy.
Animals endowed with the social instincts take pleasure in one another's
company, warn one another of danger, defend and aid one another in many
ways. These instincts do not extend to all the individuals of the species,
but only to those of the same community. As they are highly beneficial to
the species, they have in all probability been acquired through natural
selection.
A moral being is one who is capable of reflecting on his past actions and
their motives--of approving of some and disapproving of others; and the
fact that man is the one being who certainly deserves this designation, is
the greatest of all distinctions between him and the lower animals. But in
the fourth chapter I have endeavoured to shew that the moral sense follows,
firstly, from the enduring and ever-present nature of the social instincts;
secondly, from man's appreciation of the approbation and disapprobation of
his fellows; and thirdly, from the high activity of his mental faculties,
with past impressions extremely vivid; and in these latter respects he
differs from the lower animals. Owing to this condition of mind, man
cannot avoid looking both backwards and forwards, and comparing past
impressions. Hence after some temporary desire or passion has mastered his
social instincts, he reflects and compares the now weakened impression of
such past impulses with the ever-present social instincts; and he then
feels that sense of dissatisfaction which all unsatisfied instincts leave
behind them, he therefore resolves to act differently for the future,--and
this is conscience. Any instinct, permanently stronger or more enduring
than another, gives rise to a feeling which we express by saying that it
ought to be obeyed. A pointer dog, if able to reflect on his past conduct,
would say to himself, I ought (as indeed we say of him) to have pointed at
that hare and not have yielded to the passing temptation of hunting it.
Social animals are impelled partly by a wish to aid the members of their
community in a general manner, but more commonly to perform certain
definite actions. Man is impelled by the same general wish to aid his
fellows; but has few or no special instincts. He differs also from the
lower animals in the power of expressing his desires by words, which thus
become a guide to the aid required and bestowed. The motive to give aid is
likewise much modified in man: it no longer consists solely of a blind
instinctive impulse, but is much influenced by the praise or blame of his
fellows. The appreciation and the bestowal of praise and blame both rest
on sympathy; and this emotion, as we have seen, is one of the most
important elements of the social instincts. Sympathy, though gained as an
instinct, is also much strengthened by exercise or habit. As all men
desire their own happiness, praise or blame is bestowed on actions and
motives, according as they lead to this end; and as happiness is an
essential part of the general good, the greatest-happinesss principle
indirectly serves as a nearly safe standard of right and wrong. As the
reasoning powers advance and experience is gained, the remoter effects of
certain lines of conduct on the character of the individual, and on the
general good, are perceived; and then the self-regarding virtues come
within the scope of public opinion, and receive praise, and their opposites
blame. But with the less civilised nations reason often errs, and many bad
customs and base superstitions come within the same scope, and are then
esteemed as high virtues, and their breach as heavy crimes.
The moral faculties are generally and justly esteemed as of higher value
than the intellectual powers. But we should bear in mind that the activity
of the mind in vividly recalling past impressions is one of the fundamental
though secondary bases of conscience. This affords the strongest argument
for educating and stimulating in all possible ways the intellectual
faculties of every human being. No doubt a man with a torpid mind, if his
social affections and sympathies are well developed, will be led to good
actions, and may have a fairly sensitive conscience. But whatever renders
the imagination more vivid and strengthens the habit of recalling and
comparing past impressions, will make the conscience more sensitive, and
may even somewhat compensate for weak social affections and sympathies.
The moral nature of man has reached its present standard, partly through
the advancement of his reasoning powers and consequently of a just public
opinion, but especially from his sympathies having been rendered more
tender and widely diffused through the effects of habit, example,
instruction, and reflection. It is not improbable that after long practice
virtuous tendencies may be inherited. With the more civilised races, the
conviction of the existence of an all-seeing Deity has had a potent
influence on the advance of morality. Ultimately man does not accept the
praise or blame of his fellows as his sole guide, though few escape this
influence, but his habitual convictions, controlled by reason, afford him
the safest rule. His conscience then becomes the supreme judge and
monitor. Nevertheless the first foundation or origin of the moral sense
lies in the social instincts, including sympathy; and these instincts no
doubt were primarily gained, as in the case of the lower animals, through
natural selection.
The belief in God has often been advanced as not only the greatest, but the
most complete of all the distinctions between man and the lower animals.
It is however impossible, as we have seen, to maintain that this belief is
innate or instinctive in man. On the other hand a belief in all-pervading
spiritual agencies seems to be universal; and apparently follows from a
considerable advance in man's reason, and from a still greater advance in
his faculties of imagination, curiosity and wonder. I am aware that the
assumed instinctive belief in God has been used by many persons as an
argument for His existence. But this is a rash argument, as we should thus
be compelled to believe in the existence of many cruel and malignant
spirits, only a little more powerful than man; for the belief in them is
far more general than in a beneficent Deity. The idea of a universal and
beneficent Creator does not seem to arise in the mind of man, until he has
been elevated by long-continued culture.
He who believes in the advancement of man from some low organised form,
will naturally ask how does this bear on the belief in the immortality of
the soul. The barbarous races of man, as Sir J. Lubbock has shewn, possess
no clear belief of this kind; but arguments derived from the primeval
beliefs of savages are, as we have just seen, of little or no avail. Few
persons feel any anxiety from the impossibility of determining at what
precise period in the development of the individual, from the first trace
of a minute germinal vesicle, man becomes an immortal being; and there is
no greater cause for anxiety because the period cannot possibly be
determined in the gradually ascending organic scale. (2. The Rev. J.A.
Picton gives a discussion to this effect in his 'New Theories and the Old
Faith,' 1870.)
I am aware that the conclusions arrived at in this work will be denounced
by some as highly irreligious; but he who denounces them is bound to shew
why it is more irreligious to explain the origin of man as a distinct
species by descent from some lower form, through the laws of variation and
natural selection, than to explain the birth of the individual through the
laws of ordinary reproduction. The birth both of the species and of the
individual are equally parts of that grand sequence of events, which our
minds refuse to accept as the result of blind chance. The understanding
revolts at such a conclusion, whether or not we are able to believe that
every slight variation of structure,--the union of each pair in marriage,
the dissemination of each seed,--and other such events, have all been
ordained for some special purpose.
Sexual selection has been treated at great length in this work; for, as I
have attempted to shew, it has played an important part in the history of
the organic world. I am aware that much remains doubtful, but I have
endeavoured to give a fair view of the whole case. In the lower divisions
of the animal kingdom, sexual selection seems to have done nothing: such
animals are often affixed for life to the same spot, or have the sexes
combined in the same individual, or what is still more important, their
perceptive and intellectual faculties are not sufficiently advanced to
allow of the feelings of love and jealousy, or of the exertion of choice.
When, however, we come to the Arthropoda and Vertebrata, even to the lowest
classes in these two great Sub-Kingdoms, sexual selection has effected
much.
In the several great classes of the animal kingdom,--in mammals, birds,
reptiles, fishes, insects, and even crustaceans,--the differences between
the sexes follow nearly the same rules. The males are almost always the
wooers; and they alone are armed with special weapons for fighting with
their rivals. They are generally stronger and larger than the females, and
are endowed with the requisite qualities of courage and pugnacity. They
are provided, either exclusively or in a much higher degree than the
females, with organs for vocal or instrumental music, and with odoriferous
glands. They are ornamented with infinitely diversified appendages, and
with the most brilliant or conspicuous colours, often arranged in elegant
patterns, whilst the females are unadorned. When the sexes differ in more
important structures, it is the male which is provided with special sense-
organs for discovering the female, with locomotive organs for reaching her,
and often with prehensile organs for holding her. These various structures
for charming or securing the female are often developed in the male during
only part of the year, namely the breeding-season. They have in many cases
been more or less transferred to the females; and in the latter case they
often appear in her as mere rudiments. They are lost or never gained by
the males after emasculation. Generally they are not developed in the male
during early youth, but appear a short time before the age for
reproduction. Hence in most cases the young of both sexes resemble each
other; and the female somewhat resembles her young offspring throughout
life. In almost every great class a few anomalous cases occur, where there
has been an almost complete transposition of the characters proper to the
two sexes; the females assuming characters which properly belong to the
males. This surprising uniformity in the laws regulating the differences
between the sexes in so many and such widely separated classes, is
intelligible if we admit the action of one common cause, namely sexual
selection.
Sexual selection depends on the success of certain individuals over others
of the same sex, in relation to the propagation of the species; whilst
natural selection depends on the success of both sexes, at all ages, in
relation to the general conditions of life. The sexual struggle is of two
kinds; in the one it is between individuals of the same sex, generally the
males, in order to drive away or kill their rivals, the females remaining
passive; whilst in the other, the struggle is likewise between the
individuals of the same sex, in order to excite or charm those of the
opposite sex, generally the females, which no longer remain passive, but
select the more agreeable partners. This latter kind of selection is
closely analogous to that which man unintentionally, yet effectually,
brings to bear on his domesticated productions, when he preserves during a
long period the most pleasing or useful individuals, without any wish to
modify the breed.
The laws of inheritance determine whether characters gained through sexual
selection by either sex shall be transmitted to the same sex, or to both;
as well as the age at which they shall be developed. It appears that
variations arising late in life are commonly transmitted to one and the
same sex. Variability is the necessary basis for the action of selection,
and is wholly independent of it. It follows from this, that variations of
the same general nature have often been taken advantage of and accumulated
through sexual selection in relation to the propagation of the species, as
well as through natural selection in relation to the general purposes of
life. Hence secondary sexual characters, when equally transmitted to both
sexes can be distinguished from ordinary specific characters only by the
light of analogy. The modifications acquired through sexual selection are
often so strongly pronounced that the two sexes have frequently been ranked
as distinct species, or even as distinct genera. Such strongly-marked
differences must be in some manner highly important; and we know that they
have been acquired in some instances at the cost not only of inconvenience,
but of exposure to actual danger.
The belief in the power of sexual selection rests chiefly on the following
considerations. Certain characters are confined to one sex; and this alone
renders it probable that in most cases they are connected with the act of
reproduction. In innumerable instances these characters are fully
developed only at maturity, and often during only a part of the year, which
is always the breeding-season. The males (passing over a few exceptional
cases) are the more active in courtship; they are the better armed, and are
rendered the more attractive in various ways. It is to be especially
observed that the males display their attractions with elaborate care in
the presence of the females; and that they rarely or never display them
excepting during the season of love. It is incredible that all this should
be purposeless. Lastly we have distinct evidence with some quadrupeds and
birds, that the individuals of one sex are capable of feeling a strong
antipathy or preference for certain individuals of the other sex.
Bearing in mind these facts, and the marked results of man's unconscious
selection, when applied to domesticated animals and cultivated plants, it
seems to me almost certain that if the individuals of one sex were during a
long series of generations to prefer pairing with certain individuals of
the other sex, characterised in some peculiar manner, the offspring would
slowly but surely become modified in this same manner. I have not
attempted to conceal that, excepting when the males are more numerous than
the females, or when polygamy prevails, it is doubtful how the more
attractive males succeed in leaving a large number of offspring to inherit
their superiority in ornaments or other charms than the less attractive
males; but I have shewn that this would probably follow from the females,--
especially the more vigorous ones, which would be the first to breed,--
preferring not only the more attractive but at the same time the more
vigorous and victorious males.
Although we have some positive evidence that birds appreciate bright and
beautiful objects, as with the bower-birds of Australia, and although they
certainly appreciate the power of song, yet I fully admit that it is
astonishing that the females of many birds and some mammals should be
endowed with sufficient taste to appreciate ornaments, which we have reason
to attribute to sexual selection; and this is even more astonishing in the
case of reptiles, fish, and insects. But we really know little about the
minds of the lower animals. It cannot be supposed, for instance, that male
birds of paradise or peacocks should take such pains in erecting,
spreading, and vibrating their beautiful plumes before the females for no
purpose. We should remember the fact given on excellent authority in a
former chapter, that several peahens, when debarred from an admired male,
remained widows during a whole season rather than pair with another bird.
Nevertheless I know of no fact in natural history more wonderful than that
the female Argus pheasant should appreciate the exquisite shading of the
ball-and-socket ornaments and the elegant patterns on the wing-feather of
the male. He who thinks that the male was created as he now exists must
admit that the great plumes, which prevent the wings from being used for
flight, and which are displayed during courtship and at no other time in a
manner quite peculiar to this one species, were given to him as an
ornament. If so, he must likewise admit that the female was created and
endowed with the capacity of appreciating such ornaments. I differ only in
the conviction that the male Argus pheasant acquired his beauty gradually,
through the preference of the females during many generations for the more
highly ornamented males; the aesthetic capacity of the females having been
advanced through exercise or habit, just as our own taste is gradually
improved. In the male through the fortunate chance of a few feathers being
left unchanged, we can distinctly trace how simple spots with a little
fulvous shading on one side may have been developed by small steps into the
wonderful ball-and-socket ornaments; and it is probable that they were
actually thus developed.
Everyone who admits the principle of evolution, and yet feels great
difficulty in admitting that female mammals, birds, reptiles, and fish,
could have acquired the high taste implied by the beauty of the males, and
which generally coincides with our own standard, should reflect that the
nerve-cells of the brain in the highest as well as in the lowest members of
the Vertebrate series, are derived from those of the common progenitor of
this great Kingdom. For we can thus see how it has come to pass that
certain mental faculties, in various and widely distinct groups of animals,
have been developed in nearly the same manner and to nearly the same
degree.
The reader who has taken the trouble to go through the several chapters
devoted to sexual selection, will be able to judge how far the conclusions
at which I have arrived are supported by sufficient evidence. If he
accepts these conclusions he may, I think, safely extend them to mankind;
but it would be superfluous here to repeat what I have so lately said on
the manner in which sexual selection apparently has acted on man, both on
the male and female side, causing the two sexes to differ in body and mind,
and the several races to differ from each other in various characters, as
well as from their ancient and lowly-organised progenitors.
He who admits the principle of sexual selection will be led to the
remarkable conclusion that the nervous system not only regulates most of
the existing functions of the body, but has indirectly influenced the
progressive development of various bodily structures and of certain mental
qualities. Courage, pugnacity, perseverance, strength and size of body,
weapons of all kinds, musical organs, both vocal and instrumental, bright
colours and ornamental appendages, have all been indirectly gained by the
one sex or the other, through the exertion of choice, the influence of love
and jealousy, and the appreciation of the beautiful in sound, colour or
form; and these powers of the mind manifestly depend on the development of
the brain.
Man scans with scrupulous care the character and pedigree of his horses,
cattle, and dogs before he matches them; but when he comes to his own
marriage he rarely, or never, takes any such care. He is impelled by
nearly the same motives as the lower animals, when they are left to their
own free choice, though he is in so far superior to them that he highly
values mental charms and virtues. On the other hand he is strongly
attracted by mere wealth or rank. Yet he might by selection do something
not only for the bodily constitution and frame of his offspring, but for
their intellectual and moral qualities. Both sexes ought to refrain from
marriage if they are in any marked degree inferior in body or mind; but
such hopes are Utopian and will never be even partially realised until the
laws of inheritance are thoroughly known. Everyone does good service, who
aids towards this end. When the principles of breeding and inheritance are
better understood, we shall not hear ignorant members of our legislature
rejecting with scorn a plan for ascertaining whether or not consanguineous
marriages are injurious to man.
The advancement of the welfare of mankind is a most intricate problem: all
ought to refrain from marriage who cannot avoid abject poverty for their
children; for poverty is not only a great evil, but tends to its own
increase by leading to recklessness in marriage. On the other hand, as Mr.
Galton has remarked, if the prudent avoid marriage, whilst the reckless
marry, the inferior members tend to supplant the better members of society.
Man, like every other animal, has no doubt advanced to his present high
condition through a struggle for existence consequent on his rapid
multiplication; and if he is to advance still higher, it is to be feared
that he must remain subject to a severe struggle. Otherwise he would sink
into indolence, and the more gifted men would not be more successful in the
battle of life than the less gifted. Hence our natural rate of increase,
though leading to many and obvious evils, must not be greatly diminished by
any means. There should be open competition for all men; and the most able
should not be prevented by laws or customs from succeeding best and rearing
the largest number of offspring. Important as the struggle for existence
has been and even still is, yet as far as the highest part of man's nature
is concerned there are other agencies more important. For the moral
qualities are advanced, either directly or indirectly, much more through
the effects of habit, the reasoning powers, instruction, religion, etc.,
than through natural selection; though to this latter agency may be safely
attributed the social instincts, which afforded the basis for the
development of the moral sense.
The main conclusion arrived at in this work, namely, that man is descended
from some lowly organised form, will, I regret to think, be highly
distasteful to many. But there can hardly be a doubt that we are descended
from barbarians. The astonishment which I felt on first seeing a party of
Fuegians on a wild and broken shore will never be forgotten by me, for the
reflection at once rushed into my mind--such were our ancestors. These men
were absolutely naked and bedaubed with paint, their long hair was tangled,
their mouths frothed with excitement, and their expression was wild,
startled, and distrustful. They possessed hardly any arts, and like wild
animals lived on what they could catch; they had no government, and were
merciless to every one not of their own small tribe. He who has seen a
savage in his native land will not feel much shame, if forced to
acknowledge that the blood of some more humble creature flows in his veins.
For my own part I would as soon be descended from that heroic little
monkey, who braved his dreaded enemy in order to save the life of his
keeper, or from that old baboon, who descending from the mountains, carried
away in triumph his young comrade from a crowd of astonished dogs--as from
a savage who delights to torture his enemies, offers up bloody sacrifices,
practices infanticide without remorse, treats his wives like slaves, knows
no decency, and is haunted by the grossest superstitions.
Man may be excused for feeling some pride at having risen, though not
through his own exertions, to the very summit of the organic scale; and the
fact of his having thus risen, instead of having been aboriginally placed
there, may give him hope for a still higher destiny in the distant future.
But we are not here concerned with hopes or fears, only with the truth as
far as our reason permits us to discover it; and I have given the evidence
to the best of my ability. We must, however, acknowledge, as it seems to
me, that man with all his noble qualities, with sympathy which feels for
the most debased, with benevolence which extends not only to other men but
to the humblest living creature, with his god-like intellect which has
penetrated into the movements and constitution of the solar system--with
all these exalted powers--Man still bears in his bodily frame the indelible
stamp of his lowly origin.
SUPPLEMENTAL NOTE.
ON SEXUAL SELECTION IN RELATION TO MONKEYS.
Reprinted from NATURE, November 2, 1876, p. 18.
In the discussion on Sexual Selection in my 'Descent of Man,' no case
interested and perplexed me so much as the brightly-coloured hinder ends
and adjoining parts of certain monkeys. As these parts are more brightly
coloured in one sex than the other, and as they become more brilliant
during the season of love, I concluded that the colours had been gained as
a sexual attraction. I was well aware that I thus laid myself open to
ridicule; though in fact it is not more surprising that a monkey should
display his bright-red hinder end than that a peacock should display his
magnificent tail. I had, however, at that time no evidence of monkeys
exhibiting this part of their bodies during their courtship; and such
display in the case of birds affords the best evidence that the ornaments
of the males are of service to them by attracting or exciting the females.
I have lately read an article by Joh. von Fischer, of Gotha, published in
'Der Zoologische Garten,' April 1876, on the expression of monkeys under
various emotions, which is well worthy of study by any one interested in
the subject, and which shews that the author is a careful and acute
observer. In this article there is an account of the behaviour of a young
male mandrill when he first beheld himself in a looking-glass, and it is
added, that after a time he turned round and presented his red hinder end
to the glass. Accordingly I wrote to Herr J. von Fischer to ask what he
supposed was the meaning of this strange action, and he has sent me two
long letters full of new and curious details, which will, I hope, be
hereafter published. He says that he was himself at first perplexed by the
above action, and was thus led carefully to observe several individuals of
various other species of monkeys, which he has long kept in his house. He
finds that not only the mandrill (Cynocephalus mormon) but the drill (C.
leucophaeus) and three other kinds of baboons (C. hamadryas, sphinx, and
babouin), also Cynopithecus niger, and Macacus rhesus and nemestrinus, turn
this part of their bodies, which in all these species is more or less
brightly coloured, to him when they are pleased, and to other persons as a
sort of greeting. He took pains to cure a Macacus rhesus, which he had
kept for five years, of this indecorous habit, and at last succeeded.
These monkeys are particularly apt to act in this manner, grinning at the
same time, when first introduced to a new monkey, but often also to their
old monkey friends; and after this mutual display they begin to play
together. The young mandrill ceased spontaneously after a time to act in
this manner towards his master, von Fischer, but continued to do so towards
persons who were strangers and to new monkeys. A young Cynopithecus niger
never acted, excepting on one occasion, in this way towards his master, but
frequently towards strangers, and continues to do so up to the present
time. From these facts Von Fischer concludes that the monkeys which
behaved in this manner before a looking-glass (viz., the mandrill, drill,
Cynopithecus niger, Macacus rhesus and nemestrinus) acted as if their
reflection were a new acquaintance. The mandrill and drill, which have
their hinder ends especially ornamented, display it even whilst quite
young, more frequently and more ostentatiously than do the other kinds.
Next in order comes Cynocephalus hamadryas, whilst the other species act in
this manner seldomer. The individuals, however, of the same species vary
in this respect, and some which were very shy never displayed their hinder
ends. It deserves especial attention that Von Fischer has never seen any
species purposely exhibit the hinder part of its body, if not at all
coloured. This remark applies to many individuals of Macacus cynomolgus
and Cercocebus radiatus (which is closely allied to M. rhesus), to three
species of Cercopithecus and several American monkeys. The habit of
turning the hinder ends as a greeting to an old friend or new acquaintance,
which seems to us so odd, is not really more so than the habits of many
savages, for instance that of rubbing their bellies with their hands, or
rubbing noses together. The habit with the mandrill and drill seems to be
instinctive or inherited, as it was followed by very young animals; but it
is modified or guided, like so many other instincts, by observation, for
Von Fischer says that they take pains to make their display fully; and if
made before two observers, they turn to him who seems to pay the most
attention.
With respect to the origin of the habit, Von Fischer remarks that his
monkeys like to have their naked hinder ends patted or stroked, and that
they then grunt with pleasure. They often also turn this part of their
bodies to other monkeys to have bits of dirt picked off, and so no doubt it
would be with respect to thorns. But the habit with adult animals is
connected to a certain extent with sexual feelings, for Von Fischer watched
through a glass door a female Cynopithecus niger, and she during several
days, "umdrehte und dem Mannchen mit gurgelnden Tonen die stark gerothete
Sitzflache zeigte, was ich fruher nie an diesem Thier bemerkt hatte. Beim
Anblick dieses Gegenstandes erregte sich das Mannchen sichtlich, denn es
polterte heftig an den Staben, ebenfalls gurgelnde Laute ausstossend." As
all the monkeys which have the hinder parts of their bodies more or less
brightly coloured live, according to Von Fischer, in open rocky places, he
thinks that these colours serve to render one sex conspicuous at a distance
to the other; but, as monkeys are such gregarious animals, I should have
thought that there was no need for the sexes to recognise each other at a
distance. It seems to me more probable that the bright colours, whether on
the face or hinder end, or, as in the mandrill, on both, serve as a sexual
ornament and attraction. Anyhow, as we now know that monkeys have the
habit of turning their hinder ends towards other monkeys, it ceases to be
at all surprising that it should have been this part of their bodies which
has been more or less decorated. The fact that it is only the monkeys thus
characterised which, as far as at present known, act in this manner as a
greeting towards other monkeys renders it doubtful whether the habit was
first acquired from some independent cause, and that afterwards the parts
in question were coloured as a sexual ornament; or whether the colouring
and the habit of turning round were first acquired through variation and
sexual selection, and that afterwards the habit was retained as a sign of
pleasure or as a greeting, through the principle of inherited association.
This principle apparently comes into play on many occasions: thus it is
generally admitted that the songs of birds serve mainly as an attraction
during the season of love, and that the leks, or great congregations of the
black-grouse, are connected with their courtship; but the habit of singing
has been retained by some birds when they feel happy, for instance by the
common robin, and the habit of congregating has been retained by the black-
grouse during other seasons of the year.
I beg leave to refer to one other point in relation to sexual selection.
It has been objected that this form of selection, as far as the ornaments
of the males are concerned, implies that all females within the same
district must possess and exercise exactly the same taste. It should,
however, be observed, in the first place, that although the range of
variation of a species may be very large, it is by no means indefinite. I
have elsewhere given a good instance of this fact in the pigeon, of which
there are at least a hundred varieties differing widely in their colours,
and at least a score of varieties of the fowl differing in the same kind of
way; but the range of colour in these two species is extremely distinct.
Therefore the females of natural species cannot have an unlimited scope for
their taste. In the second place, I presume that no supporter of the
principle of sexual selection believes that the females select particular
points of beauty in the males; they are merely excited or attracted in a
greater degree by one male than by another, and this seems often to depend,
especially with birds, on brilliant colouring. Even man, excepting perhaps
an artist, does not analyse the slight differences in the features of the
woman whom he may admire, on which her beauty depends. The male mandrill
has not only the hinder end of his body, but his face gorgeously coloured
and marked with oblique ridges, a yellow beard, and other ornaments. We
may infer from what we see of the variation of animals under domestication,
that the above several ornaments of the mandrill were gradually acquired by
one individual varying a little in one way, and another individual in
another way. The males which were the handsomest or the most attractive in
any manner to the females would pair oftenest, and would leave rather more
offspring than other males. The offspring of the former, although
variously intercrossed, would either inherit the peculiarities of their
fathers or transmit an increased tendency to vary in the same manner.
Consequently the whole body of males inhabiting the same country would tend
from the effects of constant intercrossing to become modified almost
uniformly, but sometimes a little more in one character and sometimes in
another, though at an extremely slow rate; all ultimately being thus
rendered more attractive to the females. The process is like that which I
have called unconscious selection by man, and of which I have given several
instances. In one country the inhabitants value a fleet or light dog or
horse, and in another country a heavier and more powerful one; in neither
country is there any selection of individual animals with lighter or
stronger bodies and limbs; nevertheless after a considerable lapse of time
the individuals are found to have been modified in the desired manner
almost uniformly, though differently in each country. In two absolutely
distinct countries inhabited by the same species, the individuals of which
can never during long ages have intermigrated and intercrossed, and where,
moreover, the variations will probably not have been identically the same,
sexual selection might cause the males to differ. Nor does the belief
appear to me altogether fanciful that two sets of females, surrounded by a
very different environment, would be apt to acquire somewhat different
tastes with respect to form, sound, or colour. However this may be, I have
given in my 'Descent of Man' instances of closely-allied birds inhabiting
distinct countries, of which the young and the females cannot be
distinguished, whilst the adult males differ considerably, and this may be
attributed with much probability to the action of sexual selection.
INDEX.
Abbot, C., on the battles of seals.
Abductor of the fifth metatarsal, presence of, in man.
Abercrombie, Dr., on disease of the brain affecting speech.
Abipones, marriage customs of the.
Abortion, prevalence of the practice of.
Abou-Simbel, caves of.
Abramis brama.
Abstraction, power of, in animals.
Acalles, stridulation of.
Acanthodactylus capensis, sexual differences of colour in.
Accentor Modularis.
Acclimatisation, difference of, in different races of men.
Achetidae, stridulation of the;
rudimentary stridulating organs in female.
Acilius sulcatus, elytra of the female.
Acomus, development of spurs in the female of.
Acridiidae, stridulation of the;
rudimentary stridulating organs in female.
Acromio-basilar muscle, and quadrupedal gait.
Acting.
Actiniae, bright colours of.
Adams, Mr., migration of birds;
intelligence of nut-hatch;
on the Bombycilla carolinensis.
Admiral butterfly.
Adoption of the young of other animals by female monkeys.
Advancement in the organic scale, Von Baer's definition of.
Aeby, on the difference between the skulls of man and the quadrumana.
Aesthetic faculty, not highly developed in savages.
Affection, maternal;
manifestation of, by animals;
parental and filial, partly the result of natural selection;
mutual, of birds;
shewn by birds in confinement, for certain persons.
Africa, probably the birthplace of man;
South, crossed population of;
South, retention of colour by the Dutch in;
South, proportion of the sexes in the butterflies of;
tattooing practised in;
Northern, coiffure of natives of.
Agassiz, L., on conscience in dogs;
on the coincidence of the races of man with zoological provinces;
on the number of species of man;
on the courtship of the land-snails;
on the brightness of the colours of male fishes during the breeding season;
on the frontal protuberance of the males of Geophagus and Cichla;
male fishes hatching ova in their mouths;
sexual differences in colour of chromids;
on the slight sexual differences of the South Americans;
on the tattooing of the Amazonian Indians.
Age, in relation to the transmission of characters in birds;
variation in accordance with, in birds.
Agelaeus phoeniceus.
Ageronia feronia, noise produced by.
Agrion, dimorphism in.
Agrion Ramburii, sexes of.
Agrionidae, difference in the sexes of.
Agrotis exclamationis.
Ague, tertian, dog suffering from.
Ainos, hairiness of the.
Aitchison, Mr., on sheep.
Aithurus polytmus, young of.
Albino birds.
Alca torda, young of.
Alces palmata.
Alder and Hancock, MM., on the nudi-branch mollusca.
Allen, J.A., vigour of birds earliest hatched;
effect of difference of temperature, light, etc., on birds;
colours of birds;
on the relative size of the sexes of Callorhinus ursinus;
on the name of Otaria jubata;
on the pairing of seals;
on sexual differences in the colour of bats.
Allen, S., on the habits of Hoplopterus;
on the plumes of herons;
on the vernal moult of Herodius bubulcus.
Alligator, courtship of the male;
roaring of the male.
Amadavat, pugnacity of male.
Amadina Lathami, display of plumage by the male.
Amadina castanotis, display of plumage by the male.
Amazons, butterflies of the;
fishes of the.
America, variation in the skulls of aborigines of;
wide range of aborigines of;
lice of the natives of;
general beardlessness of the natives of.
America, North, butterflies of;
Indians of, women a cause of strife among the;
Indians of, their notions of female beauty.
America, South, character of the natives of;
population of parts of;
piles of stones in;
extinction of the fossil horse of;
desert-birds of;
slight sexual difference of the aborigines of;
prevalence of infanticide in.
American languages, often highly artificial.
Americans, wide geographical range of;
native, variability of;
and negroes, difference of;
aversion of, to hair on the face.
Ammophila, on the jaws of.
Ammotragus tragelaphus, hairy forelegs of.
Amphibia, affinity of, to the ganoid fishes;
vocal organs of the.
Amphibians, breeding whilst immature.
Amphioxus.
Amphipoda, males sexually mature while young.
Amunoph III., negro character of, features of.
Anal appendages of insects.
Analogous variation in the plumage of birds.
Anas.
Anas acuta, male plumage of.
Anas boschas, male plumage of.
Anas histrionica.
Anas punctata.
Anastomus oscitans, sexes and young of;
white nuptial plumage of.
Anatidae, voices of.
Anax junius, differences in the sexes of.
Andaman islanders, susceptible to change of climate.
Anderson, Dr., on the tail of Macacus brunneus;
the Bufo sikimmensis;
sounds of Echis carinata.
Andreana fulva.
Anglo-Saxons, estimation of the beard among the.
Animals, domesticated, more fertile than wild;
cruelty of savages to;
characters common to man and;
domestic, change of breeds of.
Annelida, colours of.
Anobium tessellatum, sounds produced by.
Anolis cristatellus, male, crest of;
pugnacity of the male;
throat-pouch of.
Anser canadensis.
Anset cygnoides; knob at the base of the beak of.
Anser hyperboreus, whiteness of.
Antelope, prong-horned, horns of.
Antelopes, generally polygamous;
horns of;
canine teeth of some male;
use of horns of;
dorsal crests in;
dewlaps of;
winter change of two species of;
peculiar markings of.
Antennae, furnished with cushions in the male of Penthe.
Anthidium manicatum, large male of.
Anthocharis cardamines;
sexual difference of colour in.
Anthocharis genutia.
Anthocharis sara.
Anthophora acervorum, large male of.
Anthophora retusa, difference of the sexes in.
Anthropidae.
Anthus, moulting of.
Antics of birds.
Antigua, Dr. Nicholson's observations on yellow fever in.
Antilocapra americana, horns of.
Antilope bezoartica, horned females of;
sexual difference in the colour of.
Antilope Dorcas and euchore.
Antilope euchore, horns of.
Antilope montana, rudimentary canines in the young male of.
Antilope niger, sing-sing, caama, and gorgon, sexual differences in the
colours of.
Antilope oreas, horns of.
Antilope saiga, polygamous habits of.
Antilope strepsiceros, horns of.
Antilope subgutturosa, absence of suborbital pits in.
Antipathy, shewn by birds in confinement, to certain persons.
Ants, large size of the cerebral ganglia in;
soldier, large jaws of;
playing together;
memory in;
intercommunication of, by means of the antennae;
habits of;
difference of the sexes in;
recognition of each other by, after separation.
Ants White, habits of.
Anura.
Apatania muliebris, male unknown.
Apathus, difference of the sexes in.
Apatura Iris.
Apes, difference of the young, from the adult;
semi-erect attitude of some;
mastoid processes of;
influences of the jaw-muscles on the physiognomy of;
female, destitute of large canines;
building platforms;
imitative faculties of;
anthropomorphous;
probable speedy extermination of the;
Gratiolet on the evolution of;
canine teeth of male;
females of some, less hairy beneath than the males.
Apes, long-armed, their mode of progression.
Aphasia, Dr. Bateman on.
Apis mellifica, large male of.
Apollo, Greek statues of.
Apoplexy in Cebus Azarae.
Appendages, anal, of insects.
Approbation, influence of the love of.
Aprosmictus scapulatus.
Apus, proportion of sexes.
Aquatic birds, frequency of white plumage in.
Aquila chrysaetos.
Arab women, elaborate and peculiar coiffure of.
Arabs, fertility of crosses with other races;
gashing of cheeks and temples among the.
Arachnida.
Arakhan, artificial widening of the forehead by the natives of.
Arboricola, young of.
Archeopteryx.
Arctiidae, coloration of the.
Ardea asha, rufescens, and coerulea, change of colour in.
Ardea coerulea, breeding in immature plumage.
Ardea gularis, change of plumage in.
Ardea herodias, love-gestures of the male.
Ardea ludoviciana, age of mature plumage in;
continued growth of crest and plumes in the male of.
Ardea nycticorax, cries of.
Ardeola, young of.
Ardetta, changes of plumage in.
Argenteuil.
Argus pheasant, display of plumage by the male;
ocellated spots of the;
gradation of characters in the.
Argyll, Duke of, on the physical weakness of man;
the fashioning of implements peculiar to man;
on the contest in man between right and wrong;
on the primitive civilisation of man;
on the plumage of the male Argus pheasant;
on Urosticte Benjamini;
on the nests of birds.
Argynnis, colouring of the lower surface of.
Aricoris epitus, sexual differences in the wings of.
Aristocracy, increased beauty of the.
Arms, proportions of, in soldiers and sailors;
direction of the hair on the.
Arms and hands, free use of, indirectly correlated with diminution of
canines.
Arrest of development.
Arrow-heads, stone, general resemblance of.
Arrows, use of.
Arteries, variations in the course of the.
Artery, effect of tying, upon the lateral channels.
Arthropoda.
Arts practised by savages.
Ascension, coloured incrustation on the rocks of.
Ascidia, affinity of the lancelet to;
tad-pole like larvae of.
Ascidians, bright colours of some.
Asinus, Asiatic and African species of.
Asinus taeniopus.
Ass, colour-variations of the.
Ateles, effects of brandy on an;
absence of the thumb in.
Ateles beelzebuth, ears of.
Ateles marginatus, colour of the ruff of;
hair on the head of.
Ateuchus cicatricosus, habits of.
Ateuchus stridulation of.
Athalia, proportions of the sexes in.
Atropus pulsatorius.
Attention, manifestations of, in animals.
Audouin, V., on a hymenopterous parasite with a sedentary male.
Audubon, J.J., on the pinioned goose;
on the speculum of Mergus cucullatus;
on the pugnacity of male birds;
on courtship of Caprimulgus;
on Tetrao cupido;
on Ardea nycticorax;
on Sturnella ludoviciana;
on the vocal organs of Tetra cupido;
on the drumming of the male Tetrao umbellus;
on sounds produced by the nightjar;
on Ardea herodias and Cathartes jota;
on Mimus polyglottus;
on display in male birds;
on the spring change of colour in some finches;
on migration of mocking thrushes;
recognition of a dog by a turkey;
selection of mate by female birds;
on the turkey;
on variation in the male scarlet tanager;
on the musk-rat;
on the habits of Pyranga aestiva;
on local differences in the nests of the same species of birds;
on the habits of woodpeckers;
on Bombycilla carolinensis;
on young females of Pyranga aestiva acquiring male characters;
on the immature plumage of thrushes;
on the immature plumage of birds;
on birds breeding in immature plumage;
on the growth of the crest and plume in the male Ardea ludoviciana;
on the change of colour in some species of Ardea.
Audobon and Bachman, MM., on squirrels fighting;
on the Canadian lynx.
Aughey, Prof., on rattlesnakes.
Austen, N.L., on Anolis cristatellus.
Australia, not the birthplace of man;
half-castes killed by the natives of;
lice of the natives of.
Australia, South, variation in the skulls of aborigines of.
Australians, colour of new-born children of;
relative height of the sexes of;
women a cause of war among the.
Axis deer, sexual difference in the colour of the.
Aymaras, measurements of the;
no grey hair among the;
hairlessness of the face in the;
long hair of the.
Azara, on the proportion of men and women among the Guaranys;
on Palamedea cornuta;
on the beards of the Guaranys;
on strife for women among the Guanas;
on infanticide;
on the eradication of the eyebrows and eyelashes by the Indians of
Paraguay;
on polyandry among the Guanas;
celibacy unknown among the savages of South America;
on the freedom of divorce among the Charruas.
Babbage C., on the greater proportion of illegitimate female births.
Babirusa, tusks of the.
Baboon, revenge in a;
rage excited in, by reading;
manifestation of memory by a;
employing a mat for shelter against the sun;
protected from punishment by its companions.
Baboon, Cape, mane of the male;
Hamadryas, mane of the male.
Baboon, effects of intoxicating liquors on;
ears of;
diversity of the mental faculties in;
hands of;
habits of;
variability of the tail in;
manifestation of maternal affection by;
using stones and sticks as weapons;
co-operation of;
silence of, on plundering expeditions;
apparent polygamy of;
polygamous and social habits of.
Baboons, courtship of.
Bachman, Dr., on the fertility of mulattoes.
Baer, K.E. von, on embryonic development;
definition of advancement in the organic scale.
Bagehot, W., on the social virtues among primitive men;
slavery formerly beneficial;
on the value of obedience;
on human progress;
on the persistence of savage tribes in classical times.
Bailly, E.M., on the mode of fighting of the Italian buffalo;
on the fighting of stags.
Bain, A., on the sense of duty;
aid springing from sympathy;
on the basis of sympathy;
on the love of approbation etc.;
on the idea of beauty.
Baird, W., on a difference in colour between the males and females of some
Entozoa.
Baker, Mr., observation on the proportion of the sexes in pheasant-chicks.
Baker, Sir S., on the fondness of the Arabs for discordant music;
on sexual difference in the colours of an antelope;
on the elephant and rhinoceros attacking white or grey horses;
on the disfigurements practised by the negroes;
on the gashing of the cheeks and temples practised in Arab countries;
on the coiffure of the North Africans;
on the perforation of the lower lip by the women of Latooka;
on the distinctive characters of the coiffure of central African tribes;
on the coiffure of Arab women.
"Balz" of the Black-cock.
Bantam, Sebright.
Banteng, horns of;
sexual differences in the colours of the.
Banyai, colour of the.
Barbarism, primitive, of civilised nations.
Barbs, filamentous, of the feathers, in certain birds.
Barr, Mr., on sexual preference in dogs.
Barrago, F., on the Simian resemblances of man.
Barrington, Daines, on the language of birds;
on the clucking of the hen;
on the object of the song of birds;
on the singing of female birds;
on birds acquiring the songs of other birds;
on the muscles of the larynx in song-birds;
on the want of the power of song by female birds.
Barrow, on the widow-bird.
Bartels, Dr., supernumerary mammae in men.
Bartlett, A.D., period of hatching of bird's eggs;
on the tragopan;
on the development of the spurs in Crossoptilon auritum;
on the fighting of the males of Plectopterus gambensis;
on the Knot;
on display in male birds;
on the display of plumage by the male Polyplectron;
on Crossoptilon auritum and Phasianus Wallichii;
on the habits of Lophophorus;
on the colour of the mouth in Buceros bicornis;
on the incubation of the cassowary;
on the Cape Buffalo;
on the use of the horns of antelopes;
on the fighting of male wart-hogs;
on Ammotragus tragelaphus;
on the colours of Cercopithecus cephus;
on the colours of the faces of monkeys;
on the naked surfaces of monkeys.
Bartlett, on courting of Argus pheasant.
Bartram, on the courtship of the male alligator.
Basque language, highly artificial.
Bate, C.S., on the superior activity of male crustacea;
on the proportions of the sexes in crabs;
on the chelae of crustacea;
on the relative size of the sexes in crustacea;
on the colours of crustacea.
Bateman, Dr., tendency to imitation in certain diseased states;
on Aphasia.
Bates, H.W., on variation in the form of the head of Amazonian Indians;
on the proportion of the sexes among Amazonian butterflies;
on sexual differences in the wings of butterflies;
on the field-cricket;
on Pyrodes pulcherrimus;
on the horns of Lamellicorn beetles;
on the colours of Epicaliae, etc.;
on the coloration of tropical butterflies;
on the variability of Papilio Sesostris and Childrenae;
on male and female butterflies inhabiting different stations;
on mimicry;
on the caterpillar of a Sphinx;
on the vocal organs of the umbrella-bird;
on the toucans;
on Brackyurus calvus.
Batokas, knocking out two upper incisors.
Batrachia, eagerness of male.
Bats, scent-glands;
sexual differences in the colour of;
fur of male frugivorous.
Battle, law of;
among beetles;
among birds;
among mammals;
in man.
Beak, sexual difference in the forms of the;
in the colour of the.
Beaks, of birds, bright colours of.
Beard, development of, in man;
analogy of the, in man and the quadrumana;
variation of the development of the, in different races of men;
estimation of, among bearded nations;
probable origin of the.
Beard, in monkeys;
of mammals.
Beautiful, taste for the, in birds;
in the quadrumana.
Beauty, sense of, in animals;
appreciation of, by birds;
influence of;
variability of the standard of.
Beauty, sense of, sufficiently permanent for action of sexual selection.
Beaven, Lieut., on the development of the horns in Cervus Eldi.
Beaver, instinct and intelligence of the;
voice of the;
castoreum of the.
Beavers, battles of male.
Bechstein, on female birds choosing the best singers among the males;
on rivalry in song-birds;
on the singing of female birds;
on birds acquiring the songs of other birds;
on pairing the canary and siskin;
on a sub-variety of the monk pigeon;
on spurred hens.
Beddoe, Dr., on causes of difference in stature.
Bee-eater.
Bees, pollen-baskets and stings of;
destruction of drones and queens by;
female, secondary sexual characters of;
proportion of sexes;
difference of the sexes in colour and sexual selection.
Beetle, luminous larva of a.
Beetles, size of the cerebral ganglia in;
dilatation of the foretarsi in male;
blind;
stridulation of.
Belgium, ancient inhabitants of.
Bell, Sir C., on emotional muscles in man;
"snarling muscles;"
on the hand.
Bell, T., on the numerical proportion of the sexes in moles;
on the newts;
on the croaking of the frog;
on the difference in the coloration of the sexes in Zootoca vivipara;
on moles fighting.
Bell-bird, sexual difference in the colour of the.
Bell-birds, colours of.
Belt, Mr., on the nakedness of tropical mankind;
on a spider-monkey and eagle;
habits of ants;
Lampridae distasteful to mammals;
mimicry of Leptalides;
colours of Nicaraguan frogs;
display of humming-birds;
on the toucans;
protective colouring of skunk.
Benevolence, manifested by birds.
Bennett, A.W., attachment of mated birds;
on the habits of Dromaeus irroratus.
Bennett, Dr., on birds of paradise.
Berbers, fertility of crosses with other races.
Bernicla antarctica, colours of.
Bernicle gander pairing with a Canada goose.
Bert, M., crustaceans distinguish colours.
Bettoni, E., on local differences in the nests of Italian birds.
Beyle, M., see Bombet.
Bhoteas, colour of the beard in.
Bhringa, disc-formed tail-feathers of.
Bianconi, Prof., on structures as explained through mechanical principles.
Bibio, sexual differences in the genus.
Bichat, on beauty.
Bickes, proportion of sexes in man.
Bile, coloured, in many animals.
Bimana.
Birds, imitations of the songs of other birds by;
dreaming;
killed by telegraph wires;
language of;
sense of beauty in;
pleasure of, in incubation;
male, incubation by;
and reptiles, alliance of;
sexual differences in the beak of some;
migratory, arrival of the male before the female;
apparent relation between polygamy and marked sexual differences in;
monogamous, becoming polygamous under domestication;
eagerness of male in pursuit of the female;
wild, numerical proportion of the sexes in;
secondary sexual characters of;
difference of size in the sexes of;
fights of male, witnessed by females;
display of male, to captivate the females;
close attention of, to the songs of others;
acquiring the song of their foster-parents;
brilliant, rarely good songsters;
love-antics and dances of;
coloration of;
moulting of;
unpaired;
male, singing out of season;
mutual affection of;
in confinement, distinguish persons;
hybrid, production of;
Albino;
European, number of species of;
variability of;
geographical distribution of colouring;
gradation of secondary sexual characters in;
obscurely coloured, building concealed nests;
young female, acquiring male characters;
breeding in immature plumage;
moulting of;
aquatic, frequency of white plumage in;
vocal courtship of;
naked skin of the head and neck in.
Birgus latro, habits of.
Birkbeck, Mr., on the finding of new mates by golden eagles.
Birthplace of man.
Births, numerical proportions of the sexes in, in animals and man;
male and female, numerical proportion of, in England.
Bischoff, Prof., on the agreement between the brains of man and of the
orang;
figure of the embryo of the dog;
on the convolutions of the brain in the human foetus;
on the difference between the skulls of man and the quadrumana;
resemblance between the ape's and man's.
Bishop, J., on the vocal organs of frogs;
on the vocal organs of cervine birds;
on the trachea of the Merganser.
Bison, American, co-operation of;
mane of the male.
Bitterns, dwarf, coloration of the sexes of.
Biziura lobata, musky odour of the male;
large size of male.
Blackbird, sexual differences in the;
proportion of the sexes in the;
acquisition of a song by;
colour of the beak in the sexes of the;
pairing with a thrush;
colours and nidification of the;
young of the;
sexual difference in coloration of the.
Black-buck, Indian, sexual difference in the colour of the.
Blackcap, arrival of the male, before the female;
young of the.
Black-cock, polygamous;
proportion of the sexes in the;
pugnacity and love-dance of the;
call of the;
moulting of the;
duration of the courtship of the;
and pheasant, hybrids of;
sexual difference in coloration of the;
crimson eye-cere of the.
Black-grouse, characters of young.
Blacklock, Dr., on music.
Blackwall, J., on the speaking of the magpie;
on the desertion of their young by swallows;
on the superior activity of male spiders;
on the proportion of the sexes in spiders;
on sexual variation of colour in spiders;
on male spiders.
Bladder-nose Seal, hood of the.
Blaine, on the affections of dogs.
Blair, Dr., on the relative liability of Europeans to yellow fever.
Blake, C.C., on the jaw from La Naulette.
Blakiston, Captain, on the American snipe;
on the dances of Tetrao phasianellus.
Blasius, Dr., on the species of European birds.
Bledius taurus, hornlike processes of male.
Bleeding, tendency to profuse.
Blenkiron, Mr., on sexual preference in horses.
Blennies, crest developed on the head of male, during the breeding season.
Blethisa multipunctata, stridulation of.
Bloch, on the proportions of the sexes in fishes.
Blood, arterial, red colour of.
Blood pheasant, number of spurs in.
Blow-fly, sounds made by.
Bluebreast, red-throated, sexual differences of the.
Blumenbach, on Man;
on the large size of the nasal cavities in American aborigines;
on the position of man;
on the number of species of man.
Blyth, E., on the structure of the hand in the species of Hylobates;
observations on Indian crows;
on the development of the horns in the Koodoo and Eland antelopes;
on the pugnacity of the males of Gallicrex cristatus;
on the presence of spurs in the female Euplocamus erythrophthalmus;
on the pugnacity of the amadavat;
on the spoonbill;
on the moulting of Anthus;
on the moulting of bustards, plovers, and Gallus bankiva;
on the Indian honey-buzzard;
on sexual differences in the colour of the eyes of hornbills;
on Oriolus melanocephalus;
on Palaeornis javanicus;
on the genus Ardetta;
on the peregrine falcon;
on young female birds acquiring male characters;
on the immature plumage of birds;
on representative species of birds;
on the young of Turnix;
on anomalous young of Lanius rufus and Colymbus glacialis;
on the sexes and young of the sparrows;
on dimorphism in some herons;
on the ascertainment of the sex of nestling bullfinches by pulling out
breast-feathers;
on orioles breeding in immature plumage;
on the sexes and young of Buphus and Anastomus;
on the young of the blackcap and blackbird;
on the young of the stonechat;
on the white plumage of Anastomus;
on the horns of Bovine animals;
on the horns of Antilope bezoartica;
on the mode of fighting of Ovis cycloceros;
on the voice of the Gibbons;
on the crest of the male wild goat;
on the colours of Portax picta;
on the colours of Antilope bezoartica;
on the colour of the Axis deer;
on sexual difference of colour in Hylobates hoolock;
on the hog-deer;
on the beard and whiskers in a monkey, becoming white with age.
Boar, wild, polygamous in India;
use of the tusks by the;
fighting of.
Boardman, Mr., Albino birds in U.S.
Boitard and Corbie, MM., on the transmission of sexual peculiarities in
pigeons;
on the antipathy shewn by some female pigeons to certain males.
Bold, Mr., on the singing of a sterile hybrid canary.
Bombet, on the variability of the standard of beauty in Europe.
Bombus, difference of the sexes in.
Bombycidae, coloration of;
pairing of the;
colours of.
Bombycilla carolinensis, red appendages of.
Bombyx cynthia, proportion of the sexes in;
pairing of.
Bombyx mori, difference of size of the male and female cocoons of;
pairing of.
Bombyx Pernyi, proportion of sexes of.
Bombyx Yamamai, M. Personnat on;
proportion of sexes of.
Bonaparte, C.L., on the call-notes of the wild turkey.
Bond, F., on the finding of new mates by crows.
Bone, implements of, skill displayed in making.
Boner, C., on the transfer of male characters to an old female chamois;
on the habits of stags;
on the pairing of red deer.
Bones, increase of, in length and thickness, when carrying a greater
weight.
Bonizzi, P., difference of colour in sexes of pigeons.
Bonnet monkey.
Bonwick, J., extinction of Tasmanians.
Boomerang.
Boreus hyemalis, scarcity of the male.
Bory St. Vincent, on the number of species of man;
on the colours of Labrus pavo.
Bos etruscus.
Bos gaurus, horns of.
Bos moschatus.
Bos primigenius.
Bos sondaicus, horns of,
colours of.
Botocudos, mode of life of;
disfigurement of the ears and lower lip of the.
Boucher de Perthes, J.C. de, on the antiquity of man.
Bourbon, proportion of the sexes in a species of Papilio from.
Bourien on the marriage-customs of the savages of the Malay Archipelago.
Bovidae, dewlaps of.
Bower-birds, habits of the;
ornamented playing-places of.
Bows, use of.
Brachycephalic structure, possible explanation of.
Brachyura.
Brachyurus calvus, scarlet face of.
Bradley, Mr., abductor ossis metatarsi quinti in man.
Brain, of man, agreement of the, with that of lower animals;
convolutions of, in the human foetus;
influence of development of mental faculties upon the size of the;
influence of the development of on the spinal column and skull;
larger in some existing mammals than in their tertiary prototypes;
relation of the development of the, to the progress of language;
disease of the, affecting speech;
difference in the convolutions of, in different races of men;
supplement on, by Prof. Huxley;
development of the gyri and sulci.
Brakenridge, Dr., on the influence of climate.
Brandt, A., on hairy men.
Braubach, Prof., on the quasi-religious feeling of a dog towards his
master;
on the self-restraint of dogs.
Brauer, F., on dimorphism in Neurothemis.
Brazil, skulls found in caves of;
population of;
compression of the nose by the natives of.
Break between man and the apes.
Bream, proportion of the sexes in the.
Breeding, age of, in birds.
Breeding season, sexual characters making their appearance in the, in
birds.
Brehm, on the effects of intoxicating liquors on monkeys;
on the recognition of women by male Cynocephali;
on the diversity of the mental faculties of monkeys;
on the habits of baboons;
on revenge taken by monkeys;
on manifestations of maternal affection by monkeys and baboons;
on the instinctive dread of monkeys for serpents;
on the use of stones as missiles by baboons;
on a baboon using a mat for shelter from the sun;
on the signal-cries of monkeys;
on sentinels posted by monkeys;
on co-operation of animals;
on an eagle attacking a young Cercopithecus;
on baboons in confinement protecting one of their number from punishment;
on the habits of baboons when plundering;
on polygamy in Cynocephalus and Cebus;
on the numerical proportion of the sexes in birds;
on the love-dance of the blackcock;
Palamedea cornuta;
on the habits of the Black-grouse;
on sounds produced by birds of paradise;
on assemblages of grouse;
on the finding of new mates by birds;
on the fighting of wild boars;
on sexual differences in Mycetes;
on the habits of Cynocephalus hamadryas.
Brent, Mr., on the courtship of fowls.
Breslau, numerical proportion of male and female births in.
Bridgeman, Laura.
Brimstone butterfly, sexual difference of colour in the.
British, ancient, tattooing practised by.
Broca, Prof., on the occurrence of the supra-condyloid foramen in the human
humerus;
anthropomorphous apes more bipedal than quadrupedal;
on the capacity of Parisian skulls at different periods;
comparison of modern and mediaeval skulls;
on tails of quadrupeds;
on the influence of natural selection;
on hybridity in man;
on human remains from Les Eyzies;
on the cause of the difference between Europeans and Hindoos.
Brodie, Sir B., on the origin of the moral sense in man.
Bronn, H.G., on the copulation of insects of distinct species.
Bronze period, men of, in Europe.
Brown, R., sentinels of seals generally females;
on the battles of seals;
on the narwhal;
on the occasional absence of the tusks in the female walrus;
on the bladder-nose seal;
on the colours of the sexes in Phoca Groenlandica;
on the appreciation of music by seals;
on plants used as love-philters, by North American women.
Browne, Dr. Crichton, injury to infants during parturition.
Brown-Sequard, Dr., on the inheritance of the effects of operations by
guinea-pig.
Bruce, on the use of the elephant's tusks.
Brulerie, P. de la, on the habits of Ateuchus cicatricosus;
on the stridulation of Ateuchus.
Brunnich, on the pied ravens of the Feroe islands.
Bryant, Dr., preference of tame pigeon for wild mate.
Bryant, Captain, on the courtship of Callorhinus ursinus.
Bubas bison, thoracic projection of.
Bubalus caffer, use of horns.
Bucephalus capensis, difference of the sexes of, in colour.
Buceros, nidification and incubation of.
Buceros bicornis, sexual differences in the colouring of the casque, beak,
and mouth in.
Buceros corrugatus, sexual differences in the beak of.
Buchner, L., on the origin of man;
on the use of the human foot as a prehensile organ;
on the mode of progression of the apes;
on want of self-consciousness, etc., in savages.
Bucholz, Dr., quarrels of chamaeleons.
Buckinghamshire, numerical proportion of male and female births in.
Buckland, F., on the numerical proportion of the sexes in rats;
on the proportion of the sexes in the trout;
on Chimaera monstrosa.
Buckland, W., on the complexity of crinoids.
Buckler, W., proportion of sexes of Lepidoptera reared by.
Bucorax abyssinicus, inflation of the neck-wattle of the male during
courtship.
Budytes Raii.
Buffalo, Cape.
Buffalo, Indian, horns of the.
Buffalo, Italian, mode of fighting of the.
Buffon, on the number of species of man.
Bufo sikimmensis.
Bugs.
Buist, R., on the proportion of the sexes in salmon;
on the pugnacity of the male salmon.
Bulbul, pugnacity of the male;
display of under tail-coverts by the male.
Bull, mode of fighting of the;
curled frontal hair of the.
Buller, Dr., on the Huia;
the attachment of birds.
Bullfinch, sexual differences in the;
piping;
female, singing of the;
courtship of the;
widowed, finding a new mate;
attacking a reed-bunting;
nestling, sex ascertained by pulling out breast feathers.
Bullfinches, distinguishing persons;
rivalry of female.
Bulls, two young, attacking an old one;
wild, battles of.
Bull-trout, male, colouring of, during the breeding season.
Bunting, reed, head feathers of the male;
attacked by a bullfinch.
Buntings, characters of young.
Buphus coromandus, sexes and young of;
change of colour in.
Burchell, Dr., on the zebra;
on the extravagance of a Bushwoman in adorning herself;
celibacy unknown among the savages of South Africa;
on the marriage-customs of the Bushwomen.
Burke, on the number of species of man.
Burmese, colour of the beard in.
Burton, Captain, on negro ideas of female beauty;
on a universal ideal of beauty.
Bushmen, marriage among.
Bushwoman, extravagant ornamentation of a.
Bushwomen, hair of;
marriage-customs of.
Bustard, throat-pouch of the male;
humming noise produced by a male;
Indian, ear-tufts of.
Bustards, occurrence of sexual differences and of polygamy among the;
love-gestures of the male;
double moult in.
Butler, A.G., on sexual differences in the wings of Aricoris epitus;
courtship of butterflies;
on the colouring of the sexes in species of Thecla;
on the resemblance of Iphias glaucippe to a leaf;
on the rejection of certain moths and caterpillars by lizards and frogs.
Butterfly, noise produced by a;
Emperor;
meadow brown, instability of the ocellated spots of.
Butterflies, proportion of the sexes in;
forelegs atrophied in some males;
sexual difference in the neuration of the wings of;
pugnacity of male;
protective resemblances of the lower surface of;
display of the wings by;
white, alighting upon bits of paper;
attracted by a dead specimen of the same species;
courtship of;
male and female, inhabiting different stations.
Buxton, C., observations on macaws;
on an instance of benevolence in a parrot.
Buzzard, Indian honey-;
variation in the crest of.
Cabbage butterflies.
Cachalot, large head of the male.
Cadences, musical, perception of, by animals.
Caecum, large, in the early progenitors of man.
Cairina moschata, pugnacity of the male.
Californian Indians, decrease of.
Callianassa, chelae of, figured.
Callidryas, colours of sexes.
Callionymus lyra, characters of the male.
Callorhinus ursinus, relative size of the sexes of;
courtship of.
Calotes maria.
Calotes nigrilabris, sexual difference in the colour of.
Cambridge, O. Pickard, on the sexes of spiders;
on the size of male Nephila.
Camel, canine teeth of male.
Campbell, J., on the Indian elephant;
on the proportion of male and female births in the harems of Siam.
Campylopterus hemileucurus.
Canaries distinguishing persons.
Canary, polygamy of the;
change of plumage in, after moulting;
female, selecting the best singing male;
sterile hybrid, singing of a;
female, singing of the;
selecting a greenfinch;
and siskin, pairing of.
Cancer pagurus.
Canestrini, G., on rudimentary characters and the origin of man;
on rudimentary characters;
on the movement of the ear in man;
of the variability of the vermiform appendage in man;
on the abnormal division of the malar bone in man;
on abnormal conditions of the human uterus;
on the persistence of the frontal suture in man;
on the proportion of the sexes in silk-moths;
secondary sexual characters of spiders.
Canfield, Dr., on the horns of the Antilocapra.
Canine teeth in man, diminution of, in man;
diminution of, in horses;
disappearance of, in male ruminants;
large in the early progenitors of man.
Canines, and horns, inverse development of.
Canoes, use of.
Cantharis, difference of colour in the sexes of a species of.
Cantharus lineatus.
Capercailzie, polygamous;
proportion of the sexes in the;
pugnacity of the male;
pairing of the;
autumn meetings of the;
call of the;
duration of the courtship of;
behaviour of the female;
inconvenience of black colour to the female;
sexual difference in the coloration of the;
crimson eye-cere of the male.
Capitonidae, colours and nidification of the.
Capra aegagrus, crest of the male;
sexual difference in the colour of.
Capreolus Sibiricus subecaudatus.
Caprice, common to man and animals.
Caprimulgus, noise made by the males of some species of, with their wings.
Caprimulgus virginianus, pairing of.
Carabidae.
Carbonnier, on the natural history of the pike;
on the relative size of the sexes in fishes;
courtship of Chinese Macropus.
Carcineutes, sexual difference of colour in.
Carcinus moenas.
Cardinalis virginianus.
Carduelis elegans, sexual differences of the beak in.
Carnivora, marine, polygamous habits of;
sexual differences in the colours of.
Carp, numerical proportion of the sexes in the.
Carr, R., on the peewit.
Carrier pigeon, late development of the wattle in the.
Carrion beetles, stridulation of.
Carrion-hawk, bright coloured female of.
Carus, Prof. V., on the development of the horns in merino sheep;
on antlers of red deer.
Cassowary, sexes and incubation of the.
Castnia, mode of holding wings.
Castoreum.
Castration, effects of.
Casuarius galeatus.
Cat, convoluted body in the extremity of the tail of a;
sick, sympathy of a dog with a.
Cataract in Cebus Azarae.
Catarrh, liability of Cebus Azarae to.
Catarrhine monkeys.
Caterpillars, bright colours of.
Cathartes aura.
Cathartes jota, love-gestures of the male.
Catlin, G., correlation of colour and texture of hair in the Mandans;
on the development of the beard among the North American Indians;
on the great length of the hair in some North American tribes.
Caton, J.D., on the development of the horns in Cervus virginianus and
strongyloceros;
on the wild turkey;
on the presence of traces of horns in the female wapiti;
on the fighting of deer;
on the crest of the male wapiti;
on the colours of the Virginian deer;
on sexual differences of colour in the wapiti;
on the spots of the Virginian deer.
Cats, dreaming;
tortoise-shell;
enticed by valerian;
colours of.
Cattle, rapid increase of, in South America;
domestic, lighter in winter in Siberia;
horns of;
domestic, sexual differences of, late developed;
numerical proportion of the sexes in.
Caudal vertebrae, number of, in macaques and baboons;
basal, of monkeys, imbedded in the body.
Cavolini, observations on Serranus.
Cebus, maternal affection in a;
gradation of species of.
Cebus Apella.
Cebus Azarae, liability of, to the same diseases as man;
distinct sounds produced by;
early maturity of the female.
Cebus capucinus, polygamous;
sexual differences of colour in;
hair on the head of.
Cebus vellerosus, hair on the head of.
Cecidomyiidae, proportions of the sexes in.
Celibacy, unknown among the savages of South Africa and South America.
Centipedes.
Cephalopoda, absence of secondary sexual characters in.
Cephalopterus ornatus.
Cephalopterus penduliger.
Cerambyx heros, stridulant organ of.
Ceratodus, paddle of.
Ceratophora aspera, nasal appendages of.
Ceratophora Stoddartii, nasal horn of.
Cerceris, habits of.
Cercocebus aethiops, whiskers, etc., of.
Cercopithecus, young, seized by an eagle and rescued by the troop;
definition of species of.
Cercopithecus cephus, sexual difference of colour in.
Cercopithecus cynosurus and griseo-viridis, colour of the scrotum in.
Cercopithecus Diana, sexual differences of colour in.
Cercopithecus griseo-viridis.
Cercopithecus petaurista, whiskers, etc., of.
Ceres, of birds, bright colours of.
Ceriornis Temminckii, swelling of the wattles of the male during courtship.
Cervulus, weapons of.
Cervulus moschatus, rudimentary horns of the female.
Cervus alces.
Cervus campestris, odour of.
Cervus canadensis, traces of horns in the female;
attacking a man;
sexual difference in the colour of.
Cervus elaphus, battles of male;
horns of, with numerous points;
long hairs on the throat of.
Cervus Eldi.
Cervus mantchuricus.
Cervus paludosus, colours of.
Cervus strongyloceros.
Cervus virginianus, horns of, in course of modification.
Ceryle, male black-belted in some species of.
Cetacea, nakedness of.
Ceylon, frequent absence of beard in the natives of.
Chaffinch, proportion of the sexes in the;
courtship of the.
Chaffinches, new mates found by.
Chalcophaps indicus, characters of young.
Chalcosoma atlas, sexual differences of.
Chamaeleo, sexual differences in the genus;
combats of.
Chamaeleo bifurcus.
Chamaeleo Owenii.
Chamaeleo pumilus.
Chamaepetes unicolor, modified wing-feather in the male.
Chameleons.
Chamois, danger-signals of;
transfer of male characters to an old female.
Champneys, Mr., acromio-basilar muscle and quadrupedal gait.
Chapman, Dr., on stridulation in Scolytus.
Chapuis, Dr., on the transmission of sexual peculiarities in pigeons;
on streaked Belgian pigeons.
Char, male, colouring of, during the breeding season.
Characters, male, developed in females;
secondary sexual, transmitted through both sexes;
natural, artificial, exaggeration of, by man.
Charadrus hiaticula and pluvialis, sexes and young of.
Chardin on the Persians.
Charms, worn by women.
Charruas, freedom of divorce among the.
Chasmorhynchus, difference of colour in the sexes of;
colours of.
Chasmorhynchus niveus.
Chasmorhynchus nudicollis.
Chasmorhynchus tricarunculatus.
Chastity, early estimation of.
Chatterers, sexual differences in.
Cheever, Rev. H.T., census of the Sandwich Islands.
Cheiroptera, absence of secondary sexual characters in.
Chelae of crustacea.
Chelonia, sexual differences in.
Chenalopex aegyuptiacus, wing-knobs of.
Chera progne.
Chest, proportions of, in soldiers and sailors;
large, of the Quechua and Aymara Indians.
Chevrotains, canine teeth of.
Chiasognathus, stridulation of.
Chiasognathus Grantii, mandibles of.
Children, legitimate and illegitimate, proportion of the sexes in.
Chiloe, lice of the natives of;
population of.
Chimaera monstrosa, bony process on the head of the male.
Chimaeroid fishes, prehensile organs of male.
Chimpanzee, ears of the;
representatives of the eyebrows in the;
hands of the;
absence of mastoid processes in the;
platforms built by the;
cracking nuts with a stone;
direction of the hair on the arms of the;
supposed evolution of the;
polygamous and social habits of the.
China, North, idea of female beauty in.
China, Southern, inhabitants of.
Chinese, use of flint tools by the;
difficulty of distinguishing the races of the;
colour of the beard in;
general beardlessness of the;
opinions of the, on the appearance of Europeans and Cingalese;
compression of the feet of.
Chinsurdi, his opinion of beards.
Chlamydera maculata.
Chloeon, pedunculated eyes of the male of.
Chloephaga, coloration of the sexes in.
Chlorocoelus Tanana.
Chorda dorsalis.
Chough, red beak of the.
Chromidae, frontal protuberance in male;
sexual differences in colour of.
Chrysemys picta, long claws of the male.
Chrysococcyx, characters of young of.
Chrysomelidae, stridulation of.
Cicada pruinosa.
Cicada septendecim.
Cicadae, songs of the;
rudimentary sound-organs in females of.
Cicatrix of a burn, causing modification of the facial bones.
Cichla, frontal protuberance of male.
Cimetiere du Sud, Paris.
Cincloramphus cruralis, large size of male.
Cinclus aquaticus.
Cingalese, Chinese opinion of the appearance of the.
Cirripedes, complemental males of.
Civilisation, effects of, upon natural selection;
influence of, in the competition of nations.
Clanging of geese, etc.
Claparede, E., on natural selection applied to man.
Clarke, on the marriage-customs of Kalmucks.
Classification.
Claus, C., on the sexes of Saphirina.
Cleft-palate, inherited.
Climacteris erythrops, sexes of.
Climate, cool, favourable to human progress;
power of supporting extremes of, by man;
want of connexion of, with colour;
direct action of, on colours of birds.
Cloaca, existence of a, in the early progenitors of man.
Cloacal passage existing in the human embryo.
Clubs, used as weapons before dispersion of mankind.
Clucking of fowls.
Clythra 4-punctata, stridulation of.
Coan, Mr., Sandwich-islanders.
Cobbe, Miss, on morality in hypothetical bee-community.
Cobra, ingenuity of a.
Coccus.
Coccyx, in the human embryo;
convoluted body at the extremity of the;
imbedded in the body.
Cochin-China, notions of beauty of the inhabitants of.
Cock, blind, fed by its companion;
game, killing a kite;
comb and wattles of the;
preference shewn by the, for young hens;
game, transparent zone in the hackles of a.
Cock of the rock.
Cockatoos, nestling;
black, immature plumage of.
Coelenterata, absence of secondary sexual characters in.
Coffee, fondness of monkeys for.
Cold, supposed effects of;
power of supporting, by man.
Coleoptera, stridulation of;
stridulant organs of, discussed.
Colias edusa and hyale.
Collingwood, C., on the pugnacity of the butterflies of Borneo;
on butterflies being attracted by a dead specimen of the same species.
Colobus, absence of the thumb.
Colombia, flattened heads of savages of.
Colonists, success of the English as.
Coloration, protective, in birds.
Colour, supposed to be dependent on light and heat;
correlation of, with immunity from certain poisons and parasites;
purpose of, in lepidoptera;
relation of, to sexual functions, in fishes;
difference of, in the sexes of snakes;
sexual differences of, in lizards;
influence of, in the pairing of birds of different species;
relation of, to nidification;
sexual differences of, in mammals;
recognition of, by quadrupeds;
of children, in different races of man;
of the skin in man.
Colours, admired alike by man and animals;
bright, due to sexual selection;
bright, among the lower animals;
bright, protective to butterflies and moths;
bright, in male fishes;
transmission of, in birds.
Colquhoun, example of reasoning in a retriever.
Columba passerina, young of.
Colymbus glacialis, anomalous young of.
Comb, development of, in fowls.
Combs and wattles in male birds.
Community, preservation of variations useful to the, by natural selection.
Complexion, different in men and women, in an African tribe.
Compositae, gradation of species among the.
Comte, C., on the expression of the ideal of beauty by sculpture.
Conditions of life, action of changed, upon man;
influence of, on plumage of birds.
Condor, eyes and comb of the.
Conjugations, origin of.
Conscience, absence of, in some criminals.
Constitution, difference of, in different races of men.
Consumption, liability of Cebus Azarae to;
connection between complexion and.
Convergence of characters.
Cooing of pigeons and doves.
Cook, Captain, on the nobles of the Sandwich Islands.
Cope, E.D., on the Dinosauria.
Cophotis ceylanica, sexual differences of.
Copris.
Copris Isidis, sexual differences of.
Copris lunaris, stridulation of.
Corals, bright colours of.
Coral-snakes.
Cordylus, sexual difference of colour in a species of.
Corfu, habits of the Chaffinch in.
Cornelius, on the proportions of the sexes in Lucanus Cervus.
Corpora Wolffiana, agreement of, with the kidneys of fishes.
Correlated variation.
Correlation, influence of, in the production of races.
Corse, on the mode of fighting of the elephant.
Corvus corone.
Corvus graculus, red beak of.
Corvus pica, nuptial assembly of.
Corydalis cornutus, large jaws of the male.
Cosmetornis.
Cosmetornis vexillarius, elongation of wing-feathers in.
Cotingidae, sexual differences in;
coloration of the sexes of;
resemblance of the females of distinct species of.
Cottus scorpius, sexual differences in.
Coulter, Dr., on the Californian Indians.
Counting, origin of;
limited power of, in primeval man.
Courage, variability of, in the same species;
universal high appreciation of;
importance of;
characteristic of men.
Courtship, greater eagerness of males in;
of fishes;
of birds.
Cow, winter change of colour.
Crab, devil.
Crab, shore, habits of.
Crabro cribrarius, dilated tibiae of the male.
Crabs, proportions of the sexes in.
Cranz, on the inheritance of dexterity in seal-catching.
Crawfurd, on the number of species of man.
Crenilabrus massa and C. melops, nests, built by.
Crest, origin of, in Polish fowls.
Crests, of birds, difference of, in the sexes;
dorsal hairy, of mammals.
Cricket, field-, stridulation of the;
pugnacity of male.
Cricket, house-, stridulation of the.
Crickets, sexual differences in.
Crinoids, complexity of.
Crioceridae, stridulation of the.
Croaking of frogs.
Crocodiles, musky odour of, during the breeding season.
Crocodilia.
Crossbills, characters of young.
Crosses in man.
Crossing of races, effects of the.
Crossoptilon auritum, adornment of both sexes of;
sexes alike in.
Crotch, G.R., on the stridulation of beetles;
on the stridulation of Heliopathes;
on the stridulation of Acalles;
habit of female deer at breeding time.
Crow, Indians, long hair of the.
Crow, young of the.
Crows, vocal organs of the;
living in triplets.
Crows, carrion, new mates found by.
Crows, Indian, feeding their blind companions.
Cruelty of savages to animals.
Crustacea, parasitic, loss of limbs by female;
prehensile feet and antennae of;
male, more active than female;
parthenogenesis in;
secondary sexual characters of;
amphipod, males sexually mature while young;
auditory hairs of.
Crystal worn in the lower lip by some Central African women.
Cuckoo fowls.
Culicidae, attracted by each other's humming.
Cullen, Dr., on the throat-pouch of the male bustard.
Cultivation of plants, probable origin of.
Cupples, Mr., on the numerical proportion of the sexes in dogs, sheep, and
cattle;
on the Scotch deerhound;
on sexual preference in dogs.
Curculionidae, sexual difference in length of snout in some;
hornlike processes in male;
musical.
Curiosity, manifestations of, by animals.
Curlews, double moult in.
Cursores, comparative absence of sexual differences among the.
Curtis, J., on the proportion of the sexes in Athalia.
Cuvier, F., on the recognition of women by male quadrumana.
Cuvier, G., on the number of caudal vertebrae in the mandrill;
on instinct and intelligence;
views of, as to the position of man;
on the position of the seals;
on Hectocotyle.
Cyanalcyon, sexual difference in colours of;
immature plumage of.
Cyanecula suecica, sexual differences of.
Cychrus, sounds produced by.
Cycnia mendica, sexual difference of, in colour.
Cygnus ferus, trachea of.
Cygnus immutabilis.
Cygnus olor, white young of.
Cyllo Leda, instability of the ocellated spots of.
Cynanthus, variation in the genus.
Cynipidae, proportion of the sexes in.
Cynocephalus, difference of the young from the adult;
male, recognition of women by;
polygamous habits of species of.
Cynocephalus babouin.
Cynocephalus chacma.
Cynocephalus gelada.
Cynocephalus hamadryas, sexual difference of colour in.
Cynocephalus leucophaeus, colours of the sexes of.
Cynocephalus mormon, colours of the male.
Cynocephalus porcarius, mane of the male.
Cynocephalus sphinx.
Cynopithecus niger, ear of.
Cypridina, proportions of the sexes in.
Cyprinidae, proportion of the sexes in the.
Cyprinidae, Indian.
Cyprinodontidae, sexual differences in the.
Cyprinus auratus.
Cypris, relation of the sexes in.
Cyrtodactylus rubidus.
Cystophora cristata, hood of.
Dacelo, sexual difference of colour in.
Dacelo Gaudichaudi, young male of.
Dal-ripa, a kind of ptarmigan.
Damalis albifrons, peculiar markings of.
Damalis pygarga, peculiar markings of.
Dampness of climate, supposed influence of, on the colour of the skin.
Danaidae.
Dances of birds.
Dancing, universality of.
Danger-signals of animals.
Daniell, Dr., his experience of residence in West Africa.
Darfur, protuberances artificially produced by natives of.
Darwin, F., on the stridulation of Dermestes murinus.
Dasychira pudibunda, sexual difference of colour in.
Davis, A.H., on the pugnacity of the male stag-beetle.
Davis, J.B., on the capacity of the skull in various races of men;
on the beards of the Polynesians.
Death's Head Sphinx.
Death-rate higher in towns than in rural districts.
Death-tick.
De Candolle, Alph., on a case of inherited power of moving the scalp.
Declensions, origin of.
Decoration in birds.
Decticus.
Deer, development of the horns in;
spots of young;
horns of;
use of horns of;
horns of a, in course of modification;
size of the horns of;
female, pairing with one male whilst others are fighting for her;
male, attracted by the voice of the female;
male, odour emitted by.
Deer, Axis, sexual difference in the colour of the.
Deer, fallow, different coloured herds of.
Deer, Mantchurian.
Deer, Virginian, colour of the, not affected by castration;
colours of.
Deerhound, Scotch, greater size of the male.
Defensive orders of mammals.
De Geer, C., on a female spider destroying a male.
Dekay, Dr., on the bladder-nose seal.
Delorenzi, G., division of malar bone.
Demerara, yellow fever in.
Dendrocygna.
Dendrophila frontalis, young of.
Denison, Sir W., manner of ridding themselves of vermin among the
Australians;
extinction of Tasmanians.
Denny, H., on the lice of domestic animals.
Dermestes murinus, stridulation of.
Descent traced through the mother alone.
Deserts, protective colouring of animals inhabiting.
Desmarest, on the absence of suborbital pits in Antilope subgutturosa;
on the whiskers of Macacus;
on the colour of the opossum;
on the colours of the sexes of Mus minutus;
on the colouring of the ocelot;
on the colours of seals;
on Antilope caama;
on the colours of goats;
on sexual difference of colour in Ateles marginatus;
on the mandrill;
on Macacus cynomolgus.
Desmoulins, on the number of species of man;
on the muskdeer.
Desor, on the imitation of man by monkeys.
Despine, P., on criminals destitute of conscience.
Development, embryonic of man;
correlated.
Devil, not believed in by the Fuegians.
Devil-crab.
Devonian, fossil-insect from the.
Dewlaps, of Cattle and antelopes.
Diadema, sexual differences of colouring in the species of.
Diamond-beetles, bright colours of.
Diastema, occurrence of, in man.
Diastylidae, proportion of the sexes in.
Dicrurus, racket-shaped feathers in;
nidification of.
Dicrurus macrocercus, change of plumage in.
Didelphis opossum, sexual difference in the colour of.
Differences, comparative, between different species of birds of the same
sex.
Digits, supernumerary, more frequent in men than in women;
supernumerary, inheritance of;
supernumerary, early development of.
Dimorphism, in females of water-beetles;
in Neurothemis and Agrion.
Diodorus, on the absence of beard in the natives of Ceylon.
Dipelicus Cantori, sexual differences of.
Diplopoda, prehensile limbs of the male.
Dipsas cynodon, sexual difference in the colour of.
Diptera.
Disease, generated by the contact of distinct peoples.
Diseases, common to man and the lower animals;
difference of liability to, in different races of men;
new, effects of, upon savages;
sexually limited.
Display, coloration of Lepidoptera for;
of plumage by male birds.
Distribution, wide, of man;
geographical, as evidence of specific distinctness in man.
Disuse, effects of, in producing rudimentary organs;
and use of parts, effects of;
of parts, influence of, on the races of men.
Divorce, freedom of, among the Charruas.
Dixon, E.S., on the pairing of different species of geese;
on the courtship of peafowl.
Dobrizhoffer, on the marriage-customs of the Abipones.
Dobson, Dr., on the Cheiroptera;
scent-glands of bats;
frugivorous bats.
Dogs, suffering from tertian ague;
memory of;
dreaming;
diverging when drawing sledges over thin ice;
exercise of reasoning faculties by;
domestic, progress of, in moral qualities;
distinct tones uttered by;
parallelism between his affection for his master and religious feeling;
sociability of the;
sympathy of, with a sick cat;
sympathy of, with his master;
their possession of conscience;
possible use of the hair on the fore-legs of the;
races of the;
numerical proportion of male and female births in;
sexual affection between individuals of;
howling at certain notes;
rolling in carrion.
Dolichocephalic structure, possible cause of.
Dolphins, nakedness of.
Domestic animals, races of;
change of breeds of.
Domestication, influence of, in removing the sterility of hybrids.
D'Orbigny, A., on the influence of dampness and dryness on the colour of
the skin;
on the Yuracaras.
Dotterel.
Doubleday, E., on sexual differences in the wings of butterflies.
Doubleday, H., on the proportion of the sexes in the smaller moths;
males of Lasiocampa quercus and on the attraction of the Saturnia carpini
by the female;
on the proportion of the sexes in the Lepidoptera;
on the ticking of Anobium tesselatum;
on the structure of Ageronia feronia;
on white butterflies alighting upon paper.
Douglas, J.W., on the sexual differences of the Hemiptera;
colours of British Homoptera.
Down, of birds.
Draco, gular appendages of.
Dragonet, Gemmeous.
Dragon-flies, caudal appendages of male;
relative size of the sexes of;
difference in the sexes of;
want of pugnacity by the male.
Drake, breeding plumage of the.
Dreams, possible source of the belief in spiritual agencies.
Drill, sexual difference of colour in the.
Dromaeus irroratus.
Dromolaea, Saharan species of.
Drongo shrike.
Drongos, racket-shaped feathers in the tails of.
Dryness of climate, supposed influence of, on the colour of the skin.
Dryopithecus.
Duck, harlequin, age of mature plumage in the;
breeding in immature plumage.
Duck, long-tailed, preference of male, for certain females.
Duck, pintail, pairing with a widgeon.
Duck, voice of the;
pairing with a shield-drake;
immature plumage of the.
Duck, wild, sexual differences in the;
speculum and male characters of;
pairing with a pin-tail drake.
Ducks, wild, becoming polygamous under partial domestication;
dogs and cats recognised by.
Dufosse, Dr., sounds produced by fish.
Dugong, nakedness of;
tusks of.
Dujardin, on the relative size of the cerebral ganglia, in insects.
Duncan, Dr., on the fertility of early marriages;
comparative health of married and single.
Dupont, M., on the occurrence of the supra-condyloid foramen in the humerus
of man.
Durand, J.P., on causes of variation.
Dureau de la Malle, on the songs of birds;
on the acquisition of an air by blackbirds.
Dutch, retention of their colour by the, in South Africa.
Duty, sense of.
Duvaucel, female Hylobates washing her young.
Dyaks, pride of, in mere homicide.
Dynastes, large size of males of.
Dynastini, stridulation of.
Dytiscus, dimorphism of females of;
grooved elytra of the female.
Eagle, young Cercopithecus rescued from, by the troop.
Eagle, white-headed, breeding in immature plumage.
Eagles, golden, new mates found by.
Ear, motion of the;
external shell of the, useless in man;
rudimentary point of the, in man.
Ears, more variable in men than women;
piercing and ornamentation of the.
Earwigs, parental feeling in.
Echidna.
Echini, bright colours of some.
Echinodermata, absence of secondary sexual characters in.
Echis carinata.
Ecker, figure of the human embryo;
on the development of the gyri and sulci of the brain;
on the sexual differences in the pelvis in man;
on the presence of a sagittal crest in Australians.
Edentata, former wide range of, in America;
absence of secondary sexual characters in.
Edolius, racket-shaped feathers in.
Edwards, Mr., on the proportion of the sexes in North American species of
Papilio.
Eels, hermaphroditism of.
Egerton, Sir P., on the use of the antlers of deer;
on the pairing of red deer;
on the bellowing of stags.
Eggs, hatched by male fishes.
Egret, Indian, sexes and young of.
Egrets, breeding plumage of;
white.
Ehrenberg, on the mane of the male Hamadryas baboon.
Ekstrom, M., on Harelda glacialis.
Elachista rufocinerea, habits of male.
Eland, development of the horns of the.
Elands, sexual differences of colour in.
Elaphomyia, sexual differences in.
Elaphrus uliginosus, stridulation of.
Elaps.
Elateridae, proportion of the sexes in.
Elaters, luminous.
Elephant, rate of increase of the;
nakedness of the;
using a fan;
Indian, forbearance to his keeper;
polygamous habits of the;
pugnacity of the male;
tusks of;
Indian, mode of fighting of the;
male, odour emitted by the;
attacking white or grey horses.
Elevation of abode, modifying influence of.
Elimination of inferior individuals.
Elk, winter change of the.
Elk, Irish, horns of the.
Ellice Islands, beards of the natives.
Elliot, D.G., on Pelecanus erythrorhynchus.
Elliot, R., on the numerical proportion of the sexes in young rats;
on the proportion of the sexes in sheep.
Elliot, Sir W., on the polygamous habits of the Indian wild boar.
Ellis, on the prevalence of infanticide in Polynesia.
Elphinstone, Mr., on local difference of stature among the Hindoos;
on the difficulty of distinguishing the native races of India.
Elytra, of the females of Dytiscus Acilius, Hydroporus.
Emberiza, characters of young.
Emberiza miliaria.
Emberiza schoeniclus, head-feathers of the male.
Embryo of man;
of the dog.
Embryos of mammals, resemblance of the.
Emigration.
Emotions experienced by the lower animals in common with man;
manifested by animals.
Emperor butterfly.
Emperor moth.
Emu, sexes and incubation of.
Emulation of singing birds.
Endurance, estimation of.
Energy, a characteristic of men.
England, numerical proportion of male and female births in.
Engleheart, Mr., on the finding of new mates by starlings.
English, success of, as colonists.
Engravers, short-sighted.
Entomostraca.
Entozoa, difference of colour between the males and females of some.
Environment, direct action of the, in causing differences between the
sexes.
Envy, persistence of.
Eocene period, possible divergence of men during the.
Eolidae, colours of, produced by the biliary glands.
Epeira nigra, small size of the male of.
Ephemerae.
Ephemeridae.
Ephippiger vitium, stridulating organs of.
Epicalia, sexual differences of colouring in the species of.
Equus hemionus, winter change of.
Erateina, coloration of.
Ercolani, Prof., hermaphroditism in eels.
Erect attitude of man.
Eristalis, courting of.
Eschricht, on the development of hair in man;
on a languinous moustache in a female foetus;
on the want of definition between the scalp and the forehead in some
children;
on the arrangement of the hair in the human foetus;
on the hairiness of the face in the human foetus of both sexes.
Esmeralda, difference of colour in the sexes of.
Esox lucius.
Esox reticulatus.
Esquimaux, their belief in the inheritance of dexterity in seal-catching;
mode of life of.
Estrelda amandava, pugnacity of the male.
Eubagis, sexual differences of colouring in the species of.
Euchirus longimanus, sound produced by.
Eudromias morinellus.
Eulampis jugularis, colours of the female.
Euler, on the rate of increase in the United States.
Eunomota superciliaris, racket-shaped feathers in the tail of.
Eupetomena macroura, colours of the female.
Euphema splendida.
Euplocamus erythrophthalmus, possession of spurs by the female.
Europe, ancient inhabitants of.
Europeans, difference of, from Hindoos;
hairiness of, probably due to reversion.
Eurostopodus, sexes of.
Eurygnathus, different proportions of the head in the sexes of.
Eustephanus, sexual differences of species of;
young of.
Exaggeration of natural characters by man.
Exogamy.
Experience, acquisition of, by animals.
Expression, resemblances in, between man and the apes.
Extinction of races, causes of.
Eye, destruction of the;
change of position in;
obliquity of, regarded as a beauty by the Chinese and Japanese.
Eyebrows, elevation of;
development of long hairs in;
in monkeys;
eradicated in parts of South America and Africa;
eradication of, by the Indians of Paraguay.
Eyelashes, eradication of, by the Indians of Paraguay.
Eyelids, coloured black, in part of Africa.
Eyes, pillared, of the male of Chloeon;
difference in the colour of, in the sexes of birds.
Eyton, T.C., observations on the development of the horns in the fallow
deer.
Eyzies, Les, human remains from.
Fabre, M., on the habits of Cerceris.
Facial bones, causes of modification of the.
Faculties, diversity of, in the same race of men;
inheritance of;
diversity of, in animals of the same species;
mental variation of, in the same species;
of birds.
Fakirs, Indian, tortures undergone by.
Falco leucocephalus.
Falco peregrinus.
Falco tinnunclus.
Falcon, peregrine, new mate found by.
Falconer, H., on the mode of fighting of the Indian elephant;
on canines in a female deer;
on Hyomoschus aquaticus.
Falkland Islands, horses of.
Fallow-deer, different coloured herds of.
Famines, frequency of, among savages.
Farr, Dr., on the effects of profligacy;
on the influence of marriage on mortality.
Farrar, F.W., on the origin of language;
on the crossing or blending of languages;
on the absence of the idea of God in certain races of men;
on early marriages of the poor;
on the middle ages.
Farre, Dr., on the structure of the uterus.
Fashions, long prevalence of, among savages.
Faye, Prof., on the numerical proportion of male and female births in
Norway and Russia;
on the greater mortality of male children at and before birth.
Feathers, modified, producing sounds;
elongated, in male birds;
racket-shaped;
barbless and with filamentous barbs in certain birds;
shedding of margins of.
Feeding, high, probable influence of, in the pairing of birds of different
species.
Feet, thickening of the skin on the soles of the;
modification of, in man.
Felis canadensis, throat-ruff of.
Felis pardalis and F. mitis, sexual difference in the colouring of.
Female, behaviour of the, during courtship.
Female birds, differences of.
Females, presence of rudimentary male organs in;
preference of, for certain males;
pursuit of, by males;
occurrence of secondary sexual characters in;
development of male character by.
Females and males, comparative numbers of;
comparative mortality of, while young.
Femur and tibia, proportions of, in the Aymara Indians.
Fenton, Mr., decrease of Maories;
infanticide amongst the Maories.
Ferguson, Mr., on the courtship of fowls.
Fertilisation, phenomena of, in plants;
in the lower animals.
Fertility lessened under changed conditions.
Fevers, immunity of Negroes and Mulattoes from.
Fiber zibethicus, protective colouring of it.
Fick, H., effect of conscription for military service.
Fidelity, in the elephant;
of savages to one another;
importance of.
Field-slaves, difference of, from house-slaves.
Fiji Archipelago, population of the.
Fiji Islands, beards of the natives;
marriage-customs of the.
Fijians, burying their old and sick parents alive;
estimation of the beard among the;
admiration of, for a broad occiput.
Filial affection, partly the result of natural selection.
Filum terminale.
Finch, racket-shaped feathers in the tail of a.
Finches, spring change of colour in;
British, females of the.
Fingers, partially coherent, in species of Hylobates.
Finlayson, on the Cochin Chinese.
Fire, use of.
Fischer, on the pugnacity of the male of Lethrus cephalotes.
Fischer, F. Von, on display of brightly coloured parts by monkeys in
courtship.
Fish, eagerness of male;
proportion of the sexes in;
sounds produced by.
Fishes, kidneys of, represented by Corpora Wolffiana in the human embryo;
male, hatching ova in their mouths;
receptacles for ova possessed by;
relative size of the sexes in;
fresh-water, of the tropics;
protective resemblances in;
change of colour in;
nest-building;
spawning of;
sounds produced by;
continued growth of.
Flamingo, age of mature plumage.
Flexor pollicis longus, similar variation of, in man.
Flies, humming of.
Flint tools.
Flints, difficulty of chipping into form.
Florida, Quiscalus major in.
Florisuga mellivora.
Flounder, coloration of the.
Flower, W.H., on the abductor of the fifth metatarsal in apes;
on the position of the Seals;
on the Pithecia monachu;
on the throat-pouch of the male bustard.
Fly-catchers, colours and nidification of.
Foetus, human, woolly covering of the;
arrangement of the hair on.
Food, influence of, upon stature.
Foot, prehensile power of the, retained in some savages;
prehensile, in the early progenitors of man.
Foramen, supra-condyloid, exceptional occurrence of in the humerus of man;
in the early progenitors of man.
Forbes, D., on the Aymara Indians;
on local variation of colour in the Quichuas;
on the hairlessness of the Aymaras and Quichuas;
on the long hair of the Aymaras and Quichaus.
Forel, F., on white young swans.
Forester, Hon. O.W., on an orphan hawk.
Formica rufa, size of the cerebral ganglia in.
Fossils, absence of, connecting man with the apes.
Fowl, occurrence of spurs in the female;
game, early pugnacity of;
Polish, early development of cranial peculiarities of;
variations in plumage of;
examples of correlated development in the;
domestic, breeds and sub-breeds of.
Fowls, spangled Hamburg;
inheritance of changes of plumage by;
sexual peculiarities in, transmitted only to the same sex;
loss of secondary sexual characters by male;
Polish, origin of the crest in;
period of inheritance of characters by;
cuckoo-;
development of the comb in;
numerical proportion of the sexes in;
courtship of;
mongrel, between a black Spanish cock and different hens;
pencilled Hamburg, difference of the sexes in;
Spanish, sexual differences of the comb in;
spurred, in both sexes.
Fox, W.D., on some half-tamed wild ducks becoming polygamous, and on
polygamy in the guinea-fowl and canary-bird;
on the proportion of the sexes in cattle;
on the pugnacity of the peacock;
on a nuptial assembly of magpies;
on the finding of new mates by crows;
on partridges living in triplets;
on the pairing of a goose with a Chinese gander.
Foxes, wariness of young, in hunting districts;
black.
Fraser, C., on the different colours of the sexes in a species of Squilla.
Fraser, G., colours of Thecla.
Frere, Hookham, quoting Theognis on selection in mankind.
Fringilla cannabina.
Fringilla ciris, age of mature plumage in.
Fringilla cyanea, age of mature plumage in.
Fringilla leucophrys, young of.
Fringilla spinus.
Fringilla tristis, change of colour in, in spring;
young of.
Fringillidae, resemblance of the females of distinct species of.
Frog, bright coloured and distasteful to birds.
Frogs, male;
temporary receptacles for ova possessed by;
ready to breed before the females;
fighting of;
vocal organs of.
Frontal bone, persistence of the suture in.
Fruits, poisonous, avoided by animals.
Fuegians, difference of stature among the;
power of sight in the;
skill of, in stone-throwing;
resistance of the, to their severe climate;
mental capacity of the;
quasi-religious sentiments of the;
resemblance of, in mental characters, to Europeans;
mode of life of the;
aversion of, to hair on the face;
said to admire European women.
Fulgoridae, songs of the.
Fur, whiteness of, in Arctic animals in winter.
Fur-bearing animals, acquired sagacity of.
Gallicrex, sexual difference in the colour of the irides in.
Gallicrex cristatus, pugnacity of male;
red carbuncle occurring in the male during the breeding-season.
Gallinaceae, frequency of polygamous habits and of sexual differences in
the;
love-gestures of;
decomposed feathers in;
stripes of young;
comparative sexual differences between the species of;
plumage of.
Gallinaceous birds, weapons of the male;
racket-shaped feathers on the heads of.
Gallinula chloropus, pugnacity of the male.
Galloperdix, spurs of;
development of spurs in the female.
Gallophasis, young of.
Galls.
Gallus bankiva, neck-hackles of.
Gallus Stanleyi, pugnacity of the male.
Galton, Mr., on hereditary genius;
gregariousness and independence in animals;
on the struggle between the social and personal impulses;
on the effects of natural selection on civilised nations;
on the sterility of sole daughters;
on the degree of fertility of people of genius;
on the early marriages of the poor;
on the ancient Greeks;
on the Middle Ages;
on the progress of the United States;
on South African notions of beauty.
Gammarus, use of the chelae of.
Gammarus marinus.
Gannets, white only when mature.
Ganoid fishes.
Gaour, horns of the.
Gap between man and the apes.
Gaper, sexes and young of.
Gardner, on an example of rationality in a Gelasimus.
Garrulus glandarius.
Gartner, on sterility of hybrid plants.
Gasteropoda, pulmoniferous, courtship of.
Gasterosteus, nidification of.
Gasterosteus leiurus.
Gasterosteus trachurus.
Gastrophora, wings of, brightly coloured beneath.
Gauchos, want of humanity among the.
Gaudry, M., on a fossil monkey.
Gavia, seasonal change of plumage in.
Geese, clanging noise made by;
pairing of different species of;
Canada, selection of mates by.
Gegenbaur, C., on the number of digits in the Ichthyopterygia;
on the hermaphroditism of the remote progenitors of the vertebrata;
two types of nipple in mammals.
Gelasimus, proportions of the sexes in a species of;
use of the enlarged chelae of the male;
pugnacity of males of;
rational actions of a;
difference of colour in the sexes of a species of.
Gemmules, dormant in one sex.
Genius, hereditary.
Genius, fertility of men and women of.
Geoffroy St.-Hilaire, Isid., on the recognition of women by male
quadrumana;
on monstrosities;
coincidences of arrested development with polydactylism;
on animal-like anomalies in the human structure;
on the correlation of monstrosities;
on the distribution of hair in man and monkeys;
on the caudal vertebrae of monkeys;
on correlated variability;
on the classification of man;
on the long hair on the heads of species of Semnopithecus;
on the hair in monkeys;
on the development of horns in female deer;
and F. Cuvier, on the mandrill;
on Hylobates.
Geographical distribution, as evidence of specific distinctions in man.
Geometrae, brightly coloured beneath.
Geophagus, frontal protuberance of, male;
eggs hatched by the male, in the mouth or branchial cavity.
Georgia, change of colour in Germans settled in.
Geotrupes, stridulation of.
Gerbe, M., on the nest-building of Crenilabus massa and C. Melops.
Gerland, Dr., on the prevalence of infanticide;
on the extinction of races.
Gervais, P., on the hairiness of the gorilla;
on the mandrill.
Gesture-language.
Ghost-moth, sexual difference of colour in the.
Giard, M., disputes descent of vertebrates from Ascidians;
colour of sponges and Ascidians;
musky odour of Sphinx.
Gibbon, voice of.
Gibbon, Hoolock, nose of.
Gibbs, Sir D., on differences of the voice in different races of men.
Gill, Dr., male seals larger than females;
sexual differences in seals.
Giraffe, its mode of using the horns;
mute, except in the rutting season.
Giraud-Teulon, on the cause of short sight.
Glanders, communicable to man from the lower animals.
Glands, odoriferous, in mammals.
Glareola, double moult in.
Glomeris limbata, difference of colour in the sexes of.
Glow-worm, female, apterous;
luminosity of the.
Gnats, dances of;
auditory powers of.
Gnu, skeletons of, found locked together;
sexual differences in colour of the.
Goat, male, wild, falling on his horns;
male, odour emitted by;
male, wild, crest of the;
Berbura, mane, dewlap, etc., of the male;
Kemas, sexual difference in the colour of the.
Goats, sexual differences in the horns of;
horns of;
mode of fighting of;
domestic, sexual differences of, late developed;
beards of.
Goatsucker, Virginian, pairing of the.
Gobies, nidification of.
God, want of the idea of, in some races of men.
Godron, M., on variability;
on difference of stature;
on the want of connexion between climate and the colour of the skin;
on the colour of the skin;
on the colour of infants.
Goldfinch, proportion of the sexes in the;
sexual differences of the beak in the;
courtship of the.
Goldfinch, North American, young of.
Goldfish.
Gomphus, proportions of the sexes in;
difference in the sexes of.
Gonepteryx Rhamni, sexual difference of colour in.
Goodsir, Prof., on the affinity of the lancelet to the ascidians.
Goosander, young of.
Goose, Antarctic, colours of the.
Goose, Canada, pairing with a Bernicle gander.
Goose, Chinese, knob on the beak of the.
Goose, Egyptian.
Goose, Sebastopol, plumage of.
Goose, Snow-, whiteness of the.
Goose, Spur-winged.
Gorilla, semi-erect attitude of the;
mastoid processes of the;
protecting himself from rain with his hands;
manner of sitting;
supposed to be a kind of mandrill;
polygamy of the;
voice of the;
cranium of;
fighting of male.
Gosse, P.H., on the pugnacity of the male Humming-bird.
Gosse, M., on the inheritance of artificial modifications of the skull.
Gould, B.A., on variation in the length of the legs in man;
measurements of American soldiers;
on the proportions of the body and capacity of the lungs in different races
of men;
on the inferior vitality of mulattoes.
Gould, J., on migration of swifts;
on the arrival of male snipes before the females;
on the numerical proportion of the sexes in birds;
on Neomorpha Grypus;
on the species of Eustephanus;
on the Australian musk-duck;
on the relative size of the sexes in Briziura lobata and Cincloramphus
cruralis;
on Lobivanellus lobatus;
on habits of Menura Alberti;
on the rarity of song in brilliant birds;
on Selasphorus platycerus;
on the Bower-birds;
on the ornamental plumage of the Humming-birds;
on the moulting of the ptarmigan;
on the display of plumage by the male Humming-birds;
on the shyness of adorned male birds;
on the decoration of the bowers of Bower-birds;
on the decoration of their nest by Humming-birds;
on variation in the genus Cynanthus;
on the colour of the thighs in a male parrakeet;
on Urosticte Benjamini;
on the nidification of the Orioles;
on obscurely-coloured birds building concealed nests;
on trogons and king-fishers;
on Australian parrots;
on Australian pigeons;
on the moulting of the ptarmigan;
on the immature plumage of birds;
on the Australian species of Turnix;
on the young of Aithurus polytmus;
on the colours of the bills of toucans;
on the relative size of the sexes in the marsupials of Australia;
on the colours of the Marsupials.
Goureaux, on the stridulation of Mutilla europaea.
Gout, sexually transmitted.
Graba, on the Pied Ravens of the Feroe Islands;
variety of the Guillemot.
Gradation of secondary sexual characters in birds.
Grallatores, absence of secondary sexual characters in;
double moult in some.
Grallina, nidification of.
Grasshoppers, stridulation of the.
Gratiolet, Prof., on the anthropomorphous apes;
on the evolution of the anthropomorphous apes;
on the difference in the development of the brains of apes and of man.
Gray, Asa, on the gradation of species among the Compositae.
Gray, J.E., on the caudal vertebrae of monkeys;
on the presence of rudiments of horns in the female of Cervulus moschatus;
on the horns of goats and sheep;
on crests of male antelopes;
on the beard of the ibex;
on the Berbura goat;
on sexual differences in the coloration of Rodents;
ornaments of male sloth;
on the colours of the Elands;
on the Sing-sing antelope;
on the colours of goats;
on Lemur Macaco;
on the hog-deer.
"Greatest happiness principle."
Greeks, ancient.
Green, A.H., on beavers fighting;
on the voice of the beaver.
Greenfinch, selected by a female canary.
Greg, W.R., on the effects of natural selection on civilised nations;
on the early marriages of the poor;
on the Ancient Greeks.
Grenadiers, Prussian.
Greyhounds, numerical proportion of the sexes in;
numerical proportion of male and female births in.
Grouse, red, monogamous;
pugnacity of young male;
producing a sound by beating their wings together;
duration of courtship of;
colours and nidification of.
Gruber, Dr., on the occurrence of the supra-condyloid foramen in the
humerus of man;
on division of malar bone;
stridulation of locust;
on ephippiger.
Grus americanus, age of mature plumage in;
breeding in immature plumage.
Grus virgo, trachea of.
Gryllus campestris, pugnacity of male.
Gryllus domesticus.
Grypus, sexual differences in the beak in.
Guanacoes, battles of;
canine teeth of.
Guanas, strife for women among the;
polyandry among the.
Guanche skeletons, occurrence of the supra-condyloid foramen in the humerus
of.
Guaranys, proportion of men and women among;
colour of new-born children of the;
beards of the.
Guenee, A., on the sexes of Hyperythra.
Guilding, L., on the stridulation of the Locustidae.
Guillemot, variety of the.
Guinea, sheep of, with males only horned.
Guinea-fowl, monogamous;
occasional polygamy of the;
markings of the.
Guinea-pigs, inheritance of the effects of operations by.
Gulls, seasonal change of plumage in;
white.
Gunther, Dr., on paddle of Ceradotus;
on hermaphroditism in Serranus;
on male fishes hatching ova in their mouths;
on mistaking infertile female fishes for males;
on the prehensile organs of male Plagiostomous fishes;
spines and brushes on fishes;
on the pugnacity of the male salmon and trout;
on the relative size of the sexes in fishes;
on sexual differences in fishes;
on the genus Callionymus;
on a protective resemblance of a pipe-fish;
on the genus Solenostoma;
on the coloration of frogs and toads;
combat of Testudo elegans;
on the sexual differences in the Ophidia;
on differences of the sexes of lizards.
Gynanisa Isis, ocellated spots of.
Gypsies, uniformity of, in various parts of the world.
Habits, bad, facilitated by familiarity;
variability of the force of.
Haeckel, E., on the origin of man;
on rudimentary characters;
on death caused by inflammation of the vermiform appendage;
on the canine teeth in man;
on the steps by which man became a biped;
on man as a member of the Catarrhine group;
on the position of the Lemuridae;
on the genealogy of the Mammalia;
on the lancelet;
on the transparency of pelagic animals;
on the musical powers of women.
Hagen, H., and Walsh, B.D., on American Neuroptera.
Hair, development of, in man;
character of, supposed to be determined by light and heat;
distribution of, in man;
possibly removed for ornamental purposes;
arrangement and direction of;
of the early progenitors of man;
different texture of, in distinct races;
and skin, correlation of colour of;
development of, in mammals;
management of, among different peoples;
great length of, in some North American tribes;
elongation of the, on the human head;
possible inherited effect of plucking out.
Hairiness, difference of, in the sexes in man;
variation of, in races of men.
Hairs and excretory pores, numerical relation of, in sheep.
Hairy family, Siamese.
Halbertsma, Prof., hermaphroditism in Serranus.
Hamadryas baboon, turning over stones;
mane of the male.
Hamilton, C., on the cruelty of the Kaffirs to animals;
on the engrossment of the women by the Kaffir chiefs.
Hammering, difficulty of.
Hancock, A., on the colours of the nudibranch Mollusca.
Hands, larger at birth, in the children of labourers;
structure of, in the quadrumana;
and arms, freedom of, indirectly correlated with diminution of canines.
Handwriting, inherited.
Handyside, Dr., supernumerary mammae in men.
Harcourt, E. Vernon, on Fringilla cannabina.
Hare, protective colouring of the.
Harelda glacialis.
Hares, battles of male.
Harlan, Dr., on the difference between field- and house-slaves.
Harris, J.M., on the relation of complexion to climate.
Harris, T.W., on the Katy-did locust;
on the stridulation of the grasshoppers;
on Oecanthus nivalis;
on the colouring of Lepidoptera;
on the colouring of Saturnia Io.
Harting, spur of the Ornithorhynchus.
Hartman, Dr., on the singing of Cicada septendecim.
Hatred, persistence of.
Haughton, S., on a variation of the flexor pollicis longus in man.
Hawks, feeding orphan nestling.
Hayes, Dr., on the diverging of sledge-dogs on thin ice.
Haymond, R., on the drumming of the male Tetrao umbellus;
on the drumming of birds.
Head, altered position of, to suit the erect attitude of man;
hairiness of, in man;
processes of, in male beetles;
artificial alterations of the form of the.
Hearne, on strife for women among the North American Indians;
on the North American Indians' notion of female beauty;
repeated elopements of a North American woman.
Heart, in the human embryo.
Heat, supposed effects of.
Hectocotyle.
Hedge-warbler, young of the.
Heel, small projection of, in the Aymara Indians.
Hegt, M., on the development of the spurs in peacocks.
Heliconidae, mimicry of, by other butterflies.
Heliopathes, stridulation peculiar to the male.
Heliothrix auriculata, young of.
Helix pomatia, example of individual attachment in.
Hellins, J., proportions of sexes of Lepidoptera reared by.
Helmholtz, on pleasure derived from harmonies;
on the human eye;
on the vibration of the auditory hairs of crustacea;
the physiology of harmony.
Hemiptera.
Hemitragus, beardless in both sexes.
Hemsbach, M. von, on medial mamma in man.
Hen, clucking of.
Hepburn, Mr., on the autumn song of the water-ouzel.
Hepialus humuli, sexual difference of colour in the.
Herbs, poisonous, avoided by animals.
Hermaphroditism, of embryos;
in fishes.
Herodias bubulcus, vernal moult of.
Heron, Sir R., on the habits of peafowl.
Herons, love-gestures of;
decomposed feathers in;
breeding plumage of;
young of the;
sometimes dimorphic;
continued growth of crest and plumes in the males of some;
change of colour in some.
Hesperomys cognatus.
Hetaerina, proportion of the sexes in;
difference in the sexes of.
Heterocerus, stridulation of.
Hewitt, Mr., on a game-cock killing a kite;
on the recognition of dogs and cats by ducks;
on the pairing of a wild duck with a pintail drake;
on the courtship of fowls;
on the coupling of pheasants with common hens.
Hilgendorf, sounds produced by crustaceans.
Hindoo, his horror of breaking his caste.
Hindoos, local difference of stature among;
difference of, from Europeans;
colour of the beard in.
Hipparchia Janira, instability of the ocellated spots of.
Hippocampus, development of;
marsupial receptacles of the male.
Hippocampus minor.
Hippopotamus, nakedness of.
Hips, proportions of, in soldiers and sailors.
Hodgson, S., on the sense of duty.
Hoffberg, on the horns of the reindeer;
on sexual preferences shewn by reindeer.
Hoffman, Prof., protective colours;
fighting of frogs.
Hog, wart-;
river-.
Hog-deer.
Holland, Sir H., on the effects of new diseases.
Homologous structures, correlated variation of.
Homoptera, stridulation of the, and Orthoptera, discussed.
Honduras, Quiscalus major in.
Honey-buzzard of India, variation in the crest of.
Honey-sucker, females and young of.
Honey-suckers, moulting of the;
Australian, nidification of.
Honour, law of.
Hooker, Dr., forbearance of elephant to his keeper;
on the colour of the beard in man.
Hookham, Mr., on mental concepts in animals.
Hoolock Gibbon, nose of.
Hoopoe, sounds produced by male.
Hoplopterus armatus, wing-spurs of.
Hornbill, African, inflation of the neck-wattle of the male during
courtship.
Hornbills, sexual difference in the colour of the eyes in;
nidification and incubation of.
Horne, C., on the rejection of a brightly-coloured locust by lizards and
birds.
Horns, sexual differences of, in sheep and goats;
loss of, in female merino sheep;
development of, in deer;
development in antelopes;
from the head and thorax, in male beetles;
of deer;
originally a masculine character in sheep;
and canine teeth, inverse development of.
Horse, fossil, extinction of the, in South America;
polygamous;
canine teeth of male;
winter change of colour.
Horses, rapid increase of, in South America;
diminution of canine teeth in;
dreaming;
of the Falkland Islands and Pampas;
numerical proportion of the sexes, in;
lighter in winter in Siberia;
sexual preferences in;
pairing preferently with those of the same colour;
numerical proportion of male and female births in;
formerly striped.
Hottentot women, peculiarities of.
Hottentots, lice of;
readily become musicians;
notions of female beauty of the;
compression of nose by.
Hough, Dr. S., men's temperature more variable than women's;
proportion of sexes in man.
House-slaves, difference of, from field-slaves.
Houzeau, on the baying of the dog;
on reason in dogs;
birds killed by telegraph wires;
on the cries of domestic fowls and parrots;
animals feel no pity;
suicide in the Aleutian Islands.
Howorth, H.H., extinction of savages.
Huber, P., on ants playing together;
on memory in ants;
on the intercommunication of ants;
on the recognition of each other by ants after separation.
Huc, on Chinese opinions of the appearance of Europeans.
Huia, the, of New Zealand.
Human, man, classed alone in a kingdom.
Human sacrifices.
Humanity, unknown among some savages;
deficiency of, among savages.
Humboldt, A. von, on the rationality of mules;
on a parrot preserving the language of a lost tribe;
on the cosmetic arts of savages;
on the exaggeration of natural characters by man;
on the red painting of American Indians.
Hume, D., on sympathetic feelings.
Humming-bird, racket-shaped feathers in the tail of a;
display of plumage by the male.
Humming-birds, ornament their nests;
polygamous;
proportion of the sexes in;
sexual differences in;
pugnacity of male;
modified primaries of male;
coloration of the sexes of;
display by;
nidification of the;
colours of female;
young of.
Humour, sense of, in dogs.
Humphreys, H.N., on the habits of the stickleback.
Hunger, instinct of.
Huns, ancient, flattening of the nose by the.
Hunter, J., on the number of species of man;
on secondary sexual characters;
on the general behaviour of female animals during courtship;
on the muscles of the larynx in song-birds;
on strength of males;
on the curled frontal hair of the bull;
on the rejection of an ass by a female zebra.
Hunter, W.W., on the recent rapid increase of the Santali;
on the Santali.
Huss, Dr. Max, on mammary glands.
Hussey, Mr., on a partridge distinguishing persons.
Hutchinson, Col., example of reasoning in a retriever.
Hutton, Captain, on the male wild goat falling on his horns.
Huxley, T.H., on the structural agreement of man with the apes;
on the agreement of the brain in man with that of lower animals;
on the adult age of the orang;
on the embryonic development of man;
on the origin of man;
on variation in the skulls of the natives of Australia;
on the abductor of the fifth metatarsal in apes;
on the nature of the reasoning power;
on the position of man;
on the suborders of primates;
on the Lemuridae;
on the Dinosauria;
on the amphibian affinities of the Ichthyosaurians;
on variability of the skull in certain races of man;
on the races of man;
Supplement on the brain.
Hybrid birds, production of.
Hydrophobia, communicable between man and the lower animals.
Hydroporus, dimorphism of females of.
Hyelaphus porcinus.
Hygrogonus.
Hyla, singing species of.
Hylobates, absence of the thumb in;
upright progression of some species of;
maternal affection in a;
direction of the hair on the arms of species of;
females of, less hairy below than males.
Hylobates agilis, hair on the arms of;
musical voice of the;
superciliary ridge of;
voice of.
Hylobates hoolock, sexual difference of colour in.
Hylobates lar, hair on the arms of;
female less hairy.
Hylobates leuciscus, song of.
Hylobates syndactylus, laryngeal sac of.
Hylophila prasinana.
Hymonoptera, large size of the cerebral ganglia in;
classification of;
sexual differences in the wings of;
aculeate, relative size of the sexes of.
Hymenopteron, parasitic, with a sedentary male.
Hyomoschus aquaticus.
Hyperythra, proportion of the sexes in.
Hypogymna dispar, sexual difference of colour in.
Hypopyra, coloration of.
Ibex, male, falling on his horns;
beard of the.
Ibis, white, change of colour of naked skin in, during the breeding season;
scarlet, young of the.
Ibis tantalus, age of mature plumage in;
breeding in immature plumage.
Ibises, decomposed feathers in;
white;
and black.
Ichneumonidae, difference of the sexes in.
Ichthyopterygia.
Ichthyosaurians.
Idiots, microcephalous, their characters and habits;
hairiness and animal nature of their actions;
microcephalous, imitative faculties of.
Iguana tuberculata.
Iguanas.
illegitimate and legitimate children, proportion of the sexes in.
Imagination, existence of, in animals.
Imitation, of man by monkeys;
tendency to, in monkeys,;
microcephalous idiots and savages;
influence of.
Immature plumage of birds.
Implacentata.
Implements, employed by monkeys;
fashioning of, peculiar to man.
Impregnation, period of, influence of, upon sex.
Improvement, progressive, man alone supposed to be capable of.
Incisor teeth, knocked out or filed by some savages.
Increase, rate of;
necessity of checks in.
Indecency, hatred of, a modern virtue.
India, difficulty of distinguishing the native races of;
Cyprinidae of;
colour of the beard in races of men of.
Indian, North American, honoured for scalping a man of another tribe.
Individuality, in animals.
Indolence of man, when free from a struggle for existence.
Indopicus carlotta, colours of the sexes of.
Infanticide, prevalence of;
supposed cause of;
prevalence and causes of.
Inferiority, supposed physical, of man.
Inflammation of the bowels, occurrence of, in Cebus Azarae.
Inheritance, of long and short sight;
of effects of use of vocal and mental organs;
of moral tendencies;
laws of;
sexual;
sexually limited.
Inquisition, influence of the.
Insanity, hereditary.
insect, fossil, from the Devonian.
Insectivora, absence of secondary sexual characters in.
Insects, relative size of the cerebral ganglia in;
male, appearance of, before the females;
pursuit of female, by the males;
period of development of sexual characters in;
secondary sexual characters of;
kept in cages;
stridulation.
Insessores, vocal organs of.
Instep, depth of, in soldiers and sailors.
Instinct and intelligence.
Instinct, migratory, vanquishing the maternal.
Instinctive actions, the result of inheritance.
Instinctive impulses, difference of the force;
and moral impulses, alliance of.
Instincts, complex origin of, through natural selection;
possible origin of some;
acquired, of domestic animals;
variability of the force of;
difference of force between the social and other;
utilised for new purposes.
Instrumental music of birds.
Intellect, influence of, in natural selection in civilised society.
Intellectual faculties, their influence on natural selection in man;
probably perfected through natural selection.
Intelligence, Mr. H. Spencer on the dawn of.
Intemperance, no reproach among savages;
its destructiveness.
Intoxication in monkeys.
Iphias glaucippe.
Iris, sexual difference in the colour of the, in birds.
Ischio-pubic muscle.
Ithaginis cruentus, number of spurs in.
Iulus, tarsal suckers of the males of.
Jackals learning from dogs to bark.
Jack-snipe, coloration of the.
Jacquinot, on the number of species of man.
Jaeger, Dr., length of bones increased from carrying weights;
on the difficulty of approaching herds of wild animals;
male Silver-pheasant, rejected when his plumage was spoilt.
Jaguars, black.
Janson, E.W., on the proportions of the sexes in Tomicus villosus;
on stridulant beetles.
Japan, encouragement of licentiousness in.
Japanese, general beardlessness of the;
aversion of the, to whiskers.
Jardine, Sir W., on the Argus pheasant.
Jarrold, Dr., on modifications of the skull induced by unnatural position.
Jarves, Mr., on infanticide in the Sandwich Islands.
Javans, relative height of the sexes of;
notions of female beauty.
Jaw, influence of the muscles of the, upon the physiognomy of the apes.
Jaws, smaller proportionately to the extremities;
influence of food upon the size of;
diminution of, in man;
in man, reduced by correlation.
Jay, young of the;
Canada, young of the.
Jays, new mates found by;
distinguishing persons.
Jeffreys, J. Gwyn, on the form of the shell in the sexes of the
Gasteropoda;
on the influence of light upon the colours of shells.
Jelly-fish, bright colours of some.
Jenner, Dr., on the voice of the rook;
on the finding of new mates by magpies;
on retardation of the generative functions in birds.
Jenyns, L., on the desertion of their young by swallows;
on male birds singing after the proper season.
Jerdon, Dr., on birds dreaming;
on the pugnacity of the male bulbul;
on the pugnacity of the male Ortygornis gularis;
on the spurs of Galloperdix;
on the habits of Lobivanellus;
on the spoonbill;
on the drumming of the Kalij-pheasant;
on Indian bustards;
on Otis bengalensis;
on the ear-tufts of Sypheotides auritus;
on the double moults of certain birds;
on the moulting of the honeysuckers;
on the moulting of bustards, plovers, and drongos;
on the spring change of colour in some finches;
on display in male birds;
on the display of the under-tail coverts by the male bulbul;
on the Indian honey-buzzard;
on sexual differences in the colour of the eyes of hornbills;
on the markings of the Tragopan pheasant;
on the nidification of the Orioles;
on the nidification of the hornbills;
on the Sultan yellow-tit;
on Palaeornis javanicus;
on the immature plumage of birds;
on representative species of birds;
on the habits of Turnix;
on the continued increase of beauty of the peacock;
on coloration in the genus Palaeornis.
Jevons, W.S., on the migrations of man.
Jews, ancient use of flint tools by the;
uniformity of, in various parts of the world;
numerical proportion of male and female births among the;
ancient, tattooing practised by.
Johnstone, Lieut., on the Indian elephant.
Jollofs, fine appearance of the.
Jones, Albert, proportion of sexes of Lepidoptera, reared by.
Juan Fernandez, humming-birds of.
Junonia, sexual differences of colouring in species of.
Jupiter, comparison with Assyrian effigies.
Kaffir skull, occurrence of the diastema in a.
Kaffirs, their cruelty to animals;
lice of the;
colour of the;
engrossment of the handsomest women by the chiefs of the;
marriage-customs of the.
Kalij-pheasant, drumming of the male;
young of.
Kallima, resemblance of, to a withered leaf.
Kulmucks, general beardlessness of;
aversion of, to hairs on the face;
marriage-customs of the.
Kangaroo, great red, sexual difference in the colour of.
Kant, Imm., on duty;
on self-restraint;
on the number of species of man.
Katy-did, stridulation of the.
Keen, Dr., on the mental powers of snakes.
Keller, Dr., on the difficulty of fashioning stone implements.
Kent, W.S., elongation of dorsal fin of Callionymus lyra;
courtship of Labrus mixtus;
colours and courtship of Cantharus lineatus.
Kestrels, new mates found by.
Kidney, one, doing double work in disease.
King, W.R., on the vocal organs of Tetrao cupido;
on the drumming of grouse;
on the reindeer;
on the attraction of male deer by the voice of the female.
King and Fitzroy, on the marriage-customs of the Fuegians.
King-crows, nidification of.
Kingfisher, racket-shaped feathers in the tail of a.
Kingfishers, colours and nidification of the;
immature plumage of the;
young of the.
King Lory, immature plumage of the.
Kingsley, C., on the sounds produced by the Umbrina.
Kirby and Spence, on sexual differences in the length of the snout in
Curculionidae;
on the courtship of insects;
on the elytra of Dytiscus;
on peculiarities in the legs of male insects;
on the relative size of the sexes in insects;
on the Fulgoridae;
on the habits of the Termites;
on difference of colour in the sexes of beetles;
on the horns of the male lamellicorn beetles;
on hornlike processes in male Curculionidae;
on the pugnacity of the male stag-beetle.
Kite, killed by a game-cock.
Knot, retention of winter plumage by the.
Knox, R., on the semilunar fold;
on the occurrence of the supra-condyloid foramen in the humerus of man;
on the features of the young Memmon.
Koala, length of the caecum in.
Kobus ellipsiprymnus, proportion of the sexes in.
Kolreuter, on the sterility of hybrid plants.
Koodoo, development of the horns of the;
markings of the.
Koppen, F.T., on the migratory locust.
Koraks, marriage customs of.
Kordofan, protuberances artificially produced by natives of.
Korte, on the proportion of sexes in locusts;
Russian locusts.
Kovalevsky, A., on the affinity of the Ascidia to the Vertebrata.
Kovalevsky, W., on the pugnacity of the male capercailzie;
on the pairing of the capercailzie.
Krause, on a convoluted body at the extremity of the tail in a Macacus and
a cat.
Kupffer, Prof., on the affinity of the Ascidia to the Vertebrata.
Labidocera Darwinii, prehensile organs of the male.
Labrus, splendid colours of the species of.
Labrus mixtus, sexual differences in.
Labrus pavo.
Lacertilia, sexual differences of.
Lafresnaye, M. de, on birds of paradise.
Lamarck, on the origin of man.
Lamellibranchiata.
Lamellicorn beetles, horn-like processes from the head and thorax of;
influence of sexual selection on.
Lamellicornia, stridulation of.
Lamont, Mr., on the tusks of the walrus;
on the use of its tusks by the walrus;
on the bladder-nose seal.
Lampornis porphyrurus, colours of the female.
Lampyridae, distasteful to mammals.
Lancelet.
Landois, H., gnats attracted by sound;
on the production of sound by the Cicadae;
on the stridulating organ of the crickets;
on Decticus;
on the stridulating organs of the Acridiidae;
stridulating apparatus, in Orthoptera;
on the stridulation of Necrophorus;
on the stridulant organ of Cerambyx heros;
on the stridulant organ of Geotrupes;
on the stridulating organs in the Cleoptera;
on the ticking of Anobium.
Landor, Dr., on remorse for not obeying tribal custom.
Language, an art;
articulate, origin of;
relation of the progress of, to the development of the brain;
effects of inheritance in production of;
complex structure of, among barbarous nations;
natural selection in;
gesture;
primeval;
of a lost tribe preserved by a parrot.
Languages, presence of rudiments in;
classification of;
variability of;
crossing or blending of;
complexity of, no test of perfection or proof of special creation;
resemblance of, evidence of community of origin.
Languages and species, identity of evidence of their gradual development.
Lanius, characters of young.
Lanius rufus, anomalous young of.
Lankester, E.R., on comparative longevity;
on the destructive effects of intemperance.
Lanugo of the human foetus.
Lapponian language, highly artificial.
Lark, proportion of the sexes in the;
female, singing of the.
Larks, attracted by a mirror.
Lartet, E., comparison of cranial capacities of skulls of recent and
tertiary mammals;
on the size of the brain in mammals;
on Dryopithecus;
on pre-historic flutes.
Larus, seasonal change of plumage in.
Larva, luminous, of a Brazilian beetle.
Larynx, muscles of the, in songbirds.
Lasiocampa quercus, attraction of males by the female;
sexual difference of colour in.
Latham, R.G., on the migrations of man.
Latooka, perforation of the lower lip by the women of.
Laurillard, on the abnormal division of the malar bone in man.
Lawrence, W., on the superiority of savages to Europeans in power of sight;
on the colour of negro infants;
on the fondness of savages for ornaments;
on beardless races;
on the beauty of the English aristocracy.
Layard, E.L., on the instance of rationality in a cobra;
on the pugnacity of Gallus Stanleyi.
Laycock, Dr., on vital periodicity;
theroid nature of idiots.
Leaves, autumn, tints useless.
Lecky, Mr., on the sense of duty;
on suicide;
on the practice of celibacy;
his view of the crimes of savages;
on the gradual rise of morality.
Leconte, J.L., on the stridulant organ in the Coprini and Dynastini.
Lee, H., on the numerical proportion of the sexes in the trout.
Leg, calf of the, artificially modified.
Legitimate and illegitimate children, proportion of the sexes in.
Legs, variation of the length of the, in man;
proportions of, in soldiers and sailors;
front, atrophied in some male butterflies;
peculiarities of, in male insects.
Leguay, on the occurrence of the supra-condyloid foramen in the humerus of
man.
Lek of the black-cock and capercailzie.
Lemoine, Albert, on the origin of language.
Lemur macaco, sexual difference of colour in.
Lemuridae, ears of the;
variability of the muscles in the;
position and derivation of the;
their origin.
Lemurs, uterus in the.
Lenguas, disfigurement of the ears of the.
Leopards, black.
Lepidoptera, numerical proportions of the sexes in the;
colouring of;
ocellated spots of.
Lepidosiren.
Leptalides, mimicry of.
Leptorhynchus angustatus, pugnacity of male.
Leptura testacea, difference of colour in the sexes.
Leroy, on the wariness of young foxes in hunting-districts;
on the desertion of their young by swallows.
Leslie, D., marriage customs of Kaffirs.
Lesse, valley of the.
Lesson, on the birds of paradise;
on the sea-elephant.
Lessona, M., observations on Serranus.
Lethrus cephalotes, pugnacity of the males of.
Leuciscus phoxinus.
Leuckart, R., on the vesicula prostatica;
on the influence of the age of parents on the sex of offspring.
Levator claviculae muscle.
Libellula depressa, colour of the male.
Libellulidae, relative size of the sexes of;
difference in the sexes of.
Lice of domestic animals and man.
Licentiousness a check upon population;
prevalence of, among savages.
Lichtenstein, on Chera progne.
Life, inheritance at corresponding periods of.
Light, effects on complexion;
influence of, upon the colours of shells.
Lilford, Lord, the ruff attracted by bright objects.
Limosa lapponica.
Linaria.
Linaria montana.
Lindsay, Dr. W.L., diseases communicated from animals to man;
madness in animals;
the dog considers his master his God.
Linnaeus, views of, as to the position of man.
Linnet, numerical proportion of the sexes in the;
crimson forehead and breast of the;
courtship of the.
Lion, polygamous;
mane of the, defensive;
roaring of the.
Lions, stripes of young.
Lips, piercing of the, by savages.
Lithobius, prehensile appendages of the female.
Lithosia, coloration in.
Littorina littorea.
Livingstone, Dr., manner of sitting of gorilla;
on the influence of dampness and dryness on the colour of the skin;
on the liability of negroes to tropical fevers after residence in a cold
climate;
on the spur-winged goose;
on weaverbirds;
on an African night-jar;
on the battle-scars of South African male mammals;
on the removal of the upper incisors by the Batokas;
on the perforation of the upper lip by the Makalolo;
on the Banyai.
Livonia, numerical proportion of male and female births in.
Lizards, relative size of the sexes of;
gular pouches of.
Lloyd, L., on the polygamy of the capercailzie and bustard;
on the numerical proportion of the sexes in the capercailzie and blackcock;
on the salmon;
on the colours of the sea-scorpion;
on the pugnacity of male grouse;
on the capercailzie and blackcock;
on the call of the capercailzie;
on assemblages of grouse and snipes;
on the pairing of a shield-drake with a common duck;
on the battles of seals;
on the elk.
Lobivanellus, wing-spurs in.
Local influences, effect of, upon stature.
Lockwood, Mr., on the development of Hippocampus.
Lockwood, Rev. S., musical mouse.
Locust, bright-coloured, rejected by lizards and birds.
Locust, migratory;
selection by female.
Locustidae, stridulation of the;
descent of the.
Locusts, proportion of sexes in;
stridulation of.
Longicorn beetles, difference of the sexes of, in colour;
stridulation of.
Lonsdale, Mr., on an example of personal attachment in Helix pomatia.
Lophobranchii, marsupial receptacles of the male.
Lophophorus, habits of.
Lophorina atra, sexual difference in coloration of.
Lophornis ornatus.
Lord, J.K., on Salmo lycaodon.
Lory, King;
immature plumage of the.
Lory, king, constancy of.
Love-antics and dances of birds.
Lowne, B.T., on Musca vomitoria.
Loxia, characters of young of.
Lubbock, Sir J., on the antiquity of man;
on the origin of man;
on the mental capacity of savages;
on the origin of implements;
on the simplification of languages;
on the absence of the idea of God among certain races of men;
on the origin of the belief in spiritual agencies;
on superstitions;
on the sense of duty;
on the practice of burying the old and sick among the Fijians;
on the immorality of savages;
on Mr. Wallace's claim to the origination of the idea of natural selection;
on the former barbarism of civilised nations;
on improvements in the arts among savages;
on resemblances of the mental characters in different races of men;
on the arts practised by savages;
on the power of counting in primeval man;
on the prehensile organs of the male Labidocera Darwinii;
on Chloeon;
on Smynthurus luteus;
finding of new mates by jays;
on strife for women among the North American Indians;
on music;
on the ornamental practices of savages;
on the estimation of the beard among the Anglo-Saxons;
on artificial deformation of the skull;
on "communal marriages;"
on exogamy;
on the Veddahs;
on polyandry.
Lucanidae, variability of the mandibles in the male.
Lucanus, large size of males of.
Lucanus cervus, numerical proportion of sexes of;
weapons of the male.
Lucanus elaphus, use of mandibles of;
large jaws of male.
Lucas, Prosper, on pigeons;
on sexual preference in horses and bulls.
Luminosity in insects.
Lunar periods.
Lund, Dr., on skulls found in Brazilian caves.
Lungs, enlargement of, in the Quichua and Aymara Indians;
a modified swim-bladder;
different capacity of, in races of man.
Luschka, Prof., on the termination of the coccyx.
Luxury, expectation of life uninfluenced by.
Lycaena, sexual differences of colour in species of.
Lycaenae, colours of.
Lyell, Sir C., on the antiquity of man;
on the origin of man;
on the parallelism of the development of species and languages;
on the extinction of languages;
on the Inquisition;
on the fossil remains of vertebrata;
on the fertility of mulattoes.
Lynx, Canadian throat-ruff of the.
Lyre-bird, assemblies of.
Macacus, ears of;
convoluted body in the extremity of the tail of;
variability of the tail in species of;
whiskers of species of.
Macacus brunneus.
Macacus cynomolgus, superciliary ridge of;
beard and whiskers of;
becoming white with age.
Macacus ecaudatus.
Macacus lasiotus, facial spots of.
Macacus nemestrinus.
Macacus radiatus.
Macacus rhesus, sexual difference in the colour of.
Macalister, Prof., on variations of the palmaris accessorius muscle;
on muscular abnormalities in man;
on the greater variability of the muscles in men than in women.
Macaws, Mr. Buxton's observations on.
McCann, J., on mental individuality.
McClelland, J., on the Indian Cyprinidae.
Macculloch, Col., on an Indian village without any female children.
Macculloch, Dr., on tertian ague in a dog.
Macgillivray, W., on the vocal organs of birds;
on the Egyptian goose;
on the habits of woodpeckers;
on the habits of the snipe;
on the whitethroat;
on the moulting of the snipes;
on the moulting of the Anatidae;
on the finding of new mates by magpies;
on the pairing of a blackbird and thrush;
on pied ravens;
on the guillemots;
on the colours of the tits;
on the immature plumage of birds.
Machetes, sexes and young of.
Machetes pugnax, supposed to be polygamous;
numerical proportion of the sexes in;
pugnacity of the male;
double moult in.
McIntosh, Dr., colours of the Nemertians.
McKennan, marriage customs of Koraks.
Mackintosh, on the moral sense.
MacLachlan, R., on Apatania muliebris and Boreus hyemalis;
on the anal appendages of male insects;
on the pairing of dragon-flies;
on dragon-flies;
on dimorphism in Agrion;
on the want of pugnacity in male dragon-flies;
colour of ghost-moth in the Shetland Islands.
M'Lennan, Mr., on infanticide;
on the origin of the belief in spiritual agencies;
on the prevalence of licentiousness among savages;
on the primitive barbarism of civilised nations;
on traces of the custom of the forcible capture of wives;
on polyandry.
Macnamara, Mr., susceptibility of Andaman islanders and Nepalese to change.
M'Neill, Mr., on the use of the antlers of deer;
on the Scotch deerhound;
on the long hairs on the throat of the stag;
on the bellowing of stags.
Macropus, courtship of.
Macrorhinus proboscideus, structure of the nose of.
Magpie, power of speech of;
vocal organs of the;
nuptial assemblies of;
new mates found by;
stealing bright objects;
young of the;
coloration of the.
Maillard, M., on the proportion of the sexes in a species of Papilio from
Bourbon.
Maine, Sir Henry, on the absorption of one tribe by another;
a desire for improvement not general.
Major, Dr. C. Forsyth, on fossil Italian apes;
skull of Bos etruscus;
tusks of miocene pigs.
Makalolo, perforation of the upper lip by the.
Malar bone, abnormal division of, in man.
Malay, Archipelago, marriage-customs of the savages of the.
Malays, line of separation between the Papuans and the;
general beardlessness of the;
staining of the teeth among;
aversion of some, to hairs on the face.
Malays and Papuans, contrasted characters of.
Male animals, struggles of, for the possession of the females;
eagerness of, in courtship;
generally more modified than female;
differ in the same way from females and young.
Male characters, developed in females;
transfer of, to female birds.
Male, sedentary, of a hymenopterous parasite.
Malefactors.
Males, presence of rudimentary female organs in.
Males and females, comparative numbers of;
comparative mortality of, while young.
Malherbe, on the woodpeckers.
Mallotus Peronii.
Mallotus villosus.
Malthus, T., on the rate of increase of population.
Maluridae, nidification of the.
Malurus, young of.
Mammae, rudimentary, in male mammals;
supernumerary, in women;
of male human subject.
Mammalia, Prof. Owen's classification of;
genealogy of the.
Mammals, recent and tertiary, comparison of cranial capacity of;
nipples of;
pursuit of female, by the males;
secondary sexual characters of;
weapons of;
relative size of the sexes of;
parallelism of, with birds in secondary sexual characters;
voices of, used especially during the breeding season.
Man, variability of;
erroneously regarded as more domesticated than other animals;
migrations of;
wide distribution of;
causes of the nakedness of;
supposed physical inferiority of;
a member of the Catarrhine group;
early progenitors of;
transition from ape indefinite;
numerical proportions of the sexes in;
difference between the sexes;
proportion of sexes amongst the illegitimate;
different complexion of male and female negroes;
secondary sexual characters of;
primeval condition of.
Mandans, correlation of colour and texture of hair in the.
Mandible, left, enlarged in the male of Taphroderes distortus.
Mandibles, use of the, in Ammophila;
large, of Corydalis cornutus;
large, of male Lucanus elaphus.
Mandrill, number of caudal vertebrae in the;
colours of the male.
Mantegazza, Prof., on last molar teeth of man;
bright colours in male animals;
on the ornaments of savages;
on the beardlessness of the New Zealanders;
on the exaggeration of natural characters by man.
Mantell, W., on the engrossment of pretty girls by the New Zealand chiefs.
Mantis, pugnacity of species of.
Maories, mortality of;
infanticide and proportion of sexes;
distaste for hairiness amongst men.
Marcus Aurelius, on the origin of the moral sense;
on the influence of habitual thoughts.
Mareca penelope.
Marks, retained throughout groups of birds.
Marriage, restraints upon, among savages;
influence of, upon morals;
influence of, on mortality;
development of.
Marriages, early;
communal.
Marshall, Dr. W., protuberances on birds' heads;
on the moulting of birds;
advantage to older birds of paradise.
Marshall, Col., interbreeding amongst Todas;
infanticide and proportion of sexes with Todas;
choice of husband amongst Todas.
Marshall, Mr., on the brain of a Bushwoman.
Marsupials, development of the nictitating membrane in;
uterus of;
possession of nipples by;
their origin from Monotremata;
abdominal sacs of;
relative size of the sexes of;
colours of.
Marsupium, rudimentary in male marsupials.
Martin, W.C.L., on alarm manifested by an orang at the sight of a turtle;
on the hair in Hylobates;
on a female American deer;
on the voice of Hylobates agilis;
on Semnopithecus nemaeus.
Martin, on the beards of the inhabitants of St. Kilda.
Martins deserting their young.
Martins, C., on death caused by inflammation of the vermiform appendage.
Mastoid processes in man and apes.
Maudsley, Dr., on the influence of the sense of smell in man;
on idiots smelling their food;
on Laura Bridgman;
on the development of the vocal organs;
moral sense failing in incipient madness;
change of mental faculties at puberty in man.
Mayers, W.F., on the domestication of the goldfish in China.
Mayhew, E., on the affection between individuals of different sexes in the
dog.
Maynard, C.J., on the sexes of Chrysemys picta.
Meckel, on correlated variation of the muscles of the arm and leg.
Medicines, effect produced by, the same in man and in monkeys.
Medusae, bright colours of some.
Megalithic structures, prevalence of.
Megapicus validus, sexual difference of colour in.
Megasoma, large size of males of.
Meigs, Dr. A., on variation in the skulls of the natives of America.
Meinecke, on the numerical proportion of the sexes in butterflies.
Melanesians, decrease of.
Meldola, Mr., colours and marriage flight of Colias and Pieris.
Meliphagidae, Australian, nidification of.
Melita, secondary sexual characters of.
Meloe, difference of colour in the sexes of a species of.
Memnon, young.
Memory, manifestations of, in animals.
Mental characters, difference of, in different races of men.
Mental faculties, diversity of, in the same race of men;
inheritance of;
variation of, in the same species;
similarity of the, in different races of man;
of birds.
Mental powers, difference of, in the two sexes in man.
Menura Alberti, song of.
Menura superba, long tails of both sexes of.
Merganser, trachea of the male.
Merganser serrator, male plumage of.
Mergus cucullatus, speculum of.
Mergus merganser, young of.
Metallura, splendid tail-feathers of.
Methoca ichneumonides, large male of.
Meves, M., on the drumming of the snipe.
Mexicans, civilisation of the, not foreign.
Meyer, on a convoluted body at the extremity of the tail in a Macacus and a
cat.
Meyer, Dr. A., on the copulation of Phryganidae of distinct species.
Meyer, Prof. L., on development of helix of ear;
men's ears more variable than women's;
antennae serving as ears.
Migrations of man, effects of.
Migratory instinct of birds;
vanquishing the maternal.
Mill, J.S., on the origin of the moral sense;
on the "greatest happiness principle;"
on the difference of the mental powers in the sexes of man.
Millipedes.
Milne-Edwards, H., on the use of enlarged chelae of the male Gelasimus.
Milvago leucurus, sexes and young of.
Mimicry.
Mimus polyglottus.
Mind, difference of, in man and the highest animals;
similarity of the, in different races.
Minnow, proportion of the sexes in the.
Mirror, behaviour of monkeys before.
Mirrors, larks attracted by.
Mitchell, Dr., interbreeding in the Hebrides.
Mitford, selection of children in Sparta.
Mivart, St. George, on the reduction of organs;
on the ears of the lemuroidea;
on variability of the muscles in lemuroidea;
on the caudal vertebrae of monkeys;
on the classification of the primates;
on the orang and on man;
on differences in the lemuroidea;
on the crest of the male newt.
Mobius, Prof., on reasoning powers in a pike.
Mocking-thrush, partial migration of;
young of the.
Modifications, unserviceable.
Moggridge, J.T., on habits of spiders;
on habits of ants.
Moles, numerical proportion of the sexes in;
battles of male.
Mollienesia petenensis, sexual difference in.
Mollusca, beautiful colours and shapes of;
absence of secondary sexual characters in the.
Molluscoida.
Monacanthus scopas and M. Peronii.
Monboddo, Lord, on music.
Mongolians, perfection of the senses in.
Monkey, protecting his keeper from a baboon;
bonnet-;
rhesus-, sexual difference in colour of the;
moustache-, colours of the.
Monkeys, liability of, to the same diseases as man;
male, recognition of women by;
diversity of the mental faculties in;
breaking hard fruits with stones;
hands of the;
basal caudal vertebrae of, imbedded in the body;
revenge taken by;
maternal affection in;
variability of the faculty of attention in;
American, manifestation of reason in;
using stones and sticks;
imitative faculties of;
signal-cries of;
mutual kindnesses of;
sentinels posted by;
human characters of;
American, direction of the hair on the arms of some;
gradation of species of;
beards of;
ornamental characters of;
analogy of sexual differences of, with those of man;
different degrees of difference in the sexes of;
expression of emotions by;
generally monogamous habits of;
polygamous habits of some;
naked surfaces of;
courtship of.
Monogamy, not primitive.
Monogenists.
Mononychus pseudacori, stridulation of.
Monotremata, development of the nictitating membrane in;
lactiferous glands of;
connecting mammals with reptiles.
Monstrosities, analogous, in man and lower animals;
caused by arrest of development;
correlation of;
transmission of.
Montagu, G., on the habits of the black and red grouse;
on the pugnacity of the ruff;
on the singing of birds;
on the double moult of the male pintail.
Monteiro, Mr., on Bucorax abyssinicus.
Montes de Oca, M., on the pugnacity of male Humming-birds.
Monticola cyanea.
Monuments, as traces of extinct tribes.
Moose, battles of;
horns of the, an incumbrance.
Moral and instinctive impulses, alliance of.
Moral faculties, their influence on natural selection in man.
Moral rules, distinction between the higher and lower.
Moral sense, so-called, derived from the social instincts;
origin of the.
Moral tendencies, inheritance of.
Morality, supposed to be founded in selfishness;
test of, the general welfare of the community;
gradual rise of;
influence of a high standard of.
Morgan, L.H., on the beaver;
on the reasoning powers of the beaver;
on the forcible capture of wives;
on the castoreum of the beaver;
marriage unknown in primeval times;
on polyandry.
Morley, J., on the appreciation of praise and fear of blame.
Morris, F.O., on hawks feeding an orphan nestling.
Morse, Dr., colours of mollusca.
Morselli, E., division of the malar bone.
Mortality, comparative, of female and male.
Morton on the number of species of man.
Moschkau, Dr. A., on a speaking starling.
Moschus moschiferus, odoriferous organs of.
Motacillae, Indian, young of.
Moth, odoriferous.
Moths, absence of mouth in some males;
apterous female;
male, prehensile use of the tarsi by;
male, attracted by females;
sound produced by;
coloration of;
sexual differences of colour in.
Motmot, inheritance of mutilation of tail feathers;
racket-shaped feathers in the tail of a.
Moult, double;
double annual, in birds.
Moulting of birds.
Moults, partial.
Mouse, song of.
Moustache-monkey, colours of the.
Moustaches, in monkeys.
Mud-turtle, long claws of the male.
Mulattoes, persistent fertility of;
immunity of, from yellow fever.
Mule, sterility and strong vitality of the.
Mules, rational.
Muller, Ferd., on the Mexicans and Peruvians.
Muller, Fritz, on astomatous males of Tanais;
on the disappearance of spots and stripes in adult mammals;
on the proportions of the sexes in some Crustacea;
on secondary sexual characters in various Crustaceans;
musical contest between male Cicadae;
mode of holding wings in Castina;
on birds shewing a preference for certain colours;
on the sexual maturity of young amphipod Crustacea.
Muller, Hermann, emergence of bees, from pupa;
pollen-gathering of bees;
proportion of sexes in bees;
courting of Eristalis;
colour and sexual selection with bees.
Muller, J., on the nictitating membrane and semilunar fold.
Muller, Max, on the origin of language;
language implies power of general conception;
struggle for life among the words, etc., of languages.
Muller, S., on the banteng;
on the colours of Semnopithecus chrysomelas.
Muntjac-deer, weapons of the.
Murie, J., on the reduction of organs;
on the ears of the Lemuroidea;
on variability of the muscles in the Lemuroidea;
basal caudal vertebrae of Macacus brunneus imbedded in the body;
on the manner of sitting in short-tailed apes;
on differences in the Lemuroidea;
on the throat-pouch of the male bustard;
on the mane of Otaria jubata;
on the sub-orbital pits of Ruminants;
on the colours of the sexes in Otaria nigrescens.
Murray, A., on the Pediculi of different races of men.
Murray, T.A., on the fertility of Australian women with white men.
Mus coninga.
Mus minutus, sexual difference in the colour of.
Musca vomitoria.
Muscicapa grisola.
Muscicapa luctuosa.
Muscicapa ruticilla, breeding in immature plumage.
Muscle, ischio-pubic.
Muscles, rudimentary, occurrence of, in man;
variability of the;
effects of use and disuse upon;
animal-like abnormalities of, in man;
correlated variation of, in the arm and leg;
variability of, in the hands and feet;
of the jaws, influence of, on the physiognomy of the Apes;
habitual spasms of, causing modifications of the facial bones, of the early
progenitors of man;
greater variability of the, in men than in women.
Musculus sternalis, Prof. Turner on the.
Music, of birds;
discordant, love of savages for;
reason of power of perception of notes in animals;
power of distinguishing notes;
its connection with primeval speech;
different appreciation of, by different peoples;
origin of;
effects of.
Musical cadences, perception of, by animals;
powers of man.
Musk-deer, canine teeth of male;
male, odoriferous organs of the;
winter change of the.
Musk-duck, Australian;
large size of male;
of Guiana, pugnacity of the male.
Musk-ox, horns of.
Musk-rat, protective resemblance of the, to a clod of earth.
Musophagae, colours and nidification of the;
both sexes of, equally brilliant.
Mussels opened by monkeys.
Mustela, winter change of two species of.
Musters, Captain, on Rhea Darwinii;
marriages amongst Patagonians.
Mutilations, healing of;
inheritance of.
Mutilla europaea, stridulation of.
Mutillidae, absence of ocelli in female.
Mycetes caraya, polygamous;
vocal organs of;
beard of;
sexual differences of colour in;
voice of.
Mycetes seniculus, sexual differences of colour in.
Myriapoda.
Nageli, on the influence of natural selection on plants;
on the gradation of species of plants.
Nails, coloured yellow or purple in part of Africa.
Narwhal, tusks of the.
Nasal cavities, large size of, in American aborigines.
Nascent organs.
Nathusius, H. von, on the improved breeds of pigs;
male domesticated animals more variable than females;
horns of castrated sheep;
on the breeding of domestic animals.
Natural selection, its effects on the early progenitors of man;
influence of, on man;
limitation of the principle;
influence of, on social animals;
Mr. Wallace on the limitation of, by the influence of the mental faculties
in man;
influence of, in the progress of the United States;
in relation to sex.
Natural and sexual selection contrasted.
Naulette, jaw from, large size of the canines in.
Neanderthal skull, capacity of the.
Neck, proportion of, in soldiers and sailors.
Necrophorus, stridulation of.
Nectarinia, young of.
Nectariniae, moulting of the;
nidification of.
Negro, resemblance of a, to Europeans in mental characters.
Negro-women, their kindness to Mungo Park.
Negroes, Caucasian features in;
character of;
lice of;
fertility of, when crossed with other races;
blackness of;
variability of;
immunity of, from yellow fever;
difference of, from Americans;
disfigurements of the;
colour of new-born children of;
comparative beardlessness of;
readily become musicians;
appreciation of beauty of their women by;
idea of beauty among;
compression of the nose by some.
Nemertians, colours of.
Neolithic period.
Neomorpha, sexual difference of the beak in.
Nephila, size of male.
Nests, made by fishes;
decoration of, by Humming-birds.
Neumeister, on a change of colour in pigeons after several moultings.
Neuration, difference of, in the two sexes of some butterflies and
hymenoptera.
Neuroptera.
Neurothemis, dimorphism in.
New Zealand, expectation by the natives of, of their extinction;
practice of tattooing in;
aversion of natives of, to hairs on the face;
pretty girls engrossed by the chiefs in.
Newton, A., on the throat-pouch of the male bustard;
on the differences between the females of two species of Oxynotus;
on the habits of the Phalarope, dotterel, and godwit.
Newts.
Nicholson, Dr., on the non-immunity of dark Europeans from yellow fever.
Nictitating membrane.
Nidification of fishes;
relation of, to colour;
of British birds.
Night-heron, cries of the.
Nightingale, arrival of the male before the female;
object of the song of the.
Nightingales, new mates found by.
Nightjar, selection of a mate by the female;
Australian, sexes of;
coloration of the.
Nightjars, noise made by some male, with their wings;
elongated feathers in.
Nilghau, sexual differences of colour in the.
Nilsson, Prof., on the resemblance of stone arrow-heads from various
places;
on the development of the horns of the reindeer.
Nipples, absence of, in Monotremata.
Nitsche, Dr., ear of foetal orang.
Nitzsch, C.L., on the down of birds.
Noctuae, brightly-coloured beneath.
Noctuidae, coloration of.
Nomadic habits, unfavourable to human progress.
Nordmann, A., on Tetrao urogalloides.
Norfolk Island, half-breeds on.
Norway, numerical proportion of male and female births in.
Nose, resemblance of, in man and the apes;
piercing and ornamentation of the;
very flat, not admired in negroes;
flattening of the.
Nott and Gliddon, on the features of Rameses II.;
on the features of Amunoph III.;
on skulls from Brazilian caves;
on the immunity of negroes and mulattoes from yellow fever;
on the deformation of the skull among American tribes.
Novara, voyage of the, suicide in New Zealand.
Nudibranch Mollusca, bright colours of.
Numerals, Roman.
Nunemaya, natives of, bearded.
Nuthatch, of Japan, intelligence of;
Indian.
Obedience, value of.
Observation, powers of, possessed by birds.
Occupations, sometimes a cause of diminished stature;
effect of, upon the proportions of the body.
Ocelli, absence of, in female Mutilidae.
Ocelli of birds, formation and variability of the.
Ocelot, sexual differences in the colouring of the.
Ocyhaps lophotes.
Odonata.
Odonestis potatoria, sexual difference of colour in.
Odour, correlation of, with colour of skin;
of moths;
emitted by snakes in the breeding season;
of mammals.
Oecanthus nivalis, difference of colour in the sexes of.
Oecanthus pellucidus.
Ogle, Dr. W., relation between colour and power of smell.
Oidemia.
Oliver, on sounds produced by Pimelia striata.
Omaloplia brunnea, stridulation of.
Onitis furcifer, processes of anterior femora of the male, and on the head
and thorax of the female.
Onthophagus.
Onthophagus rangifer, sexual differences of;
variations in the horns of the male.
Ophidia, sexual differences of.
Ophidium.
Opossum, wide range of, in America.
Optic nerve, atrophy of the, caused by destruction of the eye.
Orang-Outan, Bischoff on the agreement of the brain of the, with that of
man;
adult age of the;
ears of the;
vermiform appendage of;
hands of the;
absence of mastoid processes in the;
platforms built by the;
alarmed at the sight of a turtle;
using a stick as a lever;
using missiles;
using the leaves of the Pandanus as a night covering;
direction of the hair on the arms of the;
its aberrant characters;
supposed evolution of the;
voice of the;
monogamous habits of the;
male, beard of the.
Oranges, treatment of, by monkeys.
Orange-tip butterfly.
Orchestia Darwinii, dimorphism of males of.
Orchestia Tucuratinga, limbs of.
Ordeal, trial by.
Oreas canna, colours of.
Oreas Derbianus, colours of.
Organs, prehensile;
utilised for new purposes.
Organic scale, von Baer's definition of progress in.
Orioles, nidification of.
Oriolus, species of, breeding in immature plumage.
Oriolus melanocephalus, coloration of the sexes in.
Ornaments, prevalence of similar;
of male birds;
fondness of savages for.
Ornamental characters, equal transmission of, to both sexes, in mammals;
of monkeys.
Ornithoptera croesus.
Ornithorhynchus, reptilian tendency of;
spur of the male.
Orocetes erythrogastra, young of.
Orrony, Grotto of.
Orsodacna atra, difference of colour in the sexes of.
Orsodacna ruficollis.
Orthoptera, metamorphosis of;
stridulating apparatus of;
colours of;
rudimentary stridulating organs in female;
stridulation of the, and Homoptera, discussed.
Ortygornis gularis, pugnacity of the male.
Oryctes, stridulation of;
sexual differences in the stridulant organs of.
Oryx leucoryx, use of the horns of.
Osphranter rufus, sexual difference in the colour of.
Ostrich, African, sexes and incubation of the.
Ostriches, stripes of young.
Otaria jubata, mane of the male.
Otaria nigrescens, difference in the coloration of the sexes of.
Otis bengalensis, love-antics of the male.
Otis tarda, throat-pouch of the male;
polygamous.
Ouzel, ring-, colours and nidification of the.
Ouzel, water-, singing in the autumn;
colours and nidification of the.
Ovibos moschatus, horns of.
Ovipositor of insects.
Ovis cycloceros, mode of fighting of.
Ovule of man.
Owen, Prof., on the Corpora Wolffiana;
on the great toe in man;
on the nictitating membrane and semilunar fold;
on the development of the posterior molars in different races of man;
on the length of the caecum in the Koala;
on the coccygeal vertebrae;
on rudimentary structures belonging to the reproductive system;
on abnormal conditions of the human uterus;
on the number of digits in the Ichthyopterygia;
on the canine teeth in man;
on the walking of the chimpanzee and orang;
on the mastoid processes in the higher apes;
on the hairiness of elephants in elevated districts;
on the caudal vertebrae of monkeys;
classification of mammalia;
on the hair in monkeys;
on the piscine affinities of the Ichthyosaurians;
on polygamy and monogamy among the antelopes;
on the horns of Antilocapra Americana;
on the musky odour of crocodiles during the breeding season;
on the scent-glands of snakes;
on the Dugong, Cachalot, and Ornithorhynchus;
on the antlers of the red deer;
on the dentition of the Camelidae;
on the horns of the Irish elk;
on the voice of the giraffe, porcupine, and stag;
on the laryngeal sac of the gorilla and orang;
on the odoriferous glands of mammals;
on the effects of emasculation on the vocal organs of men;
on the voice of Hylobates agilis;
on American monogamous monkeys.
Owls, white, new mates found by.
Oxynotus, difference of the females of two species of.
Pachydermata.
Pachytylus migratorius.
Paget, on the abnormal development of hairs in man;
on the thickness of the skin on the soles of the feet of infants.
Pagurus, carrying the female.
Painting, pleasure of savages in.
Palaemon, chelae of a species of.
Palaeornis, sexual differences of colour in.
Palaeornis javanicus, colour of beak of.
Palaeornis rosa, young of.
Palamedea cornuta, spurs on the wings.
Paleolithic period.
Palestine, habits of the chaffinch in.
Pallas, on the perfection of the senses in the Mongolians;
on the want of connexion between climate and the colour of the skin;
on the polygamous habits of Antilope Saiga;
on the lighter colour of horses and cattle in winter in Siberia;
on the tusks of the musk-deer;
on the odoriferous glands of mammals;
on the odoriferous glands of the musk-deer;
on winter changes of colour in mammals;
on the ideal of female beauty in North China.
Palmaris accessorius, muscle variations of the.
Pampas, horses of the.
Pangenesis, hypothesis of.
Panniculus carnosus.
Pansch, on the brain of a foetal Cebus apella.
Papilio, proportion of the sexes in North American species of;
sexual differences of colouring in species of;
coloration of the wings in species of.
Papilio ascanius.
Papilio Sesostris and Childrenae, variability of.
Papilio Turnus.
Papilionidae, variability in the.
Papuans, line of separation between the, and the Malays;
beards of the;
teeth of.
Papuans and Malays, contrast in characters of.
Paradise, Birds of;
supposed by Lesson to be polygamous;
rattling of their quills by;
racket-shaped feathers in;
sexual differences in colour of;
decomposed feathers in;
display of plumage by the male;
sexual differences in colour of.
Paradisea apoda, barbless feathers in the tail of;
plumage of;
and P. papuana;
divergence of the females of;
increase of beauty with age.
Paradisea papuana, plumage of.
Paraguay, Indians of, eradication of eyebrows and eyelashes by.
Parallelism of development of species and languages.
Parasites, on man and animals;
as evidence of specific identity or distinctness;
immunity from, correlated with colour.
Parental feeling in earwigs, starfishes, and spiders;
affection, partly a result of natural selection.
Parents, age of, influence upon sex of offspring.
Parinae, sexual difference of colour in.
Park, Mungo, negro-women teaching their children to love the truth;
his treatment by the negro-women;
on negro opinions of the appearance of white men.
Parker, Mr., no bird or reptile in line of mammalian descent.
Parrakeet, young of;
Australian, variation in the colour of the thighs of a male.
Parrot, racket-shaped feathers in the tail of a;
instance of benevolence in a.
Parrots, change of colour in;
imitative faculties of;
living in triplets;
affection of;
colours and nidification of the;
immature plumage of the;
colours of;
sexual differences of colour in;
musical powers of.
Parthenogenesis in the Tenthredinae;
in Cynipidae;
in Crustacea.
Partridge, monogamous;
proportion of the sexes in the;
Indian;
female.
Partridge-"dances."
Partridges, living in triplets;
spring coveys of male;
distinguishing persons.
Parus coeruleus.
Passer, sexes and young of.
Passer brachydactylus.
Passer domesticus.
Passer montanus.
Patagonians, self-sacrifice by;
marriages of.
Patterson, Mr., on the Agrionidae.
Patteson, Bishop, decrease of Melanesians.
Paulistas of Brazil.
Pavo cristatus.
Pavo muticus, possession of spurs by the female.
Pavo nigripennis.
Payaguas Indians, thin legs and thick arms of the.
Payan, Mr., on the proportion of the sexes in sheep.
Peacock, polygamous;
sexual characters of;
pugnacity of the;
Javan, possessing spurs;
rattling of the quills by;
elongated tail-coverts of the;
love of display of the;
ocellated spots of the;
inconvenience of long tail of the, to the female;
continued increase of beauty of the.
Peacock-butterfly.
Peafowl, preference of females for a particular male;
first advances made by the female.
Pediculi of domestic animals and man.
Pedigree of man.
Pedionomus torquatus, sexes of.
Peel, J., on horned sheep.
Peewit, wing-tubercles of the male.
Pelagic animals, transparency of.
Pelecanus erythrorhynchus, horny crest on the beak of the male, during the
breeding season.
Pelecanus onocrotalus, spring plumage of.
Pelele, an African ornament.
Pelican, blind, fed by his companions;
young, guided by old birds;
pugnacity of the male.
Pelicans, fishing in concert.
Pelobius Hermanni, stridulation of.
Pelvis, alteration of, to suit the erect attitude of man;
differences of the, in the sexes of man.
Penelope nigra, sound produced by the male.
Pennant, on the battles of seals;
on the bladder-nose seal.
Penthe, antennal cushions of the male.
Perch, brightness of male, during breeding season.
Peregrine falcon, new mate found by.
Period of variability, relation of, to sexual selection.
Periodicity, vital, Dr. Laycock on.
Periods, lunar, followed by functions in man and animals.
Periods of life, inheritance at corresponding.
Perisoreus canadensis, young of.
Peritrichia, difference of colour in the sexes of a species of.
Periwinkle.
Pernis cristata.
Perrier, M., on sexual selection;
on bees.
Perseverance, a characteristic of man.
Persians, said to be improved by intermixture with Georgians and
Circassians.
Personnat, M., on Bombyx Yamamai.
Peruvians, civilisation of the, not foreign.
Petrels, colours of.
Petrocincla cyanea, young of.
Petrocossyphus.
Petronia.
Pfeiffer, Ida, on Javan ideas of beauty.
Phacochoerus aethiopicus, tusks and pads of.
Phalanger, Vulpine, black varieties of the.
Phalaropus fulicarius.
Phalaropus hyperboreus.
Phanaeus.
Phanaeus carnifex, variation of the horns of the male.
Phanaeus faunus, sexual differences of.
Phanaeus lancifer.
Phaseolarctus cinereus, taste for rum and tobacco.
Phasgonura viridissima, stridulation of.
Phasianus Soemmerringii.
Phasianus versicolor.
Phasianus Wallichii.
Pheasant, polygamous;
and black grouse, hybrids of;
production of hybrids with the common fowl;
immature plumage of the.
Pheasant, Amherst, display of.
Pheasant, Argus, display of plumage by the male;
ocellated spots of the;
gradation of characters in the.
Pheasant, Blood-
Pheasant, Cheer.
Pheasant, Eared, length of the tail in the;
sexes alike in the.
Pheasant, Fire-backed, possessing spurs.
Pheasant, Golden, display of plumage by the male;
age of mature plumage in the;
sex of young, ascertained by pulling out head-feathers.
Pheasant, Kalij, drumming of the male.
Pheasant, Reeve's, length of the tail in.
Pheasant, Silver, triumphant male, deposed on account of spoiled plumage;
sexual coloration of the.
Pheasant, Soemmerring's.
Pheasant, Tragopan, display of plumage by the male;
marking of the sexes of the.
Pheasants, period of acquisition of male characters in the family of the;
proportion of sexes in chicks of;
length of the tail in.
Philters, worn by women.
Phoca groenlandica, sexual difference in the coloration of.
Phoenicura ruticilla.
Phosphorescence of insects.
Phryganidae, copulation of distinct species of.
Phryniscus nigricans.
Physical inferiority, supposed, of man.
Pickering, on the number of species of man.
Picton, J.A., on the soul of man.
Picus auratus.
Picus major.
Pieris.
Pigeon, female, deserting a weakened mate;
carrier, late development of the wattle in;
pouter, late development of crop in;
domestic, breeds and sub-breeds of.
Pigeons, nestling, fed by the secretion of the crop of both parents;
changes of plumage in;
transmission of sexual peculiarities in;
Belgian, with black-streaked males;
changing colour after several moultings;
numerical proportion of the sexes in;
cooing of;
variations in plumage of;
display of plumage by male;
local memory of;
antipathy of female, to certain males;
pairing of;
profligate male and female;
wing-bars and tail-feathers of;
supposititious breed of;
pouter and carrier, peculiarities of, predominant in males;
nidification of;
Australian;
immature plumage of the.
Pigs, origin of the improved breeds of;
numerical proportion of the sexes in;
stripes of young;
tusks of miocene;
sexual preference shewn by.
Pike, American, brilliant colours of the male, during the breeding season.
Pike, reasoning powers of;
male, devoured by females.
Pike, L.O., on the psychical elements of religion.
Pimelia striata, sounds produced by the female.
Pinel, hairiness in idiots.
Pintail, drake, plumage of;
pairing with a wild duck.
Pintail Duck, pairing with a widgeon.
Pipe-fish, filamentous;
marsupial receptacles of the male.
Pipits, moulting of the.
Pipra, modified secondary wing-feathers of male.
Pipra deliciosa.
Pirates stridulus, stridulation of.
Pitcairn island, half-breeds on.
Pithecia leucocephala, sexual differences of colour in.
Pithecia Satanas, beard of;
resemblance of, to a negro.
Pits, suborbital, of Ruminants.
Pittidae, nidification of.
Placentata.
Plagiostomous fishes.
Plain-wanderer, Australian.
Planariae, bright colours of some.
Plantain-eaters, colours and nidification of the;
both sexes of, equally brilliant.
Plants, cultivated, more fertile than wild;
Nageli, on natural selection in;
male flowers of, mature before the female;
phenomena of fertilisation in.
Platalea, change of plumage in.
Platyblemus.
Platycercus, young of.
Platyphyllum concavum.
Platyrrhine monkeys.
Platysma myoides.
Plecostomus, head-tentacles of the males of a species of.
Plecostomus barbatus, peculiar beard of the male.
Plectropterus gambensis, spurred wings of.
Ploceus.
Plovers, wing-spurs of;
double moult in.
Plumage, changes of, inheritance of, by fowls;
tendency to analogous variation in;
display of, by male birds;
changes of, in relation to season;
immature, of birds;
colour of, in relation to protection.
Plumes on the head in birds, difference of, in the sexes.
Pneumora, structure of.
Podica, sexual difference in the colour of the irides.
Poeppig, on the contact of civilised and savage races.
Poison, avoidance of, by animals.
Poisonous fruits and herbs avoided by animals.
Poisons, immunity from, correlated with colour.
Polish fowls, origin of the crest in.
Pollen and van Dam, on the colours of Lemur macaco.
Polyandry, in certain Cyprinidae;
among the Elateridae.
Polydactylism in man.
Polygamy, influence of, upon sexual selection;
superinduced by domestication;
supposed increase of female births by.
In the stickleback.
Polygenists.
Polynesia, prevalence of infanticide in.
Polynesians, wide geographical range of;
difference of stature among the;
crosses of;
variability of;
heterogeneity of the;
aversion of, to hairs on the face.
Polyplectron, number of spurs in;
display of plumage by the male;
gradation of characters in;
female of.
Polyplectron chinquis.
Polyplectron Hardwickii.
Polyplectron malaccense.
Polyplectron Napoleonis.
Polyzoa.
Pomotis.
Pontoporeia affinis.
Porcupine, mute, except in the rutting season.
Pores, excretory, numerical relation of, to the hairs in sheep.
Porpitae, bright colours of some.
Portax picta, dorsal crest and throat-tuft of;
sexual differences of colour in.
Portunus puber, pugnacity of.
Potamochoerus pencillatus, tusks and facial knobs of the.
Pouchet, G., the relation of instinct to intelligence;
on the instincts of ants;
on the caves of Abou-Simbel;
on the immunity of negroes from yellow fever;
change of colour in fishes.
Pouter pigeon, late development of the large crop in.
Powell, Dr., on stridulation.
Power, Dr., on the different colours of the sexes in a species of Squilla.
Powys, Mr., on the habits of the chaffinch in Corfu.
Pre-eminence of man.
Preference for males by female birds;
shewn by mammals, in pairing.
Prehensile organs.
Presbytis entellus, fighting of the male.
Preyer, Dr., on function of shell of ear;
on supernumerary mammae in women.
Prichard, on the difference of stature among the Polynesians;
on the connection between the breadth of the skull in the Mongolians and
the perfection of their senses;
on the capacity of British skulls of different ages;
on the flattened heads of the Colombian savages;
on Siamese notions of beauty;
on the beardlessness of the Siamese;
on the deformation of the head among American tribes and the natives of
Arakhan.
Primary sexual organs.
Primates, sexual differences of colour in.
Primogeniture, evils of.
Prionidae, difference of the sexes in colour.
Proctotretus multimaculatus.
Proctotretus tenuis, sexual difference in the colour of.
Profligacy.
Progenitors, early, of man.
Progress, not the normal rule in human society;
elements of.
Prong-horn antelope, horns of.
Proportions, difference of, in distinct races.
Protective colouring in butterflies;
in lizards;
in birds;
in mammals.
Protective nature of the dull colouring of female Lepidoptera.
Protective resemblances in fishes.
Protozoa, absence of secondary sexual characters in.
Pruner-Bey, on the occurrence of the supra-condyloid foramen in the humerus
of man;
on the colour of negro infants.
Prussia, numerical proportion of male and female births in.
Psocus, proportions of the sexes in.
Ptarmigan, monogamous;
summer and winter plumage of the;
nuptial assemblages of;
triple moult of the;
protective coloration of.
Puff-birds, colours and nidification of the.
Pugnacity of fine-plumaged male birds.
Pumas, stripes of young.
Puppies learning from cats to clean their faces.
Pycnonotus haemorrhous, pugnacity of the male;
display of under-tail coverts by the male.
Pyranga aestiva, male aiding in incubation;
male characters in female of.
Pyrodes, difference of the sexes in colour.
Quadrumana, hands of;
differences between man and the;
sexual differences of colour in;
ornamental characters of;
analogy of sexual differences of, with those of man;
fighting of males for the females;
monogamous habits of;
beards of the.
Quain, R., on the variation of the muscles in man.
Quatrefages, A. de, on the occurrence of a rudimentary tail in man;
on variability;
on the moral sense as a distinction between man and animals;
civilised men stronger than savages;
on the fertility of Australian women with white men;
on the Paulistas of Brazil;
on the evolution of the breeds of cattle;
on the Jews;
on the liability of negroes to tropical fevers after residence in a cold
climate;
on the difference between field- and house-slaves;
on the influence of climate on colour;
colours of annelids;
on the Ainos;
on the women of San Giuliano.
Quechua, see Quichua.
Querquedula acuta.
Quetelet, proportion of sexes in man;
relative size in man and woman.
Quichua Indians;
local variation of colour in the;
no grey hair among the;
hairlessness of the;
long hair of the.
Quiscalus major, proportions of the sexes of, in Florida and Honduras.
Rabbit, white tail of the.
Rabbits, domestic, elongation of the skull in;
modification of the skull in, by the lopping of the ear;
danger-signals of;
numerical proportion of the sexes in.
Races, distinctive characters of;
or species of man;
crossed, fertility or sterility of;
of man, variability of the;
of man, resemblance of, in mental characters;
formation of;
of man, extinction of;
effects of the crossing of;
of man, formation of the;
of man, children of the;
beardless, aversion of, to hairs on the face.
Raffles, Sir S., on the banteng.
Rafts, use of.
Rage, manifested by animals.
Raia batis, teeth of.
Raia clavata, female spined on the back;
sexual difference in the teeth of.
Raia maculata, teeth of.
Rails, spur-winged.
Ram, mode of fighting of the;
African, mane of an;
fat-tailed.
Rameses II., features of.
Ramsay, Mr., on the Australian musk-duck;
on the regent-bird;
on the incubation of Menura superba.
Rana esculenta, vocal sacs of.
Rat, common, general dispersion of, a consequence of superior cunning;
supplantation of the native in New Zealand, by the European rat;
common, said to be polygamous;
numerical proportion of the sexes in.
Rats, enticed by essential oils.
Rationality of birds.
Rattlesnakes, difference of the sexes in the;
rattles as a call.
Raven, vocal organs of the;
stealing bright objects;
pied, of the Feroe Islands.
Rays, prehensile organs of male.
Razor-bill, young of the.
Reade, Winwood, suicide among savages in Africa;
mulattoes not prolific;
effect of castration of horned sheep;
on the Guinea sheep;
on the occurrence of a mane in an African ram;
on singing of negroes;
on the negroes' appreciation of the beauty of their women;
on the admiration of negroes for a black skin;
on the idea of beauty among negroes;
on the Jollofs;
on the marriage-customs of the negroes.
Reason in animals.
Redstart, American, breeding in immature plumage.
Redstarts, new mates found by.
Reduvidae, stridulation of.
Reed-bunting, head-feathers of the male;
attacked by a bullfinch.
Reefs, fishes frequenting.
Reeks, H., retention of horns by breeding deer;
cow rejected by a bull;
destruction of piebald rabbits by cats.
Regeneration, partial, of lost parts in man.
Regent bird.
Reindeer, horns of the;
battles of;
horns of the female;
antlers of, with numerous points;
winter change of the;
sexual preferences shown by.
Relationship, terms of.
Religion, deficiency of among certain races;
psychical elements of.
Remorse, deficiency of, among savages.
Rengger, on the diseases of Cebus Azarae;
on the diversity of the mental faculties of monkeys;
on the Payaguas Indians;
on the inferiority of Europeans to savages in their senses;
revenge taken by monkeys;
on maternal affection in a Cebus;
on the reasoning powers of American monkeys;
on the use of stones by monkeys for cracking hard nuts;
on the sounds uttered by Cebus Azarae;
on the signal-cries of monkeys;
on the polygamous habits of Mycetes caraya;
on the voice of the howling monkeys;
on the odour of Cervus campestris;
on the beards of Mycetes caraya and Pithecia Satanas;
on the colours of Felis mitis;
on the colours of Cervus paludosus;
on sexual differences of colour in Mycetes;
on the colour of the infant Guaranys;
on the early maturity of the female of Cebus Azarae;
on the beards of the Guaranys;
on the emotional notes employed by monkeys;
on American polygamous monkeys.
Representative species, of birds.
Reproduction, unity of phenomena of, throughout the mammalia;
period of, in birds.
Reproductive system, rudimentary structures in the;
accessory parts of.
Reptiles.
Reptiles and birds, alliance of.
Resemblances, small, between man and the apes.
Retrievers, exercise of reasoning faculties by.
Revenge, manifested by animals.
Reversion, perhaps the cause of some bad dispositions.
Rhagium, difference of colour in the sexes of a species of.
Rhamphastos carinatus.
Rhea Darwinii.
Rhinoceros, nakedness of;
horns of;
horns of, used defensively;
attacking white or grey horses.
Rhynchaea, sexes and young of.
Rhynchaea australis.
Rhynchaea bengalensis.
Rhynchaea capensis.
Rhythm, perception of, by animals.
Richard, M., on rudimentary muscles in man.
Richardson, Sir J., on the pairing of Tetrao umbellus;
on Tetrao urophasianus;
on the drumming of grouse;
on the dances of Tetrao phasianellus;
on assemblages of grouse;
on the battles of male deer;
on the reindeer;
on the horns of the musk-ox;
on antlers of the reindeer with numerous points;
on the moose;
on the Scotch deerhound.
Richter, Jean Paul, on imagination.
Riedel, on profligate female pigeons.
Riley, Mr., on mimicry in butterflies;
bird's disgust at taste of certain caterpillars.
Ring-ouzel, colours and nidification of the.
Ripa, Father, on the difficulty of distinguishing the races of the Chinese.
Rivalry, in singing, between male birds.
River-hog, African, tusks and knobs of the.
Rivers, analogy of, to islands.
Roach, brightness of the male during breeding-season.
Robbery, of strangers, considered honourable.
Robertson, Mr., remarks on the development of the horns in the roebuck and
red deer.
Robin, pugnacity of the male;
autumn song of the;
female singing of the;
attacking other birds with red in their plumage;
young of the.
Robinet, on the difference of size of the male and female cocoons of the
silk-moth.
Rodents, uterus in the;
absence of secondary sexual characters in;
sexual differences in the colours of.
Roe, winter changes of the.
Rohfs, Dr., Caucasian features in negro;
fertility of mixed races in Sahara;
colours of birds in Sahara;
ideas of beauty amongst the Bornuans.
Rolle, F., on the origin of man;
on a change in German families settled in Georgia.
Roller, harsh cry of.
Romans, ancient, gladiatorial exhibitions of the.
Rook, voice of the.
Rossler, Dr., on the resemblance of the lower surface of butterflies to the
bark of trees.
Rostrum, sexual difference in the length of in some weevils.
Royer, Madlle., mammals giving suck.
Rudimentary organs, origin of.
Rudiments, presence of, in languages.
Rudolphi, on the want of connexion between climate and the colour of the
skin.
Ruff, supposed to be polygamous;
proportion of the sexes in the;
pugnacity of the;
double moult in;
duration of dances of;
attraction of the, to bright objects.
Ruminants, male, disappearance of canine teeth in;
generally polygamous;
suborbital pits of;
sexual differences of colour in.
Rupicola crocea, display of plumage by the male.
Ruppell, on canine teeth in deer and antelopes.
Russia, numerical proportion of male and female births in.
Ruticilla.
Rutimeyer, Prof., on the physiognomy of the apes;
on tusks of miocene boar;
on the sexual differences of monkeys.
Rutlandshire, numerical proportion of male and female births in.
Sachs, Prof., on the behaviour of the male and female elements in
fertilisation.
Sacrifices, human.
Sagittal crest, in male apes and Australians.
Sahara, fertility of mixed races in;
birds of the;
animal inhabitants of the.
Sailors, growth of, delayed by conditions of life;
long-sighted.
Sailors and soldiers, difference in the proportions of.
St. John, Mr., on the attachment of mated birds.
St. Kilda, beards of the inhabitants of.
Salmo eriox, and Salmo umbla, colouring of the male,
during the breeding season.
Salmo lycaodon.
Salmo salar.
Salmon, leaping out of fresh water;
male, ready to breed before the female;
proportion of the sexes in;
male, pugnacity of the;
male, characters of, during the breeding season;
spawning of the;
breeding of immature male.
Salvin, O., inheritance of mutilated feathers;
on the Humming-birds;
on the numerical proportion of the sexes in Humming-birds;
on Chamaepetes and Penelope;
on Selasphorus platycercus;
Pipra deliciosa;
on Chasmorhynchus.
Samoa Islands, beardlessness of the natives of.
Sandhoppers, claspers of male.
Sand-skipper.
Sandwich Islands, variation in the skulls of the natives of the;
decrease of native population;
population of;
superiority of the nobles in the.
Sandwich Islanders, lice of.
San-Giuliano, women of.
Santali, recent rapid increase of the;
Mr. Hunter on the.
Saphirina, characters of the males of.
Sarkidiornis melanonotus, characters of the young.
Sars, O., on Pontoporeia affinis.
Saturnia carpini, attraction of males by the female.
Saturnia Io, difference of coloration in the sexes of.
Saturniidae, coloration of the.
Savage, Dr., on the fighting of the male gorillas;
on the habits of the gorilla.
Savage and Wyman on the polygamous habits of the gorilla.
Savages, uniformity of, exaggerated;
long-sighted;
rate of increase among, usually small;
retention of the prehensile power of the feet by;
imitative faculties of;
causes of low morality of;
tribes of, supplanting one another;
improvements in the arts among;
arts of;
fondness of, for rough music;
on long-enduring fashions among;
attention paid by, to personal appearance;
relation of the sexes among.
Saviotti, Dr., division of malar bone.
Saw-fly, pugnacity of a male.
Saw-flies, proportions of the sexes in.
Saxicola rubicola, young of.
Scalp, motion of the.
Scent-glands in snakes.
Schaaffhausen, Prof., on the development of the posterior molars in
different races of man;
on the jaw from La Naulette;
on the correlation between muscularity and prominent supra-orbital ridges;
on the mastoid processes of man;
on modifications of the cranial bones;
on human sacrifices;
on the probable speedy extermination of the anthropomorphous apes;
on the ancient inhabitants of Europe;
on the effects of use and disuse of parts;
on the superciliary ridge in man;
on the absence of race-differences in the infant skull in man;
on ugliness.
Schaum, H., on the elytra of Dytiscus and Hydroporus.
Scherzer and Schwarz, measurements of savages.
Schelver, on dragon-flies.
Schiodte, on the stridulation of Heterocerus.
Schlegel, F. von, on the complexity of the languages of uncivilised
peoples.
Schlegel, Prof., on Tanysiptera.
Schleicher, Prof, on the origin of language.
Schomburgk, Sir R., on the pugnacity of the male musk-duck of Guiana;
on the courtship of Rupicola crocea.
Schoolcraft, Mr., on the difficulty of fashioning stone implements.
Schopenhauer, on importance of courtship to mankind.
Schweinfurth, complexion of negroes.
Sciaena aquila.
Sclater, P.L., on modified secondary wing-feathers in the males of Pipra;
on elongated feathers in nightjars;
on the species of Chasmorhynchus;
on the plumage of Pelecanus onocrotalus;
on the plantain-eaters;
on the sexes and young of Tadorna variegata;
on the colours of Lemur macaco;
on the stripes in asses.
Scolecida, absence of secondary sexual characters in.
Scolopax frenata, tail feathers of;
Scolopax gallinago, drumming of.
Scolopax javensis, tail-feathers of.
Scolopax major, assemblies of.
Scolopax Wilsonii, sound produced by.
Scolytus, stridulation of.
Scoter-duck, black, sexual difference in coloration of the;
bright beak of male.
Scott, Dr., on idiots smelling their food.
Scott, J., on the colour of the beard in man.
Scrope, on the pugnacity of the male salmon;
on the battles of stags.
Scudder, S.H., imitation of the stridulation of the Orthoptera;
on the stridulation of the Acridiidae;
on a Devonian insect;
on stridulation.
Sculpture, expression of the ideal of beauty by.
Sea-anemones, bright colours of.
Sea-bear, polygamous.
Sea-elephant, male, structure of the nose of the;
polygamous.
Sea-lion, polygamous.
Seal, bladder-nose.
Seals, their sentinels generally females;
evidence furnished by, on classification;
polygamous habits of;
battles of male;
canine teeth of male;
sexual differences;
pairing of;
sexual peculiarities of;
in the coloration of;
appreciation of music by.
Sea-scorpion, sexual differences in.
Season, changes of colour in birds, in accordance with the;
changes of plumage of birds in relation to.
Seasons, inheritance at corresponding.
Sebituani, African chief, trying to alter a fashion.
Sebright Bantam.
Secondary sexual characters;
relations of polygamy to;
transmitted through both sexes;
gradation of, in birds.
Sedgwick, W., on hereditary tendency to produce twins.
Seemann, Dr., on the different appreciation of music by different peoples;
on the effects of music.
Seidlitz, on horns of reindeer.
Selasphorus platycercus, acuminate first primary of the male.
Selby, P.J., on the habits of the black and red grouse.
Selection as applied to primeval man.
Selection, double.
Selection, injurious forms of, in civilised nations.
Selection of male by female birds.
Selection, methodical, of Prussian grenadiers.
Selection, sexual, explanation of;
influence of, on the colouring of Lepidoptera.
Selection, sexual and natural, contrasted.
Self-command, habit of, inherited;
estimation of.
Self-consciousness, in animals.
Self-preservation, instinct of.
Self-sacrifice, by savages;
estimation of.
Semilunar fold.
Semnopithecus, long hair on the heads of species of.
Semnopithecus chrysomelas, sexual differences of colour in.
Semnopithecus comatus, ornamental hair on the head of.
Semnopithecus frontatus, beard etc., of.
Semnopithecus nasica, nose of.
Semnopithecus nemaeus, colouring of.
Semnopithecus rubicundus, ornamental hair on the head of.
Senses, inferiority of Europeans to savages in the.
Sentinels, among animals.
Serpents, instinctively dreaded by apes and monkeys.
Serranus, hermaphroditism in.
Setina, noise produced by.
Sex, inheritance limited by.
Sexes, relative proportions of, in man;
proportions of, sometimes influenced by selection;
probable relation of the, in primeval man.
Sexual and natural selection, contrasted.
Sexual characters, effects of the loss of;
limitation of.
Sexual characters, secondary;
relations of polygamy to;
transmitted through both sexes;
gradation of, in birds.
Sexual differences in man.
Sexual selection, explanation of;
influence of, on the colouring of Lepidoptera;
objections to;
action of, in mankind.
Sexual selection in spiders.
Sexual selection, supplemental note on.
Sexual similarity.
Shaler, Prof., sizes of sexes in whales.
Shame.
Sharks, prehensile organs of male.
Sharpe, Dr., Europeans in the tropics.
Sharpe, R.B., on Tanysiptera sylvia;
on Ceryle;
on the young male of Dacelo Gaudi-chaudi.
Shaw, Mr., on the pugnacity of the male salmon.
Shaw, J., on the decorations of birds.
Sheep, danger-signals of;
sexual differences in the horns of;
horns of;
domestic, sexual differences of, late developed;
numerical proportion of the sexes in;
inheritance of horns by one sex;
effect of castration;
mode of fighting of;
arched foreheads of some.
Sheep, Merino, loss of horns in females of;
horns of.
Shells, difference in form of, in male and female Gasteropoda;
beautiful colours and shapes of.
Shield-drake, pairing with a common duck;
New Zealand, sexes and young of.
Shooter, J., on the Kaffirs;
on the marriage-customs of the Kaffirs.
Shrew-mice, odour of.
Shrike, Drongo.
Shrikes, characters of young.
Shuckard, W.E., on sexual differences in the wings of Hymenoptera.
Shyness of adorned male birds;
Siagonium, proportions of the sexes in;
dimorphism in males of.
Siam, proportion of male and female births in.
Siamese, general beardlessness of the;
notions of beauty of the;
hairy family of.
Sidgwick, H., on morality in hypothetical bee community;
our actions not entirely directed by pain and pleasure.
Siebold, C.T., von, on the proportion of sexes in the Apus;
on the auditory apparatus of the stridulent Orthoptera.
Sight, inheritance of long and short.
Signal-cries of monkeys.
Silk-moth, proportion of the sexes in;
Ailanthus, Prof. Canestrini, on the destruction of its larvae by wasps;
difference of size of the male and female cocoons of the;
pairing of the.
Simiadae, their origin and divisions.
Similarity, sexual.
Singing of the Cicadae and Fulgoridae;
of tree-frogs;
of birds, object of the.
Sirenia, nakedness of.
Sirex juvencus.
Siricidae, difference of the sexes in.
Siskin, pairing with a canary.
Sitana, throat-pouch of the males of.
Size, relative, of the sexes of insects.
Skin, dark colour of, a protection against heat.
Skin, movement of the;
nakedness of, in man;
colour of the.
Skin and hair, correlation of colour of.
Skull, variation of, in man;
cubic contents of, no absolute test of intellect;
Neanderthal, capacity of the;
causes of modification of the;
difference of, in form and capacity, in different races of men;
variability of the shape of the;
differences of, in the sexes in man;
artificial modification of the shape of.
Skunk, odour emitted by the;
white tail of, protective.
Slavery, prevalence of;
of women.
Slaves, difference between field- and house-slaves.
Sloth, ornaments of male.
Smell, sense of, in man and animals.
Smith, Adam, on the basis of sympathy.
Smith, Sir A., on the recognition of women by male Cynocephali;
on revenge by a baboon;
on an instance of memory in a baboon;
on the retention of their colour by the Dutch in South Africa;
on the polygamy of the South African antelopes;
on the polygamy of the lion;
on the proportion of the sexes in Kobus ellipsiprymnus;
on Bucephalus capensis;
on South African lizards;
on fighting gnus;
on the horns of rhinoceroses;
on the fighting of lions;
on the colours of the Cape Eland;
on the colours of the gnu;
on Hottentot notions of beauty;
disbelief in communistic marriages.
Smith, F., on the Cynipidae and Tenthredinidae;
on the relative size of the sexes of Aculeate Hymenoptera;
on the difference between the sexes of ants and bees;
on the stridulation of Trox sabulosus;
on the stridulation of Mononychus pseudacori.
Smynthurus luteus, courtship of.
Snakes, sexual differences of;
mental powers of;
male, ardency of.
"Snarling muscles."
Snipe, drumming of the;
coloration of the.
Snipe, painted, sexes and young of.
Snipe, solitary, assemblies of.
Snipes, arrival of male before the female;
pugnacity of male;
double moult in.
Snow-goose, whiteness of the.
Sociability, the sense of duty connected with;
impulse to, in animals;
manifestations of, in man;
instinct of, in animals.
Social animals, affection of, for each other;
defence of, by the males.
Sociality, probable, of primeval men;
influence of, on the development of the intellectual faculties;
origin of, in man.
Soldiers, American, measurements of.
Soldiers and sailors, difference in the proportions of.
Solenostoma, bright colours and marsupial sac of the females of.
Song, of male birds appreciated by their females;
want of, in brilliant plumaged birds;
of birds.
Sorex, odour of.
Sounds, admired alike by man and animals;
produced by fishes;
produced by male frogs and toads;
instrumentally produced by birds.
Spain, decadence of.
Sparassus smaragdulus, difference of colour in the sexes of.
Sparrow, pugnacity of the male;
acquisition of the Linnet's song by a;
coloration of the;
immature plumage of the.
Sparrow, white-crowned, young of the.
Sparrows, house- and tree-.
Sparrows, new mates found by.
Sparrows, sexes and young of;
learning to sing.
Spathura Underwoodi.
Spawning of fishes.
Spear, used before dispersion of man.
Species, causes of the advancement of;
distinctive characters of;
or races of man;
sterility and fertility of, when crossed;
supposed, of man;
gradation of;
difficulty of defining;
representative, of birds;
of birds, comparative differences between the sexes of distinct.
Spectrum femoratum, difference of colour in the sexes of.
Speech, connection between the brain and the faculty of;
connection of intonation with music.
Spel, of the black-cock.
Spencer, Herbert, on the influence of food on the size of the jaws;
on the dawn of intelligence;
on the origin of the belief in spiritual agencies;
on the origin of the moral sense;
on music.
Spengel, disagrees with explanation of man's hairlessness.
Sperm-whales, battles of male.
Sphingidae, coloration of the.
Sphinx, Humming-bird.
Sphinx, Mr. Bates on the caterpillar of a.
Sphinx moth, musky odour of.
Spiders, parental feeling in;
male, more active than female;
proportion of the sexes in;
secondary sexual characters of;
courtship of male;
attracted by music;
male, small size of.
Spilosoma menthastri, rejected by turkeys.
Spine, alteration of, to suit the erect attitude of man.
Spirits, fondness of monkeys for.
Spiritual agencies, belief in, almost universal.
Spiza cyanea and ciris.
Spoonbill, Chinese, change of plumage in.
Spots, retained throughout groups of birds;
disappearance of, in adult mammals.
Sprengel, C.K., on the sexuality of plants.
Springboc, horns of the.
Sproat, Mr., on the extinction of savages in Vancouver Island;
on the eradication of facial hair by the natives of Vancouver Island;
on the eradication of the beard by the Indians of Vancouver Island.
Spurs, occurrence of, in female fowls;
development of, in various species of Phasianidae;
of Gallinaceous birds;
development of, in female Gallinaceae.
Squilla, different colours of the sexes of a species of.
Squirrels, battles of male;
African, sexual differences in the colouring of;
black.
Stag, long hairs of the throat of;
horns of the;
battles of;
horns of the, with numerous branches;
bellowing of the;
crest of the.
Stag-beetle, numerical proportion of sexes of;
use of jaws;
large size of male;
weapons of the male.
Stainton, H.T., on the numerical proportion of the sexes in the smaller
moths;
habits of Elachista rufocinerea;
on the coloration of moths;
on the rejection of Spilosoma menthastri by turkeys;
on the sexes of Agrotis exclamationis.
Staley, Bishop, mortality of infant Maories.
Stallion, mane of the.
Stallions, two, attacking a third;
fighting;
small canine teeth of.
Stansbury, Captain, observations on pelicans.
Staphylinidae, hornlike processes in male.
Starfishes, parental feeling in;
bright colours of some.
Stark, Dr., on the death-rate in towns and rural districts;
on the influence of marriage on mortality;
on the higher mortality of males in Scotland.
Starling, American field-, pugnacity of male.
Starling, red-winged, selection of a mate by the female.
Starlings, three, frequenting the same nest;
new mates found by.
Statues, Greek, Egyptian, Assyrian, etc., contrasted.
Stature, dependence of, upon local influences.
Staudinger, Dr., on breeding Lepidoptera;
his list of Lepidoptera.
Staunton, Sir G., hatred of indecency a modern virtue.
Stealing of bright objects by birds.
Stebbing, T.R., on the nakedness of the human body.
Stemmatopus.
Stendhal, see Bombet.
Stenobothrus pratorum, stridulation.
Stephen, Mr. L., on the difference in the minds of men and animals;
on general concepts in animals;
distinction between material and formal morality.
Sterility, general, of sole daughters;
when crossed, a distinctive character of species;
under changed conditions.
Sterna, seasonal change of plumage in.
Stickleback, polygamous;
male, courtship of the;
male, brilliant colouring of, during the breeding season;
nidification of the.
Sticks used as implements and weapons by monkeys.
Sting in bees.
Stokes, Captain, on the habits of the great bower-bird.
Stoliczka, Dr., on colours in snakes.
Stoliczka, on the pre-anal pores of lizards.
Stonechat, young of the.
Stone implements, difficulty of making;
as traces of extinct tribes.
Stones, used by monkeys for breaking hard fruits and as missiles;
piles of.
Stork, black, sexual differences in the bronchi of the;
red beak of the.
Storks, sexual difference in the colour of the eyes of.
Strange, Mr., on the satin bowerbird.
Strepsiceros kudu, horns of;
markings of.
Stretch, Mr., on the numerical proportion in the sexes of chickens.
Stridulation, by males of Theridion;
of Hemiptera;
of the Orthoptera and Homoptera discussed;
of beetles.
Stripes, retained throughout groups of birds;
disappearance of, in adult mammals.
Strix flammea.
Structure, existence of unserviceable modifications of.
Struggle for existence, in man.
Struthers, Dr., on the occurrence of the supra-condyloid foramen in the
humerus of man.
Sturnella ludoviciana, pugnacity of the male.
Sturnus vulgaris.
Sub-species.
Suffering, in strangers, indifference of savages to.
Suicide, formerly not regarded as a crime;
rarely practised among the lowest savages.
Suidae, stripes of the young.
Sulivan, Sir B.J., on speaking of parrots;
on two stallions attacking a third.
Sumatra, compression of the nose by the Malays of.
Sumner, Archb., man alone capable of progressive improvement.
Sun-birds, nidification of.
Superciliary ridge in man.
Supernumerary digits, more frequent in men than in women;
inheritance of;
early development of.
Superstitions, prevalence of.
Superstitious customs.
Supra-condyloid foramen in the early progenitors of man.
Suspicion, prevalence of, among animals.
Swallow-tail butterfly.
Swallows deserting their young.
Swan, black, wild, trachea of the;
white, young of;
red beak of the;
black-necked.
Swans, young.
Swaysland, Mr., on the arrival of migratory birds.
Swifts, migration of.
Swinhoe, R., on the common rat in Formosa and China;
behaviour of lizards when caught;
on the sounds produced by the male hoopoe;
on Dicrurus macrocercus and the spoonbill;
on the young of Ardeola;
on the habits of Turnix;
on the habits of Rhynchaea bengalensis;
on Orioles breeding in immature plumage.
Sylvia atricapilla, young of.
Sylvia cinerea, aerial love-dance of the male.
Sympathy, among animals;
its supposed basis.
Sympathies, gradual widening of.
Syngnathous fishes, abdominal pouch in male.
Sypheotides auritus, acuminated primaries of the male;
ear-tufts of.
Tabanidae, habits of.
Tadorna variegata, sexes and young of.
Tadorna vulpanser.
Tahitians, compression of the nose by the.
Tail, rudimentary, occurrence of, in man;
convoluted body in the extremity of the;
absence of, in man and the higher apes;
variability of, in species of Macacus and in baboons;
presence of, in the early progenitors of man;
length of, in pheasants;
difference of length of the, in the two sexes of birds.
Tait, Lawson, on the effects of natural selection on civilised nations.
Tanager, scarlet, variation in the male.
Tanagra aestiva, age of mature plumage in.
Tanagra rubra, young of.
Tanais, absence of mouth in the males of some species of;
relations of the sexes in;
dimorphic males of a species of.
Tankerville, Earl, on the battles of wild bulls.
Tanysiptera, races of, determined from adult males.
Tanysiptera sylvia, long tail-feathers of.
Taphroderes distortus, enlarged left mandible of the male.
Tapirs, longitudinal stripes of young.
Tarsi, dilatation of front, in male beetles.
Tarsius.
Tasmania, half-castes killed by the natives of.
Tasmanians, extinction of.
Taste, in the Quadrumana.
Tattooing, universality of.
Taylor, G., on Quiscalus major.
Taylor, Rev. R., on tattooing in New Zealand.
Tea, fondness of monkeys for.
Teal, constancy of.
Tear-sacs, of Ruminants.
Teebay, Mr., on changes of plumage in spangled Hamburg fowls.
Teeth, rudimentary incisor, in Ruminants;
posterior molar, in man;
wisdom;
diversity of;
canine, in the early progenitors of man;
canine, of male mammals;
in man, reduced by correlation;
staining of the;
front, knocked out or filed by some savages.
Tegetmeier, Mr., on the transmission of colours in pigeons by one sex
alone;
numerical proportion of male and female births in dogs;
on the abundance of male pigeons;
on the wattles of game-cocks;
on the courtship of fowls;
on the loves of pigeons;
on dyed pigeons;
blue dragon pigeons.
Tembeta, S. American ornament.
Temper, in dogs and horses, inherited.
Tench, proportions of the sexes in the;
brightness of male, during breeding season.
Tenebrionidae, stridulation of.
Tennent, Sir J.E., on the tusks of the Ceylon Elephant;
on the frequent absence of beard in the natives of Ceylon;
on the Chinese opinion of the aspect of the Cingalese.
Tennyson, A., on the control of thought.
Tenthredinidae, proportions of the sexes in;
fighting habits of male;
difference of the sexes in.
Tephrodornis, young of.
Terai, in India.
Termites, habits of.
Terns, white;
and black.
Terns, seasonal change of plumage in.
Terror, common action of, upon the lower animals and man.
Testudo elegans.
Testudo nigra.
Tetrao cupido, battles of;
sexual difference in the vocal organs of.
Tetrao phasianellus, dances of;
duration of dances of.
Tetrao scoticus.
Tetrao tetrix, pugnacity of the male.
Tetrao umbellus, pairing of;
battles of;
drumming of the male.
Tetrao urogalloides, dances of.
Tetrao urogallus, pugnacity of the male.
Tetrao urophasianus, inflation of the oesophagus in the male.
Thamnobia, young of.
Thecla, sexual differences of colouring in species of.
Thecla rubi, protective colouring of.
Thecophora fovea.
Theognis, selection in mankind.
Theridion, stridulation of males of.
Theridion lineatum.
Thomisus citreus, and Thomisus floricolens, difference of colour in the
sexes of.
Thompson, J.H., on the battles of sperm-whales.
Thompson, W., on the colouring of the male char during the breeding season;
on the pugnacity of the males of Gallinula chloropus;
on the finding of new mates by magpies;
on the finding of new mates by Peregrine falcons.
Thorax, processes of, in male beetles.
Thorell, T., on the proportion of sexes in spiders.
Thornback, difference in the teeth of the two sexes of the.
Thoughts, control of.
Thrush, pairing with a blackbird;
colours and nidification of the.
Thrushes, characters of young.
Thug, remorse of a.
Thumb, absence of, in Ateles and Hylobates.
Thury, M., on the numerical proportion of male and female births among the
Jews.
Thylacinus, possession of the marsupial sac by the male.
Thysanura.
Tibia, dilated, of the male Crabro cribrarius.
Tibia and femur, proportions of, in the Aymara Indians.
Tierra del Fuego, marriage-customs of.
Tiger, colours and markings of the.
Tigers, depopulation of districts by, in India.
Tillus elongatus, difference of colour in the sexes of.
Timidity, variability of, in the same species.
Tinca vulgaris.
Tipula, pugnacity of male.
Tits, sexual difference of colour in.
Toads, male, treatment of ova by some;
male, ready to breed before the female.
Todas, infanticide and proportion of sexes;
practice polyandry;
choice of husbands amongst.
Toe, great, condition of, in the human embryo.
Tomicus villosus, proportion of the sexes in.
Tomtit, blue, sexual difference of colour in the.
Tonga Islands, beardlessness of the natives of.
Tooke, Horne, on language.
Tools, flint;
used by monkeys;
use of.
Topknots in birds.
Tortoise, voice of the male.
Tortures, submitted to by American savages.
Totanus, double moult in.
Toucans, colours and nidification of the;
beaks and ceres of the.
Towns, residence in, a cause of diminished stature.
Toynbee, J., on the external shell of the ear in man.
Trachea, convoluted and imbedded in the sternum, in some birds;
structure of the, in Rhynchaea.
Trades, affecting the form of the skull.
Tragelaphus, sexual differences of colour in.
Tragelaphus scriptus, dorsal crest of;
markings of.
Tragopan, swelling of the wattles of the male, during courtship;
display of plumage by the male;
marking of the sexes of the.
Tragops dispar, sexual difference in the colour of.
Training, effect of, on the mental difference between the sexes of man.
Transfer of male characters to female birds.
Transmission, equal, of ornamental characters, to both sexes in mammals.
Traps, avoidance of, by animals;
use of.
Treachery, to comrades, avoidance of, by savages.
Tremex columbae.
Tribes, extinct;
extinction of.
Trichius, difference of colour in the sexes of a species of.
Trigla.
Trigonocephalus, noise made by tail of.
Trimen, R., on the proportion of the sexes in South African butterflies;
on the attraction of males by the female Lasiocampa quercus;
on Pneumora;
on difference of colour in the sexes of beetles;
on moths brilliantly coloured beneath;
on mimicry in butterflies;
on Gynanisa Isis, and on the ocellated spots of Lepidoptera;
on Cyllo Leda.
Tringa, sexes and young of.
Tringa cornuta.
Triphaena, coloration of the species of.
Tristram, H.B., on unhealthy districts in North Africa;
on the habits of the chaffinch in Palestine;
on the birds of the Sahara;
on the animals inhabiting the Sahara.
Triton cristatus.
Triton palmipes.
Triton punctatus.
Troglodyte skulls, greater than those of modern Frenchmen.
Troglodytes vulgaris.
Trogons, colours and nidification of the.
Tropic-birds, white only when mature.
Tropics, freshwater fishes of the.
Trout, proportion of the sexes in;
male, pugnacity of the.
Trox sabulosus, stridulation of.
Truth, not rare between members of the same tribe;
more highly appreciated by certain tribes.
Tulloch, Major, on the immunity of the negro from certain fevers.
Tumbler, almond, change of plumage in the.
Turdus merula, young of.
Turdus migratorius.
Turdus musicus.
Turdus polyglottus, young of.
Turdus torquatus.
Turkey, wild, pugnacity of young male;
wild, notes of the;
swelling of the wattles of the male;
variety of, with a top-knot;
recognition of a dog by a;
male, wild, acceptable to domesticated females;
wild, first advances made by older females;
wild, breast-tuft of bristles of the.
Turkey-cock, scraping of the wings of, upon the ground;
wild, display of plumage by;
fighting habits of.
Turner, Prof. W., on muscular fasciculi in man referable to the panniculus
carnosus;
on the occurrence of the supra-condyloid foramen in the human humerus;
on muscles attached to the coccyx in man;
on the filum terminale in man;
on the variability of the muscles;
on abnormal conditions of the human uterus;
on the development of the mammary glands;
on male fishes hatching ova in their mouths;
on the external perpendicular fissure of the brain;
on the bridging convolutions in the brain of a chimpanzee.
Turnix, sexes of some species of.
Turtle-dove, cooing of the.
Tuttle, H., on the number of species of man.
Tylor, E.B., on emotional cries, gestures, etc., of man;
on the origin of the belief in spiritual agencies;
remorse for violation of tribal usage in marrying;
on the primitive barbarism of civilised nations;
on the origin of counting;
inventions of savages;
on resemblances, of the mental characters in different races of man.
Type of structure, prevalence of.
Typhaeus, stridulating organs of;
stridulation of.
Twins, tendency to produce, hereditary.
Twite, proportion of the sexes in.
Ugliness, said to consist in an approach to the lower animals.
Umbrella-bird.
Umbrina, sounds produced by.
United States, rate of increase in;
influence of natural selection on the progress of;
change undergone by Europeans in the.
Upupa epops, sounds produced by the male.
Uraniidae, coloration of the.
Uria troile, variety of (=U. lacrymans).
Urodela.
Urosticte Benjamini, sexual differences in.
Use and disuse of parts, effects of;
influence of, on the races of man.
Uterus, reversion in the;
more or less divided, in the human subject;
double, in the early progenitors of man.
Vaccination, influence of.
Vancouver Island, Mr. Sproat on the savages of;
natives of, eradication of facial hair by the.
Vanellus cristatus, wing tubercles of the male.
Vanessae, resemblance of lower surface of, to bark of trees.
Variability, causes of;
in man, analogous to that in the lower animals;
of the races of man;
greater in men than in women;
period of, relation of the, to sexual selection;
of birds;
of secondary sexual characters in man.
Variation, laws of;
correlated;
in man;
analogous;
analogous, in plumage of birds.
Variations, spontaneous.
Varieties, absence of, between two species, evidence of their distinctness.
Variety, an object in nature.
Variola, communicable between man and the lower animals.
Vaureal, human bones from.
Veddahs, monogamous habits of.
Veitch, Mr., on the aversion of Japanese ladies to whiskers.
Vengeance, instinct of.
Venus Erycina, priestesses of.
Vermes.
Vermiform appendage.
Verreaux, M., on the attraction of numerous males by the female of an
Australian Bombyx.
Vertebrae, caudal, number of in macaques and baboons;
of monkeys, partly imbedded in the body.
Vertebrata, common origin of the;
most ancient progenitors of;
origin of the voice in air-breathing.
Vesicula prostatica, the homologue of the uterus.
Vibrissae, represented by long hairs in the eyebrows.
Vidua.
Vidua axillaris.
Villerme, M., on the influence of plenty upon stature.
Vinson, Aug., courtship of male spider;
on the male of Epeira nigra.
Viper, difference of the sexes in the.
Virey, on the number of species of man.
Virtues, originally social only;
gradual appreciation of.
Viscera, variability of, in man.
Vlacovich, Prof., on the ischio-pubic muscle.
Vocal music of birds.
Vocal organs of man;
of birds;
of frogs;
of the Insessores;
difference of, in the sexes of birds;
primarily used in relation to the propagation of the species.
Vogt, Karl, on the origin of species;
on the origin of man;
on the semilunar fold in man;
on microcephalous idiots;
on the imitative faculties of microcephalous idiots;
on skulls from Brazilian caves;
on the evolution of the races of man;
on the formation of the skull in women;
on the Ainos and negroes;
on the increased cranial difference of the sexes in man with race
development;
on the obliquity of the eye in the Chinese and Japanese.
Voice in mammals;
in monkeys and man;
in man;
origin of, in air-breathing vertebrates.
Von Baer, see Baer.
Vulpian, Prof., on the resemblance between the brains of man and the higher
apes.
Vultures, selection of a mate by the female;
colours of.
Waders, young of.
Wagner, R., on the occurrence of the diastema in a Kaffir skull;
on the bronchi of the black stork.
Wagtail, Ray's, arrival of the male before the female.
Wagtails, Indian, young of.
Waist, proportions of, in soldiers and sailors.
Waitz, Prof., on the number of species of man;
on the liability of negroes to tropical fevers after residence in a cold
climate;
on the colour of Australian infants;
on the beardlessness of negroes;
on the fondness of mankind for ornaments;
on negro ideas of female beauty;
on Javan and Cochin Chinese ideas of beauty.
Waldeyer, M., on the hermaphroditism of the vertebrate embryo.
Wales, North, numerical proportion of male and female births in.
Walkenaer and Gervais, spider attracted by music;
on the Myriapoda.
Walker, Alex., on the large size of the hands of labourers' children.
Walker, F., on sexual differences in the diptera.
Wallace, Dr. A., on the prehensile use of the tarsi in male moths;
on the rearing of the Ailanthus silkmoth;
on breeding Lepidoptera;
proportion of sexes of Bombyx cynthia, B. yamamai, and B. Pernyi reared by;
on the development of Bombyx cynthia and B. yamamai;
on the pairing of Bombyx cynthia.
Wallace, A.R., on the origin of man;
on the power of imitation in man;
on the use of missiles by the orang;
on the varying appreciation of truth among different tribes;
on the limits of natural selection in man;
on the occurrence of remorse among savages;
on the effects of natural selection on civilised nations;
on the use of the convergence of the hair at the elbow in the orang;
on the contrast in the characters of the Malays and Papuans;
on the line of separation between the Papuans and Malays;
on the birds of paradise;
on the sexes of Ornithoptera Croesus;
on protective resemblances;
on the relative sizes of the sexes of insects;
on Elaphomyia;
on the pugnacity of the males of Leptorhynchus angustatus;
on sounds produced by Euchirus longimanus;
on the colours of Diadema;
on Kallima;
on the protective colouring of moths;
on bright coloration as protective in butterflies;
on variability in the Papilionidae;
on male and female butterflies, inhabiting different stations;
on the protective nature of the dull colouring of female butterflies;
on mimicry in butterflies;
on the bright colours of caterpillars;
on brightly-coloured fishes frequenting reefs;
on the coral snakes;
on Paradisea apoda;
on the display of plumage by male birds of paradise;
on assemblies of birds of paradise;
on the instability of the ocellated spots in Hipparchia Janira;
on sexually limited inheritance;
on the sexual coloration of birds;
on the relation between the colours and nidification of birds;
on the coloration of the Cotingidae;
on the females of Paradisea apoda and papuana;
on the incubation of the cassowary;
on protective coloration in birds;
on the Babirusa;
on the markings of the tiger;
on the beards of the Papuans;
on the hair of the Papuans;
on the distribution of hair on the human body.
Walrus, development of the nictitating membrane in the;
tusks of the;
use of the tusks by the.
Walsh, B.D., on the proportion of the sexes in Papilio Turnus;
on the Cynipidae and Cecidomyidae;
on the jaws of Ammophila;
on Corydalis cornutus;
on the prehensile organs of male insects;
on the antennae of Penthe;
on the caudal appendages of dragonflies;
on Platyphyllum concavum;
on the sexes of the Ephemeridae;
on the difference of colour in the sexes of Spectrum femoratum;
on sexes of dragon-flies;
on the difference of the sexes in the Ichneumonidae;
on the sexes of Orsodacna atra;
on the variation of the horns of the male Phanaeas carnifex;
on the coloration of the species of Anthocharis.
Wapiti, battles of;
traces of horns in the female;
attacking a man;
crest of the male;
sexual difference in the colour of the.
Warbler, hedge-;
young of the.
Warblers, superb, nidification of.
Wariness, acquired by animals.
Warington, R., on the habits of the stickleback;
on the brilliant colours of the male stickleback during the breeding
season.
Wart-hog, tusks and pads of the.
Watchmakers, short-sighted.
Waterhen.
Waterhouse, C.O., on blind beetles;
on difference of colour in the sexes of beetles.
Waterhouse, G.R., on the voice of Hylobates agilis.
Water-ouzel, autumn song of the.
Waterton, C., on the Bell-bird;
on the pairing of a Canada goose with a Bernicle gander;
on hares fighting.
Wattles, disadvantageous to male birds in fighting.
Weale, J., Mansel, on a South African caterpillar.
Wealth, influence of.
Weapons, used by man;
employed by monkeys;
offensive, of males;
of mammals.
Weaver-bird.
Weaver-birds, rattling of the wings of;
assemblies of.
Webb, Dr., on the wisdom teeth.
Wedderburn, Mr., assembly of black game.
Wedgwood, Hensleigh, on the origin of language.
Weevils, sexual difference in length of snout in some.
Weir, Harrison, on the numerical proportion of the sexes in pigs and
rabbits;
on the sexes of young pigeons;
on the songs of birds;
on pigeons;
on the dislike of blue pigeons to other coloured varieties;
on the desertion of their mates by female pigeons.
Weir, J. Jenner, on the nightingale and blackcap;
on the relative sexual maturity of male birds;
on female pigeons deserting a feeble mate;
on three starlings frequenting the same nest;
on the proportion of the sexes in Machetes pugnax and other birds;
on the coloration of the Triphaenae;
on the rejection of certain caterpillars by birds;
on sexual differences of the beak in the goldfinch;
on a piping bullfinch;
on the object of the nightingale's song;
on song-birds;
on the pugnacity of male fine-plumaged birds;
on the courtship of birds;
on the finding of new mates by Peregrine falcons and Kestrels;
on the bullfinch and starling;
on the cause of birds remaining unpaired;
on starlings and parrots living in triplets;
on recognition of colour by birds;
on hybrid birds;
on the selection of a greenfinch by a female canary;
on a case of rivalry of female bullfinches;
on the maturity of the golden pheasant.
Weisbach, Dr., measurement of men of different races;
on the greater variability of men than of women;
on the relative proportions of the body in the sexes of different races of
man.
Weismann, Prof., colours of Lycaenae.
Welcker, M., on brachycephaly and dolichocephaly;
on sexual differences in the skull in man.
Wells, Dr., on the immunity of coloured races from certain poisons.
Westring, on the stridulation of males of Theridion;
on the stridulation of Reduvius personatus;
on the stridulation of beetles;
on the stridulation of Omaloplia brunnea;
on the stridulating organs of the Coleoptera;
on sounds produced by Cychrus.
Westropp, H.M., on reason in a bear;
on the prevalence of certain forms of ornamentation.
Westwood, J.O., on the classification of the Hymenoptera;
on the Culicidae and Tabanidae;
on a Hymenopterous parasite with a sedentary male;
on the proportions of the sexes in Lucanus cervus and Siagonium;
on the absence of ocelli in female Mutillidae;
on the jaws of Ammophila;
on the copulation of insects of distinct species;
on the male of Crabro cribrarius;
on the pugnacity of the male Tipulae;
on the stridulation of Pirates stridulus;
on the Cicadae;
on the stridulating organs of the cricket;
on Ephippiger vitium;
on Pneumora;
on the pugnacity of the Mantides;
on Platyblemnus;
on difference in the sexes of the Agrionidae;
on the pugnacity of the males of a species of Tenthredinae;
on the pugnacity of the male stag-beetle;
on Bledius taurus and Siagonium;
on lamellicorn beetles;
on the coloration of Lithosia.
Whale, Sperm-, battles of male.
Whales, nakedness of.
Whately, Arch., language not peculiar to man;
on the primitive civilisation of man.
Whewell, Prof., on maternal affection.
Whiskers, in monkeys.
White, F.B., noise produced by Hylophila.
White, Gilbert, on the proportion of the sexes in the partridge;
on the house-cricket;
on the object of the song of birds;
on the finding of new mates by white owls;
on spring coveys of male partridges.
Whiteness, a sexual ornament in some birds;
of mammals inhabiting snowy countries.
White-throat, aerial love-dance of the male.
Whitney, Prof., on the development of language;
language not indispensable for thought.
Widgeon, pairing with a pintail duck.
Widow-bird, polygamous;
breeding plumage of the male;
female, rejecting the unadorned male.
Widows and widowers, mortality of.
Wilckens, Dr., on the modification of domestic animals in mountainous
regions;
on a numerical relation between the hairs and excretory pores in sheep.
Wilder, Dr. Burt, on the greater frequency of supernumerary digits in men
than in women.
Williams, on the marriage-customs of the Fijians.
Wilson, Dr., on the conical heads of the natives of North-Western Africa;
on the Fijians;
on the persistence of the fashion of compressing the skull.
Wing-spurs.
Wings, differences of, in the two sexes of butterflies and Hymenoptera;
play of, in the courtship of birds.
Winter, change of colour of mammals in.
Witchcraft.
Wives, traces of the forcible capture of.
Wolf, winter change of the.
Wolff, on the variability of the viscera in man.
Wollaston, T.V., on Eurygnathus;
on musical Curculionidae;
on the stridulation of Acalles.
Wolves, learning to bark from dogs;
hunting in packs.
Wolves, black.
Wombat, black varieties of the.
Women, distinguished from men by male monkeys;
preponderance of, in numbers;
selection of, for beauty;
effects of selection of, in accordance with different standards of beauty;
practice of capturing;
early betrothals and slavery of;
freedom of selection by, in savage tribes.
Wonder, manifestations of, by animals.
Wonfor, Mr., on sexual peculiarities, in the wings of butterflies.
Wood, J., on muscular variations in man;
on the greater variability of the muscles in men than in women.
Wood, T.W., on the colouring of the orange-tip butterfly;
on the habits of the Saturniidae;
quarrels of chamaeleons;
on the habits of Menura Alberti;
on Tetrao cupido;
on the display of plumage by male pheasants;
on the ocellated spots of the Argus pheasant;
on fighting of Menura superba;
on the habits of the female cassowary.
Woodcock, coloration of the.
Woodpecker, selection of a mate by the female.
Woodpeckers, tapping of;
colours and nidification of the;
characters of young.
Woolner, Mr., observations on the ear in man.
Wormald, Mr., on the coloration of Hypopyra.
Wounds, healing of.
Wren, young of the.
Wright, C.A., on the young of Orocetes and Petrocincla.
Wright, Chauncey, great brain-power requisite for language;
on correlative acquisition;
on the enlargement of the brain in man.
Wright, Mr., on the Scotch deer-hound;
on sexual preference in dogs;
on the rejection of a horse by a mare.
Wright, W. von, on the protective plumage of the Ptarmigan.
Writing.
Wyman, Prof., on the prolongation of the coccyx in the human embryo;
on the condition of the great toe in the human embryo;
on the occurrence of the supra-condyloid foramen in the humerus of man;
on variation in the skulls of the natives of the Sandwich Islands;
on the hatching of the eggs in the mouths and branchial cavities of male
fishes.
Xenarchus, on the Cicadae.
Xenophon, selection in mankind advocated by.
Xenorhynchus, sexual difference in the colour of the eyes in.
Xiphophorus Hellerii, peculiar anal fin of the male.
Xylocopa, difference of the sexes in.
Yarrel, W., on the habits of the Cyprinidae;
on Raia clavata;
on the characters of the male salmon during the breeding season;
on the characters of the rays;
on the gemmeous dragonet;
on colours of salmon;
on the spawning of the salmon;
on the incubation of the Lophobranchii;
on rivalry in song-birds;
on the trachea of the swan;
on the moulting of the Anatidae;
on the young of the waders.
Yellow fever, immunity of negroes and mulattoes from.
Youatt, Mr., on the development of the horns in cattle.
Yura-caras, their notions of beauty.
Zebra, rejection of an ass by a female;
stripes of the.
Zebus, humps of.
Zigzags, prevalence of, as ornaments.
Zincke, Mr., on European emigration to America.
Zootoca vivipara, sexual difference in the colour of.
Zouteveen, Dr., polydactylism;
proportion of sexes at Cape of Good Hope;
spiders attracted by music;
on sounds produced by fish.
Zygaenidae, coloration of the.
THE END.
End of this Project Gutenberg Etext of The Descent of Man by Charles Darwin
Udvalgte artikler