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The Descent of Man and Selection in Relation to Sex by Charles Darwin

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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.


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.


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.



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

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

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

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

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.



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

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.


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.


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.


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 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.


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.


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;
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.


Arakhan, artificial widening of the forehead by the natives of.

Arboricola, young of.


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.


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

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.


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
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

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.


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;
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.


Birds, imitations of the songs of other birds by;
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;
male, singing out of season;
mutual affection of;
in confinement, distinguish persons;
hybrid, production of;
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
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
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
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

Bonizzi, P., difference of colour in sexes of pigeons.

Bonnet monkey.

Bonwick, J., extinction of Tasmanians.


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.


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
on the self-restraint of dogs.

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