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

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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.


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

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.)



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

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

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

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

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

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.


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.



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

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.)


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


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.


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

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

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.


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

[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.


[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

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