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,* are said
to be completely mute excepting
at this season. As the throats
(i.e. the larynx and thyroid
bodies*(2)) 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.
* Owen, Anatomy of Vertebrates,
vol. iii., p. 585.
*(2) Ibid., p. 595.
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,* 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.
* See, for instance, Major W.
Ross King (The Sportsman in Canada,
1866, pp. 53, 131) on the habits
of the moose and wild reindeer.
The voice of the adult male
gorilla is tremendous, and he
is furnished with a laryngeal
sack, as is the adult male orang.*
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.*(2) Another gibbon, the
H. agilis, is remarkable, from
having the power of giving a
complete and correct octave of
musical notes,*(3) 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,*(4) 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.
* Owen Anatomy of Vertebrates,
vol. iii., p. 600.
*(2) Mr. Green, in Journal of
Linnean Society, vol. x., Zoology,
1869, note 362.
*(3) C. L. Martin, General Introduction
to the Natural History of Mamm.
Animals, 1841, p. 431.
*(4) Naturgeschichte der Saugethiere
von Paraguay, 1830, ss. 15, 21.
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
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.*
* On the sea-elephant, see an
article by Lesson, in Dict. Class.
Hist. Nat., tom. xiii., p. 418.
For the Cystophora, or Stemmatopus,
see Dr. Dekay, Annals of Lyceum
of Nat. Hist., New York, vol.
i., 1824, p. 94. Pennant has
also collected information from
the sealers on this animal. The
fullest account is given by Mr.
Brown, in Proc. Zoolog. Soc.,
1868, p. 435.
Odour.- With some animals, as
with the notorious skunk of America,
the overwhelming odour which
they emit appears to serve exclusively
as a defence. With shrew-mice
(Sorex) both sexes possess abdominal
scent-glands and there can be
little doubt, from the rejection
of their bodies by birds and
beasts of prey, that the odour
is protective; nevertheless,
the glands become enlarged in
the males during the breeding-season.
In many other quadrupeds the
glands are of the same size in
both sexes,* 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.
* 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, Proceedings of the
Zoological Society. 1873, p.
241.
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.* 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."*(2)
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.*(3)
* Rengger, Naturgeschichte der
Saugethiere von Paraguay, 1830,
s. 355. This observer also gives
some curious particulars in regard
to the odour.
*(2) 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.
*(3) Pallas, Spicilegia Zoolog.,
fasc. xiii., 1779, p. 24; Desmoulins,
Dict. Class. d'Hist. Nat., tom.
iii., p. 586.
In most cases, when only the
male emits a strong odour during
the breeding-season, it probably
serves to excite or allure the
female. We must not judge on
this head by our own taste, for
it is well known that rats are
enticed by certain essential
oils, and cats by valerian, substances
far from agreeable to us; and
that dogs, though they will not
eat carrion, sniff and roll on
it. From the reasons given when
discussing the voice of the stag,
we may reject the idea that the
odour serves to bring the females
from a distance to the males.
Active and long-continued use
cannot here have come into play,
as in the case of the vocal organs.
The odour emitted must be of
considerable importance to the
male, inasmuch as large and complex
glands, furnished with muscles
for everting the sack, and for
closing or opening the orifice,
have in some cases been developed.
The development of these organs
is intelligible through sexual
selection, if the most odoriferous
males are the most successful
in winning the females, and in
leaving offspring to inherit
their gradually perfected glands
and odours.
Development of the Hair.- We
have seen that male quadrupeds
often have the hair on their
necks and shoulders much more
developed than the females; and
many additional instances could
be given. This sometimes serves
as a defence to the male during
his battles; but whether the
hair in most cases has been specially
developed for this purpose, is
very doubtful. We may feel almost
certain that this is not the
case, when only a thin and narrow
crest runs along the back; for
a crest of this kind would afford
scarcely any protection, and
the ridge of the back is not
a place likely to be injured;
nevertheless such crests are
sometimes confined to the males,
or are much more developed in
them than in the females. Two
antelopes, the Tragelaphus scriptus*
(see 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;*(2)
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.
* Dr. Gray, Gleanings from the
Menagerie at Knowsley, pl. 28.
*(2) Judge Caton on the wapiti,
Transact. Ottawa Acad. Nat. Sciences,
1868, pp. 36, 40; Blyth, Land
and Water, on Capra aegagrus
1867, p. 37. 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.* 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 it is
so small at other times that
it may be called rudimentary.*(2)
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 (see fig. 68). So it
is with the whiskers of some
species of Macacus,*(3) 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.
* Hunter's Essays and Observations,
edited by Owen, 1861. vol. i.,
p. 236.
*(2) See Dr. Gray's Catalogue
of Mammalia in the British Museum,
part iii., 1852, p. 144.
*(3) Rengger,
Saugthiere, &c.,
s. 14; Desmarest, Mammalogie,
p. 86.
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.*
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, &c., 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.
* 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 Berbuar goat,
see Dr. Gray, Catalogue, ibid.,
p. 157.
Hence it appears reasonable
to extend this same view to all
analogous cases with animals
in a state of nature. Nevertheless
I cannot persuade myself that
it generally holds good, as in
the case of the extraordinary
development of hair on the throat
and fore-legs of the male Ammotragus,
or in that of the immense beard
of the male Pithecia. Such study
as I have been able to give to
nature makes me believe that
parts or organs which are highly
developed, were acquired at some
period for a special purpose.
With those antelopes in which
the adult male is more strongly-coloured
than the female, and with those
monkeys in which the hair on
the face is elegantly arranged
and coloured in a diversified
manner, it seems probable that
the crests and tufts of hair
were gained as ornaments; and
this I know is the opinion of
some naturalists. If this be
correct, there can be little
doubt that they were gained or
at least modified through sexual
selection; but how far the same
view may be extended to other
mammals is doubtful.
Colour of the
Hair and of the Naked Skin.-
I will first give
briefly all the cases known to
me of male quadrupeds differing
in colour from the females. With
marsupials, as I am informed
by Mr. Gould, the sexes rarely
differ in this respect; but the
great red kangaroo offers a striking
exception, "delicate blue being
the prevailing tint in those
parts of the female which in
the male are red."* 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."*(2) 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.*(3)
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."
* Osphranter rufus, Gould, Mammals
of Australia, 1863, vol. ii.
On the Didelphis, Desmarest,
Mammalogie, p. 256.
*(2) Annals and Magazine of
Natural History, Nov., 1867,
p. 325. On the Mus minutus, Desmarest,
Mammalogie, p. 304.
*(3) 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.
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."*
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."*(2)
* Desmarest Mammalogie, 1820,
p. 220. On Felis mitis, Rengger,
ibid., s. 194.
*(2) 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*
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.*(2)
* Judge Caton, in Transactions
of the Ottawa Academy of Natural
Sciences, 1868, p. 4.
*(2) 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, pls. 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."*
Other analogous cases could be
added.
* 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.
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 differs 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.*
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.*(2) 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.
* Ottawa Academy of Sciences,
May 21, 1868, pp. 3,5.
*(2) 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.
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.* 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.*(2) 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 griseoviridis 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.
* Sclater, Proc. Zool. Soc.,
1866, p. i. The same fact has
also been fully ascertained by
M. M. Pollen and van Dam. See,
also, Dr. Gray in Annals and
Magazine of Natural History,
May, 1871, p. 340.
*(2) On Mycetes, Rengger, ibid.,
s. 14; and Brehm, Illustriertes
Thierleben, B. i., ss. 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.
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."*
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. (See 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.
* 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.
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. Amalogous 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* 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."*(2)
* The Variation of Animals and
Plants under Domestication, 1868,
vol. ii., pp. 102, 103.
*(2) Essays and Observations,
by J. Hunter, edited by Owen,
1861, 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";*- as negroes
and savages in many parts of
the world paint their faces with
red, blue, white, or black bars,-
so the male mandrill of Africa
appears to have acquired his
deeply-furrowed and gaudily-coloured
face from having been thus rendered
attractive to the female. No
doubt it is to us a most grotesque
notion that the posterior end
of the body should be coloured
for the sake of ornament even
more brilliantly than the face;
but this is not more strange
than that the tails of many birds
should be especially decorated.
* Sir S. Baker, The Nile Tributaries
of Abyssinia, 1867.
With mammals we do not at present
possess any evidence that the
males take pains to display their
charms before the female; and
the elaborate manner in which
this is performed by male birds
and other animals is the strongest
argument in favour of the belief
that the females admire, or are
excited by, the ornaments and
colours displayed before them.
There is, however, a striking
parallelism between mammals and
birds in all their secondary
sexual characters, namely in
their weapons for fighting with
rival males, in their ornamental
appendages, and in their colours.
In both classes, when the male
differs from the female, the
young of both sexes almost always
resemble each other, and in a
large majority of cases resemble
the adult female. In both classes
the male assumes the characters
proper to his sex shortly before
the age of reproduction; and
if emasculated at an early period,
loses them. In both classes the
change of colour is sometimes
seasonal, and the tints of the
naked parts sometimes become
more vivid during the act of
courtship. In both classes the
male is almost always more vividly
or strongly coloured than the
female, and is ornamented with
larger crests of hair or feathers,
or other such appendages. In
a few exceptional cases the female
in both classes is more highly
ornamented than the male. With
many mammals, and at least in
the case of one bird, the male
is more odoriferous than the
female. In both classes the voice
of the male is more powerful
than that of the female. Considering
this parallelism, there can be
little doubt that the same cause,
whatever it may be, has acted
on mammals and birds; and the
result, as far as ornamental
characters are concerned, may
be attributed, as it appears
to me, to the long-continued
preference of the individuals
of one sex for certain individuals
of the opposite sex, combined
with their success in leaving
a larger number of offspring
to inherit their superior attractions.
Equal transmission of ornamental
characters to both sexes.- With
many birds, ornaments, which
analogy leads us to believe were
primarily acquired by the males,
have been transmitted equally,
or almost equally, to both sexes;
and we may now enquire how far
this view applies to mammals.
With a considerable number of
species, especially of the smaller
kinds, both sexes have been coloured,
independently of sexual selection,
for the sake of protection; but
not, as far as I can judge, in
so many cases, nor in so striking
a manner, as in most of the lower
classes. Audubon remarks that
he often mistook the musk-rat,*
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*(2) 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.
* Fiber zibethicus, Audubon
and Bachman, The Quadrupeds of
North America, 1846, p. 109.
*(2) Novae species Quadrupedum
e Glirium ordine, 1778, p. 7.
What I have called the roe is
the Capreolus sibricus subecaudatus
of Pallas.
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 recognized and
might be attacked by a beast
of prey. Hence it is, as Mr.
Belt believes,* that the skunk
is provided with a great white
bushy tail, which serves as a
conspicuous warning.
* The Naturalist in Nicaragua,
p. 249.
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 (see 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) (see 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
(see 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.* 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.
* See the fine plates in A.
Smith's Zoology of South Africa,
and Dr. Gray's Gleanings from
the Menagerie of Knowsley.
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* 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*(2)
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.
* Westminster Review, July 1,
1867, p. 5.
*(2) Travels in South Africa,
1824, vol. ii., p. 315.
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 Manchurian 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.* 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.*(2)
* 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.
*(2) 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.* 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.*(2)
* The Variation of Animals and
Plants under Domestication, 1868,
vol. i., pp. 61-64.
*(2) Proc. Zool. Soc., 1862,
p. 164. See, also, Dr. Hartmann,
Ann. d. Landw., Dd. xliii., s.
222.
Quadrumana.- 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 (see
figs. 72 to 76) serve to shew
the arrangement of the hair on
the face and head in several
species. It is scarcely conceivable
that these crests of hair, and
the strongly contrasted colours
of the fur and skin, can be the
result of mere variability without
the aid of selection; and it
is inconceivable that they can
be of use in any ordinary way
to these animals. If so, they
have probably been gained through
sexual selection, though transmitted
equally, or almost equally, to
both sexes. With many of the
Quadrumana, we have additional
evidence of the action of sexual
selection in the greater size
and strength of the males, and
in the greater development of
their canine teeth, in comparison
with the females.
A few instances
will suffice of the strange
manner in which
both sexes of some species are
coloured, and of the beauty of
others. The face of the Cercopithecus
petaurista (see fig. 77) is black,
the whiskers and beard being
white, with a defined, round,
white spot on the nose, covered
with short white hair, which
gives to the animal an almost
ludicrous aspect. The Semnopithecus
frontatus likewise has a blackish
face with a long black beard,
and a large naked spot on the
forehead of a bluish-white colour.
The face of Macacus lasiotus
is dirty flesh-coloured, with
a defined red spot on each cheek.
The appearance of Cercocebus
aethiops is grotesque, with its
black face, white whiskers and
collar, chestnut head, and a
large naked white spot over each
eyelid. In very many species,
the beard, whiskers, and crests
of hair round the face are of
a different colour from the rest
of the head, and when different,
are always of a lighter tint,*
being often pure white, sometimes
bright yellow, or reddish. The
whole face of the South American
Brachyurus calvus is of a "glowing
scarlet hue"; but this colour
does not appear until the animal
is nearly mature.*(2) The naked
skin of the face differs wonderfully
in colour in the various species.
It is often brown or flesh-colour,
with parts perfectly white, and
often as black as that of the
most sooty negro. In the Brachyurus
the scarlet tint is brighter
than that of the most blushing
Caucasian damsel. It is sometimes
more distinctly orange than in
any Mongolian, and in several
species it is blue, passing into
violet or grey. In all the species
known to Mr. Bartlett, in which
the adults of both sexes have
strongly-coloured faces, the
colours are dull or absent during
early youth. This likewise holds
good with the mandrill and Rhesus,
in which the face and the posterior
parts of the body are brilliantly
coloured in one sex alone. In
these latter cases we have reason
to believe that the colours were
acquired through sexual selection;
and we are naturally led to extend
the same view to the foregoing
species, though both sexes when
adult have their faces coloured
in the same manner.
* I observed this fact in the
Zoological Gardens; and many
cases may be seen in the coloured
plates in Geoffroy St-Hilaire
and F. Cuvier, Histoire Nat.
des Mammiferes, tom. i., 1824.
*(2) Bates, The Naturalist on
the Amazons, 1863, vol. ii.,
p. 310.
Although many kinds of monkeys
are far from beautiful according
to our taste, other species are
universally admired for their
elegant appearance and bright
colours. The Semnopithecus nemaeus,
though peculiarly coloured, is
described as extremely pretty;
the orange-tinted face is surrounded
by long whiskers of glossy whiteness,
with a line of chestnut-red over
the eyebrows; the fur on the
back is of a delicate grey, with
a square patch on the loins,
the tail and the fore-arms being
of a pure white; a gorget of
chestnut surmounts the chest;
the thighs are black, with the
legs chestnut-red. I will mention
only two other monkeys for their
beauty; and I have selected these
as presenting slight sexual differences
in colour, which renders it in
some degree probable that both
sexes owe their elegant appearance
to sexual selection. In the moustache-monkey
(Cercopithecus cephus) the general
colour of the fur is mottled-greenish
with the throat white; in the
male the end of the tail is chestnut,
but the face is the most ornamented
part, the skin being chiefly
bluish-grey, shading into a blackish
tint beneath the eyes, with the
upper lip of a delicate blue,
clothed on the lower edge with
a thin black moustache; the whiskers
are orange-coloured, with the
upper part black, forming a band
which extends backwards to the
ears, the latter being clothed
with whitish hairs. In the Zoological
Society's Gardens I have often
overheard visitors admiring the
beauty of another monkey, deservedly
called Cercopithecus diana (see
fig. 78); the general colour
of the fur is grey; the chest
and inner surface of the fore
legs are white; a large triangular
defined space on the hinder part
of the back is rich chestnut;
in the male the inner sides of
the thighs and the abdomen are
delicate fawn-coloured, and the
top of the head is black; the
face and ears are intensely black,
contrasting finely with a white
transverse crest over the eyebrows
and a long white peaked beard,
of which the basal portion is
black.*
* I have seen most of the above
monkeys in the Zoological Society's
Gardens. The description of the
Semnopithecus nemaeus is taken
from Mr. W. C. Martin's Natural
History of Mammalia, 1841, p.
460; see also pp. 475, 523. In
these and many other monkeys,
the beauty and singular arrangement
of their colours, and still more
the diversified and elegant arrangement
of the crests and tufts of hair
on their heads, force the conviction
on my mind that these characters
have been acquired through sexual
selection exclusively as ornaments.
Summary.- The law of battle
for the possession of the female
appears to prevail throughout
the whole great class of mammals.
Most naturalists will admit that
the greater size, strength, courage,
and pugnacity of the male, his
special weapons of offence, as
well as his special means of
defence, have been acquired or
modified through that form of
selection which I have called
sexual. This does not depend
on any superiority in the general
struggle for life, but on certain
individuals of one sex, generally
the male, being successful in
conquering other males, and leaving
a larger number of offspring
to inherit their superiority
than do the less successful males.
There is another and more peaceful
kind of contest, in which the
males endeavour to excite or
allure the females by various
charms. This is probably carried
on in some cases by the powerful
odours emitted by the males during
the breeding-season; the odoriferous
glands having been acquired through
sexual selection. Whether the
same view can be extended to
the voice is doubtful, for the
vocal organs of the males must
have been strengthened by use
during maturity, under the powerful
excitements of love, jealousy
or rage, and will consequently
have been transmitted to the
same sex. Various crests, tufts,
and mantles of hair, which are
either confined to the male,
or are more developed in this
sex than in the female, seem
in most cases to be merely ornamental,
though they sometimes serve as
a defence against rival males.
There is even reason to suspect
that the branching horns of stags,
and the elegant horns of certain
antelopes, though properly serving
as weapons of offence or defence,
have been partly modified for
ornament.
When the male differs in colour
from the female, he generally
exhibits darker and more strongly-contrasted
tints. We do not in this class
meet with the splendid red, blue,
yellow, and green tints, so common
with male birds and many other
animals. The naked parts, however,
of certain Quadrumana must be
excepted; for such parts, often
oddly situated, are brilliantly
coloured in some species. The
colours of the male in other
cases may be due to simple variation,
without the aid of selection.
But when the colours are diversified
and strongly pronounced, when
they are not developed until
near maturity, and when they
are lost after emasculation,
we can hardly avoid the conclusion
that they have been acquired
through sexual selection for
the sake of ornament, and have
been transmitted exclusively,
or almost exclusively, to the
same sex. When both sexes are
coloured in the same manner,
and the colours are conspicuous
or curiously arranged, without
being of the least apparent use
as a protection, and especially
when they are associated with
various other ornamental appendages,
we are led by analogy to the
same conclusion, namely, that
they have been acquired through
sexual selection, although transmitted
to both sexes. That conspicuous
and diversified colours, whether
confined to the males or common
to both sexes, are as a general
rule associated in the same groups
and sub-groups with other secondary
sexual characters serving for
war or for ornament, will be
found to hold good, if we look
back to the various cases given
in this and the last chapter.
The law of the equal transmission
of characters to both sexes,
as far as colour and other ornaments
are concerned, has prevailed
far more extensively with mammals
than with birds; but weapons,
such as horns and tusks, have
often been transmitted either
exclusively or much more perfectly
to the males than to the females.
This is surprising, for, as the
males generally use their weapons
for defence against enemies of
all kinds, their weapons would
have been of service to the females.
As far as we can see, their absence
in this sex can be accounted
for only by the form of inheritance
which has prevailed. Finally,
with quadrupeds the contest between
the individuals of the same sex,
whether peaceful or bloody, has,
with the rarest exceptions, been
confined to the males; so that
the latter have been modified
through sexual selection, far
more commonly than the females,
either for fighting with each
other or for alluring the opposite
sex.
PART THREE.
SEXUAL SELECTION IN RELATION
TO MAN
AND CONCLUSION. |