MAN’S COUSINS THE APES
The Man-like Apes and their mode of Life—Their “Courtships”—Musical
Chimpanzees—How the Orang-utan improves his voice—His likeness to
Caliban—The truculent visage of the Gorilla—“Ornament” in the lower
Apes—The Concerts of the Howler Monkeys.
We are none of us given to boasting of our poor relations, and most
of us indignantly repudiate our kinship with the Apes. But facts are
stubborn things: the relationship is there, whether we admit it or
not: and those who love truth for truth’s sake will not shirk the
comparison between themselves and their remote cousins. Unhappily,
from our present point of view, this cannot be carried very far, for
the “Love idylls” of the Apes have yet to be written. Such facts,
however, as have been gleaned are interesting. Of the higher, man-like,
or “Anthropoid” species only the most meagre information is to be
obtained; but this nevertheless is interesting. For the most part we
have to be satisfied with inferences drawn from a study of the external
differences between the sexes—from the “Secondary Sexual Characters,”
in short, and from the records of travellers who have encountered these
creatures in their native wilds.
The species which throw most light on this theme are the Gorilla,
the Chimpanzee and the Orang-utan. Of these the Chimpanzee has most
in common with the human race. But it may satisfy the qualms of many
to know that between the Ape and the Man there is a great gulf fixed.
The brain of the largest Ape is less than half the size of that even
of the lowest of mankind. Man is a reasoning, and for the most part a
reasonable, creature; he is a tool-making animal. This is more than
can be said of any of the apes, even the most intelligent. Their teeth
and immensely powerful arms must serve their every need. No ape ever
fashioned for himself either a knife, a vessel to carry water, or any
means of transport; and herein we have a measure of his brain capacity.
The huge jaws and great canine teeth are no less conspicuous “marks of
the beast.”
These, however, man himself has but recently lost, as was proved by
the sensational discovery of the skull of an ape-like man at Piltdown,
in Sussex, during 1912. Herein the jaw was essentially that of an ape,
while the base of the skull was as markedly human. The cheek teeth, or
molars, were of the human type; but the canine was ape-like, though
much inferior in point of size. That the men of this remote age—which
was possibly that of Pliocene times and certainly not later than early
Pleistocene—had begun to use rudely-fashioned tools, is proved by the
roughly-chipped flints found with the remains. With the invention of
tools the decline in the size of his “eye” teeth began.
In all the large apes these “eye” teeth are of great size. Their
purpose, it would seem, is primarily to serve as weapons in conflicts
between rivals. Such conflicts are apparently unintentionally, and
unavoidably, provoked by the loud cries uttered by the males in their
endeavours to discover the whereabouts of females desiring mates. Of
necessity roaming far in search of food, the unmated have no means of
making their whereabouts known, save by thus giving tongue to desire.
Evidently the normal methods of voice production do not suffice for
their urgent needs, for the carrying power of the voice is immensely
fortified by means of great air sacs, or chambers, formed in part by an
enlargement of the body of the hyoid, or the bone which supports the
tongue, and in part by dilatations of the inner walls of the larynx.
The females, it is to be noted, are by no means so well equipped
in this matter. It is not necessary that they should be. All that
those desiring mates have to do is to follow up the cries of avid
males, a by no means difficult task, especially when under the spell
of the emotions which possess them. But the mechanism which serves
the Chimpanzee and the Gorilla by no means fulfils the needs of the
Orang-utan. In this uncouth creature the system of resonating chambers
is immensely increased by great, thin-walled, membranous pouches
extending round the neck and under the armpits, so that when inflated
these areas have a most extraordinarily swollen appearance. When the
Orang chooses to lift his voice even the deaf must hear.
Where fighting instead of fondling is the sequel to these impassioned
cries the conflict is probably not of long duration, for it is
certainly severe. This is attested by the fact that captured specimens,
if adult, are commonly found to be minus one or more fingers, which
have been bitten or torn off in these love affairs.
[Illustration: Plate 2.
_From a drawing by I. Thornton._
THE GORILLA PREPARING FOR HOSTILITIES.
Note the “beetling” brows, the large size of the canine teeth, and the
great development of the arms in these arboreal creatures, which play
an even more important part in locomotion than the legs. The latter in
this illustration are, however, relatively too small.
[Face page 42.]
An added ferocity of expression is given to the male Gorilla by the
development of enormous brow ridges and the huge canines. The former
are regarded by some authorities as adaptations to afford increased
powers of mastication. But if this were so, then such ridges should
be equally developed in both sexes, and this is far from being true.
Hideousness, rather than ferocity, has been given to the Orang-utan by
the out-growth of enormous ridges on each side of the face, and these,
when the great wind-bags encircling the neck are inflated, impart a
repulsiveness of expression attained by no other animal living.
Of the normal every-day life of the great Apes but little is known. It
would seem, however, that they live in family parties—an adult male
accompanied by a female and one or more young of different ages, of
which one is commonly an infant in arms. It is difficult to procure
positive evidence on the point, but it is commonly believed that the
young remain with their parents till they are several years old, when
they are gradually driven off to fend for themselves. This is a common
procedure with all animals. The dominant impulse in this is something
akin to greediness, an indefinable perception that too large a family
party will entail too great a strain on the food supply, hence the now
no longer helpless young are regarded as a danger to the safety of
the family, and are turned adrift. Incidentally this procedure is of
immense benefit to the race, for it ensures its distribution, enlarges
its chances of survival, and lessens the danger of in-breeding.
Attention must now be turned to the lower Apes. In these it is to be
remarked the secondary sexual characters differ conspicuously from
those of the man-like species. Manes and beards and brightly-coloured
areas of bare skin are now the dominant feature. But canine teeth, in
proportion rivalling those of the Gorilla, are found in the Baboons,
while in some of the New-world monkeys voice production of quite
remarkable power takes the place of ornament.
The precise part played by ornament among these animals can only be
inferred from Darwin’s observations on captive animals, and then only
in so far as they refer to colour. Manes, beards and moustaches, such
as are shown in the adjoining illustrations, are borne only by the
males, and sometimes take extravagant forms.
Darwin suggested that the mane of the Baboons, for example, served as
a shield when fighting with rivals, protecting the great blood-vessels
from injury. Incidentally this end may be attained, but from what we
know of similar developments in other animals, this cannot be regarded
as the primary function of the mane. One is tempted to look upon it
as a protective device because of its position, but it is probably
no more so than is the long flowing hair which adorns the flanks of
the Guereza. This is of a purely ornamental character, although,
according to some, it is to be reckoned as an instance of protective
coloration, the long white hair matching the long pendant masses of
lichen which hang from the boughs of the trees in the damp forests
where these creatures live, and so concealing them from their enemies.
Of beards and moustaches many examples might be cited, but the most
striking must suffice. These are furnished by the Satan Monkey or
Black Saki (_Pithecia satanas_), and the little Tamarin Monkey (_Midas
imperator_)—one of the Marmosets. In the first-named the beard is thick
and full, but in the latter scanty. This, however, is atoned for by the
enormous upwardly curled moustache giving the face a most comically
human appearance.
[Illustration: Plate 3.
_From drawings by I. Thornton._
THE BAROMETER OF MALENESS—AMONG THE APES.
All the Man-like Apes possess great canine teeth and powerful voices.
In the Orangutan the Compass of the voice is enormously heightened by
means of a huge wind-bag which encircles the neck. The wind-bag is seen
in fig. 1, which also shows the great folds of skin developed by adult
males on each side of the face. In other species, as in the Tamarin
Marmoset (_Midas imperator_) (fig. 2), and the Satan monkey (_Pithecia
satanus_) (fig. 3), “ornaments” in the shape of beards and moustaches
are developed, while in the Mandrill (fig. 4) the face is vividly
coloured.
[Face page 44.]
In the development of brilliantly-coloured areas of bare skin
the monkeys stand alone among the Mammalia. The hues displayed are
remarkable for their brilliancy, and this varies in intensity, waxing
and waning with the varying moods of their possessors, and attaining
their maximum during periods of sexual excitement. Blue, green, red,
and violet are the dominant colours, and these are confined to the
face, buttocks, and genital organs. The same hues are commonly present
in both sexes, though in the female they are less brilliant. Normally
the male appears to be unconscious of the conspicuous patches of
colour, but when under the irrepressible stimulus of sexual excitement
he seems to endeavour to make the utmost possible capital out of such
adornments, more especially presenting his buttocks to his mate in an
apparent endeavour to stimulate her desire. In some species, as with
the Baboons for example, the naked area of this hinder part of the body
is a much more conspicuous feature in the female than in the male,
becoming enormously swollen and carunculated, and from its vivid red
colour presents a positively revolting appearance, according to our
standard of what is beautiful. The most vividly coloured species of
all is the Mandrill, which, in this matter exceeds all other living
Mammals. The face, in the male, is produced forward to give the head a
dog-like shape, while the whole of the upper surface of the muzzle has
been transformed into a swollen, deeply fluted mass by the excessive
inflation of the underlying bone. The bare skin covering this is of a
brilliant cobalt blue, with lines of violet in the furrows, while the
nose is of a bright scarlet. The naked skin of the buttocks, and the
genital organs, are suffused with brilliant tints of scarlet and blue.
In spite of the purity and brilliance of the coloration the effect is
to make the creature really hideous.
Of the display Cuvier writes: “La partie postérieure du corps n’est ni
moins extraordinaire ni moins révoltante. Sous une courte queue sans
cesse relevée est un anus entouré d’un gros bourrelet d’écarlate; de
larges fesses nues, que l’animal semble montrer sans cesse avec autant
de lascivité que d’impudence, sont colorées d’un rose vif nuancé sur
les côtés de lilas et de bleu. Les parties genitales enfin sont d’un
rouge de feu d’autant plus tranché qu’elles sont absolument nues, et
qu’elles viennent a la suite d’un abdomen revêtu de poils blancs.”
While we cannot suppose these animals to possess any standard of
beauty or ugliness, it must not be forgotten that they are more or
less conscious, not only of the existence of these brightly-coloured
areas, but of the effect they produce, as Darwin showed long since in
the cases of a captive Mandrill, and some other smaller species of
Monkeys, among them a Rhesus Monkey. These, when shown a looking-glass,
at once presented their hinder ends to what they supposed to be the
new arrival. A similar mark of friendliness was shown towards their
keeper, and visitors introduced by him. Periodically, under the sexual
stimulus, this desire becomes intensified and becomes an invitation to
mating.
In this connection it is interesting to note that in some of the
Macaque Monkeys we have signs of a reversal of the usual sequence of
coloration. For in the Pigtailed Macaque the young of both sexes are
more brilliantly coloured than the adults, in regard to the bare skin
areas, while in the Hairy-eared Macaque (_M. lasiotis_) and the Rhesus
Monkey (_M. rhesus_) the face of the female is brighter than that of
the male. This surely means that this coloration is in process of
suppression, for according to the rule the male is the first to develop
new characters, then the female, and finally they are transmitted to
the young. The extra brightness in the young, then, is to be regarded
not as an incipient, but as an ancestral character in process of
elimination.
As a rule, among the Mammals at any rate, brilliant coloration and
weapons of offence are not associated in the same animal. The Baboons,
and the Mandrill in particular, are exceptions, for these animals are
provided with most formidable “tusks,” the canines of both upper and
lower jaws being of great size, and opposed one to another in such a
way that they wear away to form sharp, angular cutting-edges, more
murderous than the fangs of the Tiger.
Reference has been made already to the existence of large sound
resonators for the purpose of increasing the volume of the voice in
the Orang, Gorilla and Chimpanzee. Some of the Gibbons are also well
provided in this direction. But the most striking instances of the
kind are furnished by the Orang, and the monkeys known as Howlers. In
these last the base of the hyoid, as the skeleton for the support of
the tongue is called, is fashioned into a deep bony cup, which has the
effect of intensifying the volume of the voice to a most surprising
extent. But more than this, apparently for the protection of this bony
voice-bowl the upright branches of the lower jaw have become remarkably
deepened, and widened, a correlation of growth between unrelated parts
which is fraught with deep significance. “Terrific,” “terrible” and
“harrowing” are terms which have been used by travellers like Bates,
Belt and Wallace in describing the cavernous roar of these animals, a
roar which will easily carry two miles. It would seem that these vocal
efforts are not merely confined to what we may call the “Courting”
season, as is the roar of the stag, but that they are heard nightly
at dusk. They may be resumed again at dawn, and re-awakened when
thunder-clouds gather. They have become the normal method of giving
vent to excitement, and probably are intensified when isolated males
are desirous of discovering the whereabouts of females equally anxious
to find a mate.
Among the Apes we meet, as with the human species, with both monogamy
and polygamy. But it would be dangerous to assume that the reasons
for polygamy are the same in both. Polygamy, indeed, has by no means
always the same significance. In the most primitive, half-human races
of the past, as with the man-like Apes to-day, polygamy is determined
by accident rather than choice. These extinct peoples, like the great
anthropoids, were normally monogamous, but on the death of a male in
conflict with his neighbour, or from other causes, his mate would
probably of her own free will seek out the nearest male and even if he
were already mated would be at once adopted into the family circle.
This certainly happens in the case of the Gorilla and Chimpanzee
to-day. But among living races of mankind, both savage and civilized,
multiplicity of wives is a matter of choice on the part of the male,
and in many cases to achieve this females from other tribes have to
be secured—either by purchase or conquest. With the lower apes, or
“monkeys,” polygamy only obtains among gregarious species; and either
because the birth-rate of the females exceeds that of the males, or
because a considerable number of young males are killed annually
by exciting the jealousy of the older males, who are exceedingly
pugnacious.