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.

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.

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.