Part 15

The body is heavily built, but shorter and less robust than that of the Gorilla. The crown is depressed, and the supra-orbital ridges, from which rise stiff strong eye-brows, are prominent, but not remarkably so. The eye-lids are wrinkled, and their margins set with eye-lashes. The nose, of which the ridge is shorter than in the Gorilla, is depressed in the middle, flatter at the extremity, and, as in the last-named species, is furrowed longitudinally, its nostrils looking more downward and forwards. The lips are extremely mobile and protrusile, the upper one broad and the lower one retreating from the mouth, and not forming a true human-like chin, though it is more prominent than in the Orang. The cheeks are more wrinkled than in that Ape. The ears are large and projecting from the side of the head, and often carry a lobule. They are strangely like those of Man, and, as Mr. Darwin has remarked, the Chimpanzee never moves or erects its ears, so that they are equally rudimentary, as far as that function is concerned, as in Man. The shoulders and chest are broad, and indicate great strength. Their lower limbs are longer in proportion than in the Orang. {189}The foot, which is anatomically in no respect a hand, is sometimes shorter than the latter, the great-toe is thick, opposable, and thumb-like, the other four toes are united together by a web, the heel is somewhat developed, and the whole of the sole of the foot is applied to the ground when walking. The arms, of which the humeral segment is about equal in length to the fore-arm, are long, but reach only a little below the knee--their span being about a half more than the height of the body. The hands, which are wonderfully human in form, are broad, comparatively short, and less hook-like than in the Orang. The hair on the arm and fore-arm converges towards the elbow, as in the Gorilla and Orang. The thumb is short in comparison with the same digit in Man, and, as in the human hand, the middle finger is the longest; the outer four fingers being united by a web reaching up to the first joint. The palm of the hand can be applied flat to the ground; but though the Chimpanzees can stand or run erect on the flat sole of the foot, they prefer to advance leaning forward, supporting themselves on the knuckles of the hand. They have no callosities on the ischiatic bones, on which they sit.

The female Chimpanzees are slightly smaller than the males, but the disparity between them is much less than between the two sexes of the Gorilla. The nose and teeth are less prominent, and the belly is more tun-shaped. The young males also exhibit fewer differences from the adult than among the Gorillas, though differing in many points of their soft anatomy and osteology. The nose lengthens, and its extremity widens, while the face becomes more prognathous with increasing years. In the young the frontal bone is low and flat. The skull in the Chimpanzee is elongated, and small in proportion to the body; the forehead is smaller, the crown more rounded than {190}in the Gorilla, and the back of the head convex.[2] The central (sagittal) crest, so strongly developed in the Gorilla and the Orang, is here wanting; the supra-orbital ridges which extend across the face, and the occipital prominences for the back-muscles, though large, are also less marked. The orbits have a circular rim, and are less prominent than in the Gibbons. The nasal bones are but slightly arched, and the openings for the nostrils round and small. The jaws, which are smaller, proportionately to the cranium, in this genus, than in any other of the _Simiidæ_, protrude far forward, but the symphysis of the lower jaw is smaller than in the Gorilla, and its two halves low and wide. The bones of the skull are much hollowed out into cavities (sinuses) in the forehead, nose, and jaws, all of which communicate with each other. The plane of the _foramen magnum_ (for the passage of the spinal cord) is oblique to the plane of the base of the skull.

The volume of the cranium is from twenty-six to twenty-seven cubic inches, or about one-half of the lowest capacity of a normal human cranium. A styloid process is more or less distinctly visible in the Chimpanzees.

The canine teeth are long and conical, but less than in the Gorilla; and the diastema, or gap, between them and their neighbouring teeth is smaller than in the other Apes. The molar teeth are four-cusped, and have the oblique ridge already described extending from the front inner to the hind outer cusp; and the middle lower molar has five cusps, both these dental characters being similar to those in Man. The anterior lower pre-molar, however, is pointed, and has a long sharp anterior edge, as in the _Cercopithecidæ_.

{191}The vertebral column begins to show the S-shaped flexure, characteristic of Man's back-bone; it presents also a human character in the form of its second neck vertebræ, and there are thirteen pairs of ribs, as in Man. The hindmost vertebræ "give the impression of a rudimentary tail." (_Hartmann._)

The humerus is nearly equal in length to the fore-arm; the wrist (_carpus_) has only eight bones (the central bone being absent), agreeing, therefore, with the number in Man.

All the ridges and grooves seen in the human brain are present in that of the Chimpanzee, but "they are simpler and more symmetrical, and larger in proportion to the brain." (_Huxley._) The cerebellum, and the nerves also, are larger in proportion to the cerebrum than in Man; and certain structures (the _corpora trapezoidea_) which exist in the brains in the lower Mammalia are absent. These prominences, which are situated in that portion of the brain known as the _medulla oblongata_, at the summit of the spinal cord, disappear, as we have seen, in all the genera of higher rank than the _Cebidæ_, one of the lowest families of the _Anthropoidea_. The brain in its convolutions and in many other respects conforms to that of the Orang. This is especially the case in _A. calvus_.

The uvula, which is absent in the throat of the Orang, is pendulous in the Chimpanzees, as in Man. Large air-sacs are also present, and the hyoid bone is excavated posteriorly, suggesting the conformation of the same bone in _Alouatta_ (the South American Howlers). The stomach is very similar to that of Man, and so are the digestive and reproductive organs. The round ligament, attaching the head of the thigh-bone into its pelvic socket, is present, and restricts the flexibility of the hind-limb of the Chimpanzees, compared with that of {192}the Orang. Its presence, however, while acting somewhat less favourably in regard to the climbing capacities of these animals, whose habits are less essentially arboreal than the Orangs', beneficially assists them in walking, affording them a firmer support on the ground. In the Chimpanzee there is always a semi-lunar fold (_plica semilunaris_) in the inner corner of the eye, corresponding to the nictitating membrane (or third eyelid) of birds. In some of the Lemuroids it is well developed (_suprà_, vol. i., p. 90), and is large in some races of men.

The Chimpanzee is confined to the West African Sub-region, as defined by Dr. Bowdler Sharpe. It is known from Loango, along the banks of the Upper Congo, and Mr. Monteiro (P. Z. S., 1871, p. 544) says it is quite unknown to the south of the Congo; it also occurs throughout the country of the Manyema, in Central Africa, where Livingstone describes it under the name of Soko; and southward as far as 10° south latitude, to Lake Moero. Schweinfurth has recorded it from the Niam-niam country.

The Chimpanzees inhabit forest regions, and feed on wild fruits in the woods, and the products of cultivated gardens, not rejecting, when they can capture it, animal food. They live in separate families, or in limited communities of small families mixed together, but each male lives with his own single female. They are more arboreal than the Gorilla, but much less so than the Orangs. In many districts they seem to live on the ground.

They emit loud cries, shrieks, and howls in the morning and evening, and often during the night. "Since they are really accomplished in the art of bringing forth these unpleasant sounds, which may be heard at a great distance, and are reproduced by the echoes, it is impossible to estimate the number {193}of those who take part in the dreary noise, but often we seemed to hear more than a hundred." (_Pechuel-Lösche._) These Apes also build resting-places, not far from the ground, like the Orangs, composed of twigs and sticks on the branch of a tree or a crotch, in which the female and her young take refuge for the night, the male placing himself on guard beneath.

They seldom make an unprovoked attack on the natives wandering in the forest; on the contrary, they are peaceably disposed animals, glad to get out of the way of danger or possible enemies. Yet, when pressed, they form no mean antagonist. Biting is their principal mode of defence.

"As seen here," says Savage, "they cannot be called gregarious, seldom more than five or ten at most being found together. It has been said on good authority, that they occasionally assemble in large numbers in gambols. My informant asserts that he saw once not less than fifty so engaged, hooting, screaming, and drumming with sticks upon old logs, which is done in the latter case with equal facility by the four extremities.... When at rest, the sitting posture is that generally assumed. They are sometimes seen standing or walking, but when thus detected, they immediately take to all fours, and flee from the presence of the observer. Such is their organisation that they cannot stand erect, but lean forward. Hence they are seen, when standing, with the hands clasped over the occiput, or the lumbar region, which would seem necessary for balance or ease of posture."

Most of the accounts of the habits we have of Chimpanzees, refer to those of young individuals kept in captivity. There is still much to be discovered as to the ways and modes of life of the adults of both the Chimpanzee and the Gorilla. They are both very delicate, and in temperate climates rarely live {194}more than a few months; a Bald Chimpanzee (_A. calvus_), however, survived five years in the Zoological Gardens, in London.

I. THE COMMON CHIMPANZEE. ANTHROPOPITHECUS TROGLODYTES.

_Homo sylvestris_ (Ourang-outang), Tyson & Cowper, Phil. Trans., xxi., p. 338 (1699); Tulpius, Observ. Anat., p. 270, pl. 14 (1641).

_Homo troglodytes_, Linn., Syst. Nat., i., p. 32 (1766; pt.).

_Simia troglodytes_, Gm., Syst. Nat., p. 26 (1788); Blumenb., Handb., x., p. 73 (1803); Owen, Tr. Z. S. I., p. 344, pls. 48, 50-52, 55, 56 (1835); ii., p. 169 (1841); Schl., Mus. Pays-Bas, vii., p. 8 (1876).

_Troglodytes niger_, Geoffr., Ann. Mus., xix., p. 87 (1812); Desmar., Mammolog., p. 49 (1820); Lesson, Spec. Mamm., p. 37 (1840); var. _Marungensis_, Owen, Tr. Z. S., v., p. 3, pls. i.-ix.; p. 279, pl. xlix. (1866); Noalk, Zool. Jahrb., ii., p. 291 (1887).

_Pseudanthropos (Troglodytes) leucoprymnus_, Less., Ill., Prod. Syst. Mamm., pl. 12 (1811); Reichenb., Naturg. Affen., p. 191 (1862).

_Pithecus leucopryma_, Less., Ill. Zool., pl. 31 (1836; young).

_Satyrus lagaros_, Meyen, Arch. f. Naturg., p. 282 (1856).

_Mimetes troglodytes_, Gray, Cat. Monkeys Brit. Mus., p. 6 (1870).

_Troglodytes vellerosus_, Gray, P. Z. S., 1862, p. 181; id., Cat. Monkeys Brit. Mus., Append., p. 127.

_Troglodytes schweinfurthi_, Gigl., Studii Craniol. sui Cimpanzé iii., p. 56 (1872).

_Troglodytes aubryi_, Grat. et Alix, Nouv. Arch. Mus., ii., p. 1, pls. 1, 9 (1866).

{195}_Troglodytes tchego_, Duvernoy, Arch. Mus., viii., p. 8 (1855).

_Anthropopithecus troglodytes_, Flower & Lydekker, Mamm., p. 736, fig. 357 (1891).

CHARACTERS.--Face, ears, hands, and feet dark-reddish flesh-colour, or more rarely of a blackish-brown colour; in general the colour of the hair is wholly black, except on the upper and lower lips, where it is white and very short, and in the region of the buttocks, where it is washed with reddish-brown.

Hair on the body straight and silky, with coarser hair interspersed; on the top of the head it lies smoothly to each side, away from a median line; round the face it forms bushy whiskers, extending down into a slight beard; it encroaches on the brow, leaving only a triangular central space naked; on the upper and lower lips are short, bristly hairs; the rest of the face naked and much wrinkled; on the shoulders, the back, and the hips, the hair is longer than elsewhere; the back of the hands and feet are thinly haired, the fingers and toes nude. The margin of the ears is often folded in for the greater part of its length.

The skin of the body is of a peculiar light, yet muddy, flesh-colour, sometimes verging on brown. Brownish or black spots on many parts of the body seem to vary in different individuals.

The expression of the face is grave, but less melancholy and pre-occupied than in the Orangs.

The weight of the brain in _A. troglodytes_ varies from 6½ to 6-3/5 ounces.

This celebrated Man-like Ape has been known, by vague report at least, for nearly three hundred years. The earliest clear account of its existence, however, is derived from the "Strange {196}Adventures of Andrew Battell, of Leigh in Essex, sent by the Portugals prisoner to Angola, who lived there and in the adioining regions neere eighteene yeares." It was first published in 1613 in "Purchas his Pilgrimage," and later more fully in 1625, in "Purchas his Pilgrimes."[3] Here it is related that in the Province of Mayombe, "which is nineteen leagues from Longo along the Coast, the woods are so covered with baboones, monkies, apes, and parrots that it will fear any man to travaile in them alone. Here are also two kinds of monsters, which are common in these woods, and very dangerous. The greatest of these two monsters is called Pongo, in their language, and the lesser is called Engeco." The Pongo turned out to be the Gorilla, the description given by the old prisoner Battell proving to be wonderfully accurate. The lesser monster, the Engeco, is equally certainly the Chimpanzee. The first record of a specimen actually seen in Europe is in 1641, and is noticed by Tulpius in his "Medical Observations," and the earliest scientific description of a Chimpanzee--a young specimen of _A. troglodytes_--is that of the anatomists Tyson and Cowper, published by the Royal Society in 1699. It was, however, not till 1835, that the osteology of a full-grown specimen was described, when Sir Richard Owen's memoir appeared, and shortly after a very detailed account of its habits was given to the world by Dr. Thomas Savage, the missionary to whom we have already referred (p. 184), followed by a further anatomical investigation of its structure by Dr. Wyman, of Boston, U.S.A.

DISTRIBUTION.--This species is found over the greater part of Tropical Central Africa, and its range is co-extensive with that given above for the genus. Loango and the Gaboon, however, {197}are the districts from which this Chimpanzee has chiefly been imported into Europe.

HABITS.--The more characteristic habits of the common Chimpanzee have already been given under the description of the genus.

Its food consists of all sorts of forest fruits, and especially of the young shoots of the _Scitamineæ_, or ginger-plants.

The Chimpanzee can move the skin of its head, as the Gorilla does, but without causing the erection of the hair, which the Orang and the Gorilla are both able to accomplish. It can also to some considerable extent wrinkle its forehead, if disappointed or pleased, as when refused anything, or if tickled, when in the latter case it also utters a chuckling sound like that of smothered laughter, draws back the corners of its mouth, and wrinkles its eyelids.

The _Soko_ observed by Livingstone in the Manuyema country would seem to be the common Chimpanzee. "According to Livingstone," to quote Mr. H. H. Johnston's note in his excellent "Life" of the great traveller, "these creatures often walk in an erect position, but steady their bodies by placing the hands on the back of the head. He represents this beast as being of great intelligence, and so cunning, that it is difficult to stalk him in front without being seen, and, therefore, when he is killed, it is usually from behind. The Manuyema people frequently string a number of nets round some enclosure in the forest and drive the _Sokos_ into them and spear them. Brought to bay like this, they will frequently turn on their assailants, and will snatch their spears from them, and break them, and perhaps also bite off the ends of the men's fingers. But, as a rule, the Soko is not ferocious. They are said to kidnap children and {198}run up the trees with them, and have to be lured down by bananas. When wounded the creature tries to staunch the blood by stuffing leaves into the wound. It lives in communities of about ten, and is monogamous. The female produces occasionally twins. As parents, they are very affectionate towards their offspring, the father relieving the mother of the burden of her young one in dangerous places. Their food consists of wild fruits. At times the _Sokos_ collect together and drum with their fists on the trunks of hollow trees, and accompany this performance with loud yells and screams."

"According to the statements of the Niam-niam themselves," says Schweinfurth, "the chase of the Chimpanzee requires a party of twenty or thirty resolute hunters, who have to ascend the trees, which are some eighty feet high, and to clamber after the agile and crafty brutes until they can drive them into the snares prepared beforehand. Once entangled in a net the beasts are without much further difficulty killed by means of spears. However, in some cases, they will defend themselves savagely and with all the fury of despair. Driven by the hunter into a corner, they are said to wrest the lances from the men's hands and to make good use of them against the adversary. Nothing was more to be dreaded than being bitten by their tremendous fangs." The stories as to their carrying off young girls, and constructing nests are pure fabrications, according to Schweinfurth. Its name among the Niam-niam is "Ranya." "The life which the Ranya leads is very much like what is led by the Orang-Utan in Borneo, and is spent almost entirely in the trees, the woods on the river banks being the chief resort of the animals.... Like the Gorillas, they are not found in herds, but either in pairs, or even quite alone, and it is only the young which occasionally may be seen in groups."

PLATE XLI.

{199}II. THE BALD CHIMPANZEE. ANTHROPOPITHECUS CALVUS.

_Troglodytes calvus_, Du Chaillu, Pr. Bost. Soc. Nat. Hist., vii., p. 296 (1861); id., Travels, pp. 32, 48, 63 (1861); Gray, P. Z. S., 1861, p. 273; Bartlett, P. Z. S., 1885, p. 673, pl. xli.; Beddard, Tr. Z. S., xiii., p. 177 (1893); Romanes, P. Z. S., 1889, p. 316.

_Troglodytes kooloo-kamba_, Du Chaillu, Pr. Bost. Soc. Nat. Hist., vii., p. 358 (1861); id., Travels, pp. 39, 49, 50 (1861); Gray, P. Z. S., 1861, p. 273.

_Mimetes troglodytes_, var. a (_T. calvus_), Gray, Cat. Monkeys Brit. Mus., p. 6 (1870).

_Anthropopithecus calvus_, Flower & Lydekker, Mammals, p. 736 (1891).

(_Plate XLI._)

CHARACTERS.--This species was first indicated by Du Chaillu on his return from his celebrated journey to the Gaboon, but based on poor skins, which left much doubt as to the species being distinct. Excellently preserved specimens were, however, brought home by Marche and Dr. Compiégne, and some of them passed into the Dublin Museum, but it was not till 1885, when a living specimen, now known to fame as "Sally," was received at the Zoological Gardens in London, and lived there for five years, that the correctness of Du Chaillu, as to the distinctness of his "Kooloo-kamba," _A. calvus_, from _A. troglodytes_, was proved and accepted.

Similar to _A. troglodytes_, but distinguished from it by the face, hands, and feet being quite black, or brownish-black, instead of pale flesh-colour; the front, top, and sides of the head and face are nearly naked, having only a few short hairs on the head, which is quite destitute of any signs of the parting so {200}conspicuous in _A. troglodytes_. The hair is blacker than in the latter species, and extends only for a short distance in front of the level of the ears, and on the sides of the face; the temporal region and cheeks show a scanty growth; on the chin and upper lip a sparse crop of short hairs, chiefly white; long scattered black eyebrows, which do not meet in the mid-line, spring from the supra-orbital ridges. The ears are as large as in _A. troglodytes_, very flat, but stand out more prominently from the side of the head; their margin is nude, and there is no lobule. The hands are haired across the knuckles, and again (after a naked band) on the back of the hand and arm; the foot is haired down to the first joints of the toes; the nails and fingers are very human in appearance.

Face very prognathous; the nasal bones ridged in the mid-line; the foot less like a human hand than even in the Orang. "Sally's" brain weighed 8-3/5 ounces.

The expression of the face, the expanded nostrils, the thicker lips, especially the lower lip, and the more elevated skull, all distinguish _A. calvus_ from _A. troglodytes_; in its muscular anatomy and in its brain it also shows points of difference.

DISTRIBUTION.--The interior of Gaboon, in Western Africa.

HABITS.--The Bald Chimpanzee showed in captivity a disposition to live on animal food, which the Common Chimpanzee never does. "Sally" had also the singular habit of producing pellets, resembling the castings thrown up by Raptorial birds; they were composed of feathers (of the birds she had eaten) and other indigestible substances taken with her food. Moreover, "Sally," as this Chimpanzee, now famous in the annals of zoology, was named, was an expert rat-catcher, and caught and killed many rats that entered her cage. "Her intelligence was {201}far above that of the ordinary Chimpanzee. With but little trouble she could be taught to do many things that require the exercise of considerable thought and understanding." (_Bartlett._) In general habits _A. calvus_ differs, so far as known, in no respect from _A. troglodytes_.