Habits.—The Orang-utan, the "forest-living Man" of the Malays, and the "Mias" of the Bornean natives, lives solitary in the leafy tops of the trees in the forests, except at the pairing season. A female is generally accompanied by one of her progeny, sometimes by two, the one always an infant, and the other a more or less grown but immature individual of a previous birth; for her young—of which she has only one at a birth—do not shift for themselves before they are approaching two years of age. At what age they attain maturity is unknown, but it is probably not before twelve to fifteen years. The infant clings by its arms to its mother when she is climbing, by grasping the hair of her arm-pits, while its legs embrace her sides above the hip. As already observed, the Orangs have none of the marvellous agility of the Gibbons. They are slow and deliberate in their movements; "surprisingly awkward and uncouth," according to Sir James Brooke; but their long and extremely powerful arms and hook-like fingers, which close with an amazing rigidity of grip, and their mobile legs and hand-like feet, enable them to lift and swing their bodies with great precision from branch to branch and tree to tree. "I have frequently seen them," says Hornaday, "swing along beneath the large limbs as a gymnast swings along a tight rope, reaching six feet at a stretch. When passing from one tree to another, the Orang reaches out and gathers in its grasp a number of small branches that he feels sure will sustain his weight, and then swings himself across." On the ground all this is very different. He walks very badly and unsteadily; he uses his arms as crutches, leaning his weight upon them with his fingers as already described, and swings himself forward on them. On the ground the Orang does not move, according to Sir James Brooke, so fast as to preclude a man keeping up with him easily through a clear forest. "The very long arms, which, when he runs, are but little bent, raise the body of the Orang remarkably, so that he assumes much the posture of a very old man bent down by age, and making his way along by the help of a stick." (Huxley.) The Orang, however, rarely comes to the ground of his own accord.
Mr. Martin gives the following account of a specimen which lived in the Zoological Gardens in London many years ago:—"Its attitudes were as varied as can be imagined, its actions slow and deliberate; excepting, indeed, on one or two occasions when it wished to follow its keeper, who had opened the door of its cage; even then it did not bound from branch to branch like a Monkey, but stretching out its arms, and grasping the branches within its reach, it swung itself onward, and so descended to the floor, along which it hobbled awkwardly and unsteadily. One thing, as respects both the hands and feet of this Orang, could not be overlooked; namely, that their mode of application to the branches, during the arboreal evolutions of the animal, was hook-like; and, from the power of the adductor muscles of the thumb, and flexor muscles of the fingers, tenacious and enduring, rather than tight and fixed. This observation is especially applicable to the feet; in these the shortness of the thumb, though capable in itself of firm and close application, renders it rather a fulcrum, against which the long fingers oppose their stress, than, by folding upon them, an adjunct to them in the act of prehension; and hence, though admirably fitted for the movements of the animal among the trees of the forest, and the kind of hold necessary for freedom and security, the foot of the Orang is, perhaps, less energetic in the grasp than that of the semi-arboreal Chimpanzee, in which the hind-thumb is proportionately longer, and the foot broader, than in the Orang."
The Orang drinks by dipping its fingers into the water, as the Siamang does, and sucking the water off its knuckles, or dropping it into its protruded trough-like lower lip.
"The rude hut which they are stated to build in trees, would be more properly called a seat or nest, for it has no roof or cover of any sort. The facility with which they form this nest is curious, and I had an opportunity of seeing a wounded female weave the branches together and seat herself within a minute." (Sir James Brooke.) "The Orang usually selects," writes Mr. Hornaday, "a small tree, a sapling, in fact, and builds his nest in its top, even though his weight causes it to sway alarmingly. He always builds his nest low down, often within twenty-five feet of the ground, and seldom higher than forty feet. Sometimes it is fully four feet in diameter, but usually not more than three, and quite flat at the top. The branches are merely piled crosswise. I have never been able to ascertain to a certainty, but it is my opinion that an Orang, after building a nest, sleeps in it several nights in succession, unless he is called upon to leave its neighbourhood." In this nest he sleeps during the night or lies spread out on his back during the day, with his hands and feet grasping the nearest branches. The food of the Orang-Utan—whose eating-time is during the middle of the day—consists of leaves and nuts, especially of the durian, the rambutan, and the mangosteen.
The Orang-Utan is of a very shy and uncertain disposition. If captured when full-grown, it is wild and ferocious; when young it is easily trained; but never lives in captivity to attain maturity. When attacked and hard driven by human enemies, and it gets to close quarters with them, it can be a formidable and dangerous antagonist, and has been known to fatally injure its assailants. It will rarely, unprovoked, attack a man. "In one case," as Dr. A. R. Wallace has recorded, "a female Mias on a durian-tree kept up for at least ten minutes a continuous shower of branches and of the heavy spined fruits as large as 32-pounders, which most effectively kept us clear of the tree she was on. She could be seen breaking them off and throwing them down with every appearance of rage, uttering at intervals a loud, pumping grunt, and evidently meaning mischief." They fight and defend themselves with their hands, and appear to seize and bite each other's fingers. Many of the specimens shot in the forest of Borneo have lost one or more of their fingers or toes; and present scars on the face (especially on the lips) and bodies from the teeth of their antagonists.
"When wounded he betakes himself to the highest attainable point of the tree, and emits a singular cry, consisting at first of high notes, which at length deepen into a low roar, not unlike that of a panther. While giving out the high notes, the Orang thrusts out his lips into a funnel shape; but in uttering the low notes he holds his mouth wide open, and at the same time the great throat bag, or laryngeal sac, becomes distended." (Huxley.)
The name given by the Dyaks to the larger species is "Mias Pappan." There is, however, a smaller variety, which they designate "Mias Kassu," of which Dr. Wallace has given an excellent and detailed account. These Mias Kassu have no tumour-like expansions on the sides of the head; the median crest is absent from the skull, for the muscular ridges remain some distance apart; the teeth are very large, especially the canines and the middle upper incisors. The females, which are smaller than the males, are also without the cheek-swellings and the prominent crests of the male, and have smaller canine teeth. This variety, named Simia morio by Sir R. Owen, bears a close similarity to that found in Sumatra. It has been considered a distinct species both by Owen and Wallace, but the variation, as the latter naturalist himself admits, is so very great in just those characters which have been considered to separate "Mias Kassu" from "Mias Pappan," that it is highly probable that both are of the same species, but of different ages. Mr. Beddard found that an Ape exhibited in the Zoological Gardens as an adult example of S. morio was in reality immature.
THE GORILLAS. GENUS GORILLA.
Troglodytes, Geoffr., Ann. Mus., xix., p. 87 (1812).
Gorilla, Is. Geoffr., C. R., xxxiv., p. 84, note (1852).