CHAPTER VIII. Manlike Tendencies

MANLIKE TENDENCIES

BRAINS OF GIBBON AND ORANG-OUTANG

There is little about the Old World monkeys, either in their mode of life or in their appearance, to inspire respect or confidence. The savage fierceness of the baboon, the mischievous nonsense of the macaque, seem like flimsy foundations upon which to build a race of intelligent human beings. When these animals first made their appearance they were but vague foreshadowers of what mankind might be. It is not alone their form and structure that interests us; their actions, habits, and behaviour must be carefully studied at the same time.

The Anthropoid Gibbon

Had the human eye been able to observe all that transpired in the early days of the monkey kind, it would have been difficult to believe that a race of men was in the making. It would have seemed incredible that from these chattering, restless monkeys change and modification could eventually bring forth that development necessary for the human form. And yet in the course of time changes of this kind did bring into existence an ape which bore a much closer resemblance to man. It was then possible to foresee how, from this new kind of animal, certain human features might be derived. This particular member of the ape world is the gibbon. All of his tendencies make him somewhat shy and inconspicuous. At the zoölogical gardens he is generally sitting high up on a perch in his cage with his long arms folded over his head, peering quietly about him. His fur is usually dark, although some members of his family are quite light in colour. The most impressive thing about the gibbon is the fact that he can stand up, walk, and run upon two legs. This he does a little awkwardly, but not unlike a human being. In a certain memorable moving picture, an unusually interesting silvery gibbon nearly usurped the rôle of leading man. His marvellous feats earned for him universal applause, and whenever he appeared he was the centre of attention. Among its most stirring moments, this picture shows a dramatic scene in which a great Indian elephant whose young one has been captured demolishes the dwelling of the jungle native who has trapped her offspring. Shortly after the native with his wife and children has escaped to safety, the gibbon emerges cautiously from the wreckage of the home. Through the darkness of the forest he discerns the glistening eyes of a tiger that is about to spring upon him. Realizing that retreat is cut off, he takes to flight. In escaping he stands upright and runs like a man, screaming in his fright in a thoroughly human manner. Fortunately for the gibbon, the branch of a tree comes opportunely in his path, and then, with a single upward bound, he is off like a bird through the trees to safety.

Gibbons are gentle, affectionate creatures. They are also timid and at the first sign of danger hurry away through the forest as far up in the trees as they can go. The gibbon’s body and head are relatively small, being only a little larger than some of the smaller macaques. The animal’s legs are short and it has no tail. A prominent feature is the exceptional length of the forearm and of the fingers. The hand is slender and longer than the foot. The female bears one young at a time, which the mother carries under her body, the young one clinging to the fur on her chest with hands and feet. This burden does not embarrass her in the slightest as she swings her way from tree to tree through the forest. She makes as good time in this transportation as the unincumbered males.

In the wild state the gibbons never leave the jungle, and live for the most part throughout southern Asia and the adjacent islands. A few of them venture from the inland forests to the vicinity of the coast. All of the gibbons are highly developed for life in the trees. This specialization is important not only for the effects it has had upon these apes but also for those developments in them which were to be of subsequent and substantial advantage to the rise of man.

There are many different varieties of gibbons such as the white-handed gibbon, the silvery gibbon, the white-cheeked gibbon, the slender gibbon. The animal that we shall consider is the hoolock gibbon of India. He gets his name from a peculiar sound or cry which he makes. If it were at all possible to imitate this cry it might be expressed as “hooloo! hooloo! hooloo!” Mr. Candler has studied this interesting animal at close quarters, and his account of its habits is well worth quoting:

The Hoolock swings along the thinnest part of a bough or to the slender end of a bamboo, until it bends to its weight, then with a swing and a sort of a kick-off he flies through the air seizing another branch, and swinging along it with the accuracy of a finished trapeze performer. I fancy he does very little walking in the wild state, for I have never seen a wild Hoolock on the ground. Moreover, they are only found in the dense jungle where the ground is everywhere covered with tangled vegetation. The Hoolocks are extremely shy and it is difficult to watch them as they are concealed by leaves high up on the bamboo clumps or tops of forest trees. The cry of the Hoolock is characteristic. It is a very pleasing note, rising and falling in intensity, and reminding one somewhat of a pack of beagles giving tongue on a scent, which is waxing and waning in strength as a larger or smaller number of the band join in the chorus. It is heard chiefly in the early morning, then through all the heat of the day there is silence, but towards evening as the sun sets you may hear it again.

One might almost think that their early morning cry was like a rising bell, and their cry toward evening was their curfew.

Manners of the Gibbon

Gibbons live in fairly large communities. They are constantly on the move. From what is known of their intelligence it seems probable that their movements are guided by definite plans. They even seem to have some simple sort of governmental system. Tea planters in India often keep these gibbons as pets for years. They run about the compound quite freely. At times they suddenly disappear and are gone for several months. Eventually they return quite unconcerned, as if nothing had occurred to interrupt their pleasant human associations. For the most part the gibbon is sociable. After he has become acquainted he will often sit on the arm of a person’s chair at breakfast. Whatever his appetite, he will never reach out for food at the table, although his long arms give him much advantage over his human host. Nor will he ever snatch things off the table. His manners are above reproach and he keeps himself scrupulously clean. As the day is drawing to a close it is his habit to get ready for the night. At sunset he settles down to sleep, safely seated in the fork of a tree, usually with his long arms over his head. He is never boisterous, mischievous, or noisy. Oftentimes he seems to be more in sympathy with children than with grown-ups.

The diet of the gibbon includes a long list of foods, such as fruits, leaves, and young shoots, spiders, birds’ eggs, insects, and young birds. If captured young the gibbon is readily tamed. He is never sulky or ill tempered and shows marked intelligence both in learning many tricks and adjusting himself to the rules of the home.

The locomotion of these animals among the trees is totally different from that of the monkeys. The latter climb about using both hands and feet. Gibbons employ their arms almost exclusively, swinging from branch to branch, with the legs tucked close to the body. This is such an important change in the transportation methods of apedom that we should give it particular attention in order to note what effects it had produced upon the gibbons themselves. In the first place, swinging from one limb to another by the hands greatly elongated the forearm and the fingers. This kind of locomotion gives the gibbon the appearance of taking tremendously long strides with his arms. The right hand, first grasping a branch, permits the animal to swing twelve or more feet to the next branch which is grasped by the left hand. In the next step the forward stride is taken by the right hand. Thus the animal alternates the right and left hand just as we alternate the right and left foot. It is probably for this reason that the gibbons have been called “tree walkers” (Hylobates).

The second effect produced by this kind of swinging locomotion, called brachiation, is even more decisive in the final outcome. Transportation such as this swinging by the hands drew the body more and more into the upright position. It brought about many of those fundamental changes which made it possible for the gibbon to stand upright, walk, and run upon two legs. Compared with other animals of this class, the gibbon is the most two-legged of all the apes. He walks rather quickly in the erect posture. His gait is waddling, and if pursued he will make every effort to reach some support by which he can swing himself to safety. In walking he turns his leg and foot outward, which gives him a bow-legged appearance, added to which the shortness of his legs makes his movements in walking and running far less graceful than these acts ultimately came to be in their highest exponent, man. Here undoubtedly may be discerned important elements for the inception of human locomotion. They appear in an animal which can stand, walk, and run upright, and also possesses well-developed hands.

Gibbon’s Resemblance to Man

The gibbons are said sometimes to scoop up water in the hollow of the hand in order to drink. At other times they stretch out their long arms among the foliage and lick off the dew which adheres to their hair, in this way quenching their thirst.

In view of these facts our estimate of the gibbon may credit him with certain manlike traits. Yet his resemblance to human beings, considering the animal as a whole, is at best sketchy and vague. Casual observation of the gibbon does not bring any clear association with the human being at once to mind. Only after watching him, after noting the manner in which he gets about, after seeing him walk and run on two legs, is it possible to recognize certain tendencies which point in the human direction. It is for this reason that the gibbon is said to represent a stage preceding the manlike apes. Some students of this question class the gibbon with these anthropoid apes. It seems better judgment, however, to consider him rather an animal showing dispositions which serve as a starting point for the anthropoids. These tendencies, as they are crystallized in the gibbon, represent an introductory chapter in the history of all those animals which later became notable because they walked more or less upright and had the use of hands. Thus the gibbon is often spoken of as pro-anthropoid. He himself is a modern animal. One of his venerable ancestors, very much like himself, lived long ago--Propliopithecus of the Oligocene. The descendants of this ancient extinct ape with the long name, whose fossil remains have been found in Egypt, followed two lines of development. One line led up to the modern anthropoid apes and man, the second to the modern gibbons. The first offshoot from this line gave rise to a great ape which in many features looks much more like man than does the gibbon. This is the orang-outang. He is one of the big apes seen in the large primate cages of the zoölogical gardens. He may be recognized by the brownish-yellow hair which covers his body, by his face which bears a humorous caricatured resemblance to man, and by the erect posture which he assumes much of the time. Although he climbs about his cage and its supports like a skillful acrobat, this manlike ape lacks the grace and agility of the gibbon. He is wild and shy, but possesses enormous strength, which makes him more than a match for the most able-bodied man.

The Orang-Outang

The orang lives in Borneo and Sumatra. He has not been found elsewhere in the world. In his island home he enjoys a deserved reputation because of his prodigious strength. When full grown he stands a little over four feet in height. He has a heavy body, short thick neck, receding forehead, thick lips, and a face uncovered by hair. His muzzle protrudes to form a thick and heavy upper jaw, with a large mouth and large teeth. In the full-grown male the cheek pouches become greatly enlarged, so that they look like an old-fashioned ruff around the head. This feature gives him a hideous and gruesome appearance. The arms are long, reaching almost to the ankles when the orang stands upright. The hands are long and narrow, the thumb is short, the fingers are united by webs at their bases. The legs are short in comparison to the length of the body and considerably bowed. The feet are long and narrow. The great toe is short, but it can be used for grasping the branches. Fleshy pads over the buttocks are present in the adult male, but the orang has no tail. He is easily distinguished from the other great apes by his bulging muzzle and his light yellowish-brown hair. He seldom exceeds four feet two inches when standing upright, but his outstretched arms together measure nearly eight feet from finger tip to finger tip. Some specimens killed by hunters have been reported to stand five feet three inches high.

Among the first accurate accounts of the orang-outang’s life is that of Alfred Russell Wallace appearing in his famous book The Malay Archipelago, from which the following description is an extract:

The orang has a wide distribution, inhabiting many districts along the coast of the island [Borneo] where it appears chiefly confined to the low swampy forests. It particularly affects a country which is low and level with a few isolated mountains, on some of which the Dyaks have settled and planted many fruit trees which are a great attraction to the orang, as his most desirable food seems to be unripe fruit. The habitual habitat of the animal is in the lofty virgin forests, in which they can roam in every direction with as much facility as the Indian on the prairie, passing from treetop to treetop without being obliged to descend to the earth. The orang makes his way leisurely through the forest, with remarkable ease. He walks deliberately along the larger branches, in a semi-erect attitude which his great length of arm and the shortness of his legs causes him naturally to assume. But this proportion between his limbs is increased by his walking on his knuckles and not on the palm of his hand. He chooses those branches which intermingle with those of an adjoining tree. In approaching these he stretches out his long arms, seizing the neighboring bough with both hands and then deliberately swings himself across to the next branch, on which he walks along as before. He never jumps or springs nor even appears to hurry himself, yet he manages to get along almost as quickly as a person can run through the forest beneath. The long powerful arms are of greatest use to the animal, as they enable him to climb easily the highest trees, to seize fruit and young leaves from slender boughs which will not bear his weight and to gather leaves and branches from which to form his nest at night. When wounded he endeavors to make a nest in which to remain quiet, and similarly at night prepares a resting place in the tree to sleep. He likes this place low down in the tree, not over 20 or 30 feet from the ground, probably because in this position it is warm and less exposed to the wind.

The orang, it is said, makes a new nest for himself every night or perhaps remakes an old one. In rainy weather the animal covers himself with leaves or large ferns, and this may have led to the belief that he actually builds huts in the trees. The animal does not arise from his bed in the morning until the sun is well up and has dried the dew upon the leaves. He seldom returns to the same tree two days in succession.

They have no particular fear of man, and only retreat slowly after a considerable period of scrutinizing inspection. They do not have so much of the gregarious tendencies as do the other large apes. Two full-grown animals are seldom seen together, but males and females are sometimes accompanied by half-grown young ones. At other times three or four young animals are seen together. Their food consists almost exclusively of fruits, leaves, buds and young shoots. They seem to prefer the unripe fruit, even when very sour or intensely bitter, the red fleshy arillus being a particular favorite. The orang rarely descends to the ground except when pressed by hunger, when it seeks the succulent shoots at the riverside. In very dry weather it also comes down from the trees in quest of water, of which it generally finds sufficient in the hollow of the leaves. They have been seen upon the ground playing together, at which times they assume the erect posture and grasp each other with their arms.

Wallace believes that the orang seldom stands or walks erect unless when using its hands to support itself by the branches overhead, or when attacked. He also thinks that the representations of it walking with a stick are quite imaginary. In its general demeanour the orang would impress one as dull and apathetic. When seated among the branches its back is bent, its head is bowed, and its long arms either reach up to grasp a branch overhead or hang listlessly by its sides. Some explorers have maintained that the animal builds huts for itself in the trees. This is largely an exaggeration, but the orang has developed an interesting technique for building itself a nest in the trees as night approaches. Small branches are first laid crosswise to form a framework, and over this a thick bed of leaves is placed. The orang is quite fussy about the construction of its bedroom and takes good care to cover itself up when the wind is chilly or the night stormy. Even in captivity the animal is particular about the details of its bedchamber and always manages to cover itself with straw or newspapers if it happens to find them in the cage.

The orang has other constructive tendencies. He often manifests some engineering skill in devising supports for himself in his cage. With these he will amuse himself by the hour, climbing upon the support, dropping to the floor, and repeating the entire performance time after time in as many different ways as he can. In one instance a young male orang found a long rope hanging from the roof of his cage. He clung to the rope by his left hand and both feet. With his free right hand he passed the end of the rope around the bars, turned it through a right angle, and pulled it tight. In this way he made an interesting perch for himself. If anyone detached the rope he at once replaced it and thus remade his perch.

On the ground the orang is clumsy. He usually goes on all fours, and his walking gait has been likened to that of a very old man bent down by age, hobbling along with the aid of a cane. It is interesting to note that in walking he goes on the outer borders of his feet. His stride is short and shuffling. Even when hurrying he lopes along rather than runs. Unlike the gibbons, the orang does not use his hand as a drinking cup. His lower lip protrudes in a capacious trough for collecting rain water. If given a pail of milk or water the orang lifts the pail and pours the fluid into this trough and then swallows it. When captured young the animals can be trained and taught to obey many words of command. In time they get over their shyness and seem to like human companionship. They are, however, easily frightened. Females when pregnant separate themselves from the others and remain more or less in seclusion until the young are born. The offspring grow slowly and, like human infants, require the care of their mothers for a long time. When the mother moves about the young one clings to the hair of her chest. This is a marked characteristic of child care throughout the ape world.

The Orang in Infancy

Wallace recites an interesting experience which he had with a baby orang whose mother was shot and killed by him in the forest the preceding day. This experience is especially interesting because of its many human resemblances. When Wallace stooped to pick up the helpless infant orang that lay sprawling on its back, his long beard was immediately seized by the grasping hands and feet of the youngster. It was a long and painful ordeal to get away from this clinging infant. The baby orang had but a single tooth, but soon its milk teeth began to appear, much as in a human infant. The lack of milk on the island made it difficult to feed the young ape. When a finger was placed in its mouth it would suck with great vigour, drawing in its cheeks in a vain effort to extract milk. After persevering for a long while it would give up in disgust and start screaming, much as would a human baby under similar circumstances. When handled or nursed it was always quiet, but if laid down by itself it would invariably cry. It enjoyed being rubbed after its morning bath and was quite happy while its hair was being combed and brushed.

For the first few days it clung desperately by all four hands to everything it could reach, and Wallace remarks that it was necessary for him to be cautious in keeping his beard out of the way. He felt that the infant ape was lonely and needed companionship, so a little harelipped monkey of the macacus variety was obtained as a playmate. It was curious to see the difference in the actions of these two animals, the one an offspring of a humbler monkey, the other born of one of the great manlike apes. The two young ones were about the same age. The orang, just like a human baby, would lie upon its back helplessly rolling from side to side, stretching out all four hands into the air and striving to grasp something, although hardly able to guide its fingers to any desired object. When dissatisfied it opened wide its almost toothless mouth and expressed its discomfort in an infantile scream. The little macacus monkey, on the other hand, was constantly on the go, running and jumping about, examining everything in sight, taking hold of objects with greatest precision, balancing itself on the edge of its box and searching everywhere for food. There could scarcely be a greater contrast. One could hardly escape the conclusion that in the orang, as in man, a long period of slow growth is necessary for its final development. The advantages of such growth are sufficiently apparent and need no further comment.

Psychological Tests

The orang-outang has not yet been so extensively subjected to psychological study as its more sociable fellow ape, the chimpanzee. It is fortunate, however, that at least one of this species has come under the critical observation of an astute student of animal behaviour, Professor Robert M. Yerkes, of Yale University. In his notable contribution on the mental life of monkeys and apes, Professor Yerkes has described certain tests devised for estimating the intelligence of lower animals, and applied to the partly grown orang known as “Julius.” These tests were devised on what is known as the “multiple choice basis.” Julius, after many unsuccessful efforts to solve his problems by the method of trial and error, quite unexpectedly seemed to get the idea of what was wanted. He suddenly responded to the test without a single mistake. He seemed to solve his problem quite as if he knew what it was all about. It took him a long time, but at last he showed that he was capable of some kind of thinking. The curve of learning as it was charted day by day from the actions of Julius indicated that if he had been a human subject his mental process would possibly have been described as rational. Professor Yerkes feels justified in concluding from this evidence that the orang solves his problems ideationally. In general, Julius appeared to be far superior to other monkeys in his intelligence. His mental processes were slow, but the method of learning by ideas seemed to replace the simpler way of trial and error which is common throughout the monkey world. Julius persistently endeavoured, and often vainly, to gain some insight into a situation. Even though slow, he showed nevertheless that the brain had at length attained the development necessary for the production of real ideas. However questionable this attainment may be in the monkeys or in other lower animals, there seems to be little doubt about its existence in the orang.

Brains of the Gibbon and Orang

Upon reviewing the facts concerning the gibbon and the orang, we may ask certain questions. For example, does the real progress which these two members of the ape world show in their capacity to do things manifest itself as a measurable difference in their brains? Would it be possible to maintain that these were indeed the brains of more capable and more intelligent animals than the monkeys? Certain features about the brain of the gibbon and the orang are striking. In the first place, the pattern of their convolutions is more complicated. The orang especially has more grooves and convolutions upon the surface of the superbrain. It is believed, and many facts sustain the belief, that convolutions indicate in a general way the capacity of an animal to develop brain power. In the gibbon the increase in convolutions is not so pronounced as in the orang, although it is not difficult to see that in this respect the gibbon’s brain is much improved when compared with lower monkeys. Upon identifying the familiar landmarks, it is obvious that the groove of Sylvius, the central groove, and even the ape groove form more decisive boundaries and outline more prominent lobes than in macaque or baboon. The superbrain departments for sight (occipital lobe), for hearing (temporal lobe), for body and contact senses (parietal lobe), are all more extensive. Each lobe, by the presence in it of smaller secondary grooves which do not appear in the lower monkeys, shows how its capacity has expanded. The grooves of the brain, in their arrangement, number, and relations, now begin to assume an appearance similar to that of the human brain. Each sense department in the orang is well organized. Each has gained in prominence, thus indicating how the senses of sight and hearing, and body and contact senses, have increased their capacity. By means of its amplified sensory combinations the superbrain was eventually capable of producing intelligent reactions. The area in front of the central groove manifests the chief improvement. This is the part of the brain in contact with the frontal bone. It has made some advances in the gibbon but is still more prominent in the orang. At this stage it is possible to speak of a well-developed frontal lobe acting as the headquarters of all higher mental functions. The large increase in the size of the orang’s brain is in some degree proportional to the size of the animal’s body. Many other factors have actuated this expansion and will receive special consideration in a subsequent chapter.

If it were possible to reduce the difference in intelligence between the orang and the gibbon to actual figures, the contrasts would be marked. Certain estimations of this kind are significant. The bridge (pons Varolii) on the base of the brain, which may be regarded as an index of intelligence, has a value of .200 in the gibbon and .300 in the orang. The pyramid, indicating the degree of skill in movement attained by the animal, as well as the degree of controlling itself by the dictates of its will, also shows a considerable difference. This difference is again in favour of the orang, whose pyramid is estimated at .160, while that of the gibbon is .138.

Many other points indicating similar advantages held by the orang over the gibbon might be cited. They have the same general meaning, namely, that the orang possesses a better brain. In fact, all of the evidence gathered from this animal reveals many manlike tendencies. Such tendencies, both in brain and behaviour, first became notable in the gibbon. At this stage they were not prominent features. They were, so to speak, in a preparatory or pro-anthropoid phase. In the orang those manlike tendencies foreshadowed by the gibbon became more definite and better developed. They formed the foundations for new combinations out of which was to emerge a still higher type of animal.