Gorillas & Chimpanzees

The skeleton of the gorilla is so nearly the same as that of the chimpanzee, which has elsewhere been compared to the human skeleton, that we shall not review the comparison at length, but must note one marked feature in the external form of the skull, which differs alike from other apes and man.

The skull of the young gorilla is much like that of the chimpanzee, and remains so until he approaches the adult state; but as he approaches this period, the ridge above the eyes becomes more prominent, and at the same time a sharp, bony ridge begins to develop along the temples, and continues around the back of the head on that part of the skull called the occiput. At this point it is intersected by another ridge at right angles to it. This is called the sagittal ridge, and runs along the top of the head towards the face; but on the forehead it flattens nearly to the level of the skull, and divides into two very low ridges, which turn off to a point above the eyes and merges into that ridge. These appear to be a continuous part of the skull, and are not joined to it by sutures. The mesial crest in very old specimens rises to the height of nearly two inches above the surface of the skull, and imparts to it a fierce and savage aspect; but in the living animal the crests are not seen, as the depressions between them are filled with large muscles, which make the head look very much larger than it would otherwise. These crests affect only the exterior of the skull, and do not appear to alter the form or size of the brain cavity, which is larger in proportion than that of the chimpanzee. These crests are peculiar to the male gorilla, and the female skull shows no trace of them.

There is at least one case in which this crest has failed to develop in the male. By reference to the series of skulls found in the cuts given herewith, No. 6 is that of an adult male, which I know to be such, as I dissected him and prepared the skeleton myself. He was killed in the basin of Lake Fernan Vaz, not more than two or three hours from my cage, and his body was brought to me at once. A good idea of his size can be obtained by reference to another cut given herewith, where I have some natives skinning him. In this picture he is sitting flat on the sand; his body is limp, and is somewhat shorter than it was in life, and yet it can be seen that the top of his head is higher than the hip of the man who is holding him. On the left of the gorilla, in the foreground, sits the man who killed him. He is sitting on a log, and it did not occur to me until too late to place them side by side in order to make a comparison. The body and head of this gorilla as he sits measured nearly four feet from the base of the spinal column to the top of the head. I did not weigh him, but made an estimate by lifting him in my hand, and believed he weighed at least 240 lbs. Yet he was not an old specimen, but if compared to No. 7, in which the crests are well developed, it is found to be larger, and other things point to the fact that he was older.

I am aware that one specimen of itself does not prove anything, but it shows in this case that this ape does not always develop that crest. His head was surmounted by the red crown which we have described, and No. 1, which is the skull of Othello, had the same mark. He was captured near the place where No. 6 was killed. No. 2, which is the skull of a young female nearly four years old, had the same, and she was also captured in the same basin, but on the opposite side of the lake.

The facial bones of No. 6 showed that the animal had received a severe blow in early life, but the fragments had knitted together, and the effect could not be seen in the face of the ape while alive. In this same picture it will be noticed that the lower lip hangs down so low that the mouth is opened. The lip is very massive and mobile, and in this character he resembles the negro. The lower lip is much thicker and more flexible than the upper.

No. 8 is the skull of a large male from Lake Izanga, which is on the south side of the Ogowe River, more than a hundred miles from the coast, and is one of the three centres of population mentioned. I do not know its history. It was presented to me by Mr. James Deemin, an English trader with whom I travelled many days in the Ogowe River; and I wish here to take occasion to express my sincere thanks to him for the many kindnesses extended to me.

No. 5 is the skull of an adult female. By comparing it in profile to No. 6 it will be seen that they resemble, but the muzzle of the latter projects a little more, and the curvature of the skull across the top is less: the distance a little greater.

Nos. 2, 3, 4 and 5 are female; the others are all male.

Nos. 3, 4, 5, 7, 9 and 10 belong to the Liverpool Museum, but are shown here for comparison. The other four are all at Toronto University.

While this series is not complete in either sex, it is an excellent one for comparative study.

I do not know whether the heads of those with the crests were the same colour as No. 6 or not, but the ntyii, which I have mentioned as possibly a new species of the gorilla, does not have this crown of red. His ears are also said to be larger than those of the gorilla, but smaller than the chimpanzee's, and he is reputed to grow to a larger size than either of them.

The skin of the gorilla is a dull black or mummy colour over the body, but that of the face is a jet black, quite smooth and soft. It looks almost like velvet.

One fact peculiar to this ape is, that the palms of both hands and feet are perfectly black. In other animals these are usually lighter in colour than the exposed parts. In all races of men, in all other apes, monkeys, baboons, and lemurs, the palms are lighter than the backs of the hands, and the same is true of the feet. The thumb of the gorilla is more perfect than that of the chimpanzee, yet it is smaller in proportion to the hand than in man. The hand is very large, but has more the shape of the hand of a woman than that of man. The fingers taper in a graceful manner, but appear much shorter, by reason of the web alluded to, than they really are. It is not really a web, in the true sense, but the integument between the fingers is extended down almost to the second joint, but the forward edge of the web, when the fingers are spread, is concave; when brought together, the skin on the knuckles becomes wrinkled, and the web almost disappears. This effect is more readily noticed in the living animal than in the dead. The texture of the skin in the palms is coarsely granulated, and the palmar lines are indistinct. The great toe sets at an angle from the side of the foot, like a thumb, but has more prehensile power than that of the hand; but the foot is much less flexible, and has less prehensile power.

At this point I desire to draw attention to one important fact. The tendons of the foot, which open and close the digits, are imbedded in the palm in a deep layer of coarse, gristly matter, which forms a pad, as it were, under the sole of the foot, and prevents it from bending; therefore it is not possible for the gorilla to sleep on a perch. In this respect he resembles man more than the chimpanzee does, but it is quite certain that neither of them have the arboreal habit. The gorilla is an expert climber, but cannot sleep in a tree. In the hand the tendons which close the fingers are the same length as the line of the bones, and this permits him to open the fingers to a straight line, which the chimpanzee cannot do.

One other important point I desire to mention. The muscles in the leg of a gorilla will not permit it to stand or walk erect. The large muscle at the back of the leg is shorter than the line of the bones of the leg above and below the knee; and when this muscle is brought to a tension, those bones form an angle of about 130 degrees, or thereabouts; and so long as the sum of two sides of a triangle is greater than the other side, a gorilla can never bring his leg into a straight line. In the infant state the muscle is pliant or elastic, and the bones less rigid, so that in that state it can be made nearly straight. The habit of hanging by the arms and walking with them in a straight line develops the corresponding muscle in that member, so that the bones can be brought in line.

The gorilla can stand upon his feet alone, and walk a few steps in that position; but his motion is awkward, because his knees turn outward, forming an angle of 30 or 35 degrees on either side of the mesial plain. He never attempts to walk in this position, except at perfect leisure, and then usually holds on to something with his hands. The tallest gorilla known, when perfectly erect, is about 6 feet 2 inches.

The leg of the gorilla from the knee to the ankle is almost the same size. In the human leg there is what is called the "calf" of the leg, but this in the apes is very small; however, there is a slight tendency in that direction, and it must be noted that in the human species the calf of the leg appears to belong to the higher types of men; and as we descend from the highest races of mankind this character disappears as we approach the savage. The pigmies and the bushmen have the smallest of any other men. It is not to be inferred from this that apes would ever have this feature developed in them by elevating them to a higher plane so long as they remained apes; but it is possible that such a result would follow in the course of time.

One thing which tends to lessen this in the gorilla is the size of the muscles about the ankle and the flexibility of that joint. Also the joint of the knee, being much larger in proportion to the leg, makes the calf appear smaller than it really is.

The corresponding part of the arm is more like that part of the human body.

In a sitting posture the gorilla rests his body upon the ischial bones, with his legs extended or crossed, while the chimpanzee usually squats, resting those bones upon his heels. He sometimes sits, but more frequently squats. When in these attitudes, both usually fold their arms across their breasts.

The hair of the gorilla is irregular in growth. It is more dense than that of the chimpanzee, but less uniform in size and distribution. On the breast it is very sparse, on the arms, long, and on the back, dense, and interspersed with long coarse hairs. The ground of colour is black, but the extreme end of the hair is tipped with pale white. This is so in early youth, and with age the white encroaches, until, in extreme age, the animal is quite grey. The top of the head is covered with a thick growth of short hair, of a dark tan colour, which looks almost like a wig. This mark seems to be peculiar to certain localities, but is uniform among those captured in the Fernan Vaz basin.

A white trader living on this lake claims to have seen a gorilla which was perfectly white. It was seen on the plain near the lake. It was in company with three or four others. It was thought to be an albino, but in my opinion it was only a very aged specimen turned grey. A few of them have been secured that were almost white. It is not, however, such a shade of white as would be found in an animal whose normal colour is white. I cannot vouch for the colour of this ape seen on the plain, but there must have been something peculiar in it to attract so much attention among the natives.

So far, only one species of this ape is known to science, but there are reasons to believe that two species exist. In the forest regions of Esyira the natives described to me another kind of ape, which they averred was a half-brother to the gorilla. They know the gorilla by the native name njina, and the other type by the name ntyii. They did not confuse this with the native name ntyigo, which is the name of the chimpanzee, nor with kulu-kamba, all of which are known to them; but they described in detail, and quite correctly, the three known kinds of ape, and in addition gave me a minute account of the appearance and habits of the fourth kind, which I believe to be another species of the gorilla. They claim that he is more intelligent and human-like than any one of the others; and they say that his superior wisdom makes him more alert, and therefore more difficult to find. He is said always to live in parts of the forest most remote from human habitation.

The dental formula of the gorilla is the same as that of man, but the teeth are larger and stronger, and the canine teeth are developed almost into huge tusks. One thing to be remarked is the great variety of malformations in the teeth of this animal. It is a rare thing to find among them a perfect set of teeth, except in infancy. The cause of this appears to be violence or accident.

The eyes of the gorilla are large, dark, and expressive, but there is no trace of white in them. That part of the eye which is white in man is a dark coffee-brown in the gorilla, but becomes lighter as it approaches the base of the optic nerve. The taxidermist or the artist, who often furnishes him with a white spot in the corner of his eye, does violence to the subject; and those who pose the animal with his mouth open like a fly-trap, and his arms raised like a lancer, ought to be banished from good society. It is true that such things lend an aspect of ferocity to the creature, but they are caricatures of the thing they mean to portray.

The ears of the gorilla are very small, and lie close to the sides of the head. The model of them is much like the human ear.

I shall not pursue the comparison into minute details, but leave that to the specialist, in whose hands it will be treated with more skill and greater scope. As my especial line of research has been in the study of their speech and habits, I shall confine myself to that, but the general comparison I have made is necessary to a better understanding of the subject.

CHAPTER XV

HABITS OF THE GORILLA

A study of the habits of the gorilla in a wild state is attended with much difficulty, but the results that I obtained during a sojourn of one year among them are an ample reward for the efforts made. In a state of captivity the habits of animals are made to conform in a measure to their surroundings, and since those are different many of their habits differ also. Some are foregone, others modified, and new ones acquired, therefore we cannot know with certainty what the animal was in a state of nature. In the social life of the gorilla there are a few things perhaps that differ very much from that of the chimpanzee, but there are some that do in a certain degree. From the native accounts of the modes of life of these two apes, there would appear to be a much greater difference than a systematic study of them reveals; but the native version of things frequently has a germ of truth which may serve as a clue to the facts in the case; and while we cannot rely upon the tales they relate in all details, we can forgive the mendacity and make use of the suggestion they furnish.

It is certain that the gorilla is polygamous in habit, and it is probable that he has an incipient idea of government. Within certain limits he has a faint perception of order and justice, if not of right and wrong. I do not mean to ascribe to him the highest attributes of man, or exalt him above the plane to which his faculties assign him; but there are reasons to justify the belief that he occupies a higher social and mental sphere than other animals, except the chimpanzee.

In the beginning of his career, in independent life, the gorilla selects a wife with whom he appears to sustain the conjugal relations thereafter, and preserves a certain degree of marital fidelity. From time to time he adopts a new wife, but does not discard the old one; in this manner he gathers around him a numerous family, consisting of his wives and their children. Each mother nurses and cares for her own young, but all of them grow up together as the children of one family. There is no doubt that the mother sometimes corrects and sometimes chastises her young, which suggests a vague idea of propriety. The father exercises the function of patriarch in the sense of a ruler, and the natives call him ikomba njina, which means gorilla king. To him the others all show a certain amount of deference. Whether this is due to fear or to respect, however, is not certain, but here is at least the first principle of dignity.

The gorilla family, consisting of this one adult male and a number of females and their young, are within themselves a nation. There do not appear to be any social relations between different families, but within the same household there is apparent harmony.

The gorilla is nomadic, and rarely ever spends two nights in the same place. Each family roams about in the bush from place to place in search of food, and wherever they may be when night comes on they select a place to sleep and retire. The largest family of gorillas that I have ever heard of was estimated to contain twenty members. But the usual number is not more than ten or twelve. The chimpanzee appears to go in larger groups than these, and sometimes in a single group two or even three adult males have been seen. When the young gorilla approaches the adult state, he leaves the family group, finds himself a mate, and sets out in the world for himself. I observed that, as a rule, when one gorilla was seen alone in the forest it was usually a young male, but nearly grown; it is probable that he was then in search of a wife. At other times two only are seen together, and in this event they are usually a pair of male and female, and generally young. Again, it sometimes occurs that three adults are seen with two or three children; often one of the children two or three years old, and the others a year younger, which would indicate that the male had had one of his wives much longer than the other. In large families young ones of all ages, from one year old to five or six years old, are seen; but the fact is plain that the older children are much fewer in number. I have once seen a large female with her babe, quite alone; whether she lived alone or was only absent for the moment I cannot tell.

The king gorilla does not provide food for his family, but, on the contrary, it is said they provide for him. I have been informed on two occasions, from different sources, that the king gorilla has been seen sitting quietly under the shade of a tree, eating, while the others collected and brought to him the food. I have never witnessed such a scene myself, but it does not seem probable that the same story would have come from two sources unless there was some foundation for it.

In the matter of government, the gorilla appears to be somewhat more advanced than most animals. He leads the others on the march, and selects their feeding grounds and places to sleep; he breaks camp, and the others all obey him in these respects. Other animals that travel in groups do the same thing; but in addition to this, the natives aver that the gorillas from time to time hold palavers or a rude form of court or council in the jungle. On these occasions, it is said the king presides; that he sits alone in the centre, while the others stand or sit in a rough semicircle about him, and talk in an excited manner. Sometimes the whole of them are talking at once, but what it means or alludes to no native undertakes to say, except that it has the nature of a quarrel. To what extent the king gorilla exercises the judicial function is a matter of grave doubt, but there appears to be some real ground for the story.

As to the succession of the kingship there is no certainty, but the facts point to the belief that on the death of the king, if there be an adult male he assumes the royal prerogative, otherwise the family disbands, and they are absorbed by or attached to other families. Whether this new leader is elected in the manner that other animals appoint a leader, or assumes it by reason of his age, cannot be said; but there is no doubt that in many instances families remain intact for a time after the death of their leader.

It has been said by many that the gorilla builds a rude hut or shelter for himself and family, but I have found no evidence that such is true. The natives declare that he does so, and some white men affirm the same; but during my travels through their habitat, I offered liberal and frequent rewards to any native who would show me one of these specimens of simian architecture, but I was never able to find any trace of one made or occupied by any ape. They may sometimes, and doubtless do, take shelter from the tornadoes, but it is always under some fallen tree or cluster of broad leaves, and there is nothing to show that they arrange any part of them. So far as I could find, there is no proof that any gorilla ever put two sticks together with the idea of shelter. As to his throwing sticks or stones at an enemy, I have found nothing to verify it; in my opinion, it is a mere freak of fancy.

The current opinion or idea that a gorilla will attack a man without being provoked to it, is an error. He is shy and timid, and shrinks alike from man and other large animals. I have no doubt that when he is in a rage he is both fierce and powerful, but his ferocity and strength are rated above their true value. In combat he is a stubborn foe no doubt, but no one that I have met has ever seen him thus engaged.

The mode of attack as described by many travellers is a mere theory. It is said in this act he walks erect, beats with fury on his breast, roars and yells, and in this manner seizes his adversary, tears open his breast, and drinks the blood. I have never seen a large gorilla in the act of assault. During the time of my stay in the jungle I had a young gorilla in captivity, and I made use of him in studying the habits of his race. I kept him tied with a long line which allowed him room to play and climb, and at the same time prevented him from escaping into the forest, which he always tried to do the instant he was released. I released him frequently for the purpose of watching his mode of attack when recaptured. While being pursued he rarely looked back, but when overtaken he invariably assailed his captor. This gave me an opportunity of seeing his method of attack, in which he displayed both skill and judgment. As my boy would approach him, he would calmly turn with one side to the foe and, without facing the boy, would roll his eyes in such a manner as to see him and at the same time conceal his purpose. When the boy came within reach, the gorilla would grasp him with a thrust of the arm to one side and slightly backward. When he had seized his adversary by the leg, he would instantly swing the other arm round with a long sweep and strike the boy a hard blow; then he began to use his teeth. He seemed to depend more upon the blow than the grasp, but the latter served to hold the object of attack within reach; in every case he kept one arm and one leg in reserve until he had seized his adversary. It is true that these attacks were made upon an enemy in pursuit, but his mode appeared to be a normal one; he could strike a severe blow, and did not show any sign of tearing or scratching his opponent. In these attacks he made no sound of any kind. I do not pretend to say that other gorillas do not scream or tear their victims, but I take it that the habits of the young are much, if not quite, the same as those of their parents, and from a study of this specimen I am forced to modify many opinions imbibed from reading or from pictures and specimens which I have seen. Many of them represent the gorilla in absurd and sometimes impossible attitudes. They certainly do not represent him as I have seen him in his native wilds.

When the chimpanzee attacks, so far as I have seen among my own specimens, he approaches his enemy and strikes with both hands, one slightly in advance of the other. After striking a few blows, he will grasp his opponent and use his teeth, then shoving him away again uses his hands, and usually, on beginning the attack, accompanies the assault with a loud, piercing scream. Neither he nor the gorilla closes the hand to strike, nor uses any weapon except the hands and teeth. I had another young female gorilla for a short time as a subject for study. Her mode of attack appeared to be the same, but she was too large to risk in such experiments.

I have read and heard descriptions of the sounds made by the gorilla, but nothing ever conveyed to my mind an adequate idea of their true nature, until I heard them myself within a few hundred feet of my cage in the dead of night. By some it has been called roaring, and by others howling; but it is neither truly a roar nor a howl. They utter a peculiar combination of sounds, beginning in a low, smooth tone, which rapidly increases in pitch and frequency, until it becomes a terrific scream. The first part of the series is quite within the scope of the human voice, but as it rises in pitch and increases in volume it passes far beyond the reach of the human lungs. The first sound of the series and each alternate sound is made by expiration, while the intermediate ones appear to be by inspiration, but how it is accomplished is difficult to say. The sound as a whole resembles the braying of an ass, except the notes are shorter, the climax higher, and the sound is louder. A gorilla does not yell in this manner every night, but when he does so it is usually between two and five o'clock in the morning; I have never heard the sound during the day nor in the early part of the night. When he thus screams, he repeats the series from ten to twenty times, at intervals of one or two minutes each. I know of nothing in the way of vocal sounds that can inspire such terror as the voice of the gorilla. It can be heard over a distance of three or four miles. I could assign no definite meaning to it unless it was intended to alarm some intruder that came too near.

One morning between three and four o'clock I heard two of them screaming at the same time. I do not mean to say at the same instant, but at intervals during the same period of time. One of them was within about a third of a mile of me, and the other in another direction perhaps a mile away. The points we occupied respectively formed a scalene triangle. The sounds did not appear to have any reference to each other. Sometimes they would alternate, and at other times they would interrupt each other. They were both made by giants of their kind, and every leaf in the forest vibrated with the sound. This was during the latter part of May. They do scream in this way from time to time throughout the year, but it is most frequent and violent during February and March.

This wild screaming is sometimes accompanied by a peculiar beating sound. It has been described by travellers, and currently believed to be made by the animal beating with his hands upon his breast; but such is not the case. It is very certain that the sound cannot be made by that means. The quality of the sound shows that such cannot be the means employed. I have heard this beating several times, and have paid marked attention to its character. At a great distance it would be difficult to discern the exact quality; but on one occasion, while stopping over-night in a native town, I was aroused from sleep by a gorilla screaming and beating within a few hundred yards. I put on my boots, took my rifle, and cautiously crossed the open ground between the village and the forest. This brought me within about two hundred yards of the animal. The moon was faintly shining, but I could not see the beast, and I had no desire to approach nearer at such a time, but I heard distinctly every stroke. I believe the sound was made by beating upon a log or piece of dead wood. He was beating with both hands, the strokes alternating with great rapidity, and not unlike the manner in which the natives beat a drum, except that the hand made the same number of strokes, and the strokes were in a constant series, rising and falling from very soft to very loud, and vice versâ. A number of these runs followed one another during the time the voice continued. Between the first and second strokes the interval was slightly longer than that between the second and third, and so on through the scale. As the beating increased in loudness the interval shortened in an inverse degree, while in descending the scale the intervals lengthened as the beating softened, and the author of the sound was conscious of this fact. I could trace no relation in time or harmony between the sound of the voice and the beating, except that they began at the same time and ended at the same time. The same series of vocal sounds was repeated each time, beginning on the low note and ending on the highest note or pitch in each case, while the rise and fall of the series of the beaten sounds was not measured by the duration of the voice. The series each time began with a soft note, but ended at any part of the scale at which the voice ceased, and was not the same in every case.

I have no doubt that the gorilla beats upon his breast: he has been seen to do so in captivity, but the sounds described above were not so made. Since the gorilla makes these sounds only at night, it is not probable that any man ever saw him in the act. It does not require a delicate sense of hearing to distinguish a sound made by beating the breast from that of dead wood or other similar substance.

I have attributed the above sound to the gorilla, because I have been assured by many white men and scores of natives that it was made by him; but since my return from Africa I have had time to consider and digest certain facts tabulated on that trip, and as a result I am led to doubt whether this sound is made by the gorilla or not. There are good reasons to believe that it is made by the chimpanzee instead, and I shall state them.

I observed that my own chimpanzees made this sound exactly the same as that I heard in the forest, except that it was less in volume, which was due to their age. I could induce them at any time to make the sound, and frequently did so in order to study it. On my arrival in New York I found that Chico, the big chimpanzee belonging to Mr. Bailey, frequently made the same sound at night. It was said to be so loud and piercing that it fairly shook the stately walls of Madison Square Garden. From reading the description given by the late Professor Romanes of the sound made by "Sally" in the London Gardens, it appears to be the same sound.

It is well known to the natives that the chimpanzees beat on some sonorous body, which they call a drum. Four years ago I called attention to the habit of the two chimpanzees in the Cincinnati Gardens. They frequently indulged in beating upon the floor of their cage with their knuckles. This was done chiefly by the male. The late E. J. Glave described to me the same thing, as being done by the chimpanzees in the Middle Congo basin.

It is not probable that two animals of different genera utter the same exact sound, and this is more especially true of a sound that is complex or prolonged. Neither is it likely that the two would have a common habit, such as beating on any sonorous body. Since it is certain that one of these apes does make the sound described, it is more than probable that the other does not. The same logic applies to the beating.

Many things that are known of the chimpanzee are taken for granted in the gorilla, but it is erroneous to suppose that in such habits as these they would be identical. In some cases I have been able to prove quite conclusively that the chimpanzee alone did certain things which were ascribed to the gorilla.