Popular Science Monthly/Volume 25/August 1884/My Monkeys
I HAVE never bought any trained monkeys, but, in my experiments in domesticating wild ones, have always treated my animals with the greatest care, and chosen moral rather than physical means of discipline. The relations between the monkey and his master ought to be friendly, and, when the first causes for fear and motives to anger have been suppressed, there will remain on the animal's part only feelings of respect. He will recognize his inferiority to man, and will respect him without fear. These lively and nervous animals, abruptly torn from their native wilds, to be shut up and treated in an unnatural manner, preserve in captivity their good-humor and intelligence to a remarkable degree.
The monkeys I have kept have been both of New World and Old World species. The last are the more intelligent.
In April, 1873, I received a young male of rhesus (Macacus erythrœus, or rhesus), well tamed, and weighing about three pounds and three quarters, but coming to me with a cold and in a very thin and dejected condition. His hair was lusterless, short, and all off in spots, while his tail was quite bare. He had, although a male, received the name of Molly, and answered to it readily. I did not change it. I gave him a cage large enough for him to turn around in freely, and to afford ample room for all the manifestations of his sanguine and nervous temperament. A few days after he came, I allowed him a brief promenade in the room. Without disturbing anything, he posted himself at a window, whence he could look at the passers-by. His conduct was so rational that I determined to extend his promenade, and shut him up only while I was away. This liberty, the constant intercourse with persons who caressed him as much as he would let them instead of teasing him, the quiet of his surroundings, and the removal of every feared and exciting object, exercised a decisive and favorable influence on his mental and physical development.
His attachment to me was extreme. He was near me all day, and followed me around like a faithful dog. When I hid away from him or shut a door in his face, he would cry and try to open the door with his hands, succeeding at last by throwing his whole weight upon the latch. In May my house was painted and whitewashed, and a scaffolding was built around it to facilitate the work. The top of the highest timber became Molly's favorite place. It was some four feet above the roof; Molly was accustomed to sun himself upon it, and from it he watched attentively all who passed. He would never move from it as long as he could see me. But, as soon as I set foot out of the grove where I used to work, he would set up a plaintive cry, and slide down the timbers to hunt me up, and would not stop his whining till he had found me, an event which he marked by repeated grunts of joy.
He gave me a proof of the susceptibility of the character of his species the very day he came. Perching himself on my wife's shoulders, he amused himself with disarranging her hair. Tired of this, my wife tried to push him away, at first pleasantly, then roughly. The last movement cost her a bite on the hand, and in return for this she struck Molly sharply on the cheek, when the monkey ran to his cage in great anger. From that day the inclination he had formed toward my wife was turned to a violent hatred, which he continued to manifest till the end of his days. All his affection was turned toward me, and it was really admirable. No dog ever showed so exclusive an attachment to me as this monkey, a fact the more singular because the animal had come from a wild life, and not, like the dog, from trained ancestors. Molly never refused morsels from the hand of other persons than myself; but, accepting the gift from them, he would scratch or bite the hand that offered it.
He was greatly frightened at a gun that I shot off one day at some sparrows. He hid at once in the straw of his cage, and never left it till the gun was hung up again. After that I had only to touch the stock, to make him hide again, when nothing could be seen in the straw, except a pair of sharp eyes watching all my motions. Just a touch of my finger or of a cane upon the cock of the gun was enough to deprive him of all quiet. I used to carry on my watch-chain a little pistol, on which a percussion-cap would make a tolerably loud report. The monkey had not yet found this out, and, sitting on my knees, would amuse itself with licking the silver barrel. One day in his presence I put a percussion-cap on the nipple of the pistol. The monkey observed my movements with great attention, but without seeming disturbed by them. But when the cock, being raised, made two clicks, Molly dropped his eyebrows, while he continued sitting quietly. When the explosion took place, his fright was unbounded. Crying loudly, and full of anguish, he fell from my knees, ran across several rooms, leaped out of the window, clung to a water-pipe, slid down to the street and hid himself in a ditch in a neighboring garden. His nervousness lasted a long while, and I had to take off my watch-chain to appease it. From that day he was in such fear of the little pistol that to take hold of the chain was enough to make him disappear in the straw. But he very soon learned by experience that the source of the detonation was not in the chain but in the pistol, and could easily distinguish it from the other appendages of the chain, of which he was not afraid at all. Sitting on the straw in his cage, he would attentively watch my movements while I was handling these appendages. The closer my fingers approached the formidable object, the greater became his anxiety, and with his eyes riveted upon the instrument and with tense ears, he would dance continuously in the cage, all ready to go under the straw. He would assure himself beforehand, for greater security, that the cage-door was well shut; and one day, when the bolt had not been pushed in, he leaped out from the cage, which did not seem safe enough for him, and went and hid himself under the bed in the next room. As I gradually removed my hand from the pistol, I would receive chuckles of approbation; and, with his lips pushed forward and the muscles of his ear moving by jerks, he would manifest a very great joy.
The conclusion is forced by these facts, that monkeys by experience become more prudent and more cunning. Carrying experiments of this kind further, I have observed that the monkey can recognize the object of its fear even in a picture, manifesting a faculty which is largely wanting in little children and savages. I one day received an armorer's illustrated catalogue. It had among other objects a drawing of a revolver of the natural size, an arm which the rhesus had never yet seen. I gave the catalogue to my pet, and he, after the manner of many monkeys, began to turn the leaves. But, as soon as he got to the picture of the revolver, he dropped the catalogue, groaned lustily and made faces, and at once ran to hide himself in the straw, which he would not leave till the pamphlet was taken away.
The last fact proves the superiority of simian intelligence over that of the other mammals. I disagree on this point from Perty, who says, "A small number of animals, among which is the elephant, recognize drawings of objects that are familiar to them." I must avow that my investigations on this subject, upon the few elephants living in Europe, have given me negative results. I do not know of any domestic animal that can distinguish a picture. It is useless to show dogs faithful drawings of the dog, or of game; the result is nearly always the same. The animals will smell the paper, examining the substance, not the picture, and, once convinced there is nothing in it to exercise their teeth upon, they resignedly abstain from any more profound investigation. Monkeys, at least Old World monkeys, act differently.
The rhesus, a baboon (Inuus ecaudatus), three Java monkeys (Macacus cynomolgus), and a sajou (Cebus hypoleucus) were drawn in crayon for an illustrated magazine in pictures having a striking resemblance to the originals. I gave each monkey his portrait. The rhesus and the Java monkeys recognized the pictures at once, and acted precisely as if they were before a looking-glass. The rhesus grinned, then laughed, and at last turned his back to the picture, uttering grunts of satisfaction, as if he expected to be scratched. The Java monkeys stared at the picture; with the skin of their foreheads drawn back, their lips pushed out and constantly moving, they regarded it from a distance and close up, to find out what it was. The other species likewise recognized the nature of the pictures, but without exhibiting as strong excitement as the two species mentioned. The least intelligent of the number was the sajou, which, examining the portrait from the head down and moaning, stretched its hand toward it, trying to tear it with his nails. Evidently it did not recognize the portrait either as one of itself or of another monkey, while it took in pictured insects very well, and was frightened at the sight of the painting or drawing of a viper. Notwithstanding these examples, I was careful not to generalize so as to extend to a whole species the faculties of a few individuals belonging to it. Among monkeys, as with man and other animals, there are individuals of extensive and individuals of very limited gifts in the same species. None of the many monkeys could distinguish pictures of landscapes or houses, in respect to which they were precisely like savages.
Only a few dogs give any signs of intelligence before their image in a glass. Some just distinguish it and remain quite indifferent; others growl or bark, but they seldom try to determine whether a second individual really exists. I have remarked the same of cats, and Blanchard's cat in Paris, that dashed furiously at a looking-glass, is a unique example.
The rhesus looked into the mirror with a joyous air, stretched out his ears, drew up the skin of his forehead and his eyebrows, puckered his lips, grinned and laughed, and turned his posterior to the glass. This gesture is general among some kinds of monkeys. I had already described it as a peculiarity of a mandrill, when Darwin, having read my article, sent me a letter on the subject, asking me what significance I attached to it. I answered him that, according to my experiments, the gesture was a mark of simian politeness. Once in position, the monkey expects to be scratched, just as when we extend our hand to another person we expect to receive his. Darwin verified my observation, and compared the gesture with certain forms of salutation among savages, such as those by feeling the belly or rubbing noses. My rhesus, not succeeding in getting scratched by his image, turned around and passed his hand behind the glass to feel for it. I took the opportunity to pinch him sharply behind the glass, when he became very angry, not at me, but at the image. His face turned red, his ears were extended, and his jaws gaped open repeatedly. The gaping was so irresistible that he could not stop it, not even to chew or swallow. It is a sign of great anger and violent nervous disturbance. It occurs very frequently with the pavions, almost regularly, and the animal is often so overcome by its paroxysm that it can neither defend itself nor attack. Another sign of anger is given by shaking violently with the four hands the bars of the cage, the grating, or some support. This habit, born of the forest, is evidently intended to frighten enemies with noise. Molly never failed to exercise it when, after having been teased by any one, he heard him laugh. The cage was fastened to the table, and both were fastened to the wall. As long as the cage was loose, Molly would shake it. As soon as it was fixed, he tried to shake it, and, failing, did not do so again till time and use having worn upon the nails, the cage gained a little play, when he seized his opportunity and the racket was renewed. I then put in a piece of India-rubber to muffle the sound, and the monkey stopped his shaking. He did not care to see the cage move, but to make a noise. This habit is, however, not always a sign of anger. Some monkeys practice it under the influence of ennui or impatience, or when they wish to attract attention, and, in the lack of any other resource, the rhesus would hunt up in his straw a dry bread-crust, a nut-shell, a bone, or anything hard that he could strike against his cage-bars.
To express a desire, my monkey utters a prolonged "Oh!" or sounds the interjection in two syllables, with the second a fifth higher than the first. The tone rises according to the intensity of the desire. Thus, when I was talking with another person of the favorite eatables of the rhesus (such as milk, apples, potatoes, and rice), the monkey, although I was not speaking to him, underlined those well-known words with chuckles of approbation, and pushed his oh's through his lips, which were puckered out as if he were whistling. His attitude was the same when I gave the order from my room to have his meal brought in. The rhesus would at once fix his eyes on the door by which the anticipated feast was to come in; and this, no matter what might be the time of the day or night. The behavior was, then, not influenced by the periodicity of the want, which determines regular actions with many other animals, and was independent of the person who pronounced the words. I might cite thousands of cases observed on my premises, by hundreds of persons, that prove superabundantly that monkeys fully comprehend the relations of certain words and the objects corresponding to them.
The rhesus knew, besides, the names of all the animals that lived in the same room with him but in different cages—some sixty or seventy in number. If I pronounced the name of any of them, without giving any sign of voice or look, he would put his head through the hole in the cage, and turn it significantly toward the animal in question.
This monkey's fear of snakes was extreme, and extended to everything that had any resemblance to them. The same feeling is common to all monkeys. A very fine mandrill of my pets having a habit of prying about, I found no better way of restricting his investigations, which were sometimes annoying, than to put snake-skins under the objects I wished him to respect. The device succeeded admirably. It was to the same mandrill I once showed a prospectus of Semper's "Journey to the Philippine Islands," in which there was a picture of a holuthuria. At the unexpected view of this sea-horn, the mandrill made a jump and struck the ground with his hands, while his hair stood out and his body trembled from head to foot. The rhesus gave me a yet more striking example of this horror. I had received a large python, which I had brought into the room every day for a warm bath. After nine days, I had only to call out, "Bring in the serpent," for the monkey to disappear under the straw. Long after the serpent had been restored to health and the baths had been discontinued, the repetition of the order would set Molly a-trembling at any time.
Perty says that dogs are the only animals capable of reading human physiognomy; but one has only to possess monkeys and be acquainted with them to know that they too can read it better than children can. I except New World monkeys, which have little or none of the faculty. I had a little female Java macacus, of an exceedingly pleasant and timid nature. I had only to raise my voice in speaking to her, to arrest all her motions. When I returned into the room, she would follow me with her eyes, trying to read the expression of my face, and endeavoring to gain my sympathy by a low murmuring, going away or coming up to me according to the play of my features. If she saw me smile she would make a sound of gladness, clasp my knees and press against me, with murmuring lips and eyes gazing into mine. But, at the first frown or hard look, the macacus would drop down crying and run away. The rhesus responded in a somewhat similar manner to my expressions.
Monkeys have a passion for cleanliness. Once on your knees, they will pick you from head to foot, not letting a wrinkle escape, and all with the most serious air. My rhesus could not endure badly dressed persons. He was always ready to defend me, and to spring upon any one who would touch me with the tip of his finger. He had no respect for children, but acted as if he took them to be large monkeys, and would sometimes attack them when they were too saucy. Some of the other monkeys, however, seemed to be quite fond of them. The rhesus appreciated the inferiority of my servants to myself, and would become angry at any one of them when I reprimanded him, his anger being modulated according to my tone, and sometimes leading him to acts. He co-operated in all my gestures when I acted as if I were beating a man or a dog, but if it were another monkey that was threatened he took its side. The feeling of compassion is not strange to monkeys. They will defend and protect threatened individuals, sometimes offering their own bodies as a shield. They extend their commiseration to animals of another species. The rhesus became furious when he saw the ferret, in the course of his training-lessons, biting rats, and, taking him by the tail, bit him to save the rat.
The rhesus slept at first perched on the bars of his cage, but soon learned to accustom himself to easier positions. He could cover himself up with the quilt, and would finish by drawing it over his head with his teeth. He often had lively dreams. I could see him grin, and hear him utter low but distinct sounds of comfort, of desire, and sometimes of fright. In the latter case he would always awake, jump to the highest stick, and cast frightened looks around.
His obedience was complete, and was never wrecked except upon the rock of gluttony. If I left any delicacy on the table, he would never touch it when I was looking on; but, after my back was turned, nothing of it could be found. I could not contend with this fault except by stratagem; but to put a stuffed snake-skin by the side of the coveted object was always enough to secure its protection.
The feeling of the right of property is common to all monkeys. I gave a red quilt to a Java macacus and a blue one to another macacus. Each one was jealous of his own garment, and the least infringement by one on the proprietary rights of the other was followed by a battle.
Perty says that monkeys can untie knots, but can not tie them. Is this a mark of inferiority? Monkeys, like other animals, have for most of their actions a determined object. My rhesus was obliged, to get honey, to open the closet and, to be at liberty, to untie the rope. He did both. But why should he shut the door, or tie the rope again? Do we not have to teach children and boors to shut doors?
Monkeys can estimate weights. I gave the rhesus full eggs and empty shells, between which there was no difference to the eye. At first he bit both alike, but he soon learned to throw the empty shells away without biting them. I continued the egg experiments by filling the egg-shells with iron filings, lead, sawdust, and sand. After several trials, he never could be deceived except by eggs of the same density as normal ones. This faculty is not, however, equally possessed by all monkeys.
It can not be denied that monkeys have some, but a weak, notion of number. My rhesus was accustomed to get a certain number of carrots, or apples, or potatoes, and, if his ration fell short, he would always take notice of the deficiency. If he got only three apples when he was expecting four, he would not move from the grating till the fourth apple was brought him. Music had but little effect upon him; but the sound of a hunting-horn would send him under the straw, and cause him to scratch his ears as he would do when one was driving a nail near him. Nothing delighted him more than to have a lighted cigar or pipe in his mouth. He would fill his cheek-pouches with the smoke and send it out through his nostrils like any expert at the cigarette.
The anecdotes about the propensity of monkeys to imitate man are much exaggerated. They have a physical structure like his, and mental qualities in some respects not wholly dissimilar from his, and naturally make gestures like those of men; and that is the most of truth there is in those stories.
Monkeys have a language, as among themselves, that is easily understood by individuals of the same species. Individuals of different species, if not too far remote, can after a time learn to understand each other; but if the species are very different, like those of the Old and the New World, the effort is tantamount to that of learning a new language, and frequently requires several years. As the thoughts of monkeys are excessively limited in extent and their wants relate solely to food and the struggle for existence, their language is but little varied, and is composed chiefly of vowels pronounced with different intonations and accompanied by different expressions of the figure, the most common of which are laughing and grinning, and which each species performs in its own peculiar fashion. The expressions of anger are also characteristic, and vary with the species.
My rhesus, together with a large mandrill and a Cynopithecus niger of unusual size, ate at my table, and received all the dishes that I had. The rhesus preferred roast fowl and roast mutton to all other meats, and also liked eggs, raw or cooked. His weakness for eggs once cost me a considerable sum, which I had to pay to a neighbor for one hundred and fifty eggs of high-bred fowls which my pet had destroyed. He ate all kinds of seeds, and liked much to vary his food. Among vegetables he preferred asparagus, and had a strong appetite for fruits, to gratify which he made my own and my neighbors' orchards suffer.
His ordinary drink was milk and half a glass of Bordeaux, which he took in his hand as a man would have done, without spilling a drop. I sometimes gave him tea, chocolate, cocoa, coffee, beer, and white Tokay wine. He frequently abused the last drink, and learned to go into a room where a bottle of it was kept. He would then get drunk—dead-drunk—like any man, and my servant would find him and call to me to help put him into the cage. But, even in this condition, he never failed to have a degree of respect for me, though he would resist being moved, as the street-toper resists the policeman. Put in the cage, he would sleep off his draught stupidly, and then be sick for two or three days, obstinately refusing to eat anything, but never to drink.—Translated for the Popular Science Monthly from the Revue Scientifique.