Animal Intelligence Part 45

He crunched the frame and gla.s.s together with his teeth, he beat on the floor, he crunched again, till nothing but splinters was left.

Mr. Darwin writes: 'Rengger, a most careful observer, states that when first he gave eggs to his monkeys in Paraguay, they smashed them, and thus lost much of their contents; afterwards they generally hit one end against some hard body, and picked off the bits with their fingers.

After cutting themselves only _once_ with any sharp tool, they would not touch it again, or would handle it with the greatest caution. Lumps of sugar were often given them wrapped up in paper; and Rengger sometimes put a live wasp in the paper, so that in hastily unfolding it they got stung; after this had _once_ happened, they always first held the packet to their ears to detect any movement within.'[277]

The powers of observation and readiness to establish new a.s.sociations thus rendered apparent, display a high level of general intelligence.

Mr. Darwin further observes that Mr. Belt 'likewise describes various actions of a tamed cebus, which, I think, clearly show that this animal possessed some reasoning power.' The following is the account to which Mr. Darwin here refers, and I quote it _in extenso_, because, as I shall presently show, I have myself been able to confirm most of the observations on another monkey of the same genus:--

It would sometimes entangle itself round a pole to which it was fastened, and then unwind the coils again with the greatest discernment. Its chain allowed it to swing down below the verandah, but it could not reach to the ground. Sometimes, when there were broods of young ducks about, it would hold out a piece of bread in one hand, and when it had tempted a duckling within reach, seize it by the other, and kill it with a bite in the breast. There was such an uproar amongst the fowls on these occasions, that we soon knew what was the matter, and would rush out and punish Mickey (as we called him) with a switch; so that he was ultimately cured of his poultry-killing propensities.

One day, when whipping him, I held up the dead duckling in front of him, and at each blow of the light switch told him to take hold of it, and at last, much to my surprise, he did so, taking it and holding it tremblingly in one hand. He would draw things towards him with a stick, and even used a swing for the same purpose. It had been put up for the children, and could be reached by Mickey, who now and then indulged himself in a swing on it. One day I had put down some bird-skins on a chair to dry, far beyond, as I thought, Mickey's reach; but, fertile in expedients, he took the swing and launched it towards the chair, and actually managed to knock the skins off in the return of the swing, so as to bring them within his reach. He also procured some jelly that was set out to cool in the same way. Mickey's actions were very human-like. When any one came near to fondle him, he never neglected the opportunity of pocket-picking. He would pull out letters, and quickly take them from their envelopes.[278]

I shall now proceed to state some further facts, showing the high level of intelligence to which monkeys of various kinds attain.

The orang which Cuvier had used to draw a chair from one end to the other of a room, in order to stand upon it so as to reach a latch which it desired to open; and in this we have a display of rationally adaptive action which no dog has equalled, although, as in the case before given of the dog dragging the mat, it has been closely approached. Again, Rengger describes a monkey employing a stick wherewith to prise up the lid of a chest, which was too heavy for the animal to raise otherwise.

This use of a lever as a mechanical instrument is an action to which no animal other than a monkey has ever been known to attain; and, as we shall subsequently see, my own observation has fully corroborated that of Rengger in this respect. More remarkable still, as we shall also subsequently see, the monkey to which I allude as having myself observed, succeeded also by methodical investigation, and without any a.s.sistance, in discovering for himself the mechanical principle of the screw; and that monkeys well understand how to use stones as hammers is a matter of common observation since Dampier and Wafer first described this action as practised by these animals in the breaking open of oyster-sh.e.l.ls. The additional observation of Gernelli Carreri of monkeys thrusting stones into the open valves of oysters so as to save themselves the trouble of smas.h.i.+ng the sh.e.l.ls, though not incredible, requires confirmation. But Mr. Haden, of Dundee, has communicated to me the following very remarkable appreciation of mechanical principles which he himself observed in a monkey (species not noted), and which would certainly be beyond the mental powers of any other animal:--

'A large monkey, confined alone in a large cage, had its sleeping-place in the form of a kind of hut in the centre of the cage. Springing near the hut was a tree, or imitation tree, the main branch of which ascended over the top of the hut, and then came forwards away from it. Whether the roof of the hut enabled this animal to gain any part of this branch, I did not observe, but only remarked its method at the time of gaining the part of the branch which led frontwards, and away from the hut.

This could be done by means of the hut door, which, when opened, swung beneath this part of the branch. The door, either by accident or by the design of its construction, _swung_ to each time the animal opened it to mount upon its top edge. After one or two efforts to mount by it in spite of its immediate swinging to, the creature procured a thick blanket which lay in the cage, and threw it over the door, having opened the same, so that its complete swinging to was prevented sufficiently for the creature to mount upon its free edge, and so gain that part of the branch which ran above it.'

The following, which I quote from 'Nature' (vol. xxiii., p. 533), also displays high intelligence:--

One of the large monkeys at the Alexandra Palace had been for some time suffering from the decay of the right lower canine, and an abscess, forming a large protuberance on the jaw, had resulted. The pain seemed so great, it was decided to consult a dentist as to what should be done; and, as the poor creature was at times very savage, it was thought that if the tooth had to be extracted, gas should be used for the safety of the operation. Preparations were made accordingly, but the behaviour of the monkey was quite a surprise to all who were concerned. He showed great fight on being taken out of the cage, and not only struggled against being put into a sack prepared with a hole cut for his head, but forced one of his hands out, and snapped and screamed, and gave promise of being very troublesome. Directly, however, Mr. Lewen Moseley, who had undertaken the operation, managed to get his hand on the abscess and gave relief, the monkey's demeanour changed entirely. He laid his head down quietly for examination, and, without the use of the gas, submitted to the removal of a stump of a tooth as quietly as possible.

According to D'Osbonville, certain monkeys that he observed in the wild state were in the habit of administering corporal chastis.e.m.e.nt to their young. After suckling and cleansing them, the mothers used to sit down and watch the youngsters play. These would wrestle, throw and chase each other, &c.; but if any of them grew malicious, the dams would spring up, and, seizing their offspring by the tail with one hand, correct them severely with the other.

We have already seen that dogs and cats display the idea of maintaining discipline among their progeny.

According to Houzeau the sacred monkey of India (_Semnopithecus entellus_) is very clever in catching snakes, and in the case of poisonous species destroy the fangs by breaking them against stones.[279]

Of the fact that monkeys act in co-operation, many proofs might be given, but one will suffice.

Lieutenant Schipp, in his Memoirs, says:--

A Cape baboon having taken off some clothes from the barracks, I formed a party to recover them. With twenty men I made a circuit to cut them off from the caverns, to which they always fled for shelter. They observed my movements, and detaching about fifty to guard the entrance, the others kept their post. We could see them collecting large stones and other missiles. One old grey-headed one, who had often paid us a visit at the barracks, was seen distributing his orders, as if a general. We rushed on to the attack, when, at a scream from him, they rolled down enormous stones on us, so that we were forced to give up the contest.

I shall here bring to a close my selections from the literature of monkey psychology, because I wish to devote a good deal of s.p.a.ce to detailing a number of observations which have not yet been published.

Thinking it desirable for the purposes of this work that an intelligent monkey should be subjected to close observation for some length of time, I applied to Mr. Sclater for the loan of one from the collection of the Zoological Society. He kindly consented to my proposal, and I selected a specimen of _Cebus fatuellus_, which appeared to me to be the most intelligent monkey in the collection. Not having facilities for keeping the animal in my own house, I consigned him to the charge of my sister (who lives close by), with the request that she should carefully note all points of interest connected with his intelligence. Therefore, from the day of his arrival till that of his departure she kept a diary, or note-book, in which all the observations that she made when I was absent were entered. It was originally my intention to make an abstract of this note-book; but on afterwards reading it through for this purpose, it seemed to me that I should rather spoil matters by attempting a condensation. There is a certain graphic effect incidental to the diary form and spontaneous style of diction--the notes, of course, not having been written with a view to verbatim publication; and besides, as the psychology of monkeys has been so little studied, I think it is well to give all the details of a continuous series of observations. It is desirable to add that on occasions subsequent to the taking of this or that particular note, I generally had the opportunity of verifying the observation myself; but I may state that I attach no more importance to this circ.u.mstance than I should to verifying an observation of my own; for as a careful observer of animals I have quite as much confidence in my sister as in myself. It only remains to explain that my mother, being an invalid, is confined most of the time to her bedroom; and that the monkey was kept there for the first six weeks of his stay at her house, partly in order that he might be under constant observation, and partly also to furnish her with an entertaining pet. The following are my sister's notes _in extenso_ and without alteration:--

_Brown Capuchin_ (_Cebus fatuellus_--Linn.), _Brazil_.

DIARY, 1880.

_December_ 18th. Arrived in box with keeper. Seemed rather frightened and screamed a good deal on being transferred from small box to a larger one.

19th. Took him out of the box he had been in all night and fastened chain on to collar. Was meek and subdued, hiding his face in my lap.

20th. Has become much more lively and somewhat aggressive, especially towards the servants. He has taken a fancy to my mother, and (she holding his chain) he plays with her in a gentle and affectionate manner in her bed, but flies angrily at any of the servants who come near the bed. I observed to-day that he breaks walnuts (which are too hard for him to crack with his teeth) by striking them with the flat bottom of a dish he has for drinking out of. He is ceaselessly active all day, and at night covers himself very neatly with warm shawls, and sleeps soundly till about eight o'clock.

21st. I notice that the love of mischief is very strong in him. To-day he got hold of a wine-gla.s.s and an egg-cup. The gla.s.s he dashed on the floor with all his might, and of course broke it. Finding, however, that the egg-cup would not break for being thrown down, he looked round for some hard substance against which to dash it. The post of the bra.s.s bedstead appearing to be suitable for the purpose, he raised the egg-cup high over his head and gave it several hard blows. When it was completely smashed he was quite satisfied. He breaks a stick by pa.s.sing it down between a heavy object and the wall, and then hanging on to the end, thus breaking it across the heavy object. He frequently destroys an article of dress by carefully pulling out the threads (thus unripping it) before he begins to tear it with his teeth in a more violent manner. If he gets hold of anything that he sees we do not care about, he soon leaves it again; but if it is an article of value (even if it be only a sc.r.a.p of paper) which he sees we are anxious about, nothing will induce him to give it up. No food, however inviting, will distract his attention: scolding only makes him more angry, and he keeps the article until it is quite destroyed. To-day I gave him a hammer to break his walnuts with, and he uses it in a proper manner for that purpose.

22nd. To-day a strange person (a dressmaker) came into the room where he is tied up, and I gave him a walnut that she might see him break it with his hammer. The nut was a bad one, and the woman laughed at his disappointed face. He then became very angry, and threw at her everything he could lay hands on; first the nut, then the hammer, then a coffee-pot which he seized out of the grate, and, lastly, all his own shawls. He throws things with great force and precision by holding them in both hands, and extending his long arms well back over his head before projecting the missile, standing erect the while.

23rd. There is continual war between him and Sharp [a small terrier], but they both seem to have a certain mutual respect for each other. The dog makes s.n.a.t.c.hes at nuts, &c., and runs away with them beyond the reach of his chain, and the monkey catches at the dog, but seems afraid to hold him or hurt him. He however pelts him with nuts or bits of carrot, and chatters at him.

At other times he holds out his hand as if to make friends, but the dog is too suspicious to go near him.

His hostility towards the servants (one especially) increases, so that he will not even take a nut from her without catching fiercely at her hand; he also frequently throws things at her. On the other hand, he allows my mother to do anything with him.

24th. He bit me in several places to-day when I was taking him away from my mother's bed after his morning's game there. I took no notice, but he seemed ashamed of himself afterwards, hiding his face in his arms and sitting quiet for a time.[280] In accordance with his desire for mischief, he is of course very fond of upsetting things, but he always takes great care they do not fall on himself. Thus he will pull a chair towards him till it is almost over-balanced, then he intently fixes his eyes on the top bar of the back, and when he sees it coming over his way, darts from underneath and watches the fall with great delight; and similarly with heavier things. There is a washhand-stand, for example, with a heavy marble top, which he has with great labour upset several times, and always without hurting himself.[281]

25th. I observed to-day that if a nut or any object he wishes to get hold of is beyond the reach of his chain, he puts out a stick to draw it towards him, or, if that does not succeed, he stands upright and throws a shawl back over his head, holding it by the two corners so that it falls down his back; he then throws it forward with all his strength, still holding on by the corners; thus it goes out far in front of him and covers the nut, which he then draws towards him by pulling in the shawl. When his chain becomes twisted round the bars of a 'clothes-horse' (which is given him to run about upon), and thus too short for his comfort, he looks at it intently and pulls it with his fingers this way and that, and when he sees how the turns are taken, he deliberately goes round and round the bars, first this way, then that, until the chain is quite disentangled. He often carries his chain grasped in his tail and held high over his back to keep it from getting into the way of his feet. He is always rather excited in the morning when I loosen his chain preparatory to taking him to my mother's bed; jumps about and tugs at the chain. Sometimes, however, if the chain is entangled, and I am rather long in getting it unfastened, he sits quietly down beside me, and begins picking at the chain with his fingers as if to help me to untie it. I cannot say, however, that he succeeds in helping me at all.

26th. He seems very fond of spinning things round. If he gets a whole apple or orange he generally sits spinning it on one end, before beginning to eat it. He eats an orange by biting off a tiny piece of the peel, and putting his long, thin finger deep into the fruit; he then lays the whole orange under a piece of wire netting he has near him, and, putting his mouth to the hole he has made, presses the wire netting down upon the fruit, thus squeezing the juice up into his mouth.

When a good deal of juice begins to run out, he holds the orange up over his head and lets the juice run into his mouth.

27th. To-day he obtained possession of a rather valuable doc.u.ment, and, as usual, nothing I could do would persuade him to give it up. He neglected any kind of food I offered him, and only chattered when I coaxed him. When at last I tried threatening him with a cane, he only became savage and flew at me, chattering. My mother now came and sat down in a chair beside him. He immediately jumped into her lap, and remained quite still while she took the paper out of his hands. When, however, she handed it to me and I laughed at her success, he showed his teeth and screamed and chattered at me angrily. I find laughing generally irritates him. Thus, when he is playing with my mother in the bed in the best of humour, as long as I sit quietly on the bed all is well, but if I laugh, for example at any of his affectionate glances, he makes a dart at me to send me off, and then returns with renewed demonstrations of affection to my mother, tumbling head over heels and lying on his back, grinning in a most comical manner, and making a sound very like slight laughter.

28th. His chain is fastened to the marble slab of a washhand-stand, placed on the floor against the wall.

It is too heavy for him to pull along by his chain without hurting himself, so when he desires to do any mischief which is beyond the reach of his chain, he deliberately goes to the marble and pushes an arm down between an upright part of it and the wall, until he has moved the whole slab sufficiently far from the wall to admit of his slipping down behind the upright part himself. He then places his back against the wall and his four hands against the upright part of the marble, and pushes the slab as far as he can stretch his long legs. He only does this, however, when he is bent on mischief, as the fact of food being beyond the reach of his chain does not furnish a strong enough inducement to lead him to take so much exertion. Thus to-day he began to pull the glazed leather cover off a trunk which was near him. I pulled the trunk away, and when he found it was out of his reach he ran and pushed the marble towards the trunk in the manner I have described, and when he knew his chain was then sufficiently long to reach the trunk, he ran to the latter and hastily resumed his destructive process.

29th. I notice that nothing the person does who has hold of his chain offends him. I mean, although he is furiously angry at having anything taken away from him, he is not at all angry if he is pulled away by his chain. If he is trying to bite a person, and another person takes hold of his chain behind him and so prevents his spring forward, he does not turn to bite the person who has taken hold of his chain, as a dog would do under similar circ.u.mstances, but quietly submits to be thus held. He seems to look upon his confinement and management by a chain as a natural law against which it is useless to struggle. On the other hand, he seems to be quite aware of the place where his chain is fastened, and to know that if he were clever enough to undo it he would be free. After we found he could move about the marble slab of the washhand-stand in the way described, we had a ring sunk in the floor to tie him to. The moment the chain was fastened to that[282] he began to investigate its new connection, and continued to do so for hours, pa.s.sing the chain rapidly backward and forwards through the ring. When he found this did not loosen it, he began to hammer it and the ring also with all his strength, and this he continued to do for the rest of the day.

30th. He still continues to work at the chain where it is fastened to the ring. He pa.s.sed the whole of the chain through the ring so many times with his fingers that it became quite blocked up in the ring, which made it very short, and it took me a quarter of an hour to disentangle it. He was very much interested in this process, sitting quietly beside me and watching my fingers intently, sometimes gently pulling my fingers on one side in order to see better, and sometimes casting a quick intelligent glance into my face as if asking how I did it. After I had disentangled and lengthened the chain he worked at it again for hours, but took care not to twist it into the ring a second time.

31st. To-day he hurt himself by getting one of his toes caught in a hinge of the clothes-horse. He did not make any fuss, although the accident must have been somewhat a painful one, nor did he try to pull the toe out, which would have been useless and only hurt him more; but he sat almost motionless, making slight complaining noises until I discovered that there was something wrong with him. When I began to extricate his foot, he remained perfectly pa.s.sive--although I dare say I hurt him a good deal--and only looked at me gratefully.

_January_ 1, 1881. He has now quite given up trying to loosen his chain himself; having tried every way and failed, he has evidently become hopeless about it. He now resents being tied up. When I loosen him he is quite pleased, and when I tie him he waits until he is quite sure he is being tied, and not loosened, and then he flies at me and bites me.

10th. As he is always tied up in the same place he has no new opportunities given him of showing his intelligence. His attachment to my mother has increased. When she goes out he immediately gives up all play and mischief, and does nothing but run round and round in a restless manner, making a peculiar sweet calling noise, such as he never makes when she is in the room, listening intently between times. As long as she remains away he takes no rest or amus.e.m.e.nt, nor does he ever, or hardly ever, become angry; but the moment she returns he begins all his old ways again, usually becoming more savage at other people than before.

My mother frequently takes things away from him, and he never resents it to her as he would do to any other person. He generally, however, chatters angrily at some one else when my mother removes anything he wishes to keep. At first I thought he was deceived in the matter--that he could not believe it possible that his best friend could deprive him of what he valued, and so thought someone else must have done it. But the same thing has now happened so frequently that I can hardly think he is not really aware of who takes the things away. He seems rather to think it politic to keep on good terms with one person, and that although he does see her remove the things, and feels angry in consequence, he thinks it more prudent to vent his anger upon someone with whom he has already quarrelled. He always shows more irritation when my mother gives anything to me after having taken it away from him, than when she keeps it herself (as mentioned on December 26), and this may be the reason partly why he resents these matters to me; he thinks when I obtain possession of anything he wants that it is a sort of triumph to me. In the same way my mother may laugh as much as she likes whether he is with her or not, but if I laugh at all at anything it generally results in something being thrown at me. If my mother calls out to the servants--if, for instance, a servant has left the room and my mother calls her back--he becomes very angry at the servant, and salutes her on her return with a shower of missiles. Sometimes my mother pretends to scold or beat the servants, and then he joins with great energy, by way of supporting his friend. If I scold or beat the servants he does not mind so much. When my mother comes back after being out he does not show any great demonstrations of joy. He screams out with pleasure when he hears her voice approaching on the stairs, but does not make much ado when she enters the room. While my mother is out I can do anything I like with him, just as she can when she is at home. Perhaps being in low spirits he does not feel angry, or perhaps he thinks it prudent to be amiable when his best friend is away. When my mother comes back, all his ill-temper returns at once and even in an increased degree towards other people, and he immediately resumes playing with all his toys.

11th. When he throws things at people now he first runs up the bars of the clothes-horse; he seems to have found out that people do not much care for having things thrown at their feet, and he is not strong enough to throw such heavy objects as a poker or a hammer at people's heads; he therefore mounts to a level with his enemy's head, and thus succeeds in sending his missile to a greater height and also to a greater distance.

14th. To-day he obtained possession of a hearth-brush, one of the kind which has the handle screwed into the brush. He soon found the way to unscrew the handle, and having done that he immediately began to try to find out the way to screw it in again. This he in time accomplished. At first he put the wrong end of the handle into the hole, but turned it round and round the _right way for s.c.r.e.w.i.n.g_. Finding it did not hold, he turned the other end of the handle and carefully stuck it into the hole, and began again to turn it the right way. It was of course a very difficult feat for him to perform, for he required both his hands to hold the handle in the proper position and to turn it between his hands in order to screw it in, and the long bristles of the brush prevented it from remaining steady or with the right side up. He held the brush with his hind hand, but even so it was very difficult for him to get the first turn of the screw to fit into the thread; he worked at it, however, with the most unwearying perseverance until he got the first turn of the screw to catch, and he then quickly turned it round and round until it was screwed up to the end.

The most remarkable thing was that, however often he was disappointed in the beginning, he never was induced to try turning the handle the wrong way; he always screwed it from right to left. As soon as he had accomplished his wish, he unscrewed it again, and then screwed it in again the second time rather more easily than the first, and so on many times. When he had become by practice tolerably perfect in s.c.r.e.w.i.n.g and uns.c.r.e.w.i.n.g, he gave it up and took to some other amus.e.m.e.nt. One remarkable thing is that he should take so much trouble to do that which is no material benefit to him. The desire to accomplish a chosen task seems a sufficient inducement to lead him to take any amount of trouble. This seems a very human feeling, such as is not shown, I believe, by any other animal.

It is not the desire of praise, as he never notices people looking on; it is simply the desire to achieve an object for the sake of achieving an object, and he never rests nor allows his attention to be distracted until it is done.

16th. When he is angry, and has at hand only those things which he wishes to keep, he makes a great show of throwing them at people, but always retains a hold.

Thus if he has had a plaything a long time and is tired of it, he throws it right at a person without the least hesitation; but if he has a new thing which he values, he goes through all the appropriate motions for throwing, but only brings the object down with a noise upon the ground, taking care not to let go his hold. He beats people with a long cane he has, and when he cannot reach people he strikes it with all his strength upon the ground to show what he would do if he had the chance. There is no more comical sight than to see him hurriedly climbing his screen in fierce anger, taking (not without great difficulty) his long and awkward stick up with him in order to be high enough to give a good blow to a person. The dog is quite afraid of the stick in the monkey's hands, although he is too petted to be afraid of it in a person's. The monkey is jealous of the dog lying in the arm-chair in which he sometimes seats himself with my mother, so he pokes the stick at the dog (as the chair is beyond the reach of his chain) and makes him get off.

18th. He was very angry to-day at a servant girl sweeping out his place with a long brush, and he seized the brush every time the servant attempted to sweep. My mother then took it, and he at once became not only quite good-tempered, but a.s.sisted her in sweeping, by gathering the rubbish in the corners of his place into little heaps with his hands, and putting the heaps into the way of the brush.

20th. To-day he broke his chain, and flew at a servant savagely, but seeing my mother he immediately jumped into her lap. While another chain was being prepared he got to the trunk where his nuts are kept.

I have long noticed that he looks upon that trunk as in some special sense his own property. There are other things kept in the trunk as well as the nuts, and if any person goes to the trunk for anything he becomes furiously angry. Indeed nothing makes him so angry as people opening the trunk, and this is not because he wants nuts out of it, for he always has more than he can eat beside him, and generally refuses to take any that are offered to him. Well, to-day, as soon as the breaking of his chain enabled him to get to the trunk, he began picking at the lock with his fingers. I then gave him the key, and he tried for two full hours without ceasing to unlock the trunk with this key. It was a very difficult lock to open, being slightly out of order, and requires the lid of the trunk to be pressed down before it would work, so I believe it was absolutely impossible for him to open it, but he found in time the right way to put the key in, and to turn it backwards and forwards, and after every attempt he pulled the lid upwards to see if it were unlocked. That this was the result of observing people is obvious, from the fact that after every time he put the key into the lock and failed to open the trunk, he pa.s.sed the key round and round the outside of the lock several times. The explanation of this is that, my mother's sight being bad, she often misses the lock when putting in the key, and then feels round and round the lock with the key; the monkey therefore evidently seems to think that this feeling round and round the lock with the key is in some way necessary to the success of unlocking the lock, so that, although he could see perfectly well how to put the key in straight himself, he went through this useless operation first.

21st. To-day I gave him a wooden box with the lid nailed on, and an iron spoon, to see if he would use the latter as a lever wherewith to raise the lid. The experiment was somewhat spoiled by my mother putting the handle of the spoon into the crack between the lid and the box to show him how to do it. Therefore I cannot tell whether or not he would have taken this first step himself, if he had had time to do so.

However, when the handle of the spoon was in he certainly used it in the proper manner, pulling it down with all his strength at the extreme end, thus drawing the nails out of the box and raising the lid.