Popular Science Monthly/Volume 23/May 1883/How Much Animals Know
NO phenomena in nature are watched with more interest by all classes, young and old, ignorant and educated, than the displays of intelligence in the inferior animals. From the dog, which occupies a position of intelligent companionship with man, down through the less favored species even to the lowest groups of animal life, we see manifested all degrees of that wonderful attribute which in its highest perfection constitutes the human mind. It is not surprising that these various indications of something like a capacity for thought should be of universal interest, but it also has a deeper meaning, which it is the office of science and philosophy to explore, and which relates to the profound and mysterious problem of "mind in nature." Before philosophy can make much headway with this question, however, there must be a more critical scrutiny of the question as to what degrees of intelligence different grades of animals really possess. Dr. George J. Romanes, in his recent interesting book on "Animal Intelligence," engages with this subject as a scientific question of comparative psychology, and he has done a good deal toward winnowing away the fictions that have become current in relation to the mental manifestations of the lower tribes, and has given us probably the most trustworthy book extant upon the subject. We cull from his pages a series of representative instances of animal sagacity which the reader will find both entertaining and instructive.
It is common to quote the oyster as the lowest example of stupidity, or absence of anything mental, and, as it is a headless creature, the accusation might not seem wholly unfounded. Yet the oyster is not such a fool but that it can learn by experience, for Dicquemase asserts that, if it be taken from a depth never uncovered by the sea, it opens its shell, loses the water within, and perishes. But oysters taken from the same depth, if kept in reservoirs where they are occasionally left uncovered for a short time, learn to keep their shells closed, and then live for a much longer time when taken out of the water.
This fact is also stated by Bingley, and is now turned to practical account in the so-called "oyster-schools" of France. The distance from the coast to Paris being too great for the newly-dredged oysters to travel without opening their shells, they are first taught in the schools to bear a longer and longer exposure to the air without gaping, and when their education in this respect is completed, they are sent on their journey to the metropolis, where they arrive with closed shells and in a healthy condition.
The social life of ants has many parallels to that of the barbarous races of human beings. Thus, the habit of making slaves is said to obtain among at least three species of ant. A community attacks a nest of another species in a body; there is a great fight with much slaughter, and, if victorious, the slave-makers carry off the pupae of the vanquished nest in order to hatch them out as slaves. When the pupae hatch out in the nest of their captors, the young slaves begin their life of work, and seem to regard their masters' home as their own; for they never attempt to escape, and they fight no less keenly than their masters in defense of the nest. In the nests of Formica sanguinea the comparatively few captives are kept as household slaves. They never leave the nest, and so all the out-door work of foraging, slave-capturing, etc., is performed by the masters.
F. rufescens, on the other hand, assigns a much larger share of labor to the slaves. In this species the males and fertile females do no work of any kind, and the workers, or sterile females, though most energetic in capturing slaves, do no other kind of work. Therefore the whole community is absolutely dependent upon its slaves. Huber shut up thirty masters without a slave and with abundance of their favorite food, and also with their own larvæ and pupæ as a stimulus to work; but they could not feed even themselves, and many died of hunger. He then introduced a single slave, and she at once set to work, fed the surviving masters, attended to the larvæ, and made some cells.
A predatory expedition of ants for capturing slaves, or robbing the storehouse of another nest, marches out in a close column numbering from a few hundreds to several thousands. The army is guided to its destination, which may be an hour's march distant, by several ants who run from side to side with heads down, evidently finding their way by scent. A marauding excursion of the F. rufescens, or Amazons, against the F. rufibarbis, a sub-species of the F.fusca, or small black ants, took place as follows: The vanguard of the robber army found that it had reached the neighborhood of the hostile nest more quickly than it had expected; for it halted suddenly and decidedly, and sent a number of messengers which brought up the main body and the rear-guard with incredible speed. In less than thirty seconds the whole army had closed up, and hurled itself in a mass on the dome of the hostile nest. This was the more necessary, as the rufibarbes during the short halt had discovered the approach of the enemy, and had utilized the time to cover the dome with defenders. An indescribable struggle followed, but the superior numbers of the Amazons overcame, and they penetrated into the nest, while the defenders poured by thousands out of the same holes, with their larvae and pupae in their jaws, and escaped to the nearest plants and bushes, running over the heaps of their assailants. These looked on the matter as hopeless, and began to retreat. But the rufibarbes, furious at their proceedings, pursued them, and endeavored to get away from them the few pupa? they had obtained, by trying to seize the Amazons' legs and to snatch away the pupae. The Amazon lets its jaws slip slowly along the captive pupa, as far as the head of its opponent, and pierces it, if it does not, as generally happens, draw back. But it often manages to seize the pupa at the instant at which the Amazon lets it go, and flees with it. This is managed the more easily when a comrade holds the robber by the legs, and compels it to loose its prey in order to guard itself against its assailant. The strength of the rufibarbes proved at last so great that the rear-guard of the retreating army was seriously pressed, and was obliged to give up its booty. A number of the Amazons also were overpowered and killed, but not without the rufibarbes also losing many people. Nevertheless, some individuals, as though desperate, rushed into the thickest hosts of the enemy, penetrated again into the nest, and carried off several pupæ by sheer audacity and skill. Ten minutes after the commencement of the retreat, all the Amazons had left the nest, and, being swifter than their opponents, they were only pursued for about half-way back. Their attack had failed on account of a short delay.
It seems to be a pretty general habit among many species of ants to dispose of the dead bodies of their comrades very carefully. The following especially notable account is given by an Australian observer:
"I saw a large number of ants surrounding the dead ones, and determined to watch their proceedings closely. I followed four or five that started off from the rest toward a hillock a short distance off, in which was an ants' nest. This they entered, and in about five minutes they reappeared, followed by others. All fell into rank, walking regularly and slowly two by two, until they arrived at the spot where lay the dead bodies of the soldier-ants. In a few minutes two of the ants advanced and took up the dead body of one of their comrades; then two others, and so on, until all were ready to march. First walked two ants bearing a body, then two without a burden; then two others with another dead ant, and so on, until the line was extended to about forty pairs, and the procession now moved slowly onward, followed by an irregular body of about two hundred ants. Occasionally the two laden ants stopped, and, laying down the dead ant, it was taken up by the two walking unburdened behind them, and thus, by occasionally relieving each other, they arrived at a sandy spot near the sea. The body of ants now commenced digging with their jaws a number of holes in the ground, into each of which a dead ant was laid, where they now labored on until they had filled up the ants' graves. This did not quite finish the remarkable circumstances attending this funeral of the ants. Some six or seven of the ants had attempted to run off without performing their share of the task of digging; these were caught and brought back, when they were at once attacked by the body of ants and killed. A single grave was quickly dug, and they were all dropped into it."
A remarkable acquaintance with mechanical principles is shown by spiders in building and attaching their webs. This ingenuity is perhaps most strikingly shown in making the repairs that some accident has necessitated. A web had been broken from one of its attachments during a storm and flapped violently in the wind. The spider let itself down to the ground, and crawled to a place where lay some splintered pieces of a wooden fence thrown down by the storm. It fastened a thread to one of the bits of wood, turned back with it, and hung it to the lower part of its nest, about five feet from the ground. The performance was a wonderful one, for the weight of the wood sufficed to keep the nest tolerably firm, while it was yet light enough to yield to the wind, and so prevent further injury. The piece of wood was about two and a half inches long, and as thick as a goose quill. On the following day a careless servant knocked her head against the wood and it fell down. But in the course of a few hours the spider had found it and brought it back to its place. When the storm ceased the spider mended her web, broke the supporting thread, and let the wood fall to the ground!
The following interesting observation on the intelligence of snakes shows, not only that these animals are well able to distinguish persons, but also that they possess an intensity of amiable emotion scarcely to be expected in this class. A writer to the London "Times" thus describes the behavior of some pet snakes kept by a gentleman and lady of his acquaintance:
"Mr. M——, after we had talked for a little time, asked if I had any fear of snakes; and after a timid 'No, not very,' from me, he produced out of a cupboard a large boa-constrictor, a python, and several small snakes, which at once made themselves at home on the writing table among pens, ink, and books. I was at first a good deal startled, especially when the two large snakes coiled round and round my friend, and began to notice me with their bright eyes and forked tongues; but soon finding how tame they were, I ceased to feel
frightened. After a short time Mr. M——expressed a wish to call Mrs. M——, and left me with the boa deposited on an arm-chair. I felt a little queer when the animal began gradually to come near, but the entrance of my host and hostess, followed by two charming little children, put me at my ease again. After the first interchange of civilities, she and the children went at once to the boa, and, calling it by the most endearing names, allowed it to twine itself most gracefully round about them. I sat talking for a long time, lost in wonder at the picture before me. Two beautiful little girls and their charming mother sat before me with a boa-constrictor (as thick as a small tree) twining playfully round the lady's waist and neck, and forming a kind of turban round her head, expecting to be petted and made much of like a kitten. The children, over and over again, took its head in their hands and kissed its mouth, pushing aside its forked tongue in doing so. The animal seemed much pleased, but kept turning its head continually toward me with a curious gaze, until I allowed it to nestle its head for a moment up my sleeve. Nothing could be prettier than to see this splendid serpent coiled all round Mrs. M——while she moved about the room and when she stood to pour out our coffee. He seemed to adjust his weight so nicely, and every coil with its beautiful marking was relieved by the black velvet dress of the lady. It was long before I could make up my mind to end the visit."
Birds often show much ingenuity in attaining some desired end. Several stories are told of geese which show that they are by no means such scant-witted fowls as the common use of their name implies. Thus at Ardglass, county Down, Ireland, is a long tract of turf coming to the edge of the rocks overhanging the sea, where cattle and geese feed: at a barn on this tract there was a low inclosure, with a door fastening by a hook and staple to the side-post: when the hook was out of the staple the door fell open by its own weight. One day a goose with a large troop of goslings was seen coming off the turf to this door, which was secured by the hook being in the staple. The goose waited for a minute or two as if for the door to be opened, and then turned round as if to go away, but what she did was to make a rush at the door, and making a dart with her beak at the point of the hook nearly threw it out of the staple; she repeated this manœuvre, and succeeded at the third attempt, the door fell open, and the goose led her troop in with a sound of triumphant chuckling. How had the goose learned that the force of the rush was needful to give the hook a sufficient toss?
The intelligence of crows is well attested by the following account contributed by a lady: "In the inn-garden I saw a dog eating a piece of carrion in the presence of several of these covetous birds. They evidently said a great deal to each other on the subject, and now and then one or two of them tried to pull the meat away from him, which he resented. At last a big strong crow succeeded in tearing off a piece, with which he returned to the pine where the others were congregated, and after much earnest speech they all surrounded the dog, and the leading bird dexterously dropped the small piece of meat within reach of his mouth, when he immediately snapped at it, letting go the big piece unwisely for a second, on which two of the crows flew away with it to the pine, and with much fluttering and hilarity they all ate, or rather gorged it, the deceived dog looking vacant and bewildered for a moment, after which he sat under the tree and barked at them inanely."
Crows have also been observed to hold general assemblies whose functions seem to be those of a criminal court. It often takes a day or two for the meeting to assemble; a palaver is then held, at the close of which the whole body sets upon two or three apparent culprits and kills them. No witness of such a scene can fail to be convinced that the accused have had a fair trial, and have not been put to death without cause.
The higher mental faculties are more developed in the elephant than in any other animal, except the dog and the monkey. The general fact that elephants are habitually employed in parts of India for storing timber, building, etc., shows a high level of docile intelligence. But perhaps in no labor in which they are employed do they display a more wonderful sagacity than in helping to catch wild elephants. A herd of wild elephants is driven into a corral, and two tame ones ridden in among them. The decoys will crowd up on either side of a wild one, and protect the nooser until a rope is fastened round the wild elephant's leg, when the tame one, to whose collar the other end of the rope is attached, will drag the captive out, and wind the rope round a tree, while the other decoy prevents any interference from the herd, and pushes the captive toward the tree, thus enabling the first one to take in the slack of the rope. The conduct of the tame ones during all these proceedings is truly wonderful. They display the most perfect conception of every movement, both of the object to be attained and of the means to accomplish it. On one occasion, in tying up a large elephant, he contrived, before he could be hauled close up to the tree, to walk once or twice round it, carrying the rope with him; the decoy, perceiving the advantage he had thus gained over the nooser, walked up of her own accord, and pushed him backward with her head, till she made him unwind himself again; upon which the rope was hauled tight and made fast.
One could almost fancy there was a display of dry humor in the manner in which the decoys thus play with the fears of the wild herd, and make light of their efforts at resistance. When reluctant they shove them forward, when violent they drive them back; when the wild ones throw themselves down, the tame ones butt them with head and shoulders and force them up again; and, when it is necessary to keep them down, they kneel upon them, and prevent them from rising, till the ropes are secured.
A remarkable degree of cunning was displayed by an elephant who had been chained to a tree, and whose driver had then made an oven at a short distance, into which he put some rice-cakes to bake. The man covered his cakes with stones and grass, and went away. When he was gone, the elephant with his trunk unfastened the chain round his foot, went to the oven and uncovered it, took out and ate the cakes, re-covered the oven with the stones and grass as before, and went back to his place. He could not fasten the chain again round his own foot, so he twisted it round and round it, in order to look the same, and when the driver returned the elephant was standing with his back to the oven. The driver went for his cakes, discovered the theft, and, looking round, caught the elephant's eye as he looked back over his shoulder out of the corner of it. Instantly he detected the culprit, and condign punishment followed.
The well-known intelligence of the dog is seldom more curiously manifested than in the cases of those who learn the use of money. A gentleman in Birmingham was acquainted with a small mongrel dog who, on being presented with a penny or a half-penny, would run with it in his mouth to a baker's, jump on to the top of the half-door leading into the shop, and ring the bell behind the door until the baker came forward and gave him a bun or a biscuit in exchange for the coin. The dog would accept any small biscuit for a half-penny, but nothing less than a bun would satisfy him for a penny. On one occasion the baker (being annoyed at the dog's too frequent visits), after receiving the coin, refused to give the dog anything in exchange, and on every future occasion the latter (who declined being taken in a second time) would put the coin on the floor, and not permit the baker to pick it up until he had received its equivalent.
In what may be called the chief pursuit of dogs—that of game—they often show great ingenuity in overcoming unusual obstacles. A little Skye terrier was once observed snuffing about on a wheat-stack which was in the course of being thrashed, when suddenly a very large rat bounced off, just from under her nose. It darted into a pit of water about a dozen yards from the stack, and tried to escape. The Skye, however, plunged after, and swam for some distance, but found she was being left behind. So she turned to the shore again, and ran round to the other side of the pit, and was ready and caught it just on landing.
Another dog, which had been sent to bring in a couple of wounded ducks from across a pretty wide stream, at first attempted to bring them both, but one always struggled out of his mouth; he then laid down one, intending to bring the other, but, whenever he attempted to cross, the bird left fluttered into the water; he immediately returned again, laid down the first on the shore, and recovered the other. The first now fluttered away, but he instantly secured it, and, standing over them both, seemed to cogitate for a moment; then, although on any other occasion he never ruffled a feather, he deliberately killed one, brought over the other, and then returned for the dead bird.
An instance of sagacity—indeed, amounting to reason—in a French poodle is told by Canon——. Being a guest at luncheon with the dog's master, the canon fed the dog with pieces of beef. After luncheon the beef was taken into the larder. The dog did not think he had his fair share. What did he do? Now, he had been taught to stand on his hind-legs, put his paw on a lady's wrist, and hand her into the dining-room. He adopted the same tactics with the canon, stood on his hind-legs, put his paw on his arm, and made for the door. To see what would follow, Canon —— suffered himself to be led, but the sagacious dog, instead of steering for the dining-room, led him in the direction of the larder, along a passage, down steps, etc., and did not halt till he brought him to the larder, and close to the shelf where the beef had been put. The dog had a small bit given him for his sagacity, and Canon —— returned to the drawing-room. But the dog was still not satisfied. He tried the same trick again, but this time fruitlessly. The canon was not going again with him to the larder. What was Mori to do? And here comes the instance of reason in the poodle: Finding he could not prevail on the visitor to make a second excursion to the larder, he went out into the hall, took in his teeth the canon's hat from off the hall-table, and carried it under the shelf in the larder where the coveted beef lay out of his reach. There he was found, waiting for the owner of the hat, and expecting another savory bit when he should come for it.