The Mind of the Mammal
When we watch a collie at a sheep-driving competition, or an elephant helping the forester, or a horse shunting waggons at a railway siding, we are apt to be too generous to the mammal mind. For in the cases we have just mentioned, part of man's mind has, so to speak, got into the animal's. On the other hand, when we study rabbits and guinea-pigs, we are apt to be too stingy, for these rodents are under the average of mammals, and those that live in domestication illustrate the stupefying effect of a too sheltered life. The same applies to domesticated sheep contrasted with wild sheep, or even with their own lambs. If we are to form a sound judgment on the intelligence of mammals we must not attend too much to those that have profited by man's training, nor to those whose mental life has been dulled by domestication.
What is to be said of the behaviour of beavers who gnaw the base of a tree with their chisel-edged teeth till only a narrow core is left—to snap in the first gale, bringing the useful branches down to the ground? What is to be said of the harvest-mouse constructing its nest, or of the squirrel making cache after cache of nuts? These and many similar pieces of behaviour are fundamentally instinctive, due to inborn predispositions of nerve-cells and muscle-cells. But in mammals they seem to be often attended by a certain amount of intelligent attention, saving the creature from the tyranny of routine so marked in the ways of ants and bees.
Besides instinctive aptitudes, which are exhibited in almost equal perfection by all the members of the same species, there are acquired dexterities which depend on individual opportunities. They are also marked by being outside and beyond ordinary routine—not that any rigorous boundary line can be drawn. We read that at Mathura on the Jumna doles of food are provided by the piety of pilgrims for the sacred river-tortoises, which are so crowded when there is food going that their smooth carapaces form a more or less continuous raft across the river. On that unsteady slippery bridge the Langur monkeys (Semnopithecus entellus) venture out and in spite of vicious snaps secure a share of the booty. This picture of the monkeys securing a footing on the moving mass of turtle-backs is almost a diagram of sheer dexterity. It illustrates the spirit of adventure, the will to experiment, which is, we believe, the main motive-force in new departures in behaviour.
Power of Association
A bull-terrier called Jasper, studied by Prof. J. B. Watson, showed great power of associating certain words with certain actions. From a position invisible to the dog the owner would give certain commands, such as "Go into the next room and bring me a paper lying on the floor." Jasper did this at once, and a score of similar things.
Lord Avebury's dog Van was accustomed to go to a box containing a small number of printed cards and select the card TEA or OUT, as the occasion suggested. It had established an association between certain black marks on a white background and the gratification of certain desires. It is probable that some of the extraordinary things horses and dogs have been known to do in the way of stamping a certain number of times in supposed indication of an answer to an arithmetical question (in the case of horses), or of the name of an object drawn (in the case of dogs), are dependent on clever associations established by the teacher between minute signs and a number of stampings. What is certain is that mammals have in varying degrees a strong power of establishing associations. There is often some delicacy in the association established. Everyone knows of cases where a dog, a cat, or a horse will remain quite uninterested, to all appearance, in its owner's movements until some little detail, such as taking a key from its peg, pulls the trigger. Now the importance of this in the wild life of the fox or the hare, the otter or the squirrel, is obviously that the young animals learn to associate certain sounds in their environment with definite possibilities. They have to learn an alphabet of woodcraft, the letters of which are chiefly sounds and scents.
The Dancing Mouse as a Pupil
The dancing or waltzing mouse is a Japanese variety with many peculiarities, such as having only one of the three semicircular canals of the ear well developed. It has a strong tendency to waltz round and round in circles without sufficient cause and to trip sideways towards its dormitory instead of proceeding in the orthodox head-on fashion. But this freak is a very educable creature, as Professor Yerkes has shown. In a careful way he confronted his mouse-pupil with alternative pathways marked by different degrees of illumination, or by different colours. If the mouse chose compartment A, it found a clear passage direct to its nest; if it chose compartment B, it was punished by a mild electric shock and it had to take a roundabout road home. Needless to say, the A compartment was sometimes to the right hand, sometimes to the left, else mere position would have been a guide. The experiments showed that the dancing mice learn to discriminate the right path from the wrong, and similar results have been got from other mammals, such as rats and squirrels. There is no proof of learning by ideas, but there is proof of learning by experience. And the same must be true in wild life.
Many mammals, such as cats and rats, learn how to manipulate puzzle-boxes and how to get at the treasure at the heart of a Hampton Court maze. Some of the puzzle-boxes, with a reward of food inside, are quite difficult, for the various bolts and bars have to be dealt with in a particular order, and yet many mammals master the problem. What is plain is that they gradually eliminate useless movements, that they make fewer and fewer mistakes, that they eventually succeed, and that they register the solution within themselves so that it remains with them for a time. It looks a little like the behaviour of a man who learns a game of skill without thinking. It is a learning by experience, not by ideas or reflection. Thus it is very difficult to suppose that a rat or a cat could form any idea or even picture of the Hampton Court maze—which they nevertheless master.
Given sufficient inducement many of the cleverer mammals will learn to do very sensible things, and no one is wise enough to say that they never understand what they are doing. Yet it is certain that trained animals often exhibit pieces of behaviour which are not nearly so clever as they look. The elephant at the Belle Vue Gardens in Manchester used to collect pennies from benevolent visitors. When it got a penny in its trunk it put it in the slot of an automatic machine which delivered up a biscuit. When a visitor gave the elephant a halfpenny it used to throw it back with disgust. At first sight this seemed almost wise, and there was no doubt some intelligent appreciation of the situation. But it was largely a matter of habituation, the outcome of careful and prolonged training. The elephant was laboriously taught to put the penny in the slot and to discriminate between the useful pennies and the useless halfpennies. It was not nearly so clever as it looked.
Using their Wits
In the beautiful Zoological Park in Edinburgh the Polar Bear was wont to sit on a rocky peninsula of a water-filled quarry. The visitors threw in buns, some of which floated on the surface. It was often easy for the Polar Bear to collect half a dozen by plunging into the pool. But it had discovered a more interesting way. At the edge of the peninsula it scooped the water gently with its huge paw and made a current which brought the buns ashore. This was a simple piece of behaviour, but it has the smack of intelligence—of putting two and two together in a novel way. It suggests the power of making what is called a "perceptual inference."
On the occasion of a great flood in a meadow it was observed that a number of mares brought their foals to the top of a knoll, and stood round about them protecting them against the rising water. A dog has been known to show what was at any rate a plastic appreciation of a varying situation in swimming across a tidal river. It changed its starting-point, they say, according to the flow or ebb of the tide. Arctic foxes and some other wild mammals show great cleverness in dealing with traps, and the manipulative intelligence of elephants is worthy of all our admiration.
Why is there not more Intelligence?
When we allow for dexterity and power of association, when we recognise a certain amount of instinctive capacity and a capacity for profiting by experience in an intelligent way, we must admit a certain degree of disappointment when we take a survey of the behaviour of mammals, especially of those with very fine brains, from which we should naturally expect great things. Why is there not more frequent exhibition of intelligence in the stricter sense?
The answer is that most mammals have become in the course of time very well adapted to the ordinary conditions of their life, and tend to leave well alone. They have got their repertory of efficient answers to the ordinary questions of everyday life, and why should they experiment? In the course of the struggle for existence what has been established is efficiency in normal circumstances, and therefore even the higher animals tend to be no cleverer than is necessary. So while many mammals are extraordinarily efficient, they tend to be a little dull. Their mental equipment is adequate for the everyday conditions of their life, but it is not on sufficiently generous lines to admit of, let us say, an interest in Nature or adventurous experiment. Mammals always tend to "play for safety."
We hasten, however, to insert here some very interesting saving clauses.
Experimentation in Play
A glimpse of what mammals are capable of, were it necessary, may be obtained by watching those that are playful, such as lambs and kids, foals and calves, young foxes and others. For these young creatures let themselves go irresponsibly, they are still unstereotyped, they test what they and their fellows can do. The experimental character of much of animal play is very marked.
It is now recognised by biologists that play among animals is the young form of work, and that the playing period, often so conspicuous, is vitally important as an apprenticeship to the serious business of life and as an opportunity for learning the alphabet of Nature. But the playing period is much more; it is one of the few opportunities animals have of making experiments without too serious responsibilities. Play is Nature's device for allowing elbow-room for new departures (behaviour-variations) which may form part of the raw materials of progress. Play, we repeat, gives us a glimpse of the possibilities of the mammal mind.
Other Glimpses of Intelligence
A squirrel is just as clever as it needs to be and no more; and of some vanishing mammals, like the beaver, not even this can be said. Humdrum non-plastic efficiency is apt to mean stagnation. Now we have just seen that in the play of young mammals there is an indication of unexhausted possibilities, and we get the same impression when we think of three other facts. (a) In those mammals, like dog and horse, which have entered into active cooperative relations with man, we see that the mind of the mammal is capable of much more than the average would lead us to think. When man's sheltering is too complete and the domesticated creature is passive in his grip, the intelligence deteriorates. (b) When we study mammals, like the otter, which live a versatile life in a very complex and difficult environment, we get an inspiriting picture of the play of wits. (c) Thirdly, when we pass to monkeys, where the fore-limb has become a free hand, where the brain shows a relatively great improvement, where "words" are much used, we cannot fail to recognise the emergence of something new—a restless inquisitiveness, a desire to investigate the world, an unsatisfied tendency to experiment. We are approaching the Dawn of Reason.