THE MIND OF MONKEYS
There is a long gamut between the bushy-tailed, almost squirrel-like marmosets and the big-brained chimpanzee. There is great variety of attainment at different levels in the Simian tribe.
To begin at the beginning, it is certain that monkeys have a first-class sensory equipment, especially as regards sight, hearing, and touch. The axes of the two eyes are directed forwards as in man, and a large section of the field of vision is common to both eyes. In other words, monkeys have a more complete stereoscopic vision than the rest of the mammals enjoy. They look more and smell less. They can distinguish different colours, apart from different degrees of brightness in the coloured objects. They are quick to discriminate differences in the shapes of things, e.g. boxes similar in size but different in shape, for if the prize is always put in a box of the same shape they soon learn (by association) to select the profitable one. They learn to discriminate cards with short words or with signs printed on them, coming down when the "Yes" card is shown, remaining on their perch when the card says "No." Bred to a forest life where alertness is a life-or-death quality, they are quick to respond to a sudden movement or to pick out some new feature in their surroundings. And what is true of vision holds also for hearing.
Power of Manipulation
Another quality which separates monkeys very markedly from ordinary mammals is their manipulative expertness, the co-ordination of hand and eye. This great gift follows from the fact that among monkeys the fore-leg has been emancipated. It has ceased to be indispensable as an organ of support; it has become a climbing, grasping, lifting, handling organ. The fore-limb has become a free hand, and everyone who knows monkeys at all is aware of the zest with which they use their tool. They enjoy pulling things to pieces—a kind of dissection—or screwing the handle off a brush and screwing it on again.
Activity for Activity's Sake
Professor Thorndike hits the nail on the head when he lays stress on the intensity of activity in monkeys—activity both of body and mind. They are pent-up reservoirs of energy, which almost any influence will tap. Watch a cat or a dog, Professor Thorndike says; it does comparatively few things and is content for long periods to do nothing. It will be splendidly active in response to some stimulus such as food or a friend or a fight, but if nothing appeals to its special make-up, which is very utilitarian in its interests, it will do nothing. "Watch a monkey and you cannot enumerate the things he does, cannot discover the stimuli to which he reacts, cannot conceive the raison d'etre of his pursuits. Everything appeals to him. He likes to be active for the sake of activity."
This applies to mental activity as well, and the quality is one of extraordinary interest, for it shows the experimenting mood at a higher turn of the spiral than in any other creature, save man. It points forward to the scientific spirit. We cannot, indeed, believe in the sudden beginning of any quality, and we recall the experimenting of playing mammals, such as kids and kittens, or of inquisitive adults like Kipling's mongoose, Riki-Tiki-Tavi, which made it his business in life to find out about things. But in monkeys the habit of restless experimenting rises to a higher pitch. They appear to be curious about the world. The psychologist whom we have quoted tells of a monkey which happened to hit a projecting wire so as to make it vibrate. He went on repeating the performance hundreds of times during the next few days. Of course, he got nothing out of it, save fun, but it was grist to his mental mill. "The fact of mental life is to monkeys it own reward." The monkey's brain is "tender all over, functioning throughout, set off in action by anything and everything."
Correlated with the quality of restless inquisitiveness and delight in activity for its own sake there is the quality of quickness. We mean not merely the locomotor agility that marks most monkeys, but quickness of perception and plan. It is the sort of quality that life among the branches will engender, where it is so often a case of neck or nothing. It is the quality which we describe as being on the spot, though the phrase has slipped from its original moorings. Speaking of his Bonnet Monkey, an Indian macaque, second cousin to the kind that lives on the Rock of Gibraltar, Professor S. J. Holmes writes: "For keenness of perception, rapidity of action, facility in forming good practical judgments about ways and means of escaping pursuit and of attaining various other ends, Lizzie had few rivals in the animal world.... Her perceptions and decisions were so much more rapid than my own that she would frequently transfer her attention, decide upon a line of action, and carry it into effect before I was aware of what she was about. Until I came to guard against her nimble and unexpected manœuvres, she succeeded in getting possession of many apples and peanuts which I had not intended to give her except upon the successful performance of some task."
Quick to Learn
Quite fundamental to any understanding of animal behaviour is the distinction so clearly drawn by Sir Ray Lankester between the "little-brain" type, rich in inborn or instinctive capacities, but relatively slow to learn, and the "big-brain" type, with a relatively poor endowment of specialised instincts, but with great educability. The "little-brain" type finds its climax in ants and bees; the "big-brain" type in horses and dogs, elephants and monkeys. And of all animals monkeys are the quickest to learn, if we use the word "learn" to mean the formation of useful associations between this and that, between a given sense-presentation and a particular piece of behaviour.
The Case of Sally
Some of us remember Sally, the chimpanzee at the "Zoo" with which Dr. Romanes used to experiment. She was taught to give her teacher the number of straws he asked for, and she soon learned to do so up to five. If she handed a number not asked for, her offer was refused; if she gave the proper number, she got a piece of fruit. If she was asked for five straws, she picked them up individually and placed them in her mouth, and when she had gathered five she presented them together in her hand. Attempts to teach her to give six to ten straws were not very successful. For Sally "above six" meant "many," and besides, her limits of patience were probably less than her range of computation. This was hinted at by the highly interesting circumstance that when dealing with numbers above five she very frequently doubled over a straw so as to make it present two ends and thus appear as two straws. The doubling of the straw looked like an intelligent device to save time, and it was persistently resorted to in spite of the fact that her teacher always refused to accept a doubled straw as equivalent to two straws. Here we get a glimpse of something beyond the mere association of a sound—"Five"—and that number of straws.
The Case of Lizzie
The front of the cage in which Professor Holmes kept Lizzie was made of vertical bars which allowed her to reach out with her arm. On a board with an upright nail as handle, there was placed an apple—out of Lizzie's reach. She reached immediately for the nail, pulled the board in and got the apple. "There was no employment of the method of trial and error; there was direct appropriate action following the perception of her relation to board, nail, and apple." Of course her ancestors may have been adepts at drawing a fruit-laden branch within their reach, but the simple experiment was very instructive. All the more instructive because in many other cases the experiments indicate a gradual sifting out of useless movements and an eventful retention of the one that pays. When Lizzie was given a vaseline bottle containing a peanut and closed with a cork, she at once pulled the cork out with her teeth, obeying the instinct to bite at new objects, but she never learned to turn the bottle upside down and let the nut drop out. She often got the nut, and after some education she got it more quickly than she did at first, but there was no indication that she ever perceived the fit and proper way of getting what she wanted. "In the course of her intent efforts her mind seemed so absorbed with the object of desire that it was never focussed on the means of attaining that object. There was no deliberation, and no discrimination between the important and the unimportant elements in her behaviour. The gradually increasing facility of her performances depended on the apparently unconscious elimination of useless movements." This may be called learning, but it is learning at a very low level; it is far from learning by ideas; it is hardly even learning by experiment; it is not more than learning by experience, it is not more than fumbling at learning!
Trial and Error
A higher note is struck in the behaviour of some more highly endowed monkeys. In many experiments, chiefly in the way of getting into boxes difficult to open, there is evidence (1) of attentive persistent experiment (2) of the rapid elimination of ineffective movements, and (3) of remembering the solution when it was discovered. Kinnaman taught two macaques the Hampton Court Maze, a feat which probably means a memory of movements, and we get an interesting glimpse in his observation that they began to smack their lips audibly when they reached the latter part of their course, and began to feel, dare one say, "We are right this time."
In getting into "puzzle-boxes" and into "combination-boxes" (where the barriers must be overcome in a definite order), monkeys learn by the trial and error method much more quickly than cats and dogs do, and a very suggestive fact emphasized by Professor Thorndike is "a process of sudden acquisition by a rapid, often apparently instantaneous abandonment of the unsuccessful movements and selection of the appropriate one, which rivals in suddenness the selections made by human beings in similar performances." A higher note still was sounded by one of Thorndike's monkeys which opened a puzzle-box at once, eight months after his previous experience with it. For here was some sort of registration of a solution.
Two chimpanzees in the Dublin Zoo were often to be seen washing the two shelves of their cupboard and "wringing" the wet cloth in the approved fashion. It was like a caricature of a washerwoman, and someone said, "What mimics they are!" Now we do not know whether that was or was not the case with the chimpanzees, but the majority of the experiments that have been made do not lead us to attach to imitation so much importance as is usually given to it by the popular interpreter. There are instances where a monkey that had given up a puzzle in despair returned to it when it had seen its neighbour succeed, but most of the experiments suggested that the creature has to find out for itself. Even with such a simple problem as drawing food near with a stick, it often seems of little use to show the monkey how it is done. Placing a bit of food outside his monkey's cage, Professor Holmes "poked it about with the stick so as to give her a suggestion of how the stick might be employed to move the food within reach, but although the act was repeated many times Lizzie never showed the least inclination to use the stick to her advantage." Perhaps the idea of a "tool" is beyond the Bonnet Monkey, yet here again we must be cautious, for Professor L. T. Hobhouse had a monkey of the same macaque genus which learned in the course of time to use a crooked stick with great effect.
The Case of Peter
Perhaps the cleverest monkey as yet studied was a performing chimpanzee called Peter, which has been generally described by Dr. Lightner Witmer. Peter could skate and cycle, thread needles and untie knots, smoke a cigarette and string beads, screw in nails and unlock locks. But what Peter was thinking about all the time it was hard to guess, and there is very little evidence to suggest that his rapid power of putting two and two together ever rose above a sort of concrete mental experimenting, which Dr. Romanes used to call perceptual inference. Without supposing that there are hard-and-fast boundary lines, we cannot avoid the general conclusion that, while monkeys are often intelligent, they seldom, if ever, show even hints of reason, i.e. of working or playing with general ideas. That remains Man's prerogative.
The Bustle of the Mind
In mammals like otters, foxes, stoats, hares, and elephants, what a complex of tides and currents there must be in the brain-mind! We may think of a stream with currents at different levels. Lowest there are the basal appetites of hunger and sex, often with eddies rising to the surface. Then there are the primary emotions, such as fear of hereditary enemies and maternal affection for offspring. Above these are instinctive aptitudes, inborn powers of doing clever things without having to learn how. But in mammals these are often expressed along with, or as it were through, the controlled life of intelligent activity, where there is more clear-cut perceptual influence.
Higher still are the records or memories of individual experience and the registration of individual habits, while on the surface is the instreaming multitude of messages from the outside world, like raindrops and hailstones on the stream, some of them penetrating deeply, being, as we say, full of meaning. The mind of the higher animal is in some respects like a child's mind, in having little in the way of clear-cut ideas, in showing no reason in the strict sense, and in its extraordinary educability, but it differs from the child's mind entirely in the sure effectiveness of a certain repertory of responses. It is efficient to a degree.
"Until at last arose the Man."
Man's brain is more complicated than that of the higher apes—gorilla, orang, and chimpanzee—and it is relatively larger. But the improvements in structure do not seem in themselves sufficient to account for man's great advance in intelligence. The rill of inner life has become a swift stream, sometimes a rushing torrent. Besides perceptual inference or Intelligence—a sort of picture-logic, which some animals likewise have—there is conceptual inference—or Reason—an internal experimenting with general ideas. Even the cleverest animals, it would seem, do not get much beyond playing with "particulars"; man plays an internal game of chess with "universals." Intelligent behaviour may go a long way with mental images; rational conduct demands general ideas. It may be, however, that "percepts" and "concepts" differ rather in degree than in kind, and that the passage from one to the other meant a higher power of forming associations. A clever dog has probably a generalised percept of man, as distinguished from a memory-image of the particular men it has known, but man alone has the concept Man, or Mankind, or Humanity. Experimenting with concepts or general ideas is what we call Reason.
Here, of course, we get into deep waters, and perhaps it is wisest not to attempt too much. So we shall content ourselves here with pointing out that Man's advance in intelligence and from intelligence to reason is closely wrapped up with his power of speech. What animals began—a small vocabulary—he has carried to high perfection. But what is distinctive is not the vocabulary so much as the habit of making sentences, of expressing judgments in a way which admitted of communication between mind and mind. The multiplication of words meant much, the use of words as symbols of general ideas meant even more, for it meant the possibility of playing the internal game of thinking; but perhaps the most important advance of all was the means of comparing notes with neighbours, of corroborating individual experience by social intercourse. With words, also, it became easier to enregister outside himself the gains of the past. It is not without significance that the Greek Logos, which may be translated "the word," may also be translated Mind.
When we take a survey of animal behaviour we see a long inclined plane. The outer world provokes simple creatures to answer back; simple creatures act experimentally on their surroundings. From the beginning this twofold process has been going on, receiving stimuli from the environment and acting upon the environment, and according to the efficiency of the reactions and actions living creatures have been sifted for millions of years. One main line of advance has been opening new gateways of knowledge—the senses, which are far more than five in number. The other main line of advance has been in most general terms, experimenting or testing, probing and proving, trying one key after another till a door is unlocked. There is progress in multiplying the gateways of knowledge and making them more discriminating, and there is progress in making the modes of experimenting more wide-awake, more controlled, and more resolute. But behind both of these is the characteristically vital power of enregistering within the organism the lessons of the past. In the life of the individual these enregistrations are illustrated by memories and habituations and habits; in the life of the race they are illustrated by reflex actions and instinctive capacities.
Body and Mind
We must not shirk the very difficult question of the relation between the bodily and the mental side of behaviour.
(a) Some great thinkers have taught that the mind is a reality by itself which plays upon the instrument of the brain and body. As the instrument gets worn and dusty the playing is not so good as it once was, but the player is still himself. This theory of the essential independence of the mind is a very beautiful one, but those who like it when applied to themselves are not always so fond of it when it is applied to other intelligent creatures like rooks and elephants. It may be, however, that there is a gradual emancipation of the mind which has gone furthest in Man and is still progressing.
(b) Some other thinkers have taught that the inner life of thought and feeling is only, as it were, an echo of the really important activity—that of the body and brain. Ideas are just foam-bells on the hurrying streams and circling eddies of matter and energy that make up our physiological life. To most of us this theory is impossible, because we are quite sure that ideas and feelings and purposes, which cannot be translated into matter and motion, are the clearest realities in our experience, and that they count for good and ill all through our life. They are more than the tickings of the clock; they make the wheels go round.
(c) There are others who think that the most scientific position is simply to recognise both the bodily and the mental activities as equally important, and so closely interwoven that they cannot be separated. Perhaps they are just the outer and the inner aspects of one reality—the life of the creature. Perhaps they are like the concave and convex curves of a dome, like the two sides of a shield. Perhaps the life of the organism is always a unity, at one time appearing more conspicuously as Mind-body, at another time as Body-mind. The most important fact is that neither aspect can be left out. By no jugglery with words can we get Mind out of Matter and Motion. And since we are in ourselves quite sure of our Mind, we are probably safe in saying that in the beginning was Mind. This is in accordance with Aristotle's saying that there is nothing in the end which was not also in kind present in the beginning—whatever we mean by beginning.
What has led to the truly wonderful result which we admire in a creature like a dog or an otter, a horse or a hare? In general, we may say, just two main processes—(1) testing all things, and (2) holding fast that which is good. New departures occur and these are tested for what they are worth. Idiosyncrasies crop up and they are sifted. New cards come mysteriously from within into the creature's hand, and they are played—for better or for worse. So by new variations and their sifting, by experimenting and enregistering the results, the mind has gradually evolved and will continue to evolve.