Page:Popular Science Monthly Volume 59.djvu/288

278 was smoking and making such movements and sounds as in his experience had attracted attention and caused the smoker to blow in his face. He was often given a lighted cigar or cigarette to test him for imitation. He formed the habit of rubbing it on his back. After doing so he would scratch himself with great vigor and zest. He came to do this always when the proper object was given him. I have recounted all this to show that the monkey enjoyed scratching himself. Yet he apparently never scratched himself except in response to some sensory stimulus. He did not with all his experiences of scratching ever get the idea of that act and use it to arouse the delightful act. He was apparently incapable of thinking 'scratch' and so doing. Yet the act was quite capable of association with circumstances with which as a matter of hereditary organization it had no connection. For by taking a certain well-defined position in front of his cage and feeding him whenever he did scratch himself I got him to scratch always within a few seconds after I took that position.

The fact that monkeys do not possess the human type of ideas must not be taken as evidence that they are no nearer relatives to us mentally than are the other lower animals. On the contrary they occupy an intermediate position in every main psychological feature between mammals in general and the human species.

The essentials in an inventory of an animal's mental capacities are its sense powers, the kinds of movements it can make and their delicacy, complexity and number, its instincts or the sum of those tendencies to feel and act which it has apart from experience or learning, and its methods of learning or of modifying its behavior to suit the multitudinous circumstances of life. In each of these respects the monkeys show kinship with man.

In point of sense powers they rely little on smell and much on vision. They possess the power of clear, detailed vision which is absent, for instance, in dogs and cats and is so important a possession of man. A monkey will notice a hair on your hand or a pin six feet off. He thus resembles man in what has been universally recognized as the most intellectual of the senses.

In their motor equipment monkeys possess first of all the muscular coordinations necessary to sustain an upright position and consequently the free use of the fore-limbs. The movements of these fore-limbs are more in number and suited to more complex and varied tasks than are those of lower animals. The attractiveness of the monkey cage in a zoological garden is largely due to the similarity of the monkeys' movements and our own. The monkey not only has a body like a man's, but he also uses it like a man.

Our native tendencies are so metamorphosed by the education of a civilized environment that in adult age they seldom appear in