The science of life : fully illustrated in tone and line and including many diagrams

THE EVOLUTION OF MAN

frog’s eye is much poorer and it pays no attention to any but moving objects. The frog can hear, but its miserable little bag of a hearing organ compares very poorly with an ape’s long, coiled cochlea. The range of sound which our ears permit us to hear and the delicacy with which we can discriminate between different tones are almost identical in ourselves and in apes; but the sound-world to which the frog has access is hmited and crude in comparison. In one respect, however, the frog has the advantage over us and over the apes. Its whole skin possesses organs of chemical sense, which in us are confined to the moist coverings of nose, eye, mouth, and other mucous membranes. Thus it is able, albeit it would seem in a very crude way, to smell or taste or at least to be stimulated by various chemicals, all over its body. Finally, what emotions a frog possesses appear to be few in number and low in intensitywholly unlike the extremely human passions of apes.

But if the very bricks out of which it builds its mental life are different from ours, its ability to build with them is no less different. The frog has powers of learning and association, but so feeble that we find it difficult to realize the extent of a frog’s inability to profit by experience. Almost the whole of its actions are reflex, predetermined for it from the start by the inherited constitution of its nervous system. The ape, like ourselves, has its due share of reflexes and its complement of inborn instincts with their accompanying emotions ; but, like ourselves, it can not only learn, but learn rapidly. Though its actions, like ours, are always built on foundations of reflexes and instincts, yet the great majority of them are what they are because of the animal’s individual experience. In a frog’s _ life, learning by experience plays an insignificant part; it plays a preponderant part in a chimpanzee’s.

This would be true of a dog as well as an ape, but the ape can go farther than this. One chimpanzee studied by Professor Koehler, though wholly untaught, had the idea of fitting one stick into the hollow end of another in order to get at a banana which was out of reach of either stick by itself; and to do that is to anticipate experience by thought. This observation is only one of many, but it must suffice us for the present.

What concerns us here is the fact that chimpanzees and other true apes do have this faculty of anticipating experience, of putting two and two together so as to deal with a new kind of situation in an intelligent way, and that this power, in spite of the most careful tests, has never been detected in any lower animal, even in tailéd monkeys. Many animals have that form of intelligence which we may call intelligent learning, but no others show deliberate invention. It is true that the ape’s free ideas are very rudimentary when compared with ours. None the less, our chimpanzee who, instead of doing nothing at all, or of aimlessly fiddling with his two sticks until one chanced to fit into the other, saw beforehand that they

2. A Comparison of Hands. Left, Man ; centre,

Chimpanzee ; right, Frog.

The hands of Man and Chimpanzee are much alike, the main differences being differences of proportion and of hairiness. built on the same general plan, but differs in many important respects. It has only four instead of five fingers, the true thumb having been reduced to a vestige, so that the apparent thumb is really equivalent to our index finger. une gue opposed to the fingers for grasping purposes ; there are no nails ; an

The Frog’s hand is

This false thumb cannot be bent round and the skin is hairless and moist.

would fit and would then serve his purpose —he was, albeit in a humble way, showing the same power which enables an engineer to design a bridge on paper instead of putting something up and trusting to luck that it will stand, or a physicist using his mathematical faculties to calculate how his atoms and electrons should behave if his assumptions are right, so that he can plan the crucial experiment which will tell him if they ee right or no. In mental life and menta powers a chimpanzee is less like a frog than he is like a man.

When we compare our human and our simian, not only when full-grown, but sue their respective developments as well, the resemblances increase. Compared with a man, an adult chimpanzee has pee ately longer arms and shorter legs ; so has

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