THE EVOLUTION OF THE BRAIN
—perhaps the most amazingly complex pieces of living machinery—is so similar that even the most experienced anatomist is unable to distinguish between them.
The physical instruments that are the sources of man’s highest mental qualities are thus represented in the brain of the ape. Their construction in both is identical, but in the ape they are very much smaller. The difference between the brain of a man and the brain of an ape are not qualitative but quantitative. The ape has the germs of the mental powers that are man’s supreme distinction. This conclusion has recently been confirmed by the careful observations of Professor Yerkes of Johns Hopkins University and Professor Köhler of Berlin, who have devoted years to the study of the chimpanzee’s behaviour. When serious consideration is given to the identity of structure in the brain of man and the brain of the man-like ape—even though the ape’s brain may be but half or a third of the bulk of the human brain—the only conception that affords a credible explanation of the resemblance is that ape and man had their origin in a common, even if very remote ancestor.
But if it be admitted that men and apes are derived from a common source, though the apes have neglected to develop their possibilities as men have done, the implication is that the work accomplished by man’s brain, which finds expression in the human mind and personality, must necessarily be of the same kind that a brain of simian type is capable of doing and that man has been evolved from some lower type.
It must not be forgotten that on the most conservative estimate it is much more than a million years since the ancestors of man and of the apes parted company from their common parents. The apes gradually lost the power to develop
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