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 

 Kohler 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 com- 

 mon, 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 expres- 

 sion 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 esti- 

 mate 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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