GENESIS OF MAN, INTELLECTUALLY 



while his outward physical appearance has un- 

 dergone few modifications ; and of these the most 

 striking would seem to be directly or indirectly 

 consequent upon the cerebral changes/ 



It is a corollary from the foregoing considera- 

 tions, that no race of organisms can in future be 

 produced through the agency of natural selec- 

 tion and direct adaptation, which shall be zoolo- 

 gically distinct from, and superior to, the hu- 



1 To the general observer, as to the anatomist, the most 

 notable points of difference between civilized and uncivilized 

 man, as well as between man and the chimpanzee or gorilla, 

 are the differences in the size of the jaws and the inclination 

 •of the forehead. The latter difference is directly consequent 

 upon increase of intelligence ; and the former is indirectly 

 occasioned by the same circumstance. For the diminution of 

 the jaws entailed by civilization is, no doubt, primarily due to 

 disuse ; and the disuse is occasioned partly by difference in 

 food, and partly by the employment of tools, and the conse- 

 quent increased reliance upon the hands as prehensile organs. 

 All these circumstances are the result of increased intelligence. 

 ;And in addition to this, it is probable that increased frontal 

 development has directly tended, by correlation of growth, to 

 diminish the size of the jaws, as well as to push forward the 

 bridge of the nose. To the increased reliance upon the hands 

 as prehensile organs — a circumstance which we have seen to 

 be in an especial degree characteristic of developing intelligence 

 — is probably also due the complete attainment of the erect 

 position of the body, already partially obtained by the anthro- 

 poid apes. Cerebral development thus accounts for all the 

 conspicuous physical peculiarities of man except his bare skin, 

 ■ — a phenomenon for which no satisfactory explanation has 

 yet been suggested. 



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