CH. XXI.] GENESIS OP MAN, INTELLECTUALLY. 319 



variatious. Communities whose members are best able to 

 meet by intelligent contrivances the changes in the environ- 

 ment will prevail over other communities, and will also be 

 less easily destroyed by physical catastrophes. Still more 

 strikingly must this superior availability o: variations in 

 intelligence be exemplified, when the intelligence has pro- 

 gressed so far as to sharpen spears, to use rude bows, to dig 

 pitfalls, to cover the body with leaves or skins, and to strike 

 fire by rubbing sticks, according to the Indian version of the 

 myth of Prometheus. 



So soon, in short, as the intelligence of an animal has, 

 through ages of natural selection and direct adaptation, be- 

 come so considerable that a slight variation in it is of more 

 use to the animal than any variation in physical structure, 

 then such variations will be more and more constantly 

 selected, while purely physical variations, being of less vital 

 importance to the species, will be relatively more and more 

 neglected. Thus, while the external appearance of such ah 

 animal, and the structure of his internal nutritive and njus- 

 cular apparatus, may vary but little in many ages, his cere- 

 bral structure will vary with comparative rapidity, entailing 

 a more or less rapid variation in intellectual and emotional 

 attributes. 



Here we would seem to have the key to the singular con- 

 trast in the relations of man to contemporary anthropoid 

 apes. We may now understand why man differs so little, 

 in general physical structure and external appearance, from 

 the chimpanzee and gorilla, while, with regard to the 

 special point of cerebral structure and its correlative intel- 

 ligence, he differs so vastly from these, his nearest living 

 congeners, and the most sagacious of animals save himself. 

 Coupled with what we now know concerning the immense 

 Antiquity of the human race, Mr. Wallace's brilliant sugges- 

 tion goes far to bridge over the interval, which formerly 

 leemed so impracticable, between brute and man. If we 



