CHAPTER III 



FORCING INTELLIGENCE 



In the two previous chapters the aim has been to 

 make it clear to the reader that, firstly, with the be- 

 ginning of those slight physical differences which 

 distinguish mankind from the quadrumana, the race 

 would have been doomed to inevitable extermina- 

 tion, except for the absence of panmixia and the 

 slow but steady progress of human intelligence; 

 secondly, that a higher type of intelligence, like all 

 other new traits involving great physiological 

 changes in highly specialized forms of life, must 

 have emerged from small beginnings through varia- 

 tion by sexual reproduction ; thirdly, that a special 

 incentive must have existed in the human race, 

 which is not found in any other, to make our brute 

 ancestors exercise their intelligence more exten- 

 sively than other genera, species, or races do. This 

 incentive will be the next object of consideration. 



It has already been mentioned in foot note to 

 page 65, that the higher elevation of the organs of 

 sight and hearing increases their potential availa- 

 bility directly as the square of their distance from 

 the surface of the earth, and that in the human race 

 this exceeds the height at which most other creatures, 



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