136 PHYSICAL BASIS OF CIVILIZATION 



ful and ferocious competitors and enemies. This 

 demanded agility, audacity, ferocity; the determi- 

 nation to possess and conquer, no matter at what 

 cost of blood or pains to self or others, and heartless 

 disregard for the sufferings of others, that is to say, 

 destructive, disruptive, cruel egoism. 



Since race conditions inexorably required males 

 of such characteristics, therefore would nature 

 rigorously select those endowed with them. 



Upon the females in concealment devolved the 

 propagation of the race. To succeed in this they 

 had, firstly, to guard the secrecy of their places of 

 concealment. A cautious, cunning disposition was 

 suited to this. Secondly, to preserve the lives of 

 their young. This required patience, tenderness, 

 sympathy, conservative, constructive self -surrender . 



Since the race conditions demanded women of 

 such characteristics, therefore would females en- 

 dowed with them be naturally selected. 



It is obvious, from the above, that the set of quali- 

 ties which was required by the race conditions for 

 the females is the antithesis of that required by them 

 for the males. One set can exist in an individual 

 only by the exclusion of the other. The growth, 

 increase, or development of one set in a person, 

 therefore, implies the decrease or decay of the other. 

 Since both sets of sex traits favor the survival of the 

 race, therefore, was the ever greater development 

 of these differences between the sexes in character 

 fostered by natural selection. In other words, the 



