ti8 PHYSICAL BASIS OF CIVILIZATION 



enemies or in the pursuit of prey. This would 

 gradually and almost imperceptibly force the male, 

 without comprehending the mysterious cause which 

 produced the changes in his consort's actions, to do 

 a little more and a little harder fighting than before, 

 and, for a little distance, to follow the prey alone 

 when the female had fallen behind ; to carry a little 

 larger share of the food captured or collected to the 

 common resting-place, etc. 



Thus, as by slow degrees her share in life-sus- 

 taining actions diminished, his would increase, and 

 yet her portion in the results would not be less. 

 This process would continue until she would be 

 unable to give assistance to her mate in any vio- 

 lent encounters. Even before this, however, efforts 

 to keep up her part in the fight and in the chase 

 would make her liable to suffer pain from over- 

 exertion for hours or even days. These tendencies 

 would culminate in her being finally forced to 

 remain in concealment while he would go forth 

 alone in search of food and prey, portions of which 

 he would be likely to bring to the place of her con- 

 cealment, because the habit had been established 

 during the long months of companionship. See 

 Appendix, Note III, "On Altruism." 



So very gradually had his share in the efforts 

 increased without diminishing her participation in 

 the food, that after she remained behind in conceal- 

 ment the surrender to her of a portion sufficient for 

 her support would hardly be perceived by him as 



