224 THE SOCIAL LIFE OF ANIMALS 



psychological advantage of belonging apparently to 

 the winning side, suffered the physiological disad- 

 vantage of an increasingly severe food shortage, while 

 France averaged an adequate food ration. In Eng- 

 land during the same time, where there was neither 

 invasion nor starvation, there was the same tendency 

 toward increase of deaths in proportion to births, 

 though less marked. These statistics, of course, do 

 not take into account the almost unprecedented 

 death rates in the fighting lines. 



Temporarily the population growth was checked, 

 but almost immediately following the close of the 

 war the ratio of births to deaths resumed their pre- 

 war trend lines. Pearl, writing in 1921, (93) summed 

 up his study in these words: "Those persons who see 

 in war and pestilence any absolute solution of the 

 world problem of population . . . are optimists in- 

 deed. As a matter of fact, all history tells us, and re- 

 cent history fairly shouts in its emphasis, that such 

 events make the merest ephemeral flicker in the 

 steady onward march of population growth." 



Fifteen years later, in 1936, (94) Pearl again wrote, 

 alluding particularly to the effects of wars of con- 

 quest by one nation to acquire the territory of an- 

 other: "The world problem of population and area, 

 however, remains unaltered in theory, though prac- 

 tically it will have been made worse because of the 



