HUMAN IMPLICATIONS 227 



to supply food to one person, if the soil is fair to 

 good and the husbandry is good according to present 

 standards. This means that under modern condi- 

 tions of agriculture the upper limit of a relatively 

 self-contained population is about 250 people per 

 square mile. It will be seen that Belgium with its 

 700 per square mile almost triples this upper limit, 

 and that England and Wales and the Netherlands 

 more than double it. Such high population densities 

 can be supported by trade conducted with other 

 countries on a large scale. They could also, as we 

 have seen earlier, be supported by improved meth- 

 ods of agriculture. An Italian expert on populations 

 said in my hearing some years ago that population 

 pressure is not a direct cause for war, but can be 

 used by a clever leader to range a nation behind 

 aggressive policies which lead to war. In the short 

 run that is easier than to educate people to apply 

 the available knowledge which would allow Italy, 

 for example, to feed her present population, and 

 more, from the products of her own soil. 



It is time now to turn to the second of the ques- 

 tions concerning the biological background of war. 

 In the light of the preceding discussion we can re- 

 state this question as follows: Although underlying 

 biological relationships do not necessarily lead to 



