THE UNIQUE MAMMAL 39 



neighbors which threatens the maintenance of that which begins 

 to mark them as a nationality. It is the business of their national 

 leaders to be on the lookout for such things. They may merely 

 fancy that they detect some danger to the maintenance of even 

 their present status in something that a neighboring nation does. 

 It may be a very intangible thing, and the interpretation of its 

 significance may be entirely wrong, but that does not matter. The 

 explanation of why men fight is very simple. It is, first, because 

 their kind of people is different from other kinds j second, be- 

 cause they want to make sure that their kind shall either main- 

 tain or improve its status in the world j and that which is thought 

 to ensure most certainly the maintenance and extension of group 

 differences in the widest sense is relative politico-social domina- 

 tion by the group j and third, because of a general physiological 

 law that certain emotions tend to lead to action.'*'^ 



Quite plainly the more the differences between peoples are 

 bred out by universal intercrossing the more difficult it will be 

 to stir up wars. Biological internationalism supplements and aids 

 political and social internationalism. In the far-off end all man- 

 kind will presumably be a rather uniform lot; all looking, 

 thinking, and acting pretty much the same way, like sheep. Just 

 in proportion as biological differences between peoples diminish 

 so will the frequency of wars diminish. But the diminution 

 seems likely to be at a fearfully slow rate; it will be a long 

 time yet before the last war is fought. And a low cynic might 

 suggest that even war, horrid and stupid as it is, would perhaps 

 be preferable to that deadly uniformity among men towards 

 which we are slowly but surely breeding our way. 



VI. 



In considering the consequences of the universal fertility 

 between the varieties of the human species emphasis has been put 

 upon the initial group differences between these varieties, and 

 their gradual diminution and probable eventual complete ob- 

 literation as the result of ever more widespread interbreeding. 

 Let us now give some consideration to the differences between 



