344 pearl: biology and war 



studies the effect on the race of modifications in the environment, 

 of crossing the different races, and of various other factors which 

 may be supposed to have a determinative influence in bringing 

 about evolutionary change or modification. A great war per- 

 forms all these experiments on a stupendous scale with the. human 

 organism as material. 



In saying this I am not at the moment referring to the relation 

 of natural selection to war. That is a topic to which I shall come 

 later. I am here referring to a very much broader aspect of the 

 question. War is not merely selective (if it be so at all) through 

 elimination by death of men at the front. Its biological effect 

 on the human species is much more profound than anything 

 which could possibly result from any merely selective process. 

 War makes a most complete and far-reaching change in the whole 

 biological environment of the human beings of the countries 

 engaged in it, and if the number of these countries is sufficiently 

 large it affects the whole world. In this regard, it is most nearly 

 comparable to what the geologist calls a catastrophic change in 

 evolutionary history. The reason why war induces so profound 

 a change in human environment is that it disturbs every -psy- 

 chological and social relation of men with each other. For 

 modern civilized man the environment does not mean primarily 

 the climate, the flora, or the geological structure of the place in 

 which he lives. To a very considerable extent civilized man con- 

 trols and modifies the impirgement of the direct physical elements 

 in his environment. I'he important elements of human environ- 

 raent are those which grow out of the activities of the human 

 mind, or as one may broadly say, the psychological and social 

 elements. These include all the social relations which are built 

 up during yesLra of peace. But war, in and of itself, brings about 

 an entirely new revaluation of all existing social, economic, 

 intellectual, and moral relations. This is true not alone for the 

 combatants, but for all the non-combatant or neutral nations. 

 In a war such as the present one men everywhere begin to recon- 

 sider their thought and action about such things as what con- 

 stitutes proper education for their children, what is a desirable 

 mode of activity for the church, what sort of activities in the 



