136 SCIENCE PROGRESS 



It is obviously very difficult to estimate the net result of such conflicting 

 factors as we have mentioned ; but, altogether, and giving due and full weight to 

 the considerations, that it is only depart of the male population (the part between 

 the ages of 19 and 45) who are subject to the direct selection of war ; that many 

 of these leave children ; that many skilled workmen of war age are shielded in 

 war factories ; that all females are unselected by war ; that variations in physique, 

 even if selected, are often only nurtural, and that in any case all stocks remain 

 well represented in the survivors — taking everything together, and giving due 

 weight to these special considerations, I think we might be justified in concluding 

 that the present war is unlikely to have any important eugenic or dysgenic effects 

 on the three nations we have under view. 



But one very interesting and important eugenic action — an action that has been 

 hitherto strangely overlooked — the war will have. 



It will lead to a much more stringent selection of women by men. 



If men and women are about equal in numbers there is some assortment, but 

 little selection. If there are more men than women there is a selection of men 

 by women. If there are more women than men there will be a selection of 

 women by men. And the greater the disparity in numbers the more stringent 

 will be the selection. 



In the case of the four nations under review, there has always been a 

 deficiency of adult males with corresponding selection of females ; but, after the 

 war, the deficiency will be much greater, and will lead — especially in view of a 

 probably reduced marriage rate — to a much more stringent selection. 



How this fact, and the interest and importance of this fact, have so long 

 escaped scientific notice, it is difficult to understand ; but there it is, an un- 

 questionable evolutionary factor. 



Such increased stringency, too, of selection of women must in some degree 

 follow every war, so that it is a general law ; and it is quite possible that in it may 

 be found the main evolutionary significance and use of war. 



I do not for a moment agree with Prof. David Starr Jordan when he asserts 

 that race progress finds its cause in selection only : I believe that there is a vis a 

 tergo driving life along certain progressive lines quite apart from selection. But 

 selection plays its part, and no one can doubt the evolutionary value of sexual 

 selection ; and war, in this way we have indicated, greatly increases the potency 

 of such selection. If, in the nations we are considering, five million men are 

 killed, that means some millions of women denied motherhood, and a more 

 stringent selection of those chosen to bear children. It is not men the bullets 

 select, but women. War slays men blindly and indiscriminately ; there is no 

 racial selection there : the real racial selection is the selection of women made by 

 the eyes and the hearts of the men who survive the war. 



Now, on what lines does this selection proceed, and what are its main 

 biological results? 



When men have an opportunity to select wives, or when in their hands the 

 choice chiefly lies, there are certain physical characters they usually seek ; and 

 these are health, physique, and beauty : for Nature has wisely arranged that men 

 should be attracted by characters that imply capacity for motherhood. 



Since health, physique, and beauty are transmitted, it follows that this matri- 

 monial selection favours the evolution of these qualities, and will probably more 

 than compensate for any possible reverse selection by the chances of war. 



The upper-class Turks and the upper-class English, who for generations have 

 had the opportunity and have taken the opportunity of selecting healthy and 



