256 INBREEDING AND OUTBKEEDING 



is not difficult to develop. Whatever the causes of racial 

 separation under the isolation characteristic of former 

 times, peoples did come to have a rather narrow vari- 

 ability. They were, one might say, homozygous for cer- 

 tain traits. These traits naturally differed in their value. 

 There were great peoples, mediocre peoples, and wretched 

 peoples. But each was more or less standardized. When 

 there came occasion for these standardized peoples dif- 

 fering in their transmissible characters to intermingle, 

 great variability was produced; and if the differences 

 were not too great, the chances were high that valuable 

 character combinations would come to light. Later 

 through the close breeding due to the marriage selection 

 which always develops within human society, the ten- 

 dency was again to produce purer strains characterized 

 differently ; but without the chance of repeated Mendelian 

 recombinations the probability of establishing superior 

 strains was small. 



This hypothesis, developed wholly from a considera- 

 tion of the genetic facts, is not refuted by ethnological 

 data. Thus, if one considers the peoples of Europe, he 

 finds high civilizations, invariably following the migra- 

 tion of that ancient race or mixture of races termed 

 Aryan, a people of whom there is now only circumstantial 

 evidence. It was manifestly not mere hybridization 

 which brought results of outstanding value, however, but 

 hybridization of "good strains not too widely differen- 

 tiated, followed by periods of more or less intensive in- 

 breeding. This is a reasonable deduction from the 

 rapidity with which European and particularly North 

 European culture has outstripped that of Central and 

 Southern Asia. 



