HUMAN AND ANIMAL EVOLUTION CONTRASTED 13 



and that nothing that we may do subsequently can 

 possibly modify it. There seems little hope for the 

 future with such a view, for we cannot believe that 

 even the most extended discussion will have any 

 material effect upon the mating habits of mankind. 

 The choice of husband and wife is bound up in the 

 complex social conditions in such a way that it is 

 determined by an indefinite number of artificial 

 factors of which physical fitness hardly plays even 

 a minor part. It is not possible to expect that mar- 

 riages will be determined by fitness, nor that human 

 breeding will ever be controlled as is the breeding of 

 domestic animals. It is probably not desirable that 

 it should be. But, remembering the inexorable laws 

 of inheritance, the re seems to be no hope for the 

 future except By^ontrolling marriages, and the 

 'manifest im})Ossibnity of this leaves us helpless and 

 despondent. Marriages will continue to be deter- 

 mined by passion and accident rather than by fitness. 



The second unfortunate tendency of the emphasis 

 placed upon eugenics is that it inevitably makes us 

 neglect certain other phases of the inheritance ques- 

 tion which in reality have had great influence upon 

 the evolution of mankind. Reference is here made 

 to phenomena which in the subsequent pages of this 

 work are together called social heredity. Since a 

 discussion of this topic is to follow, no further refer- 

 ence need be made to it here. 



Eugenics and Disease. — In our reference to eugenics 

 in this discussion in this work it must be clearly 

 understood that we take into consideration only 

 those phases of the subject that have to do with he- 

 redity in the strict sense of that term, and not certain 

 other matters that are frequently considered with 



