EVOLUTION OF MAN 37 



special development on the head looks like a non- 

 adaptive feature. It is difficult, then, to regard man 

 as merely a genus of anthropoid apes. 



On the other hand, we do not find that man can 

 obviously be divided into a number of distinct 

 species as other families of mammals can, or as even a 

 genus can be divided. There are distinct races of 

 man, and the question is whether these correspond 

 to species among other animals. To discuss this 

 question we have to consider the diagnostic characters 

 of these races. Darwin considers them very carefully 

 in the work I have already mentioned, and comes to 

 two remarkable conclusions which are of chief im- 

 portance in relation to the object of this paper — 

 firstly, that these characters graduate into each 

 other so that the races cannot be absolutely defined ; 

 secondly, that they are in no sense adaptational. 

 He says that, so far as we can judge, none of the 

 differences between the races of man are of any direct 

 or special service to him, nor can they be accounted 

 for in a satisfactory manner by the direct action of 

 the conditions of life, nor by use and disuse, nor 

 through the principle of correlation. He then pro- 

 ceeds to enquire whether they can be explained by 

 sexual selection. He concludes that this process will 

 not explain all the differences, but that there is a 

 residuum which must provisionally, at least, be 

 regarded as due to spontaneous variations which have 

 become constant and general without selection. 

 Thus we find Darwin in this case compelled to adopt 

 the view which in my opinion still holds good in man 



