226 THE DESCENT OF MAN, 



by the objection that beneficial variations alone can be 

 thus preserved; and as far as we are enabled to judge, 

 although always liable to err on this head, none of the dif- 

 ferences between the races of man are of any direct or 

 special service to him. The intellectual and moral or 

 social faculties must of course be excepted from this 

 remark. The great variability of all the external differ- 

 ences between the races of man, likewise indicates that 

 they cannot be of much importance; for if important, they 

 would long ago have been either fixed and preserved or 

 eliminated. In this respect man resembles those forms, 

 called by naturalists protean or polymorphic, which have 

 remained extremely variable, owing, as it seems, to such 

 variations being of an indifferent nature, and to their 

 having thus escaped the action of natural selection. 



We have thus far been baffled in all our attempts to 

 account for the differences between the races of man ; but 

 there remains one important agency, namely Sexual Selec- 

 tion, which appears to have acted powerfully on man, as 

 on many other animals. I do not intend to assert that 

 sectual selection will account for all the differences between 

 the races. An unexplained residuum is left, about which 

 we can only say, in our ignorance, that as individuals are 

 continually born with, for instance, heads a little rounder 

 or narrower, and with noses a little longer or shorter, such 

 slight differences might become fixed and uniform, if the 

 unknown agencies which induced them were to act in a 

 more constant manner, aided by long-continued inter- 

 crossing. Such variations come under the provisional 

 class, alluded to in our second chapter, which for the want 

 of a better term are often called spontaneous. Nor do I 

 pretend that the effects of sexual selection can be indicated 

 with scientific precision ; but it can be shown that it 

 would be an inexplicable fact if man had not been modi- 

 fied by this agency, which appears to have acted power- 

 fully on innumerable animals. It can further be shown 

 that the differences between the races of man, as in color, 

 hairiness, form of features, etc., are of a kind which might 

 have been expected to come under the influence of sexual 

 selection. But in order to treat this subject properly, I 

 have found it necessary to pass the whole animal kingdom 

 in review. I have therefore devoted to it Part II of this 

 work, At the qlos^ I shall return to man, and, after 



