THE EVOLUTION OF MAN 201 



but it seemed to me that he found all the Indian characters 

 segregating together in one individual, and that this could only 

 occur in a much smaller proportion of cases than he stated. 1 

 His evidence would have been more convincing if he had dealt 

 with single, marked features, and proved that they segregated 

 In negro crosses we have no satisfactory evidence of segregation 

 in any character, whether adaptive or otherwise. 



A word or two may be devoted to the consideration of 

 Darwin's suggestion that sexual selection may account for the 

 non-adaptive characters of human races. I have shown that 

 where the characters are confined to one sex, selection cannot 

 be the cause of this limitation. Where a character is already 

 unisexual, however, it may vary and remain unisexual — as, for 

 instance, in the human beard. The question then is whether 

 selection by the female is required to account for a difference in 

 the beard, or whether the mutation might not establish itself 

 without selection. In deer the antlers differ in different species 

 in size and shape, and it could scarcely be suggested that the 

 particular size and shape in a given species was due to the fact 

 that they were the best for fighting, or the most admired by the 

 female. But sexual selection might affect characters which were 

 not limited in inheritance — for example, the black of negroes 

 might be due to the preference by either or both sexes for the 

 darkest skin, but this is not a probable view. 



In a short paper like the present, I can only give a very 

 imperfect outline of the subject, but I hope I have said enough 

 to show that anthropology requires to be reinvestigated from 

 modern points of view. My own provisional conclusions are 

 that man affords an example of a single species which has 

 started a new group, which might become a genus or family. 

 Other genera or families may have originated in this way by a 

 single species adopting a new mode of life. The evidence does 

 not seem to me to support the view that all human characters, 

 adaptive and non-adaptive, can be regarded as mutations in- 

 dependent in their origin of habits or functional or other stimuli. 

 The evidence seems to me to agree with the view I take of 

 animals in general— that adaptive characters are due, not to 

 selection, but to the effects of functional and physical stimu- 

 lation, and that diagnostic characters are not adaptive, and 

 therefore not due to selection, but to blastogenic variation. 



1 Nature, November 7, 1907, p. 9. 



