EVOLUTION OF MAN 41 



The type with blonde hair and blue eyes is found 

 chiefly in the north, e.g., in Scandinavia and North 

 .Germany, but representatives of it are found in 

 North Africa and in Western Asia. There can be 

 little doubt that this is a pure type, but Huxley 

 suggests that the Melanochroi originated from the 

 mixture of the Xanthochroi and Austral ioids of India 

 and North Africa. 



I can only pretend to offer a few suggestions on 

 the characters which distinguish the races thus 

 rapidly surveyed. Mendelians will assume that they 

 are all simple mutations, but this does not seem to 

 me to be a reasonable conclusion. Some of them, 

 as in other groups of animals, are differences of degree 

 in those adaptive characters which distinguish man 

 from the apes. For example, prognathism and the 

 size of the cranium and brain. The decrease in 

 prognathism is obviously associated with the degree 

 and duration of civilisation, so that this character in 

 negroes and Australians is adaptive. Perhaps the 

 same may be said of the extreme dolichocephaly 

 associated with a sloping forehead in the same races, 

 but we cannot say that the men with the shortest 

 skulls are the most civilised, for some of the least 

 civilised Mongolians are more brachycephalic than 

 the English. In my opinion, there is good evidence 

 that dark or black skin-colour is correlated with the 

 light and heat of the tropical sun. It may be objected 

 to this that the American Indians of the tropics are 

 not black like the negroes, but they are known to be 

 considerably darker than those of the north. At 



