EVOLUTION OF PHYSICAL CHAKACTEES 371 



several varieties closely resembling types of modern European 

 man. It seems, therefore, that, so far as this period is concerned, 

 we have to account not merely for the evolution of the main 

 types but also for the evolution of the less easily distinguishable 

 varieties of man. The splitting up may have begun in the former 

 period but it probably did not go far. As to how this evolution 

 took place certain conclusions may first be drawn from what we 

 know must have been the general conditions of life. Secondly, 

 from what we know as to the position among races of the first 

 group, rather more definite conclusions may be added concerning 

 the nature and direction of selection. 



It has already been remarked that in all probability man 

 spread into various climatic zones before the beginning of the first 

 period of history. The consequences of this spreading of man 

 must have been twofold. Mankind became segregated into 

 groups, the surroundings of which differed, first in that they 

 were subject to different climatic environments, and secondly 

 in that they were forced to pursue different modes of life. It 

 is clear that, whereas in some tropical regions man would be 

 supporting himself by hunting and collecting in such a way as 

 to require a certain type of bodily exertion, in a temperate region 

 he would be supporting himself by a very different form of exer- 

 tion. This difference between the needs of daily life would result 

 in the favouring of different types in the two regions. The 

 type best adapted to gain a living in one region would be different 

 to that best adapted to gain a living in another region. 1 



Of far more importance in the production of varieties of men 

 than the factors already noted are differences in climate to which 

 man has become exposed. How great these differences are is 

 familiar and need not be laboured. We know little with regard 

 to the manner in which different types of man are suited to 

 different types of climatic zones. But it is clear that in general 

 the races of men are innately adapted to different climates. 

 There is no historical reason why in all parts of North and South 

 America the European races should not have ousted the American 

 Indian as they have done in the ^United States. In Mexico and 

 other regions, however, where the climate differs most markedly 

 from that in Europe, Europeans have not succeeded in establishing 



1 Pruner-Bey (' Memoire sur les Negres ', Mem. Soc. Antk., vol. i, p. 334) has 

 shown in detail how the peculiarities of negro structure are to be regarded as 

 adaptations to the surrounding conditions. 



Aa2 



