EVOLUTION OF MENTAL CHAEACTEES 403 



find that there are factors distinctly favouring unusual intelligence. 

 Some progress there probably was. On the whole those men 

 who attained the leadership were probably rather more intelligent 

 than the average, though among the qualities which assisted 

 such men to gain the leadership many other mental qualities 

 played a more prominent part than intellect ; thus, by practising 

 polygamy, or practising it to a greater extent than the rest, they 

 left more than the average number of descendants — and, while 

 perhaps raising the intellectual level of the race, more certainly 

 altering the average mental endowment in respect of these other 

 qualities. 



Such an examination also shows that a somewhat different 

 disposition is favoured in different cases. Thus a warlike type 

 is favoured among the American Indians, for, though possibly 

 the most warlike may be killed off the most quickly, this is more 

 than counterbalanced by the ease which with such men get 

 numerous wives. But such differences in no way conflict with 

 the fact that the tendency is towards the preservation of a 

 mean, which though it may vary somewhat, is in general outline 

 the same among all these races. 



There still remains to be noticed the result of conflict be- 

 tween groups, other than normal warfare, which at times led 

 to the substitution, whole or partial, of a less intelligent by 

 a more intelligent race, or at least of a less skilled by a more 

 skilled race ; for by this time the outward manifestation of 

 intellect was to a considerable extent overlaid by tradition. 

 But such substitution, though it changes the average germinal 

 constitution of the species as a whole, scarcely accounts in any 

 noteworthy degree for the evolution of a higher level of intellectual 

 capacity. The conditions which did favour further evolution 

 within these two periods are the same as those which, when 

 present to a more marked degree and acting over a longer period 

 of time, finally gave rise to the races of the third period, and 

 to these conditions we may now turn. 



9. There are certain regions of the world's surface which 

 contain within them areas abutting one upon the other and 

 differing sharply one from the other. Such a region is found in 

 that part of Western Asia which embraces Asia Minor, Armenia, 

 Syria, Arabia, Mesopotamia, and Western Iran. In such areas 

 races live in close contact with other races of very different 



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