THE REGULATION OF NUMBERS 301 



lower degree of skill there arises a tendency for the former to 

 eject the latter. The immediate motive is desire to possess their 

 land where the land is fertile relative to the skill of the first men- 

 tioned race. Thus the Bantu people have pushed back the 

 Bushmen until the latter were left with regions infertile relatively 

 to the Bantu culture. Throughout human history there must 

 have been this tendency for migrations to follow the great steps 

 in the acquirement of power over nature. But there is no reason 

 to think that, even in early times, migrations only arose as 

 a result of increase of skill. What we know of even the most 

 primitive races, such as the Australians, shows that we can 

 imagine movements to have been initiated quite apart from any 

 differences in skill. The accounts given of the respect in which 

 the older men are held among the Australians renders it possible 

 to understand how an impulse to movement might be initiated 

 by them which, once having taken shape, might have far-reaching 

 consequences. We have further accounts of the existence of a 

 spirit of restlessness among primitive races. This restlessness 

 proves on analysis to be nothing more than the currency of an idea — 

 an idea that some benefit would arise if a movement took place. 



We have, however, to remember when dealing with this matter 

 that many if not most of the migrations of pre-history were 

 probably not migrations at all in the usual sense of the term. 

 They are probably better thought of as driftings of people ; they 

 may have occupied very long periods of time and have been con- 

 nected with slow changes in climate. At any one time the move- 

 ment may have been quite imperceptible, and, when this was so, 

 such driftings are seen clearly enough to have had nothing to 

 do with over-population if the immensity of the power of increase 

 is borne in mind. 



Some reference may now be made to the much-discussed theory 

 to the effect that historical migrations are due to climatic changes. 

 Ellsworth Huntington has put forward in a number of publications 

 the view that not only have important climatic changes occurred 

 within the historical period, but that these changes have been 

 what he calls ' pulsatory ' — that is to say, there has been an 

 alteration between humid and arid conditions in many parts of 

 the world.i This view has been contested.^ In particular doubt 



' See especially his Pulse of Asia, and Civilization aiid Climate, ch. xi. « See 



Gregory, Oeographical Jouriud, vol. xliii. 



