ORIGIN OF AGRICULTURE 669 



fertile loess on the semiarid borders of such regions and the equally 

 generous soil of the delta oasis were the foundation on which the inde- 

 pendent cultures of village communities were built up. Only later, 

 when the knowledge thus obtained could be applied to the utilization of 

 great rivers in turning wide deserts into gardens, was it possible to ren- 

 der populous great countries under the centralized power that constituted 

 empire. 



This stage was never fully reached in central Asia and northern Persia. 

 The countless isolated oases, even under Chaldean, Persian, and Arab 

 dominion, never advanced really much more than nominally beyond the 

 feudal stage. 



If the hypothesis outlined in the last pages be well founded in its 

 essentials, it follows that where we find among the acquisitions of the 

 earliest of the cultures at Anau resemblance to those of neolithic cultures 

 in the West, such similarity can not be due to importation from the 

 Western spheres. If they are not due to coincidence, these acquisitions 

 must be considered as having originated in our oasis world, and to have 

 been transported beyond its limits after the domestication of the horse, 

 or of the horse and camel, rendered extended intercourse possible. 



Among such acquisitions we must include a knowledge of copper and 

 lead and I think also the art of spinning. 



We have seen the birth of the great inner-continental region of the 

 Eurasian continent. We have seen that from the very conditions of its 

 birth it was predestined to a definite course of life history peculiar to its 

 kind, and, treating it as an organic whole, we have seen this course 

 toward ultimate desolation temporarily modified by the climate of the 

 Glacial period. 



What I wish particularly to emphasize is the conception that, in the 

 intervention of the Glacial period and its reaction on the inner- 

 continental conditions, we must see the initial — the motiving — -factors 

 in the evolution of the intellectual and social life of man. 



Shut off from the periphery of Asia and from the other continents 

 while still in a low stage of savagery, we see him gradually broken up 

 into smaller groups, which are forced into isolation on, in the main, 

 continually diminishing, habitable oases ; and we see on these the growth 

 of differentiated, but fundamentally related, cultures. Lastly, and most 

 important of all to us, we see here man under the spur of Necessity, 

 the relentless goddess of evolution, building in village communities, in 



LX — Bull. Geol. Soc. Am., Vol. 17, 1905 



