TEE HUMAN SPECIES. 451 



had become accustomed in the Indo-Malaysian abode. Furthermore, 

 upon the final retreat of the ice the people of the north became marked 

 off from the inhabitants of the south by climate bounds. Regarded 

 collectively, therefore, ]\Iongols, Caucasians and Americans alike may 

 be distinguished from the tropical Negroes as products of the temper- 

 ate zone. The several stocks that migrated northward from the Indo- 

 Malaysian abode were, however, separated from each other from the 

 start by the mountain barriers and open seas that intervened between 

 the different lines of march. Thus though subjected to somewhat the 

 same climatic conditions during the period of dispersion, upon set- 

 tling in their respective habitats, the geographic groups were influenced 

 by different surroundings. As a result, ethnic diversity was established 

 along the northern latitudes, and the three temperate races became 

 separated from one another by topographic differences. Taking 

 this as our clue we may go back again to the original point of de- 

 parture and follow the several lines of northerly dispersion in detail. 



As was indicated above, the Indo-Malaysian cradle-land is cut off 

 from the Asiatic area by the Himalayan line. Passage was possible, 

 however, between the longitudinal ranges of Cochin-China, and, judg- 

 ing from the remains that have recently been discovered in this moun- 

 tainous region, it is probable that primeval man proceeded northward 

 along these lines during the interglacial epochs. The effect of the 

 Himalayan barrier was, therefore, not so much to prevent migration 

 into the continental area, as to shut the Asiatic immigrants in, and 

 separate them from the inhabitants of the south. Those that remained 

 in this region — Mongols in the forming — must, accordingly, have been 

 subjected for long ages to the influences of their own surroundings. 



This Asiatic area is not characterized by any such uniformity as 

 the eastern equatorial region, but as nature has operated here upon so 

 stupendous a scale, there is still a certain sameness in the salient fea- 

 tures of the environment. Speaking generally, Asia is a continental 

 territory, made up for the most part of bleak plateaux and deforested 

 steppes. Such at least were the prevailing conditions which impressed 

 themselves upon the majority of the original inhabitants and con- 

 stituted the basic type. The Mongolians may thus be regarded as the 

 product of temperate plains, much as the Negroes were considered to be 

 the children of the tropical forest. 



Here as elsewhere, however, variations from the characteristic en- 

 vironment made for corresponding modifications of the normal ethnic 

 type. Being of such enormous extent and cut off on two sides from 

 the sea, the climate of the Asiatic section is predominantly continental. 

 Nevertheless, as the region stretches from the Arctic circle to the tropic 

 of Cancer, and rises in altitude from 100 feet below to 25,000 feet 

 above sea-level, there is naturally a wide range of temperature within 



