452 POPULAR SCIENCE MONTHLY. 



its borders. Topographically, the Asiatic section is dominated on the 

 south by the Tibetan table-land, culminating in the Pamir region, 

 called the 'roof of the world,' from which the land falls off rather 

 abruptly on the west, and more gradually toward the north and east 

 to the level of the sea. The bleak plateaux are thus succeeded by 

 grassy plains and deforested steppes, which in turn are bordered by a 

 comparatively narrow Tiaga, or wooded belt, extending to the Arctic 

 Tundra and in places to the Pacific shore. The heart of the continent 

 contains deserts and enclosed seas, while the surrounding lands are 

 furrowed by forest-bordered streams flowing to the north, and by more 

 open rivers of uncertain course draining toward the east. In conse- 

 quence of these climatic and topographic differences, the Mongolic race 

 has in the course of time become subdivided into a number of geo- 

 graphic groups. There are plateaux people, desert folk and steppe tribes, 

 forest dwellers and typical Hyperboreans, and the settled inhabitants 

 of the eastern valleys. Migration has moreover been succeeded by 

 miscegenation, so that the lines of heredity and environment have be- 

 come confused. Withal, however, enough Mongolian traits have per- 

 sisted everywhere over the region, and during all the centuries that 

 have elapsed since the original type was constituted, to allow us to 

 set the Yellow people in a separate racial category, and distinguish the 

 typical Mongol from his human fellows by his round head with high 

 cheek-bones; the texture and pigment of his skin; his coarse straight 

 hair, which is cylindrical in cross section; his thin colorless lips; and 

 his small oblique black eyes. 



South of the Himalayan line the peninsular portion of the old world 

 spreads out like a fan from the Indo-Malaysian cradle-land to the 

 Atlantic coast of the continent. On the east, the Indian section of 

 this territory is connected with the equatorial region through the south- 

 ern peninsulas, which once formed part of the Indo- African continent; 

 but cut off from the Asiatic area by the lofty Himalayan range. On 

 the west the conditions are reversed, the Mediterranean and European 

 sections of this territory being cut off from the equatorial region by 

 the Sahara, and connected with the Asiatic area through what is 

 called the open gateway of the east, lying between the Ural mountains 

 and the Caspian sea. There was access to the Indo-Mediterranean- 

 European section, therefore, from two sides ; from the equatorial region 

 on the southeast, and from the Asiatic area on the northwest. The 

 ancestry of the so-called Caucasians can accordingly be traced back to 

 two sources. From the southeast, dolichocephalic Negroids pushed 

 westward from Indo-Africa into the Mediterranean region and over- 

 ran Europe in very early times. Somewhat later successive streams 

 of brachycephalic Asiatics poured in through the open gateway of the 

 east and mingled with the primitive inhabitants of these parts. From 



