If the distribution of the several races be examined in the light of this conclusion, it becomes apparent that the races who have succeeded in appropriating only limited portions of the earth’s surface, though each may be a marked variant of the human family, are characterized by few inner diversities, either of physical features or culture.  Their subdivisions feel only in a slight degree the differentiating effects of geographic remoteness, which in a small area operates with weakened force; and they enjoy few of those diversities of environment which stimulate variation.  They form close and distinct ethnic unities also because their scant numbers restrict the appearance of variations.  The habitat of the negro race in Africa south of the Sahara, relatively small, limited in its zonal location almost wholly to the Tropics, poorly diversified both in relief and contour, has produced only a retarded and monotonous social development based upon tropical agriculture or a low type of pastoral life.  The still smaller, still less varied habitat of the Australian race, again tropical or sub-tropical in location, has produced over its whole extent only one grade of civilization and that the lowest, one physical, mental and moral type.[301]

[Sidenote:  Wide race distribution and inner diversities.]

The Mongoloid area of distribution, on the other hand, is so large that it necessarily includes a great range of climates and variety of geographic conditions. [Maps pages 103 and 225.] Representatives of this race, reflecting their diversified habitats, show many ethnic differentiations.  They reveal also every stage and phase of cultural development from the industrialism of Japan, with its artistic and literary concomitants, to the savage economy and retarded intellectual life of the Chukches fisher tribes or the Giljak hunters of Sakhalin.  The white race, identified primarily with Europe, that choice and diversified continent, comprised also a large area of southwestern Asia and the northern third of Africa.  It thus extended from the Arctic Circle well within the Tropics.  Its area included every variety of geographic condition and originally every degree of cultural development; but the rapid expansion in recent centuries of the most advanced peoples of this race has made them the apostles of civilization to the whole world.  It has also given them, through the occupation of Australia and the Americas, the widest distribution and the most varied habitats.  As agents of the modern historical movement, however, they are subjected to all its assimilating effects, which tend to counteract the diversities born of geographic segregation, and to raise all branches of the white race to one superior cosmopolitan type.  On the other hand, the vast international division of labor and specialization of production, geographically based and entailed by advancing economic development, besides the differences of traditions and ideals reaching far back into an historic past and rooted in the land, will serve to maintain many subtle inner differences between even the most progressive nations.