Page:American Journal of Sociology Volume 11.djvu/557

BIOLOGICAL FOUNDATIONS OF SOCIOLOGY 541 While, therefore, the native races of all temperate America, as well as of all Australasia and Polynesia, seem irrevocably doomed to extinction, it is possible that the aborigines of tropical America, strengthened as they have been by a large infusion of European blood, may persist. In the more temperate regions even half-castes perish of consumption ; hence the absence of a mixed race.

The political effects of the invasion of the New World by the disease of the Eastern Hemisphere have been very remarkable. Spain and Portugal, powerful nations in the fifteenth and sixteenth centuries, had the first start in the race for empire, and chose the seemingly richer tropics. But there malaria checked colonization, and consumption did not cause the elimination of the natives. The weaker British were shouldered into the inhospitable north, where the vast void cleared by disease gave their race almost limitless room for expansion. Subsequently they secured all Australasia, in which the conditions are similar. In the New World, then, the Anglo-Saxons have founded permanent empires. Under no probable conjunction of circumstances are they likely to be uprooted. But the fate of their Old World dependencies will be different. Here the natives outnumber, and will always outnumber, them. In the course of time they are sure to be expelled or absorbed. Their fate will be like that of the Romans and the Normans in England, not like that of the Saxons who nearly exterminated the Britons. Disease has spread over the whole world, and no other race will ever again have the opportunities so unconsciously used by the Anglo-Saxons. So vast and fertile are their territories that it seems probable that their world-predominance in the future has been secured by disease.

Roughly speaking, the stimuli under which a human being develops are three in number: nutrition, use, and injury. All individuals develop at first under what may be regarded as the sole stimulus of nutrition. Thus up to the time of birth the human being develops under the influence of this stimulus alone. Subsequently some of his structures continue to develop under it; for example, his ears, his hair, and his teeth. He never uses his hair nor his external ears in any active sense; obviously, therefore, they grow simply because they absorb food. He uses his teeth,