38. Disease
Pathology might seem to promise more than normal physiology. So far as mortality goes, there are enormous differences between races. And the mortality is often largely the result of particular diseases. Measles, for instance, has often been a deadly epidemic to uncivilized peoples, and smallpox has in some regions at times taken toll of a quarter of the population in a year or two. Yet it is short-sighted to infer from such cases any racial predisposition or lack of resistance. The peoples in question have been free for generations, perhaps for their entire history, from these diseases, and have therefore not maintained or acquired immunity. Their difference from us is thus essentially in experience, not hereditary or racial. This is confirmed by the fact that after a generation or two the same epidemics that at first were so deadly to Polynesians or American Indians sink to almost the same level of mild virulence as they show among ourselves.
Then, too, immediate environment plays a part. The savage often has no idea of contagion, and still less of guarding against it; he thinks in terms of magic instead of physiology—and succumbs. How far heavy mortality is the result of lack of resistance or of fundamentally vicious treatment, is often hard to say. If we tried to cure smallpox by subjecting patients to a steam-bath and then having them plunge into a wintry river, we should perhaps look upon the disease as a very nearly fatal one to the Caucasian race.