Page:Popular Science Monthly Volume 17.djvu/12

2 the Peruvian Andes are darker than the Yuracaras of the forests to the east. The inhabitants of the Altai Mountains are yellow; those of the plains of European Russia, at the same distance from the equator, white. According to Foissac, the blackness of the negro is a consequence of his vegetable diet, by which his blood is overloaded with carbon. But this theory, likewise, breaks down when submitted to the test of a comparison with the facts. The nomads of the Asiatic deserts, who live mainly on milk and flesh, are certainly not fairer than the grain eating peasants whom they plunder; and the Buddhists of China and Japan, whose religion prohibits the use of animal food, do not differ in color from their neighbors of other creeds. The influence of humidity has attracted the attention of some writers. Sir R. SchomburgkSchomburg [sic] and M. d'Orbigny hold that it tends to lighten, Dr. Livingstone and others that it tends to darken, the hue. I shall state below my reasons for agreeing with the former.

Mr. Charles Darwin, Professor Huxley, M. Quatrefages, and others, think it probable that racial distinctions owe their origin to the selective operation of the prevailing diseases of particular climates. Assuming, what is amply supported by facts, that individuals slightly diverging in various directions from the type are constantly being produced, it is obvious that if a dark or a light complexion be correlated with power to resist a particular disease, or group of diseases, a white race may, by natural selection, be gradually developed from a colored one, or vice versa. M. Quatrefages has suggested that the malarial fevers of Africa have wrought this effect there, and that phthisis has been the agent in *the north of Europe. It certainly is the case that the tropical regions of Africa are very unhealthy for whites, and that the negro dies out north of the parallel of 40° in both hemispheres; but this does not show that both races might not be acclimatized by slow degrees without loss of color. In other words, no reason has been shown for thinking that it is to the complexion and not to some other racial peculiarity that the relative immunity from certain maladies is due. To connect the color with this immunity is the object of this paper.

I may say at the outset that I do not attach much importance to the direct influence of climatic conditions. It is, indeed, a matter of common observation that these produce considerable effects on the individual. Primer, for example, states-that he has noticed that "the European acclimated in Egypt acquires after some time a tawny skin, and in Abyssinia a bronzed skin; he becomes pallid on the coast of Arabia, cachectic white in Syria, clear brown in the deserts of Arabia, and ruddy in the Syrian mountains." But there is no proof that these cutaneous changes are inherited. If, however, it can be shown that a particular kind of skin is better than others for withstanding certain obvious weakening influences of a given climate, it stands to