We will first direct our attention to the differences between civilized man and primitive man, both being members of the same race. For the white race this difference can no longer be observed, because there are no primitive white men in the strict sense of the term. Nevertheless we may discover certain analogues. Some of the peasants in the remote mountain districts of southeastern Europe do not live in a manner so very different from the way of living of what we ordinarily call primitive people; for the mode of life of the agricultural Indians of North America at the time of Columbus, or that of some agricultural negro tribes, is, so far as nutrition and occupation are concerned, quite similar to theirs. Also some of the fishermen on the coast of Europe may well be compared, in their mode of life, with the fishermen of America or Asia. More direct comparisons may be made among the people of eastern Asia, where we may contrast the cultured Chinese and the primitive Amur River tribes, the northern Japanese and the Ainu, the civilized Malay and the mountain tribes of Sumatra or the Philippines. Similar comparisons are possible for the negro race when we contrast the small educated class of negroes in America and the African tribesmen; and for the American race when we compare the educated Indians, particularly of Spanish America, and the tribes of the prairies and of the virgin forests. It is obvious that in all these cases we are comparing groups of the same descent, but living in distinct economic, social, and other environmental conditions. If we find differences among them, they can only be due, directly or indirectly, to environment. Thus the fundamental problem presents itself, In how far are human types stable, in how far variable under the influences of environment? It is difficult to take up this inquiry on the basis of a direct comparison between primitive and civilized types belonging to the same races, partly because material is hard to obtain, partly because the homogeneity of the race is often open to doubt; but it is at once apparent that every inquiry into the variability of human types living under the effect of different types of environment will help us to gain an insight into the question at issue, so that we are led to a more general discussion of the problem of the stability or variability of the form of the human body.