When we compare two series of this class which are grouped around different values, they may overlap each other. For instance, in a people of tall stature and another one of lower stature, the following theoretical distribution of numerical values of stature would be possible:—
| I | II | |
|---|---|---|
| 1415-1455 mm. | 1425-1455 mm. | 5 cases |
| 1455-1495 mm. | 1455-1485 mm. | 11 cases |
| 1495-1535 mm. | 1485-1515 mm. | 44 cases |
| 1535-1575 mm. | 1515-1545 mm. | 135 cases |
| 1575-1615 mm. | 1545-1575 mm. | 325 cases |
| 1615-1655 mm. | 1575-1605 mm. | 607 cases |
| 1655-1695 mm. | 1605-1635 mm. | 882 cases |
| 1695-1735 mm. | 1635-1665 mm. | 1000 cases |
| 1735-1775 mm. | 1665-1695 mm. | 882 cases |
| 1775-1815 mm. | 1695-1725 mm. | 607 cases |
| 1815-1855 mm. | 1725-1755 mm. | 325 cases |
| 1855-1895 mm. | 1755-1785 mm. | 135 cases |
| 1895-1935 mm. | 1785-1815 mm. | 44 cases |
| 1935-1975 mm. | 1815-1845 mm. | 11 cases |
| 1975-2015 mm. | 1845-1875 mm. | 5 cases |
Fig. 2.
In these two series the group of statures from 1575 mm. to 1695 mm. occurs 1814 times in the first series, 3371 times in the second; that is to say, 1814 individuals are found in both classes, and 1557 (i.e., 3371-1814) are found only in the class of people of tall stature. In [Fig. 2] I have represented these two series in one system of coordinates. Evidently all the individuals who belong to both series, and who are shown in the surface enclosed between both curves, are found in both series; and only the others, who are outside of this surface, and who belong to one of the groups, are not found in the other one.
Bearing in mind these facts relating to types and variability, we are in a position to turn to a consideration of the characteristics of primitive man and of civilized man, and of members of distinct races.
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.
The principles of biological science forbid us to assume a permanent stability of bodily form. Our whole modern concept of the development of varieties and of species is based on the assumption of cumulative or sudden variation. The variations that have been found in the human body are quite in accordance with this view, and I may quote here a few words from Wiedersheim’s admirable treatise on the structure of man as an index of his past history: “In the course of Phylogeny the body of Man has undergone a series of modifications which still in part find expression in his ontogeny. There are indications that changes in his organization are still continuing, and that the Man of the future will be different from the Man of to-day.” The best illustrations of those changes are found in the forms of organs which are undergoing reduction. Thus we may observe that in modern man the little toe is often two-jointed, a phenomenon presumably due to lack of functional use. This condition has been observed in races going barefooted as well as in those wearing shoes, so that it cannot be ascribed to artificial causes. The teeth also show a tendency to gradual reduction, especially in the variable size of the molars and of the upper outer incisors. The third molar, or wisdom tooth, is often retained, and is in most races considerably reduced in size. Retention or slight development of the upper outer incisor is also of frequent occurrence. A similar reduction may be observed at the lower end of the thorax, where the development of ribs and sternum shows great variations.