The Pygmy aside, we find long-headedness common to early peoples and then gradually giving way to round-headedness. Round-headedness is a progressively modern tendency; there seem to be more round heads than there used to be. (Round-headedness seems to have increased sharply with the advent of agriculture. Are the two related? Does a vegetable diet have a functional effect upon head shape?) Among modern peoples, the Australian, the Negro, the Nordic, and the Mediterranean are long-headed. The Pygmy, the Alpine of Central Europe, and the Chinese are generally round-headed. Most Indians, being heavily Mongoloid, are likewise round-headed. The cephalic index alone is not too good a means of determining races today, but it has definite value in dealing with early man in the Americas. Here, as in the Old World, he seems to have been, with two exceptions, as long-headed as the modern Australian.
[Illustration: _In this diagrammatic description of one of the most important measurements of the head, the length is given as 100, instead of 18 centimeters, or some other actual measurement, in order to make the matter simpler to comprehend._]
Cephalic Index—width ÷ length × 100 Dolichocephalic, or long-headed, below 75 Mesocephalic, or intermediate, 75-80 Brachycephalic, or round-headed, above 80
[Illustration: _A map showing the centrifugal dispersal, first of long-headed Negroes and Australoids, then intermediate to long-headed Mediterraneans, and finally round-headed Mongoloids and Alpines, from an Asiatic homeland. The maker of this map prefers “narrow-headed” for “long-headed,” “broad-headed” for “round-headed.” (After Taylor, 1937, with some modifications.)_]
There are other important measurements, which we shall not describe at such length. The facial index tells us whether the face is relatively broad or narrow, the breadth is measured from cheekbone to cheekbone, and the length from the root, or topmost point, of the nose between the eyes to the bottom of the chin. This facial index is not so useful as the cephalic in determining race, because some of the bones involved are affected by age and sex. The nasal index tells us whether the nose—or, in a skull, the nasal aperture—is broad or narrow, adapted to a warm, moist climate or to a dry, cold one. Then there is the matter of prognathism, with a receding chin. Heavy brow ridges, which usually go with a retreating forehead, and the shape of the vault may be important indications of race. No one of these measurements or observations can definitely denote race, but a number of them taken together are rather reliable.