The Mongoloids include the round skulled Mongols and their derivatives, the Amerinds or American Indians. This group is essentially Asiatic and occupies the centre and the eastern half of that continent.
A description of these Negroids and Mongoloids and their derivatives, as well as of certain aberrant species of man, lies outside the scope of this work.
In the structure of the head hair of all races of mankind we find a regular progression from extreme kinkiness to lanky straightness and this straightness or curliness depends on the shape of the cross section of the hair itself. This cross section has three distinct forms, corresponding with the most extreme divergences among human species.
The cross section of the hair of the Negroes is a flat ellipse with the result that they all have kinky hair. This kinkiness of the Negroes’ hair is also due somewhat to the acute angle at which the hair is set into the skin and the peppercorn form of hair probably represents an extreme specialization.
The cross section of the hair of the Mongols and their derivatives, the Amerinds, is a complete circle and their hair is perfectly straight and lank.
The cross section of the hair of the so-called Caucasians, including the Mediterranean, Alpine and Nordic subspecies, is an oval ellipse and consequently is intermediate between the cross-sections of the Negroes and Mongoloids. Hair of this structure is wavy or curly, never either kinky or absolutely straight and is characteristic of all the European populations almost without exception.
Of these three hair types the straighter forms most closely represent the earliest human form of hair.
We have confined the discussion to the most important characters but there are many other valuable aids to classification to be found in the proportions of the body and the relative length of the limbs. In this latter respect, it is a matter of common knowledge that there occur two distinct types, the one long legged and short bodied, the other long bodied and short legged.
Without going into further physical details, it is probable that all relative proportions in the body, the features, the skeleton and the skull which are fixed and constant and lie outside of the range of individual variation represent dim inheritances from the past. Every generation of human beings carries the blood of thousands of ancestors, stretching back through thousands of years, superimposed upon a prehuman inheritance of still greater antiquity and the face and body of every living man offer an intricate mass of hieroglyphs that science will some day learn to read and interpret.
Only the foregoing main characters will be used as the basis for determining race and attention will be called later to such temperamental and spiritual traits as seem to be associated with distinct physical types.