INTRODUCTION TO SOCIOLOGY 797
5. Cephalic index. The index is the relation of two oppo- site diameters. Thus to get the cephalic index one measures the maximum anterior-posterior diameter, then the transverse diame- ter, according to the centesimal relation conforming to the pro- portion of Broca :
D transverse maximum x D ant. -post, maximum ~ 100 or
D transverse maximum X 100 , ,. . ,
_ = x or cephalic index.
D ant.-post maximum
The cephalic index gives, for the extreme limits, two human anatomical varieties, represented by the dolichocephalic and the brachycephalic types.
The classification resulting from this seems to indicate that the highest civilizations do not belong to the peoples having the extreme types of cephalic index, but rather to mixed types pro- duced by selection and fusion. Also, almost all civilizations, and especially the highest, do not present homogeneous but rather very heterogeneous types. The latter is an important statement for sociology a statement of a nature to reduce much of the importance attributed to race. This law is in accord with that announced earlier, that is, that the species having the wid- est distribution are more variable than those confined within nar- row limits (Darwin). The human cephalic variations in this respect are as variable as the muscular variations. Nevertheless these variations can be considered as relatively secondary to the numerous bodily and mental resemblances among the most distinct human races, which, moreover, are themselves more or less mixed.
I. DOLICHOCEPHALIC TYPE INDEX BELOW 75.
Australians - 7 x -49 Eskimos - 71.71 to 73
New Caledonians - - 7 I -78
People of Canstadt 72
Hottentots and Bushmen - - 7 2 -4 2
Botocudos - 73
Negroes of western Africa - 73-4Q
Arabs - 74
Kabyles - - - 74-Q4
