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G. The Head Index - The form of the head is ascertained by measuring in a horizontal plane the greatest length from a definite point on the forehead(the glabella) to the back of the head, and the greatest breadth a little above the ears. The proportion of the breadth to the length is a little above the ears. The proportion of the breadth to the length is than expressed as a percentage called the Cephalic Index. The cephalic index is an expression of the breadth of the head or skull in terms of percentage of the length.

Formula for calculation of C.I.
B + 100IL
or more clearly, cephalic index
Maximum breadth/Max. length + 100.
Example= 160/187 + 100= 87

Head shape has been arbitrarily classified, on the basis of cephalic index, into three categories as follows:

					Dry skull	Living head
Delicocephalic or long headed		74.99		76.99
Mesocephalic or mid headed		75-79.99	77-81.99
Brachycephalic or round headed		80 over		82 over

The difference of the index taken on the living and on the skull is about two units. The head form of skulls is called cranial index. Hence the cephalic index can be converted into the cranial index by the subtraction and vice versa.

H. Shape of the face and Jaw - The face usually harmonizes with the form of the head, so that a narrow face accompanies a narrow head. There are notable exceptions, however; for broad faces with long heads occur among sonic Eskimos. Projection of the jaw is found to be an important criterion of the racial classification. The facial angle indicates the angle made by the whole face with brain cap i.e. the angle between the horizontal line and the straight-line joining the centre of the chin and the fore head. If the facial angle is 90 it is called orthognathism. If it is less than 83, prognathism. If it is between 83 90, it is mesognathism. Most of the white races are orthognathists. Black races are prognathists, and yellow races are mesognathists.

Dr Tailor has propounded the theory of classification of human race on the basis of migration. It is known as Migration Theory of Race Evolution. His theory asserts that whole of the human race was born in central Asia and because of climatic changes, physical changes developed and became diversified. According to him Negrito race become first to be evolved and races, which were evolved, afterwards, forced them to go out of the periphery and this process continued. According to this Migration Zone Theory first evolved races are centered towards the poles and the races, which became evolved in the last, are located in the centre. According to Tailor human race may be divided into seven groups.

Next: Racial Distribution 1