What two features make hair a good subject for establishing individual identity? to which layer of the hair shaft are much of these features attributed?

The two features that make hair a good subject for establishing individual identity are scale structure and medullary index. The scale structure involves the length, color and diameter of the hair.

The medullary shape is the layer of hair shaft where the above attributes are featured. The medullar layer is an inside layer that runs down to the center of the cortex.