"Almost all anthropologists working on the Indian material have been having these archetypes ' before their mind , with the result that each skull has been taken singly and compared with one of the hypothetical racial types. If the comparison shows a closeness to a type , the skull has been regarded as belonging to that particular race . If , on the other hand , the resemblance is less exact , the skull has been relegated to a mixed group . It may very often happen that a single skull shows features that belong to two or more hypothetical types ; in such cases , the skull has been immediately considered to have been the result of mixture of these races . Sometimes , the most likely racial types ' have been considered in the skulls from a particular area , so that the conclusions could generally confirm a conventional story of invasion or migration put forward in history . Since the individual variability in physical characteristics is very great , it has not been difficult to find the type suitable in a particular situation from a collection of skeletal material."