My project explores the scientific attempts to map identities in India and South Africa in the period between 1950 and the 1980s. Such efforts included both efforts to determine individual identities as well as those to determine the identities of entire groups. I trace how multiple scientific efforts to map such identities regularly fluctuated between a somatic and a mnemonic basis for determining such identities. My inquiry ranges widely across a number of distinct scientific disciplines such as genetics, evolutionary biology, physical anthropology, parapsychology, psychosomatic medicine, etc. and pays particular attention to the political possibilities overdetermined by such inquiries.