Genetic structure and phylogeny of populations of India: Andhra Pradesh

This paper focuses on the genetic structure of castes and tribal groups from Andhra Pradesh, southern India. The R-matrix analysis (HARPENDING and JENKINS 1972) employed in this study is based on 12 blood group, serum protein and red cell enzyme alleles from 5 generic loci. A total of 16 and 21 castes and tribes are compared in separate analyses in order to determine if castes were genetically heterogeneous or homogeneous and whether they differed genetically from tribal populations. The effects of migration patterns and stochastic processes on the distribution of alleles in castes and tribes were ascertained using HARPENDING and WARD's (1982) method of regressing the distance from the centroid of distribution (r(ii)) and mean locus heterozygosity ((H) over bar). The results from these analyses of standard genetic markers were compared to the incidence of DNA markers (mtDNA and beta-globin region of the genome) in populations of India. The results of this comparison are supportive of the theory that India was invaded by so-called ''Aryans'' who in turn imposed the caste system on the indigenous groups. Similarly, the tribes appear to be remnants of the aboriginal populations of India that escaped the caste hierarchy by relocating in more marginal regions.