Mitochondrial DNA diversity in tribal and caste groups of Maharashtra (India) and its implication on their genetic origins.

Genetic relationships among caste-groups are not uniform across the geographical regions of India. Many anthropologists have speculated on the tribal origin of some caste groups in Maharashtra and other states of India. To test this hypothesis, we used neutral mtDNA markers to study genetic relatedness among tribal and caste groups from Maharashtra. Descriptive statistics such as nucleotide diversity, gene diversity and average mismatches were found to be of the same magnitude. Phylogenetic network analysis exhibited a star-like expansion that may date back to the peopling of Eurasia, approximately 50,000 year ago. The reconstruction of mtDNA haplogroups showed that both the caste and tribal populations share similar branches of the tree. Also, the coalescence age estimation of caste and tribal populations suggests the persistence of maternal lineages with their root in early late Pleistocene. Our mtDNA analyses show some preliminary and significant evidence for the origin of prehistoric tribal and hierarchical caste societies of Maharashtra.