DEMOGRAPHIC HISTORY OF INDIA AND MTDNA-SEQUENCE DIVERSITY

The demographic history of India was examined by comparing mtDNA seque nces obtained from members of three culturally divergent Indian subpop ulations (endogamous caste groups). While an inferred tree revealed so me clustering according to caste affiliation, there was no clear separ ation into three genetically distinct groups along caste lines. Compar ison of pairwise nucleotide difference distributions, however, did ind icate a difference in growth patterns between two of the castes. The B rahmin population appears to have undergone either a rapid expansion o r steady growth. The low-ranking Mukri caste, however, may have either maintained a roughly constant population size or undergone multiple b ottlenecks during that period. Comparison of the Indian sequences to t hose obtained from other populations, using a tree, revealed that the Indian sequences, along with ah other non-African samples, form a star like cluster. This cluster may represent a major expansion, possibly o riginating in southern Asia, taking place at some point after modern h umans initially left Africa.