Mitochondrial DNA variation in Nicobarese Islanders

The aboriginal populations living in the Nicobar Islands are hypothesized t o be descendants of people who were part of early human dispersals into Sou theast Asia. However, analyses of ethnographic histories, languages, morpho metric data, and protein polymorphisms have not yet resolved which worldwid e populations are most closely related to the Nicobarese. Thus, to explore the origins and affinities of the Nicobar Islanders, we analyzed mitochondr ial DNA (mtDNA) hypervariable region I sequence data from 33 Nicobarese Isl anders and compared their mtDNA haplotypes: to those of neighboring East As ians, mainland and island Southeast Asians, Indians, Australian aborigines, Pacific Islanders, and Africans. Unique Nicobarese mtDNA haplotypes, inclu ding five Nicobarese mtDNA haplotypes linked to the COII/tRNA(Lys) 9-bp del etion, are most closely related to mtDNA haplotypes from mainland Southeast Asian Mon-Kmer-speaking populations (e.g., Cambodians). Thus, the dispersa l of southern Chinese into mainland Southeast Asia may have included a west ward expansion and colonization of the islands of the Andaman Sea.