Reconstructing the population history of the Nicobarese.

The Nicobarese are the major tribal groups in the Nicobar district, situated south of the Andaman group of Islands. Linguistic phylogeny suggests that the linguistic ancestors of the Nicobarese settled the Nicobar archipelago in the early Holocene. So far, genetic research on them is low-resolution and restricted to the haploid DNA markers. Therefore, in the present analysis, we have used the high-resolution biparental (1554 published and 5 newly genotyped Nicobarese individuals) and uniparental genetic markers and looked at the genetic association of Nicobarese with the South and Southeast Asian populations. We report a common ancestral component shared among the Austroasiatic of South and Southeast Asia. Our analyses have suggested that the Nicobarese peoples retain this ancestral Austroasiatic predominant component in their genomes in the highest proportion. On the Southeast Asian mainland, the Htin Mal, who speak an Austroasiatic language of the Khmuic branch, represent a population that has preserved their ethnic distinctness from other groups over time and consequently shown the highest drift with the Nicobarese. The analysis based on haplotypes indicated a significant level of genomic segment sharing across linguistic groups, indicating an ancient broader distribution of Austroasiatic populations in Southeast Asia. Based on the temporal analyses of haploid DNA, it is suggested that the forebears of the Nicobarese people may have arrived on the Nicobar Islands in the last 5000 YBP. Therefore, among the modern populations, the Nicobarese peoples and the Htin Mal language community represent good genetic proxies for ancient Austroasiatics.