An odontometric biodistance analysis of the Rong and the A'chik

Abstract

Little is known about the population history and genetic affinities of many of the tribal groups of northeastern India, including the Rong and the A'chik. Previous linguistic and genetic studies have suggested that these non-Hindu tribal groups may be descendants of East Asian immigrants. Due to the linguistic and genetic research, cultural differences between the groups, and geographic barriers it was hypothesized that members of these two tribal groups share a population history different from that of ethnic groups of other regions of the subcontinent. This study employs tooth size allocation analysis to test hypotheses concerning the origins of the Rong and the A'chik as well as the nature and extent of odontometric variation found among members of both tribes. The author took measurements of the mesiodistal and buccolingual dimensions of the permanent teeth among 166 A'chik and 185 Rong individuals. The author compared the aforementioned data with measurements obtained among 1,151 members of seven ethnic groups from other regions of South Asia. Group centroids from canonical variates analysis were plotted in three dimensions to assess patterns of similarities among samples. Canonical variates, from both sex-pooled and non-pooled analyses, identify the Rong and A'chik as possessing closer affinities to each other than to members of the other groups, thereby supporting the hypothesis of separate population origins from members of other South Asian ethnic groups. Overall, the results suggest the Rong and A'chik have a different geographic origin than, and little admixture with, the other population groups from elsewhere on the subcontinent.