Northeast India: Genetic Inconsistency across Ethnicity and Geography

The genetic landscape of South Asia is intriguing. In a vast geographical region like India, mostly genes follow geography, whereas in a smaller geographical region e.g., Nepal, the genetic landscape is more akin to languages. Moreover, in neighboring regions like East and Southeast Asia, language is the major denominator of the genes. However, these are not just the two alternatives, in many geographical pockets, ethnicity plays a stronger role than either of these. Being a crossroads of South and Southeast Asia, the Himalayan region is mostly populated by people speaking the Trans-Himalayan language. Archaeological and anthropological studies suggest migration and cultural diffusion in this region with the Tibetan plateau in the North. To understand this complex pattern, we have performed a fine-grained genetic analysis of the major Mizo population and its various clans living in the Himalayan geography. We have investigated 110 individuals belonging to seven different clans of Mizo people for a hundred thousand autosomal markers. We have used various statistical methods and tested the role of ethnicity and geography in shaping the genetic landscape of the Himalayan region. In contrast to the East and Southeast Asian genetic landscape, our results suggested that the fine-scaled genetic structure of Northeast India is much more complex and a mixture of interplay between languages, ethnicity, and geography. Allelic frequency-based analyses indicated that a novel Trans-Himalayan ancestry unite all the populations of this region.