Wednesday, July 2, 2008

New in PLoS ONE: Genetic structure of Adi tribes of North-East India

PLoS ONE today published a crop of 60 brand new articles, several of them are hitting the headlines. An interesting article from India by TS Vasulu and colleagues is also being talked about a lot since this morning (see below). The paper discusses 'Microsatellite based analysis of the genetic status of Adi tribes of Northeast India'.

Population biologists and anthropologists have been traditionally interested in aspects of human history and population migration in India -a homeland of a large number of genetic lineages of tribals and mainstream populations which speak 1600 different languages and dialects.

The article by Vasulu presents important genetic data from a number of closely related Tibeto-Burman speaking tribes from north-east India. The authors correctly present this region of India of utmost importance with respect to ancient human migration processes. In addition, the novel results obtained from these populations are compared with similar data from a range of other populations obtained from the literature.

Based on 15 autosomal microsatellite (STR) markers, the authors studied the genetic affinity, differentiation and sub-structuring among six Adi subgroups, as well as their genetic affinity with other neighbouring, Tibeto-Burman-speaking, tribes of India and with the linguistically divergent east and south-east Asian populations, with whom they share common ethno-historical and cultural attributes. The researchers investigated to what extent the six Adi subgroups are genetically divergent or affiliated. A comparison with the 16 Tibeto-Burman-speaking tribes of the neighbouring region in northern and north-eastern parts of the country as revealed by the cluster analyses indicates geographically proximate populations forming a close cluster. This is to be expected if these populations have indeed diverged from a common source after their settlement in different regions of the country in the recent past. In a comparison of the 50 populations (including populations from east and south-east Asia) for genetic diversity based on the autosomal loci, the resultant clustering tree showed some of the Tibeto-Burman tribes clustering with the populations from Tibet and China and whereas other Tibeto-Burman tribes of India cluster with linguistically different Southeast Asian populations. These results support the possibility that Tibeto-Burman populations were derived from more than one common source. Overall, the Adi and other Tibeto-Burman speaking populations of India are regionally well differentiated and exhibit genetic affinity with the neighboring populations of East/Southeast Asia, based on their shared ethno-history. However, a clearer picture may well emerge from the analysis of increased number of informative genetic markers and from the uniparental markers like mitochondrial DNA and Y chromosome.

You can read the news coverage about this study here and you may post your own reactions and comments directly on the article of Vasulu and colleagues by creating an account on the PLoS ONE website.

[Source: Press release of T S Vasulu, Indian Statistical Institute, Kolkata, India]