November 29, 2012

Y-DNA survey of Tamil Nadu

Fig. 1 - Sampling sites
Warning (Dec 1): table 2 was so messed up that I had to postpone most of the commentary on this important paper. Please disregard this entry and head to the new, much more extensive and correct version HERE.

Always welcome to find more about the genetics of India, surely one of the key geographical nodes of prehistoric human expansion (and, of course, a huge region with interest of its own right).

Ganesh Prasad Arun Kumar et al., Population Differentiation of Southern Indian Male Lineages Correlates with Agricultural Expansions Predating the Caste System. PLoS ONE 2012. Open accessLINK [doi:10.1371/journal.pone.0050269]

The authors took special interest into sampling tribes, some of which are still foragers and a reference for all kind of anthropological research of South Asia, all Eurasia and even beyond. They also sorted the various populations into groups or classes based on socio-economic reality (and language in some cases) rather than the, arguably overrated, varna (caste) system. See table 1 for details.

The bulk of the data is in table 2, an edited and annotated version of which I include here (two columns, R2 and SD, were transposed in the original, I resized for optimal visualization and annotated wildly to highlight most important clades, etc. - that's how I read papers, rather than paying too much attention to the wording or beliving blindly all what geneticists say on age estimates and other educated hunches):

Annotated and corrected version of table 2 (click to view in optimal size).

As I'm not totally sure that the tabulation (even after correction) is right, I'm going to withhold judgment. Hopefully it'll be corrected soon and we can analyze the data properly.

Update (Nov 30): I wrote to the authors on the issue and got prompt reply. Apparently the shifted column is that of J2-M172 and not R2 as I thought first, but instead of a simple swap all columns since J2a1 shifted one place to the left (so  all that K* is actually L1, all that R* is actually R1a1, etc.)

I am very interested on what this paper seems to have found and therefore I will wait a bit for the formal correction (which is apparently in wait for PLoS ONE editors to perform only) and write on the matter anew. Because, if nothing else, the high levels of F* and C among hunter-gatherer tribals seem very important.

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