Friday, May 31, 2013

Vijaya Kuveni: Paradigm for M mtDNA in South Asia

PCA (left) and Admixture Bar (right)  plot
All Sri Lankans know the story of Vijaya and Kuveni from the Mahavamsa and Rajavali.  The basic crux of the story is that invaders, predominantly male married local women.  The gist of what DNA research is saying is that in India (and for Sri Lanka*) our mothers ancestry (mtDNA) is the same, but our paternal lines (Y-DNA) can be different.  One paper found that 70%  of India including 26 tribal populations carried the M mtDNA haplogroup.   In the Harappa DNA project 50% of the few Sri Lankan participants (8) had M mtDNA.  Two of the four self identified Tamils and two of the four self identified Sinhalese.
(* my extrapolation)

Before I get to excerpts of the research articles a few words on the PCA (Principal Component Analysis) plot on this page.  Its one of the few plots that I have seen where PCA captures the geographic distribution without a geo position data in the PCA analysis.  What I am trying to say is the V shape of India's genetic Cline is evident in the in the PCA Plot.

 From Chandrasekar et al
Macrohaplogroup M is ubiquitous in India and covers more than 70 per cent of the Indian mtDNA lineages The lineages M2, M3, M4, M5, M6, M18 and M25 are exclusive to South Asia, with M2 reported to be the oldest lineage on the Indian sub-continent.

The deep rooted lineages of macrohaplogroup ‘M’ suggest in-situ origin of these haplogroups in India. Most of these deep rooting lineages are represented by multiple ethnic/linguist groups including tribals of India
From Discover Magazine
An interesting point though is that the mtDNA, the female lineage, does not seem to diverge from other South Asians much at all. I find it intriguing that this is the same pattern we see along the major NW-SE axis of variation. It seems that mtDNA lineages unite South Asians, while the Y lineages separate them (by caste and region). The generality has many exceptions, but it points to a peculiar sex mediated admixture process from both the northwest and northeast. Men on the move have reshaped the genetics and culture of South Asia, but the mtDNA lineages still point to an ancient Eurasian group with distant but stronger affinities to the east than the west. The mtDNA are likely the purest distillation of ASI (Ancestral South Indian)
From  Witas et al in PLOSone
Ancient DNA methodology was applied to analyse freshly unearthed remains (teeth) of 4 individuals. Dated to the period between 2.5 Kyrs BC and 0.5 Kyrs AD the studied individuals carried mtDNA haplotypes corresponding to the M4b1, M49 and/or M61 haplogroups, which are believed to have arisen in the area of the Indian subcontinent during the Upper Paleolithic and are absent in people living today in Syria . 
Studied remains were excavated at two archaeological sites in the middle Euphrates valley and dated between the Early Bronze Age and the Late Roman period. The obtained data enrich the as yet modest database of Mesopotamian ancient DNA and suggest a possible genetic link of the region with the Indian subcontinent in the past leaving no traces in the modern population.
Also see:
Sinhalese and Tamil DNA Admixture Analyis
My DNA 01: Heroin Addiction, Smoking etc
Sri Lankan Population DNA Genetics 01
Basic Primer on Population DNA Genetics
List of reference and excerpts

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