Monday, May 23, 2016
The Rakhigarhi 15
Samples from fifteen Indus Valley Civilization (IVC) skeletons recently unearthed at Rakhigarhi have been sent to three different ancient DNA labs for analysis. The Tribune India reports that one of these labs is located at Howard University, USA (see here).
Why Howard University and not, say, Harvard University? Or did the reporter really mean the Howard Hughes Medical Institute?
It might be an important detail, because Harvard's David Reich is affiliated with the Howard Hughes Medical Institute. So if that's actually where the IVC samples are going, we're likely to see good quality genome-wide genotype data from them at some point, probably in the not too distant future.
In any case, I know that a lot of people are eagerly awaiting ancient DNA from the IVC, so a paper based on just basic uniparental markers from up to fifteen IVC individuals is really going to cause a stir. For instance, check out this discussion thread at a popular Indian forum: Out-of-India - From Theory to Truth: Part 2.
Holy shit. Let's be realistic here; the probability that ancient DNA from South Asia will make the Out-of-India theory (OIT) a credible proposition is nil. I'd say we have a better chance of finding extraterrestrial life in the next few years than the OIT ever becoming a viable option in the Proto-Indo-European (PIE) homeland debate.
If we eventually see genotype data from IVC samples, my guess is that they'll either resemble present-day Dravidians from South India, Brahuis from Pakistan with no discernible recent admixture from Africa and Arabia, Munda-speaking tribals from near the Himalayas, or a complex mixture of two or all three of these groups.
Unfortunately, knowing this won't tell us what language the IVC people spoke. The only way to learn that is to decipher the Harappan seals.
However, comparing the IVC samples to present day North Indians, particularly high caste North Indians like Brahmins, is likely to reveal whether South Asia experienced a large scale population shift during or shortly after the IVC collapse, especially at the top end of its society. If so, it's also likely to tell us what type of population(s) moved into South Asia at this time and basically laid the foundations for modern South Asia. This information is going to be very valuable in the PIE homeland debate.
So, now the waiting game begins.
Update 24/05/2016: I ran a series of D-stats of the form D(IVC_proxy,Test_population)(Source_population1,Source_population2) to try and profile the non-IVC ancestors of present-day high caste North Indians. All results with Z scores of > negative 2 are in bold print.
If we assume that the IVC people were a lot like present-day Dravidian-speaking South Indians, which I think is a pretty good assumption, then the newcomers came from the Bronze Age Eurasian steppe, and were probably very similar to the Poltavka outlier individual that I blogged about recently. See here.
If, on the other hand, the IVC people were basically like the least admixed Brahuis from present-day Pakistan, then the newcomers were very similar to the Afanasievo pastoralists of the Early Bronze Age (EBA) Altai region.
But, if the IVC people were like the present-day Munda-speakers from near the Himalayas, then the newcomers were probably a mixture of both Kotias-related agriculturalists from West Asia and pastoralists from the Eurasian steppe. Note the lack of any Z scores lower than -2. In other words, the results are very close to neutral.
Rakhigarhi ancient DNA paper probably a while away