Big deal of 2016: the territory of present-day Iran cannot be the Indo-European homeland

It's been a pretty big year. Not as big as many of us had hoped for, but there's still a few more weeks till 2017, so who knows what will happen?

In any case, for me 2016 will be the year in which we finally saw hard data - courtesy of Lazaridis et al. and Broushaki at al. - that crossed off the territory of present-day Iran from the list of potential Proto-Indo-European (PIE) homelands.

Now, it's true, Lazaridis et al. and Broushaki et al. were somewhat vague in what their data meant in this context, and indeed, both sets of authors left open the possibility that what is now Iran might prove to be the PIE homeland. However, their data left no doubt: look elsewhere for the PIE Urheimat.

Why? Here it is, in point form, as simply as I can put it:

- the Mesolithic and Neolithic peoples of the Zagros range and South Caspian region were highly distinct both in terms of genome-wide genetic structure and uniparental markers, and clearly only contributed meaningful gene flow to South Asia, not to Europe or Anatolia

- after the descendants of Neolithic farmers from the Zagros range, or at least their very close relatives, migrated to South Asia, the territory of present-day Iran, as per the data in Lazaridis et al. and Broushaki et al., saw waves of migrations from the west and north that dramatically shifted the population structure of the region, bringing it closer in this respect to the Levant and Europe

- most of the Neolithic samples from Iran in Lazaridis et al. and Broushaki et al. came from near the proto-Elamite homeland in the Kor River basin in central Fars, which strongly suggests that their close relatives who streamed into South Asia were not Indo-Europeans, but rather speakers of languages closely related to Elamite

- even though Lazaridis et al. successfully modeled Early/Middle Bronze Age steppe populations, including Yamnaya, as largely of Iran Chalcolithic origin, this appeared to be a coincidence, because the Chalcolithic samples from Iran showed fairly typical South Caspian uniparental markers, such as Y-chromosome haplogroups J and G1 and mitochondrial (mtDNA) haplogroup U7, which are conspicuous by their absence from an exceptionally wide range of Bronze Age steppe samples.

I do realize that many readers won't accept these arguments for emotional reasons, because the PIE homeland debate is an emotional one for a lot of people. Nevertheless, if you decide to argue with me in the comments, make sure you have a coherent argument.

Actually, the territory of present-day Iran has never been a serious contender in the PIE homeland debate. This is something that many Iranian scholars will freely admit.

Not only was central Fars the proto-Elamite homeland, but much of what is now western Iran was the stomping ground of the Hurrians. The Indo-Europeans, in the form of Indo-Iranians such as the Medes, only got there late in the game, in all likelihood from the Eurasian steppes.

But a lot of newbies to the PIE debate don't know this, or they don't want to know it. I guess to them Iran makes sense because it's in between Europe and South Asia? Or maybe it's the fact that the word Iran is kind of similar to the word Aryan? No idea, really, but like I say, it's now all over.

See also...

A homeland, but not the homeland

Zarathushtra and his steppe posse

The story of mtDNA haplogroup U7

Days of high adventure

I've redesigned and streamlined my Principal Component Analysis (PCA) plot of West Eurasia in anticipation of the arrival of many more ancient samples. Rumor has it we'll not only get stuff from the Balkans, but also finally from the steppes north of the Black Sea and South Asia.

I'd say my new plot does a better job of highlighting relationships between the different prehistoric groups and population shifts across space and time. The datasheet is available here.

It should be pretty clear from this plot how the modern-day European gene pool came about. So I don't expect any major surprises when the new samples come in. Nevertheless, the wait is killing me, and many others I'm sure.

Update 13/11/2017: A year on, I've acquired many new samples and, as a result, streamlined the PCA some more, see...

Who's your (proto) daddy Western Europeans?

Caste is in the genes

I've built up a pretty good record over the past couple of years of pre-empting results that eventually show up in high end scientific journals.

Here's another major finding that you'll see at some point in Nature or Science: in present-day India upper caste membership is strongly associated with Eneolithic/Bronze Age steppe-related ancestry, while low caste membership and Dravidian languages are strongly associated with indigenous South Asian and Zagros Neolithic-related ancestry.

As far as I can see, with my somewhat limited dataset, the best way to show this is by plotting D-stats of the form D(Outgroup;Samara_Eneolithic)(Onge;X) versus D(Outgroup;Iran_Neolithic)(Onge;X). The relevant datasheet is available here.

Like I say, my dataset is still not great for this type of analysis, but the results are very striking and I have no doubt that they will be confirmed with more comprehensive sampling of Indian populations.

If they are confirmed, this will probably mean three things: 1) the caste system was introduced into the Indian subcontinent from the Eurasian steppe after the demise of the Chalcolithic Harappan civilization, 2) Zagros Neolithic farmers and closely related Neolithic/Chalcolithic populations of South Asia were not Indo-European-speaking, 3) like the caste system, Indo-Aryan (and thus Indo-European) languages were introduced into the Indian subcontinent from the Eurasian steppe after the Chalcolithic.

See also...

On the doorstep of India

Indian confirmation bias

The Out-of-India Theory (OIT) challenge: can we hear a viable argument for once?