REFUTING the Steppe Alchemists

                        On Davidski's supposed ZERO West Asian ancestry of Yamnaya. 

Eurogenes blogger Davidski, is persistent in his defense of Steppe homeland, despite the majority of mainstream opinion currently supporting a S. Caucuses homeland.  Steppe theory has long had it's fans, but as studies involving ancient DNA emerged, it became clear that any notion that PIE emerged from the Steppe, went from being unfoundedly optimistic, to a dogged delusion.  As they say, poor theories die hard - and Steppe theory is pretty bad.  

More recently Davidski posted a (psuedo) analysis in an attempt to argue that "Yamnaya" had ZERO West Asian influence (by analyzing an arbitrary Samara sample, which he eagerly declares as 'earliest Yamnaya' - even though the discussion of earliest Yamnaya has never even been resolved in the mainstream).  It's interesting to how one can arrive at such , but without going into details, more sophisticated admixture analysis has revealed a sizeable percentage of Iranian input at 4400BC on the proto-Yamnaya population (Chintalapati et all, 2022).  Okay, so the fact that there was Iranian admixture present among  proto-Yamnaya,  nullifies the notion that Iranians have any influence on Yamnaya proper, right?    

Well, the problem with that is that it falls on the spectrum of  Steppe apologetics - or any attempt to salvage the notion that Indo-Europeanization of the Steppe came from elsewhere, at the expense of reason or good empiricism. 

          

        REFUTING STEPPE APOLOGETICS

THE YAMNAYA CHICKEN AND EGG

When Yamnaya became Yamnaya is a bit arbitrary - and it is also entirely irrelevant in the discussion of Indo-European origins.  The fact remains the variance attributed to proper Yamnaya,  is attributable to CHG/Iranians, and is by no means accounted for by a deep period of indigenous evolution (as in the case of WHG, EHG, or Iranian Neolithic).  As Chintalapati et all,  show, using more sophisticated analysis, which accounts for pulses of admixture across time, the Iranian influence on Yamnaya (~estimate 4400BC) is not a distant Paleolithic influence that can be conveniently written off as insignificant, as Davidski likes to preach.  (Max Plank Institute has even argued a date for PIE ~8kybp, out of Iran).  The later influence of Yamnaya on the S. Caucuses, and much lesser extent NW Iran, is not shown to be meaningful (related to IE question), nor surprising.  Nobody rejects that Bronze Age populations had admixture (in each and every direction), but the point is that in light of the cumulation of evidence (more below), Yamnaya is not a good PIE candidate.  

THE CHG PAWN - A STEPPE THEROISTS INSURANCE AGAINST A SOUTHERN HYPOTHESIS

The designation of CHG has been met with confusion for some time.  I was compelled to reach out to a notable researcher (which I will not name), to justify the CHG grouping.  Sometime ago, I wrote:

It seems as with a few of these recent studies, CHG being 'older' than Iranian Neolithic is merely a tautological point;  Taking an 11Kbp Caucasus sample and calling it 'CHG', and taking a 9kbp Iranian sample and calling it 'Iranian Neolithic', and  then implying because the former is older, any shared genetics must involve a scenario where the direction of gene flow is from the older population to the younger (From CHG to Iran).  However, unless you have Iranian samples from the same period time period, it doesn't make sense to draw any  such conclusion about the direction of genetic influence, correct?

The response I received was,  

"Yes, we would need older samples from Iran to know for sure"

Regardless of the labeling bias, I couldn't help to notice that with broad enough sampling, the Neo-Iran almost always emerges as the parent population of CHG - this is even considering the CHG samples are 2-3ky older!

(from Wang et al 2019, supplementary material)

Notice the Blue Iranian component that maximized in Iran_Neolithic and in lesser amount CHG

So we pardon the ignorance among many researchers, and simply assume that CHG is parental.  But  the direction of influence is not the only problem.  When we use Global PCA analysis, to help put things to scale, you can see that the variance between Iranian Neolithics and CHG is almost the same as the variance within the WHG sample!  

(Notice the distance between median Neolithic Iranian and median CHG is similar to the distance between the furthest most samples within WHG)  Also of interest, note that modern Europeans are, ultimately, the product of polar WHG, EHG, and nothing possible, other than Iran-N.

So in conclusions, tt appears that CHG should more properly be considered as West Shifted, Neolithic Iranians.  Or better yet, we should drop Neo-Iran and CHG altogether for the designator TRANS-CAUCASIA , as Neo-Iranian is a bit ethnocentric. 

So why does CHG exist as a grouping in the first place?  

Well, the answer is that it has served as a kind of insurance against any evidence of a NW genetic influence, from the S.Caucauses/Iran and onto the Steppe.  It enables Steppe theorists to trivialize, the Armenian highland (Armenia/NW Iran) gene flow that has time and time again, has been shown independently.  Because the diffusion of genes originating in the S. Caucuses (Armenia/Iran), moving NW through the Caucuses and onto the Steppe, will naturally pick up on CHG admixture on it's way, and the result of this is that it provides the illusion that the admixture is more CHG, than S. Caucasus (Armenia/ Iran) - this is because after this admixture, much of shared genes between Armenia/CHG that originally overlap cannot be recounted, resulting in the true percentage of S. Caucuses admixture to be underestimated. 

ON THE QUITE POSSIBLE WEST ASIAN ORIGIN OF R1b-M269 

Davidski seems rather confident (or perhaps arrogant) on the European origin of R1b-M269.  Indeed, the high frequency of R1b related groups in early Europe is clear - The Yamnaya themselves (at some point) were 50% R1b -  nonetheless, frequency of a haplogroup is not the sole indicator of it's origin.  In small populations, a phenomena known as genetic drift often amplifies haplogroup markers (for example, 80%+ R1a in obscure Central Asian tribes).  This is basically, why it's improper to define populations on the basis of single genes.  It's literally Bio 101 type stuff.  But the internet is not filled with experts, and so stupidity ad infinitum.  

As for the association of PIE and R1b, despite convictions among Steppe theorists, it is not something that is non-objectionable.  While I personally believe that R1b is a defining marker of the Indo-Europeanization of Europeans beyond the Steppe (from Yamnaya) - given it's scant frequency among among some known IE groups in the East/S. Caucuses, it's worth questioning to what degree it should be associated with early IE, even if you wish to tentatively accept Steppe theory.  It is relevant that  (per Grungi 2012), that modern West Asians: Armenians, Zoroastrian Iranians, Central Persians, Assyrians do harbor a unusually high, relative frequency, of early clades of M269*, - exceedingly rare among modern populations.  While again, one cannot rule out the role of genetic drift, the sheer rarity of R1b- M269* in any other corner of the world, combined with the recent "South Caucasian" proposal by the Max Plank Institute, and earlier by David Reich, makes it worth investigating a scenario where R1b- M269* was related to movements from the S. Caucuses and onto the Steppe.  In other words, diametrically opposite to what has been suggested by Lazaridis et al, in the Southern Arc paper, and enthusiastically supported by Steppe theorists. 

The authors of the Southern Arc paper (Lazaridis et all 2022), imply that R1b made it's way into Armenia and NW Iran - but the authors assumption is that it came in with the late Yamnaya admixture, from what can be inferred autosomally.  Unfortunately, it is quite possible, if not likely, the authors are conflating late Yamnaya admixture, which diffused into the region, with the supposed arrival of R1b in Armenia/Iran.  Given the Yamnaya (or Proto-Yamnaya) have been determined to have a significant Iranian structure at 4400BC (see Chintalapati et all, 2022), it is not a stretch to imagine that R1b was brought there from the S. Caucauses, at or before 4400BC.  While that scenario has not been investigated, it is possibly an explanation to the source of Steppe R1b.