Paleolithic DNA from the Caucasus reveals core of West Eurasian ancestry – Lazaridis et al. 2018 – preprint

20 Comments

A great day for West Eurasian deep prehistory thanks to ancient DNA! First with “Late Pleistocene human genome suggests a local origin for the first farmers of central Anatolia” (Feldman et al. 2018, preprint) and now with this unexpected and very surprising “Paleolithic DNA from the Caucasus reveals core of West Eurasian ancestry” (Lazaridis et al. 2018, preprint).

The earliest ancient DNA data of modern humans from Europe dates to ~40 thousand years ago, but that from the Caucasus and the Near East to only ~14 thousand years ago, from populations who lived long after the Last Glacial Maximum (LGM) ~26.5-19 thousand years ago. To address this imbalance and to better understand the relationship of Europeans and Near Easterners, we report genome-wide data from two ~26 thousand year old individuals from Dzudzuana Cave in Georgia in the Caucasus from around the beginning of the LGM. Surprisingly, the Dzudzuana population was more closely related to early agriculturalists from western Anatolia ~8 thousand years ago than to the hunter-gatherers of the Caucasus from the same region of western Georgia of ~13-10 thousand years ago. Most of the Dzudzuana population’s ancestry was deeply related to the post-glacial western European hunter-gatherers of the ‘Villabruna cluster’, but it also had ancestry from a lineage that had separated from the great majority of non-African populations before they separated from each other, proving that such ‘Basal Eurasians’ were present in West Eurasia twice as early as previously recorded. We document major population turnover in the Near East after the time of Dzudzuana, showing that the highly differentiated Holocene populations of the region were formed by ‘Ancient North Eurasian’ admixture into the Caucasus and Iran and North African admixture into the Natufians of the Levant. We finally show that the Dzudzuana population contributed the majority of the ancestry of post-Ice Age people in the Near East, North Africa, and even parts of Europe, thereby becoming the largest single contributor of ancestry of all present-day West Eurasians.

After a still very shallow look at the paper, I’ll gather my preliminary thoughts. First the things that were more or less expected (a few of them mentioned in this previous post and the rest in other places) and that are more or less confirmed by these samples:

  • Basal Eurasian is in a way (or all the way) not part of the main Out of Africa, if we understand the latter as the people who ventured into Eurasia and mixed with Neanderthals in the Near East before spreading throughout the rest of Eurasia. In contrast, Basal Eurasians split from this population before, and whether they were geographically located somewhere in North or East Africa, or deep down the Arabian Peninsula is still unknown, but it all indicates that they probably lacked Neanderthal admixture.
  • This Basal Eurasian admixture appeared in the Near East before 26K YBP, since it’s already present in these Dzudzuana samples. The people with whom they mixed where what we’ve been calling Unknown Hunter Gatherers (UHG), the direct ancestors of the WHG found in Europe from the late UP.
  • Since these UHG that entered Europe didn’t carry this Basal Eurasian admixture, this means that they must have moved out of the Near East before 26K YBP. The samples we have from Europe prior to the LGM go down to 25K YBP and these UHG/WHG have not been detected. This means that they were still not widespread at that time. However we already see admixture from them in El Miron, a sample from North Iberia ca. 18K YBP, which again confirms that the time of arrival must have been prior to the LGM (expanding from the Balkans or near after the LGM).
  • Natufians seem to have some other kind of (North?) African admixture that post-dates the Basal Eurasian one.
  • Finally, ANE again gets more support from having some sort of ENA admixture.

And now for what was less expected:

  • ANE was still not present in the Caucasus by the time of these samples. We knew that this admixture came from further east (first sample we have is MA-1, from Lake Baikal in southern Siberia ca. 24K YBP).
  • This, together with the likelihood of ANE/ENA contacts raises the question of the origin of ANE. Did these contacts happen in Siberia? Or did they happen in SC Asia? This is still an unknown issue, but I’ll try comment further on it tomorrow.

I’m sure there are a lot more things to comment from this (and the Anatolian HG) paper(s), so stay tuned and share your thoughts!

20 thoughts on “Paleolithic DNA from the Caucasus reveals core of West Eurasian ancestry – Lazaridis et al. 2018 – preprint

  1. Great to have a much needed propper Paleolithic sample from the Near East.
    One of the main thrusts is that the putative ”Villabruna” population forms a clade with the non-B.E. portion of a 27000 yr old individuals from Dzuadzuna cave (and both in turn form a clade with Goyet (west European Aurignacian).

    They further suggest that ” In Europe, descendants of this lineage admixed with pre-existing hunter-gatherers related to Sunghir3 from Russia for the Gravettians and GoyetQ116-1 from Belgium for the Magdalenian”

    Simply outlined, the above suggests a scenario of:

    Villabruna + Sungir (or eastern Euro Aurignacian) -> Vestonice (Gravettian)
    &
    V.B. + Goyet -> Magdalenians / El Miron

    They also highlight ”However, it is unlikely that the Villabruna cluster sojourned in mainland Europe, as members of the cluster have been attested there only by ~14kya”
    Of course, we have no data from the Balkans or Black Sea between 36000 and 10000 BC, so they might wish to re-word this slightly.

    But the real details derive in the supplement. ”Villabruna, is also shown as a 3-way mixture in the model of Table S3.3, tracing about half its ancestry from Dzudzuana, and the remainder from Vestonic16 and MA1. This is not a priori implausible as all these sources are earlier than Villabruna. The admixture graph model presents a simpler model for Villabruna as a simple clade, and an unadmixed Villabruna acts as a plausible source for several other simpler mixtures of (Table S3.2). We are thus cautious about accepting this qpAdm result at face value as well.

    And ”“Western” Near Eastern populations, including Dzudzuana from the Caucasus, belonged to a cline of decreasing Villabruna/increasing deep ancestry: Villabruna → Dzudzuana/Anatolia_N → PPNB → Natufian → Taforalt

    So what seems feasible in ”real life terms”, putting their models through a reading of the archaeological – cultural evidence ?
    A plausible scenario is that the earlier Aurignacian -like population in Europe experienced an introgression from a proto-Gravettian population. Therefore, the ”UHG” admixture noted in El Miron could have arrived even prior the LGM – because the Gravettian made it to France and Iberia by 25 kya.

    During and after the LGM, populations from SEE / Black Sea continued to expand to western Europe, strata upon strata with progressive diminution of ”old Aurignacian” ancestry throughout Europe, although Aurignacian ancestry remained tangible in the West, as late as Mesolithic La Brana, Loschbour, La Chan, and presumably some of the upcoming British Mesolithics.

    In turn, the north Balkan – Black Sea region experienced ongoing contacts with the Upper Near East, but no definitive migration event after 30 kya. Sometime around or after the LGM, it experienced admixture from Afontova-Gora like peoples, and this hybrid population in turn was responsible for the Late Glacial shifts and the ascendance of ”WHG” groups.

  2. As far as the Caucasus itself goes, the Supp Sect 1 outlines that there seems to be a settlement hiatus in the Caucasus during the LGM. Thus, even though the later ”CHG ” groups like Satsurblia and Kotias also harbour the Dzudzuana ancestry, it could have come from somewhere else, nearby, like NW Iran.
    Indeed, CHG now has additional ”eastern ancestry” related to MA-1 compared to its geographic precursor, and a has new Industry invoking Zarzian parallels.

    Lastly, it’s surprising that MA-1 has up to 75 % west Eurasian, from a node which also leads to east European EUPs (Kostenki, Sungir). I guess the mtDNA U and Venus figurines corroborate such contacts.
    More importantly, MA-1 denotes a population replacement in Siberia of previous East Eurasian -tilted groups like Ust-Ishm (as its indeed known they he left no later descendants). The question is where this crown West Eurasian population came from.

  3. Lastly, to the Anatolian hunter-gatherer paper (Feldmen et al).
    They suggest that later Anatolian aceramic and ceramic farmers derived 90% of their ancestry from the Pinarbasi Epipaleolithic – like groups.

    It is worth exploring if this is an overestimate.
    Two reasons raise this possibility, aside from Chad’s comment on P-right population choice on their draft.
    First
    (1) The late paleolithic population in Anatolia is poorly documented. Whist this might relate to research state, it could also reflect a reality : Anatolia wasn’t swarming with hunter-gatherers.
    (2) If we assume, on the admittedly tenuous basis of n=1, that C1a -like individuals are the norm in Paleolithic Anatolia, then the subsequent dominance of G2a in the Neolithic must imply a migration of populations from the adjacent east (Syria, north Iraq ?), which might have been autosomally rather similar. Thus susbsumed within statistical continuity is a more complex reality of mobility with the inception of agriculture in the Near East.

  4. @Rob

    If we assume, on the admittedly tenuous basis of n=1, that C1a -like individuals are the norm in Paleolithic Anatolia, then the subsequent dominance of G2a in the Neolithic must imply a migration of populations from the adjacent east (Syria, north Iraq ?), which might have been autosomally rather similar. Thus susbsumed within statistical continuity is a more complex reality of mobility with the inception of agriculture in the Near East.

    Yes, I was thinking the same while looking at the paper. Once we have populations that are autosomally very similar it becomes difficult to say how much of continuity and replacement there is.

    Though we have those Boncuklu samples too, which seem to be hunter-gatherers in transition to early farming, and these ones were already G2a. So this question of migrations vs. local adoption of farming in Anatolia remains a bit unclear.

  5. Quick little chime in. I think that Vestonice + Dzu + ANE and excess ENA makes WHG. WHG isn’t going to be hiding anywhere. Near the same time as Dzu, we have Kostenki12, which is basically just like Kostenki14. So, count that area out.
    Plus, from 34KYA to 26 KYA, there really is no change in Gravettians. If someone was hiding there, why didn’t they mix in? Why would the 14KYO sample be pure, but things over 26 KYO be mixed? I don’t see that happening.

    Onto the UP Anatolians, I think they have Iranian/Zarzian stuff. Too much going on there to not be related. Them, plus more Iranian equals Boncuklu. Add Levant N to that and you get Barcin. As far as the one YDNA, not a big deal. First Euro HG we got was the same. Soon, it was I2 and R1b that took over the data. One sample is nothing to get worked up about. The next ten from there could be G2.

  6. Nice study. The Ancestral North African population definitely has no genetic relation to sub-saharan african populations. And we can safely conclude that the ANA where not SSA/negroid in phenotype either.
    This explains why the natufians who also completely lacked SSA morphology and admixture still showed an affinity towards north africa in some graphs.

    Y-haplogroup E must be associated either with Basal eurasian or these ancestral north africans, but at least we have confirmed now that E1b is the result of foreign paternal admixture into sub-saharan populations.

  7. @Chad

    I was thinking about these king of possibility, and I guess it might turn out to be correct. Though there’s still the problem with this “Basal Eurasian” admixture that requires a complicated balance between the different ancestries to explain it.

    For example, the D-stats in Extended Data Figure 5 (c) show that both Gravettian and UP_WHG share more alleles with ENA (Ust-Ishim, Tianyuan, Onge, Papuan) than Dzudzuana does, but at the same time there is no difference between Gravettian and UP_WHG in this extra affinity to ENA.

    Any extra ENA in UP_WHG (Villabruna, Bichon) should be mediated by ANE, because how else would it arrive to Europe? So this requires that the decrease in ENA affinity provoked by the 40-50% (?) Dzudzuana admixture in UP_WHG should be exatly compensated by the ~10% (?) ANE admixture. Which itself requires that ANE shows a very significant increase in allele sharing to ENA (Ust-Ishim, Tianyuan, Onge, Papuan) when compared to Vestonice16/Ostuni1. This I’ve seen in qpGraph, but I don’t think I’ve ever seen it in D-stats.

    So I’m not sure that is any less complicated than a movement of pre-Dzudzuana (i.e, a Dzudzuana-like population sans the Basal Eurasian admixture) into the Balkans in the 30-25 Kya period, and a post LGM expansion from there.

    Until the Dzudzuana samples become available, have you been able to model successfully Villabruna as Ostuni1 + Anatolia_N + ANE?

  8. @ Chad

    “‘ Why would the 14KYO sample be pure, but things over 26 KYO be mixed? ”

    Good points bud.
    But Chad, read their supp (wich I pointed out above) – it’s because they model it as such (I think the paper should bring this forth in the main text, IMHO.)

    @ Alberto

    ”Though we have those Boncuklu samples too, which seem to be hunter-gatherers in transition to early farming, and these ones were already G2a. So this question of migrations vs. local adoption of farming in Anatolia remains a bit unclear.”‘

    I think a scenario of steady trickling in during the gradual process of development from Epipaleo -> aceramic farming -> Pottery Neolithic.
    By the classic Neolithic, there was definite a swelling of population in east Anatolia. Then we see a drift westward, changing population densities etc
    Most interesting of all, is the population decline in large parts of central -west Anatolia c. 5000 BC. Did they all leave for Europe ? And who replaced them ? But that’s another topic for another day..

  9. @ Anthrogenin

    I find Hg E very interesting. I know it elicits considerable debate. I’m not proficient in terms of it’s overall story, but w.r.t. E-V13 in Europe, I one notable aspect, if I recall correct, E-V13 is closer to Ibero-Maurisian then Natufian E. It has been found in Neolithic Spain and Balkans. It’ll probably show up in Italy too.

    For other lineages, broadly, i think the region of north Mesopotamia to Iran (and perhaps as far as India) was a core zone of Paleolithic populations and lineage diversification. Hg G, H, I-J, LT, etc

  10. @ Chad: “Onto the UP Anatolians, I think they have Iranian/Zarzian stuff.

    The Laz. paper, p.5., states “we find an adequate two-way admixture model using qpAdm (χ2p = 0.158), in which AHG derives around half of his ancestry from a Neolithic Levantine-related gene pool (48.0 ± 4.5 %; estimate ± 1 SE) and the rest from the WHG-related one (tables S4 and S5).

    A very detailed description and analysis of EP Pinarbasi is provided by Baird e.a. 2013 (https://www.researchgate.net/publication/272254077_Juniper_smoke_skulls_and_wolves%27_tails_The_Epipalaeolithic_of_the_Anatolian_plateau_in_its_South-west_Asian_context_insights_from_Pinarbasi ). Highlights:

    1. Isotopic and archeobotanic/ -faunal analysis shows strong dietal reliance on sweetwater fish (much of the Konya plain was during the Glacial lake-covered ), bird and mammal hunting. No use of (wild) cereals, but occasional wild almonds, pistacchios and lentils. No maritime fish.

    2. Evidence of long-distance trade (Cappadocian obsidian, ca. 190 km; Dentalium shells, min. 180 km). At least the latter apparently have been traded in (for Obsidian?), since the diet lacked maritime fish.

    3. Significant cultural parallels to Natufians (e.g. shell use, Obsidian tools, one burial post-mortem decapitated) indicate cultural contact (posibly indirect). However, the subsistence mode is very different. Some parallels to (Italian) WHG are also visible (not discussed in detail). [So, in general, the 50/50 WHG/Levantine mix identified by Laz. isn’t archeologically completely off the mark]

    4. [ In relation to Rob’s remarks] “The apparent scarcity of Epipalaeolithic sites can be ascribed to the relatively high mobility, small scale and low density of these communities, combined with the low-level visibility of occupations. (..) Our evidence raises the concrete possibility that the plateau saw reduced occupation, or abandonment, during the GS-1 [Younger Dryas]”
    IOW: AHG isn’t neccesarily directly ancestral to AAF. More likely, Central Anatolia was unsettled during the Younger Dryas, and re-colonised in the early Holocene by an AHG-like population from, e.g., the Side-Alanya area, or populations exploiting Cappadocian Obsidian.

    As concerns the latter, a good graphical summary of EP/ EN trade routes to the Jordan Valley (Jericho) and the Zagros foothills is provided by A. Sheratt https://www.archatlas.org/ObsidianRoutes/ObsidianRoutes.php .
    That trade seems to be the key mechanism connecting Anatolia and the Levante, later (late PPN B) also with the Zagros, and bringing forward genetic admixture – quite symmetrically, apparently, the Laz. 2018 paper has 21.3 % Levantine ancestry in ACF, and 21.3 % AAF ancestry in Levant_Neol.
    I suppose the “Obsidian traders” were transhumating pastoralists, spending the summers in Cappadocia, and the winters in the Syrian lowlands. As pastorlists require salt (for their cattle, but also meat and dairy preservation), it makes perfect sense that the “Obsidian routes” target Jericho at the Dead Sea.

  11. @Chad

    I looked at all the qpAdm models in the supplements (section 4) and the only successful models for different WHGs must include Villabruna as a source. Since they only report the successful models it’s not totally clear whether they attempted something like Dzudzuana + Gravettian + ANE to model WHG though.

    Regarding what I was saying about the D-stats to make such a model feasible, it would require that something like f4(ANE, Gravettian, Ust-Ishim; Mbuti) to be quite significantly positive. If you have the chance, could you check if ANE alone would suffice to achieve that? Or would it require something more like an Amerindian population to do so (and maybe that doesn’t work either with Ust-ishim as ENA, but maybe it would work with Onge in its place).

  12. So, if CHG was not in the Caucasus before the LGM, they must have arrived there from Iran. I was wondering if Iran_N was the best ancestor for CHG, but in G25 I get this:

    CHG
    Sarazm_Eneolithic 82.9%
    Tepecik_Ciftlik_N 17.1%
    Ganj_Dareh_N 0%
    Barcin_N 0%
    Boncuklu_N 0%
    Kostenki14 0%
    Vestonice16 0%
    AfontovaGora3:I9050.damage 0%
    EHG 0%
    Comb_Ceramic 0%
    Latvia_HG 0%
    Baltic_HG 0%
    Narva_Estonia 0%
    Narva_Lithuania 0%
    WHG 0%

    Distance 13.9802%

    Which probably makes sense, even if this test cannot be taken as something very reliable.

    The thing is that the North Caucasus steppe population and Yamnaya-CWC-BB have some mtDNA clades that are steppe markers for Europe, but we also find them in SC Asia (J1b1a1 in Geoksiur Eneolithic, w3a1 in Tepe Anau Eneolithic, T1a1 and W6 in Gonur Tepe BA), which suggests an ancient connection between CHG and SC Asia (West Iran has not shown this connection through mtDNA so far).

    On a related note (probably for another future post), I was also wondering if there’s genetic evidence of migration from Neolithic West Iran to North India. This has been given for granted so far, but I’m not sure why. The genetic structure of the Indus_diaspora samples could be defined as Iran_N + ANE + AASI. If one proposes a migration of Iran_N, you’d need a local population that were pure ANE and pure AASI or a mix of both already. I don’t think we’ll find that in Mesolithic North India. The alternative is a model of something more closely related to Sarazm_Eneolithic + AASI:

    Shahr_I_Sokhta_BA3
    Onge 51.2%
    Sarazm_Eneolithic 43.8%
    Ganj_Dareh_N 5%
    AfontovaGora3:I9050.damage 0%
    EHG 0%
    Naxi 0%

    Distance 13.0729%

    So is there shared ancestry between Iran_N and Indus_diapora or is there migration from Iran_N?

  13. @Alberto: “If CHG was not in the Caucasus before the LGM …”

    I think it was (depending on what excactly is meant by “Caucasus”). Plaeoclimatic modelling suggests that during the LGM, glaciation of the Caucasus may have reached down as far as 500 m a.s.l. All the caves that have yielded aDNA so far (Dzudzuana, Satsurblia, Kotias) are located at around or slightly below that elevation and may well have been uninhabitated during the LGM. A good discussion, w. maps & terrain models, is provided in
    https://besarion.wordpress.com/2017/10/09/colchis-lgm-chg-isolated-refugium-and-refugia-glaciers-and-permafrost-dzudzuana-example/
    However, paleoclimatic modelling also suggests that the Colchian plain had a temperate climate with sufficient precipitation suitable for leaf-bearing trees. The Colchian plain is evidenced as LGM refugium for various trees and mammals, see, e.g.
    https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8312.2011.01788.x

    It should consequently also have served as human LGM refugium. Respective sites still have to be found, but may well be covered by fluvial/ post-glacial sediments (c.f. a similar situation in the Kura plain in Azerbaijan, where it required pipeline construction to uncover various archeological sites), or lie below current Black Sea Level, which may have been more than 100 m lower than today during the LGM.

    The Laz. 2018 paper, Table 1, models CHG as
    0.643 Dzudzuana
    0.222 AG3
    0.081 Tianyuan
    0.054 Mbuti (Basal)
    (p = 0.685, which is quite high)

    In contrast, Iran_N, while having similar shares of Dzudzuana and AG3, displays almost twice as much Mbuti (basal), and Onge instead of Tianyuan. Especially the latter indicates different sources of immigration (East Asian in the Colchian, South Asian in the Iranian case), rendering an Iranian origin of CHG unlikely. In addition, the Likhi mountains (Black Sea – Caspian watershed), while not particularly high (ca. 1000m), should still have presented a substantial barrier to late LGM immigration into Colchis from the East, while a (North-)western route along the Black Sea coast (or across the Black Sea) was passable. The post-LGM UP Kamennobalkovsky culture (Rostov area) is generally regarded at closely resembling the Colchian Imereti Culture, and has yielded Near Eastern (Caucasian) stone tools.

  14. @FrankN

    So the suggestion is that CHG might have been in the North West Caucasus before the LGM? I guess that’s a possibility, but we don’t have any evidence of Basal Eurasian admixture North of the Caucasus until much later (though the closest samples in space and time are the Kostenki ones and the Romanian one, some 32-33Kya). ANE is not present in those samples either.

    I hope the comment made by someone long ago about pre-LGM samples from the North Caucasus coming was true and we get to see them soon.

  15. @Alberto

    Isn’t their suggestion that CHG _didn’t exist_ before the LGM? That CHG is the result of ANE/ENA arriving south of the Caucasus after the LGM and admixing into the existing Dzudzuana-like population there? And the same goes for Iran_N, though the existing population there was more BE and less Villabruna, and the incoming one might also have been slightly different as well.
    As the abstract states: “We document major population turnover in the Near East after the time of Dzudzuana, showing that the highly differentiated Holocene populations of the region were formed by ‘Ancient North Eurasian’ admixture into the Caucasus and Iran and North African admixture into the Natufians of the Levant. “

  16. @Angantyr

    Yes, it’s probable that CHG as such didn’t exist. It’s likely the product of an incoming population mixing into the existing one.

    But it’s not parsimonious to think that some ANE/ENA population arrived from the north and some pure Basal Eurasian from the south, it’s more likely that a population similar to CHG was the one that arrived, contributing 70-80% to the formation of CHG, while the other 20-30% would be from Dzudzuana.

    Though this is all speculation at this point. There are many different possible scenarios, and I was just testing with the two samples that could be ancestral to CHG to see which one would fare better.

  17. @Seb: “Does higher P value mean the model is accurate?
    p = 0.685 means 68,5% probability that their model is correct. Considering the time depth involved and the unavoidable quality issues associated with such ancient aDNA, this is anything but a bad result. It is probably not the full story of what happened over those 12,000 years that separate Dzudzuana and Satsurblia, but something to start with.

    @Alberto:
    The analysis in the Laz. 2018 paper suggests the following:

    1. Dzudzuana represents more or less a prototypical UP Near Eastern AMH. He is set aside from Villabruna (Balkans to Ural UP HG??) by substantial Mbuti (Basal) admix – 27,5% acc. to Laz. 2018 Table 1. The geographical origin of that Basal Eurasian source is unclear; the Persian Gulf and surrounds is among the likely candidates.

    2. Holocene Near Eastern populations can generally be modelled well as Dzudzuana plus additional Basal Eurasian (Natufian +11% , Iran_N + 10%, CHG + 5.4% Basal), suggesting the BE “homeland” being moreless equidistant to the Levante and the Central Zagros, but somewhat further removed from Colchis.

    3. Both CHG and Iran_N also acquired substantial (22%) ANE (MA1/AG3) ancestry. The fact that these admixture percentages are almost identical suggests (but of course, doesn’t prove) that we are dealing with the reflex of one and the same population movement here from Siberia into Caucasia and beyond.

    4. Finally, CHG is analysed to incorporate 8% Tianyuan ancestry, while Iran_N holds 11% Onge ancestry.

    IMO, we have to see all these admixtures (BE, ANE, Tianyuan, Onge) as separate, possibly multiple events , rather than as just one “population similar to CHG” arriving after the LGM. The timescale involved, roughly 12,000 years between Dzudzuana and Satsurblia, certainly allows for more than one migration, even when considering that it included the LGM that clearly wasn’t conducive to longer-distance population movement.

    More specifically,

    a. supposing that the BE “homeland” was at/around the Persian Gulf (dry until the early-Holocene), BE ancestry may quite constantly have trickled into the Levante, the Zagros and the Caucasus.
    [Btw, while it is undisputed that the Colchian plain served as LGM refugium at least for a number of leaf-bearing trees and mammals, the Zagros’s role in this respect is much less clear. Iran_N-like populations may well represent relatively recent arrivals from a LGM/ Younger Drias refugium closer to the Persian Gulf, possibly bringing with them the Onge element]

    b. There seem to have been at least two Siberian/ East Asian entrances, the first one bringing ANE admix into both Iran_N and CHG, the second one Tianyuan admix only into the latter.
    Dating these entrances is highly speculative at the moment. Nevertheless, my gut feeling is that the pre-LGM period should have been more conducive for allowing Tianyuan ancestry finding its way into Colchis than the LGM and its aftermath. Since absence of Tianyuan ancestry in Iran_N indicates that the ANE entrance was still lacking Tianyuan elements and as such preceded the latter’s advance, this also applies to the ANE (MA1/ AG3) admixture event(s).

  18. In a very interesting article, Gronenborn suggests that the spread of ANE might have something to do with the appearance of Trapeze blade and bullet core technology into Europe and W Asia.
    https://www.academia.edu/35162189/Migrations_before_the_Neolithic_The_Late_Mesolithic_blade-and-trapeze_horizon_in_Central_Europe_and_beyond

    However, such technology appears c. 8000 ybp in W Asia, and is thus too late to account for the ANE shift seen in post-Glacial Caucasus. After the LGM, a new culture appears there, called the Imeretian, which comprises of some Epigravettian features but also Zarzian points, seen in Iran (This implies that there is already ANE in Iran by 20000 ybp, and perhaps even earlier) as well as gemoetric microliths typical of the Kebaran.
    I think this is consistent with what the aDNA shows.

  19. @FrankN

    Yes, that’s all consistently explained, and I don’t disagree with the theoretical part of it. But I’d make some observations:

    – The model you posted for CHG has 64.3% Dzudzuana + 5.4% Mbuti. What this really means is that the Dzudzuana population had turned more into a Natufian-like one due to the increase in Basal Eurasian admixture. This does not seem to have occurred in Anatolia.

    – The assumption that that ANE arrived to Iran from Siberia seems unlikely. There’s ANE all the way to South India (Paniya), which rather suggests an origin of ANE closer to the Hindu Kush, from where it moved north, west and south. Therefor, populations similar to CHG may have formed all over the place, from India to Central Asia to West Iran. These can all be plausible sources for Satsurblia.

    – Finally, we have the mtDNA connection I mentioned between the Caucasus (north and south) and SC Asia, to the exclusion of West Iran, Anatolia and North Eurasia.

    In the end, this is a question difficult to answer at this point, so it’s good to look at the options available. But the final answer can only come from aDNA.

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