Of Stone & Blood: The demography of the Megalithic expansions (work in progress)

18 thoughts on “Of Stone & Blood: The demography of the Megalithic expansions (work in progress)”

1. Very interesting Chad.I know you’re busy, but the more you post, the better.

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   1. Thank you! I have another one in the works.

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2. Chad, kudos. I remember debating this topic (Cardial vs Danubian in the megalithic sphere and shared ancestry across the megalithic sphere) with you before in the Eurogenes comments, where you were pretty adamant that the Globular Amphora Culture and Funnelbeaker was of solely Danubian inspiration, following archaeological evidence.

   (To be fair my arguments to the reverse did not exactly have strong evidence in favour – as I recall Davidski’s Global 25 and other PCA, haplotype chunk sharing in present day and ancient peoples, shared D-stat behaviour between all northern MN like populations relative to other samples, possibly others).

   So major props going back and being able to look at the evidence, reexamine assumptions and take a rigorous, formal look at the genetic evidence, carefully examine for possible inflators and biases in models, and revise your own ideas. Less people than we’d like can do that.

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3. Thanks, Matt! I think my contention was that Globe25 had GAC as mostly Iberia EN or MN. They do come out more Danubian, but yeah the Western thing is a surprise. Use of Africans had a bad effect too, as shown in the post. Lots of things may need to be looked at again.

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4. Thanks for the clarification, looking more carefully at your graphs I see what you mean. In retrospect, if I remember those conversations well, I possibly was not considering the full range of possibilities patterns of migration, and may have been overattached to mediating the genetic patterns through the idea of a specifically Cardial rooted migration both into and then *out* of Iberia, and that may have served to muddy the waters a little here.

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   1. Things change. I missed this earlier. I’m going to re-do everything where I had used Africans in graphs, to see what all changes.

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5. I’m wondering if the odd affinity between Euro farmers and SSA shown in the D-stats table could be a reflection of some Upper Paleolithic gene flow from Iberia into the ancestors of Iberomaurusians, followed by IBM admixture into SSA? As the incoming Anatolian farmers move into Europe they would’ve picked up some remnant UP hunter-gatherer ancestry as well (I know WHG wasn’t a straightforward continuation of a UP Euro HG group but they should have had some ancestry ultimately stemming from such a pop, right?), perhaps causing some excess sharing between European Neolithic and SSA by way of the IBM conduit.

   Also, the qpGraph with IBM below the aforementioned table is interesting, it has a sister branch of South African_HG leading directly to IBM. Prior to IBM, there was an apparently deep-rooted preceding culture in northwest Africa, the Aterian. In the original IBM paper, the authors found a signal of increased IBM affinity to east and south African HG pops to the exclusion of other Eurasians or Africans. I’m wondering if this graph is picking up on some admixture from an Aterian source into IBM.

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6. Great work Chad, This and further elaboration will be of great use for specialists and enthusiasts interested in meating out Neolithic dynamics. There’s a lot more to be discerned after the arrival of Anatolian pioneer farmers to Europe.

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   1. I may have a little tweaking left. I’m trying a few more things.

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7. BTW, cool Title 😉

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   1. My friend, Rob, came up with it. 🤣

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8. Chad, not sure about the etiquette here re: external links, but can you take a look at this post I made on anthrogenica: https://anthrogenica.com/showthread.php?15415-Paleolithic-DNA-from-the-Caucasus-reveals-core-of-West-Eurasian-ancestry&p=497019&viewfull=1#post497019

   I know this i just playing w/nMonte not formal stats but I think I picked up something here that I’m sure you’ll test when the Dzudzuana genotype sample is available: modern North Africans’ “Neolithic farmer” affinity ISN’T by and large from the more proximate (spatially and temporally) Europe_N/Chl/BA farming cultures but the more distal Dzudzuana source. (My theory is that Pelopponese_N_outlier is the closest proxy we have to Dzudzuana becuz:
   a) it has more Villabruna affinity and less Basal Eurasian affinity relative to Anatolia_EN/Europe_EN, and
   b) it’s Villabruna-like ancestry probably came from a more ‘easterly’ variant than the “WHG” substrate found in European farmers….

   Dzudzuana should share these two distinguishing traits w/Pelopponese_outlier, relative to Europe_N/Chl/BA. The modern N African populations STRONGLY prefer a Dzudzuana-like source over Anatolia_N/Europe_N/Chl/BA type sources… this is telling us something IMO.

   To the point in your post, I DO think Dzudzuana-like ancestry was quite widespread from N Africa down to at least the Sahel as early as the late Paleolithic (even modern Saharawi accept 25% Dzudzuana-like ancestry on top of that found in Iberomarusians– that can’t all come from Cardial Europe??). From there, it’s not too far gone to posit a push deeper into Africa.

   As for why Iberomaursians don’t have “excess” Dzudzuana-related ancestry relative to modern N Africans, the northwestern pulse from Chalcolithic Iberia is plays a role but that’s accounted for separately and its less significant. The bigger reason reason Taforalt didn’t have excess Dzudzuana is b/c this ancestry infiltrated Africa in the Paleolithic from the NORTHEAST. This is consistent with the most “conservative” modern N African populations– Algerians, Mozabites, and Saharawi– scoring the highest peloponese_N_o and the most proximate pop to European farmers (Moroccans) scoring among the lowest. IOW, Pelopponese_N_o isn’t acting as a substitute for Iberian farmer ancestry, but as a substitute for the older Dzudzuana substrate.

   Can you comment on the possibly apocryphal accounts of a population approximating a Sardinian-San 50/50 mixture surviving into medieval times in N Africa ?!?!

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9. That Dzudzuana paper was interesting as well, the author’s main qpGraph appeared to show a Mota/African like population mixing into IBM. Chad, have you had any chance (or any interest) in trying to tease out some of the odd relationships between SSA, IBM, and Natufians lately?

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10. Check out Lazaridis’ twitter, he links to a paper relevant to your post.

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    1. Thanks!

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11. Chad, any ETA on a new post? Eurogenes is almost unreadable these days because of David’s pathological obsession with the immortal steppe and Indo-Europeans and Bell Beakers or whatever else. I appreciate your efforts to at least try to broaden the scope of discourse around population genetics, especially since it doesn’t seem like there are too many people out there getting in the weeds of this stuff with Admixtools (or whatever else) and doing their own analysis and investigations, outside of academia anyway…

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    1. I will get to the new Caucasus paper later on. I have a new one on European farmers, with lots of new information. Europeans are much more mixed than I had noticed before. Much different from the story at Barcin.

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    2. My next post should be up in the next few days. Making a lot of graphs and compiling stats now.

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