Substack cometh, and lo it is good. (Pricing)

Eurasia, the Stone Age and revenge of the Danes!

In the last week, I put up a big two-part series of posts on Substack, The wolf at history’s door and Casting out the wolf in our midst, about the spread of Indo-European (men) 5,000 years ago. By coincidence, a massive preprint on ancient DNA just came out of the Willerslev coalition of researchers, Population Genomics of Stone Age Eurasia. It really is massive, and is hard to summarize, but here’s the abstract:

The transitions from foraging to farming and later to pastoralism in Stone Age Eurasia (c. 11-3 thousand years before present, BP) represent some of the most dramatic lifestyle changes in human evolution. We sequenced 317 genomes of primarily Mesolithic and Neolithic individuals from across Eurasia combined with radiocarbon dates, stable isotope data, and pollen records. Genome imputation and co-analysis with previously published shotgun sequencing data resulted in >1600 complete ancient genome sequences offering fine-grained resolution into the Stone Age populations. We observe that: 1) Hunter-gatherer groups were more genetically diverse than previously known, and deeply divergent between western and eastern Eurasia. 2) We identify hitherto genetically undescribed hunter-gatherers from the Middle Don region that contributed ancestry to the later Yamnaya steppe pastoralists; 3) The genetic impact of the Neolithic transition was highly distinct, east and west of a boundary zone extending from the Black Sea to the Baltic. Large-scale shifts in genetic ancestry occurred to the west of this “Great Divide”, including an almost complete replacement of hunter-gatherers in Denmark, while no substantial ancestry shifts took place during the same period to the east. This difference is also reflected in genetic relatedness within the populations, decreasing substantially in the west but not in the east where it remained high until c. 4,000 BP; 4) The second major genetic transformation around 5,000 BP happened at a much faster pace with Steppe-related ancestry reaching most parts of Europe within 1,000-years. Local Neolithic farmers admixed with incoming pastoralists in eastern, western, and southern Europe whereas Scandinavia experienced another near-complete population replacement. Similar dramatic turnover-patterns are evident in western Siberia; 5) Extensive regional differences in the ancestry components involved in these early events remain visible to this day, even within countries. Neolithic farmer ancestry is highest in southern and eastern England while Steppe-related ancestry is highest in the Celtic populations of Scotland, Wales, and Cornwall (this research has been conducted using the UK Biobank resource); 6) Shifts in diet, lifestyle and environment introduced new selection pressures involving at least 21 genomic regions. Most such variants were not universally selected across populations but were only advantageous in particular ancestral backgrounds. Contrary to previous claims, we find that selection on the FADS regions, associated with fatty acid metabolism, began before the Neolithisation of Europe. Similarly, the lactase persistence allele started increasing in frequency before the expansion of Steppe-related groups into Europe and has continued to increase up to the present. Along the genetic cline separating Mesolithic hunter-gatherers from Neolithic farmers, we find significant correlations with trait associations related to skin disorders, diet and lifestyle and mental health status, suggesting marked phenotypic differences between these groups with very different lifestyles. This work provides new insights into major transformations in recent human evolution, elucidating the complex interplay between selection and admixture that shaped patterns of genetic variation in modern populations.

There’s so much, I can’t really reduce. Here are some highlights

1 – New hunter-gatherer cluster with a focus in the eastern Ukraine/Russian border region. Between the Dnieper and Don. Because I can barely read the admixture grap in extended figure 4, I’m not totally clear where this group is positioned in the graph, though it has some Causus hunter-gatherer

2 – Neolithicization was pretty slow (demic) in most of Europe, except Scandinavia. We knew this. Steppe arrival was faster everywhere, but mixed with local Neolithic substrate…except in Scandinavia, where there was straight up replacement. But Scandinavians do have Neolithic ancestry…so where’s that from?

3 – The paper claims that the Corded Ware people mixed with Globular Amphora culture. I’m pretty sure if they looked closely all the South Asians will steppe ancestry will show this too, and not any other type of European Neolithic.

4 – Scandinavia seems to have had several replacements even after the arrival of the early Battle Axe people. This is clear in Y chromosome turnover, from R1a to R1b and finally to mostly I1, the dominant lineage now. They claim that later Viking and Norse ancestry is mostly from the last pulse during the Nordic Bronze Age.

5 – They claim to detect it’s clear that Neolithic ancestry in North/Central/Eastern Europe was from Southeast Europe, while that in Western Europe was from Southwest Europe. This is expected.

6 – They confirm that in terms of polygenic prediction Yamnaya people were taller. They claim that it looks like N vs. S European differences in height aren’t selection, but stratification (Yamnaya predicts tallness).

7 – They find that dark hair and skin in Europeans seems correlated with WHG ancestry. This seems to confirm that the WHG were indeed dark of hair and eye. They find that lighter skin/hair really seems to come with Anatolian farmers and Yamnaya. Not the hunter-gatherers. Though selection does start earlier. They assert this has something to do with UV/Vitamin D, but if that, why were the HG groups dark? (if blue-eyed in the case of WHG) I think the explanation is some interaction with the agro-pastoralist lifestyle.

They also confirm that pigmentation selection went on until 3,000 years ago. This is obvious, and to me, it explains easily the heterogeneity in some CWC and post-CWC populations. Some of the early Bell Beakers in Britain look totally modern in pigmentation, but other populations are darker than they should be.

8 – Lots of selection in diet and immune system. What you’d expect. Basically a lot of illnesses might be mixture of the various populations. For example, diabetes comes from WHG.

9 – Neolithic Anatolians seem associated with some psychiatric issues. Could this be due to early dense-living? No idea. Also, they find EDU was selected for (one locus). Might be pleiotropy though.

10 – They find the African R1b around Lake Chad in some Ukrainian samples. Seems to confirm that somehow it’s from Eastern Europe? Weird.

Anyway, read it and tell me what you think.

18 thoughts on “Eurasia, the Stone Age and revenge of the Danes!

  1. “They find the African R1b around Lake Chad in some Ukrainian samples. Seems to confirm that somehow it’s from Eastern Europe? Weird”.

    I wrote about that, i.e. the origin from Europe, linked with the R1b found after in Villabruna, Italy, 14000 years ago, already 15 years ago of course against the “levantinists” who supported the origin in Near East, and it is clear from so long also in the YFull tree.

  2. Not sure about Cornwall, but Scandinavia, Wales, and Scotland might have been pretty marginal places for hunter-gatherers and neolithic farmers, and very vulnerable to climatic shifts. It would explain the turnover if their populations had crashed hard before the steppe folk showed up (and the steppe folk had life-ways that adapted better to those environments, especially the heavy use of animal husbandry to produce dairy products).

    Maybe the later Neolithic ancestry was from migrants from further south with mixed ancestry who came later and intermingled with the first wave.

    Imagine being a five foot Neolithic farmer, and suddenly having these 6-foot giants on horse-back showing up to raid your farms and kidnap women.

  3. Paper: “Among them, we report a 0.83X genome of an Upper Palaeolithic (UP) skeleton from Kotias Klde Cave in Georgia, Caucasus (NEO283), directly dated to 26,052 – 25,323 cal BP (95%). In the PCA of all non-African individuals, it occupies a position distinct from other previously sequenced UP individuals, shifted towards west Eurasians along PC1 (Supplementary Note 3d). Using admixture graph modelling, we find that this Caucasus UP lineage derives from a mixture of predominantly West Eurasian UP hunter-gatherer ancestry (76%) with ~24% contribution from a “basal Eurasian” ghost population, first observed in West Asian Neolithic individuals29 (Extended Data Fig. 5A). Models attempting to reconstruct major post-LGM clusters such as European hunter-gatherers and Anatolian farmers without contributions from this Caucasus UP lineage provided poor admixture graph fits or were rejected in qpAdm analyses (Extended Data Fig. 5B,C). “

    Basically this is the Dzudzuana type HG that Iosif Lazaridis group reported in a preprint in 2018(!). Confirms this is important to explain WHG. It looks like this will probably be published with the similar Dzudzuana sample from Iosif Lazaridis paper from 2018. (Which was featured in a recent paper about different adna reagents by Reich Lab – https://www.biorxiv.org/content/10.1101/2022.01.13.476259v1).

  4. Paper: “Interestingly, two herein reported ~7,300-year-old imputed genomes from the Middle Don River region in the Pontic-Caspian steppe (Golubaya Krinitsa, NEO113 & NEO212) derive ~20-30% of their ancestry from a source cluster of hunter-gatherers from the Caucasus (Caucasus_13000BP_10000BP) (Fig. 3). Additional lower coverage (non-imputed) genomes from the same site project in the same PCA space (Fig. 1D), shifted away from the European hunter-gatherer cline towards Iran and the Caucasus. Our results thus document genetic contact between populations from the Caucasus and the Steppe region as early as 7,300 years ago, providing documentation of continuous admixture prior to the advent of later nomadic Steppe cultures”

    Provides some validation for the idea that part the steppe genotype was forming by 5300 BCE (to be supplemented by other ancestry to form the Yamnaya genotype). An earlier paper by Wang et al found samples like this by 4300 BCE, so this backdates by 1000 years to that.

    Though there’s some complexity here in that they use these Middle Don HG *with* Caucasus Hunter Gatherer to form Yamnaya. Might need some further investigation.

    Basically it seems like the mix is beginning, but the actual total ratio of CHG:EHG that the Yamnaya/Sredny Stog stabilized cluster which expands later have is not really settled. So there seems to be a pattern that there is some expansion of a CHG like population north of the steppe in this era and its mixing with the EHG, but this is still an ongoing process.

    (Note that the previous early samples reported by Wang at 4300 BCE recently showed as having traces of milk proteins in their teeth, so some of these cultures with this ancestry were experimenting with milk consumption and herding at that time).

    Their IBD based admixture models in this paper do look to have quite a “binary” tendency to me (e.g. in some models they simplify Europe down to almost Middle Don+Anatolian only, without the WHG resurgence into MN Europe that is required), so it also looks like they simplify and don’t consider the EEF/WHG related extra input into the Yamnaya (which may come from Ukraine HG+Makyop or may come from European EEF, and that’s not really properly settled, though we’d probably lean to the latter option so far).

  5. Paper: Another cool thing is it looks like they may have found more evidence of fairly early I1 in the Bronze Age Denmark dataset, which would help to resolve some of its mystery.

    Assuming I’m reading Fig 4 right. After 2700 BCE, very little R1a, some R1b and some I2a (and the I2a is in people with steppe ancestry, as in some samples in Switzerland), then transition to I1 predominance around 2000 BCE. They date this to 1800 BCE (a final stage from c. 3,800 BP onwards, where a distinct cluster of Scandinavian individuals dominated by males with I1 Y-haplogroups appears (Extended Data Fig.8E” with earliest sample at 2000 BCE). This is cool because other I1 is fairly absent in much of Europe and only creeps in during the Iron Age. And in fact not seen before that, so must be cryptically present somewhere.

    Some folk had suggested that I1 in Scandinavia was actually a founder effect associated with north moving populations in the Iron Age, so this seems to neatly falsify that.

    On that point, their Supplementary Data has in Table S7 has a transect of lots of samples from Norway, Sweden and Denmark, including the new ones, and their Table S9 has a “deep ancestry” proportions model which “Middle Don ancestry” as one of the streams (which is the stream that contributes most to Yamnaya. The model seems to tend to two-way fits and I think is a bit simplified but is probably a decent proxy.

    So, putting these together with the haplogroup information: https://imgur.com/a/60TEsCO (Middle Don ancestry) / https://imgur.com/a/Ph8U0XA (Boncuklu Anatolian ancestry)

    You can see where there’s a pretty even mix of R1a, I2a and R1b after the sudden emergence of Middle Don ancestry around 4600 BP (2600 BCE), and then I1 supercedes all these around 4000 BP (2000 BCE), with continuation of R1b (but R1a and I2a absence).

    Then the Viking Era (samples mainly from Margaryen’s paper) later on shows contribution of R1a, I1 and R1b, with little I2 reemergence, and new haplogroups coming in at a minor frequency (with N1a at the highest minor frequency but a few E1b, G2 and J2 and even L showing up as well – that fits with a notional picture that the Iron Age may show more high status male and trader mobility from south to north, but this is regionally diluted by larger local populations, leaving only a few male haplogroups?). While R1b seems in their models to have some association with the samples in the Viking Era who have richer EEF ancestry and less Steppe related ancestry compared to the Bronze Age (which might possibly be thought to represent population movements from the south which dilute local ancestry mix a bit, like in Bronze Age Britain – the R1b subclades might be important here and we need more samples from the intervening?).

  6. The presence of some (few in number but comparable) I2as among the early Single Grave Culture may help to validate a bit the idea that the early Corded Ware Culture that moved into Europe and then led to the largely R1a later Corded Ware and R1b-M269 Bell Beaker may have been slightly more diverse in y haplogroups, with “pruning” coming later, and also possibly that Single Grave, as follows some archaeolgy, was actually one of the more eccentric descendents of the larger early CWC culture (while the other descendents had more y-dna homogenity). It may be that there’s tendency to some unusual interaction in this region that explains the I1 survival/introgression.

    Some other examples like were the Papac paper last year – https://www.science.org/doi/10.1126/sciadv.abi6941 – where their early set, although not diverse, had some samples who were R1a, R1b-Z2103 (the haplogroup found in Yamnaya but not much in later Europe), R1b-L51 (the subclade dominant in Europe), Q1b2a, an I2, and then a more homogenous set of R1b-L51 and R1a-M417 later on. Or there is another Single Grave sample in Denmark who has R1b-V88, and then also the Spreitenbach Corded Ware who were reported in Switzerland with I2a.

    Doesn’t change the overall picture that the expanding culture was likely chiefly R1b and R1a but does indicate there might have been some more early diversity in y-dna for various reasons, that then got smooshed out in the mid-later 3rd Millennium as patrilineal groups competed.

    (Particularly they note about NEO792 who had I2a that “The Danish Neolithic remains of NEO792 are interesting as this individual carried the highest proportion of steppe-ancestry among the Danish individuals … We find individuals with steppe ancestry mainly clustering together under macro haplogroup M, although we also identify a few steppe individuals in U2735 closely related to a Danish Neolithic individual, NEO792, who also carried a high proportion of steppe-ancestry in the nuclear genome.” So he seems to have a steppe mtdna.

    His actual archaeological description as well is: Megalithic tomb, presumably a passage grave, excavated 1838, containing Funnel Beaker pottery and flint objects from the Middle or Late Neolithic (the National Museum of Denmark, inv. no. 4630-31). Among the bones of several individuals was the skull of a man 30-40 years of age with trepanation (Figure S6.15). 14C dated 4020±35 BP (UB-35723), it is one of the very few individuals currently known from the time of the Single Grave Culture in eastern Denmark (MN BII).”. So he’s buried in a neolithic passage grave tomb.)

  7. On the polygenic height stuff, as Razib says they note that:

    “The finding that steppe individuals have consistently high genetic values for height (Supplementary Note 4c), is mirrored by the UK Biobank results, which find that the ‘Steppe’ ancestral components (Yamnaya/EHG) contributed to increased height in present-day populations (Supplementary Note 4h). This shows that the height differences in Europe between north and south may not be due to selection, as claimed in many previous studies, but may be a consequence of differential ancestry.”

    However, I don’t know about this. In supplement you have Fig S4c – https://imgur.com/a/i2t9WLL

    And it really does look here like the PRS for height is higher in the admixed LNBA European cluster compared to the samples from out at the Steppe_EMBA with the unadmixed steppe ancestry, or at minimum they’re not intermediate between Steppe_EMBA and EEF. I don’t know how this could be possible without subsequent selection…

    The blonde hair colour and skin colour PRS are also the same (admixed LNBA show a derived phenotype rather than intermediate).

    The height PRS also shows a rather fast shift between the top of the Italy cline and Central Europe, which seems not the most compatible with a model where its decided by ancestral streams from 3000 BCE.

    Another point on this is that they have another supplement 4f where they give PRS scores based on UK Biobank data for 100 ancient samples from Denmark.

    When I graph the data they give in Supplementary Table S4f.1: https://imgur.com/a/TWxRqQe

    … with a spline on it there’s a really strong pattern for later samples after the steppe admixture to have a higher PRS score than the early ones, even though there’s no change in steppe ancestry after 2600 BCE, when I look at the subset of data that they model. Albeit the sample size is low.

    (The differences modelled here are also rather modest. Danish EEF are predicted to only be 0.25 inches shorter than present-day Danes while the Danish steppe admixed group are predicted to be 0.5 inches taller. There’s certainly quite a bit of overlap between Danish EEF and Danish steppe admixed. Perhaps this is due to compression of the scores due to ancient dna or still current limitations of the GWAS.)

    So it kind of looks more like the data is pointing to post 2600 BCE selection rather than not selection, even though steppe ancestry is associated with an increase in height PRS independently of selection. So I’m a bit baffled as to why they came to the conclusion they came to in the main text.

  8. Fig 5 seems like it could be a useful reference by another method (GLOBETROTTER) for ancient ancestry proportions in modern Europeans (the published ones are out of date) with the intuitive finding of the maximum steppe ancestry in Ireland, Scandinavia, and the Baltic with the balance of remaining ancestry differences from east->west in the north being due to greater WHG+EHG in the east and Anatolian ancestry in the west. Shame the graphic is so compressed, and there is no accompanying table. The model probably does not work outside of Europe so probably is misleading in the graphic to include these countries.

    Will stop babbling all over the comments now; anyway, that just scratches the surface of what is in this paper!

  9. “This seems to confirm that the WHG were indeed dark of hair and eye.”
    I think you meant dark of hair and skin.

    “Neolithic Anatolians seem associated with some psychiatric issues.”
    This seems interesting. What kind of issues were they?

  10. I was confident hunter gatherers on the Don river would have lots of CHG ancestry back in May 2020. I emailed David Anthony about it.

    I planned on making a youtube video about my theories this year. It was going to be apart of my IE series.

    But I was too late. I didn’t finish the video. Now people might not believe I saw this coming.

  11. David Anthony leaked that DNA from hunter gatherers near the Volga have more CHG than later Yamnaya. Proving a Stone age origin of CHG ancestry in PIEs.

    Based on this, he created a theory that CHG from “Iran” migrated into specifically the Volga region, and no where else, around 6300 BC.

    Then on the Volga they created a pre-proto Indo European population.

    This Don river DNA disproves his theory. It instead suggests CHG ancestry was already widespread in the Neolithic not restricted to the Volga.

    Therefore, later PIE speakers descended from a race of people in Russia (prob. also Ukraine) not one tribe who lived on the Volga.

  12. @Matt
    “Will stop babbling all over the comments now”

    Please don’t. I find it really interesting and learn a lot.

  13. @Philip, cheers, OK then. 🙂

    @Genos, yeah, I think the finding of the Middle Don hunters has some new implications for the idea that the CHG:EHG blend in Yamnaya/Progress had long preceded these cultures and was widespread outside the southern steppes and Volga.

    On the one hand, the points as you note of where these samples come from and when they come from, does directly evidence that the mixture process was widespread by this time!

    On the other, they do seem to have a different ratio of CHG:EHG to Yamnaya and the later Progress, needing a “top up” of CHG ancestry to be used as an ancestor for Yamnaya.

    (I think they’re actually dispersed quite broadly and sit above Yamnaya/Steppe on the PCA – e.g. see here for where I think they sit on their PCA: https://imgur.com/a/gQaiXic. More like the top of Khvalynsk cline than they are like Progress. Here’s the PCA from Anthony’s presentation in 2020 for the Khvalynsk cline for comparison: https://imgur.com/a/MWX38hE).

    So the second of these points is not so good for the more maximal versions of the “CHG+EHG is a long term group native to the steppes”, where it was proposed that Progress_Eneolithic might represent a population that had formed by 7000 BCE (almost contemporary with Kotias) or even earlier or something like this, without further admixture process.

    It points, to me at least anyway, more to the CHG+EHG fusion being ongoing still at the time of these samples and the slightly later Khvalynsk sites. They’re possibly more just like another point on a cline that’s not really stabilized. But, yeah, I think that definitely is a win for the idea that the process is not just confined to one location on the Volga at this time (if that’s what Anthony was suggesting I can’t totally remember) because it points against that.

    The other thing that’ll be important in this regard that’s probably coming soon is the upcoming paper by Ayshin Ghalichi et al on “Genomic signals of continuity and admixture in the Caucasus” where the abstract mentions “the first genomic data from a Mesolithic individual (6100 calBCE) from the Northwest Caucasus that shows Eastern hunter-gatherer ancestry”. So if that person is admixed between CHG-EHG, then that shows more clearly that the admixture process is already by 6100 BCE (about 1500 years after Kotias) stretching down into the Caucasus and need not focus on the Volga like Anthony’s suggestion.

    One fact on these Middle Don HG that may interest the R1a reader 😉 : “Haplogroup R1a was found in the newly reported samples mainly among Eastern European hunter-gatherer individuals. Phylogenetic placement suggests that the oldest individuals from Mesolithic and Neolithic Russia represent early diverging lineages (Fig. S3b.5). Notably, a ~7,300-year-old Neolithic individual from the Middle Don region (NEO113) was placed in a basal R1a clade together with early individuals associated with the Corded Ware complex (poz81, RISE446), which would make it the earliest observation of this lineage reported to date.” (poz81 is a very early CWC person from Poland who has nearly no extra EEF ancestry compared to Yamnaya).

  14. @Genos, this might be interesting to you as well as a longtime member of the Eurogenes commenting community.

    So, the main PCA in this paper are different from long-standing ones, because they use imputed ancient genomes in the inference of PCA step, and they don’t just project on modern variation.

    Here’s a comparison of their main PCA doing this, vs a projected PCA they provide, and against Vahaduo’s “West Eurasia PCA” based on Davidski’s G25 data: https://imgur.com/a/01DguVC

    The imputed genomes PCA is least compressed in ancients particularly for the Euro HG cline, while their projected PCA is quite compressed. The Eurogenes data is somewhere in-between.

    This suggests to me that, provided the imputation procedure is accurate here, perhaps the some the cases we were finding with G25 where it seemed there was a small difference with qpAdm and like differences in WHG:ANF ratio between modern and ancient may be less of a problem on PCA inferred with imputed ancient genomes included and you’ll get a closer result to qpAdm (where for instance GAC+Steppe works pretty well for Beakers without any need for top-up of WHG). Though there may still be some top up required. And particularly the BA Latvia population with the distinctive high HG proportions on G25 may get a little bit more normal for example.

    Davidski actually did some PCA before using imputed ancient genomes, but was limited to the 67 high quality ancient genomes which were available in Martiniano 2017 (https://eurogenes.blogspot.com/2018/01/genetic-maps-featuring-67-ancient.html), which I thought was some of his best work and even maybe less compressed (https://imgur.com/a/jniu9DX), but has been very limited by the small number of available ancient genomes (which should affect inference a bit as well). (Where the G25 is more limited by the techniques he has to use with smartpca2 to take best advantage of its projection to get the most limited shrinkage of projected samples).

  15. One other point about this paper that strikes me now that I could guess about; the slightly enriched “free” WHG ancestry in Central and Northern England.

    Now, when I say “free” ancestry, I mean, WHG ancestry that does not come through the intermediary channel of farmer populations.

    One slightly confusing thing about Figure 5, which I didn’t notice before, is that Lawson and Barrie model populations by combining different subclusters of farmers in Europe, with very different levels of WHG ancestry ranging from about 5% to about 30% into a single farmer label. Using all these farmers is probably a good idea, but it does sort of confuse reading the figures as “Anatolian ancestry” = “Farmer ancestry”.

    Hence, what WHG means in the model under Figure 5 is not the same as in qpAdm but rather, in the authors’ words, “Ancestry proportions assigned to the oldest groups (e.g. WHG) should be interpreted as an excess of this ancestry, which cannot be explained by simply travelling through more recent ancient populations up to present times.” (i.e. which is not donated via Late Neolithic farmers).

    What I think I remember from some of these IBD / haplotype driven models in the past is that generally is found is that Western European populations take all their WHG ancestry *via* Middle/Late Neolithic farmers (usual model is principally via the Globular Amphora Culture). Where there is WHG outside this model is more usually in Eastern Europe, where we find more outliers with rich extra WHG ancestry in the Bronze Age.

    There is often some cline of this where this excess WHG that is *outside* MN farmers is higher in Scandinavia than Ireland (following isolation-by-distance from Eastern Europe).

    Hence my guess is that the excess of WHG in Central and Northern England is possibly explained by the imprint of the Vikings, which is also higher in Central and Northern England?

  16. Quick observation about the paper’s IBD analyses IBD3 “postNeol”, in case authors are reading (no comments allowed on bioRxiv for this one!):

    This analysis finds fairly plentiful amounts of ancestry/source in samples from Bronze Age France from a source IBD cluster “LevantEuropeS_4700BP_1700BP”. This seems to average 9.5% across 4 samples ranging from 3,900 to 2,800 YBP.

    This is somewhat common across samples from Bronze Age Southern and Western Europe, e.g. this cluster in the same model contributes 27% to a sample from Italy dated 3013 YBP (NEO806) or 10% to 9 samples from Bronze Age Iberia.

    Given that the about half of the samples in the source IBD cluster are aged from the Roman Imperial period, that would seem to have a potential issue that the source contribution might reflect a contribution from Bronze Age Western Europe -> the Roman Imperial period.

    This cluster also contributes some donation of 14.5% of ancestry to Iron Age and Roman Era British samples (without much pattern), which seems hard to reconcile with the lack of dilution of steppe ancestry (and it .

    It seems like it would more ideal for the authors to include a further analysis specific to the Bronze Age Era that removes the samples from the “LevantEuropeS_4700BP_1700BP” that post-date the Bronze Age, as a source, to clarify identify the direction of sharing (e.g. whether there was a real phenomenon of donation from a Levant/S Europe source into Western Europe during the BA->IA, or whether this represents the reverse phenomenon).

  17. “10 – They find the African R1b around Lake Chad in some Ukrainian samples. Seems to confirm that somehow it’s from Eastern Europe? Weird.”

    My bet would be a common source in the Balkans connected to whatever expansion brought it to Villabruna.

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