Ahead of the (Indo-European – Uralic) game: in theory and in numbers

yamnaya-expansion-bell-beaker

There is a good reason for hope, for those who look for a happy ending to the revolution of population genomics that is quickly turning into an involution led by beliefs and personal interests. This blog is apparently one of the the most read sites on Indo-European peoples, if not the most read one, and now on Uralic peoples, too.

I’ve been checking the analytics of our sites, and judging by the numbers of the English blog, Indo-European.eu (without the other languages) is quickly turning into the most visited one from Academia Prisca‘s sites on Indo-European languages, beyond Indo-European.info (and its parent sites in other languages), which host many popular files for download.

If we take into account file downloads (like images or PDFs), and not only what Google Analytics can record, Indo-European.eu has not more users than all other websites of Academia Prisca, but at this pace it will soon reach half the total visits, possibly before the end of 2019.

Overall, we have evolved from some 10,000 users/year in 2006 to ~300,000 active users/year and >1,000,000 page+file views/year in 2018 (impossible to say exactly without spending too much time on this task). Nothing out of the ordinary, I guess, and obviously numbers are not a quality index, but rather a hint at increasing popularity of the subject and of our work.

NOTE. The mean reading time is ~2:40 m, which I guess fits the length of most posts, and most visitors read a mean of ~2+ pages before leaving, with increasing reader fidelity over time.

indo-european-eu-analytics
Number of active users of indo-european.eu, according to Google Analytics since before the start of the new blog. Notice the peaks corresponding to the posts below (except the last one, corresponding to the publication of A Song of Sheep and Horses).

The most read posts of 2018, now that we can compare those from the last quarter, are as follows:

  1. – The series on the Corded Ware-Uralic theory, with a marked increase in readers, especially with the last three posts:
    1. Finno-Permic and the expansion of N-L392/Siberian ancestry,
    2. “Siberian ancestry” and Ugric-Samoyedic expansions, and
    3. Haplogroups R1a and N in Finno-Ugric and Samoyedic
  2. Haplogroup is not language, but R1b-L23 expansion was associated with Proto-Indo-Europeans
  3. The history of the simplistic ‘haplogroup R1a — Indo-European’ association
  4. On the origin of haplogroup R1b-L51 in late Repin / early Yamna settlers
  5. On the origin and spread of haplogroup R1a-Z645 from eastern Europe
  6. The Caucasus a genetic and cultural barrier; Yamna dominated by R1b-M269; Yamna settlers in Hungary cluster with Yamna
  7. Something is very wrong with models based on the so-called ‘Yamnaya admixture’ – and archaeologists are catching up (II)
  8. Olalde et al. and Mathieson et al. (Nature 2018): R1b-L23 dominates Bell Beaker and Yamna, R1a-M417 resurges in East-Central Europe during the Bronze Age
  9. Early Indo-Iranian formed mainly by R1b-Z2103 and R1a-Z93, Corded Ware out of Late PIE-speaking migrations
  10. “Steppe ancestry” step by step: Khvalynsk, Sredni Stog, Repin, Yamna, Corded Ware

NOTE. Of course, the most recent posts are the most visited ones right now, but that’s because of the constant increase in the number of visitors.

I think it is obvious what the greatest interest of readers has been in the past two years. You can see the pattern by looking at the most popular posts of 2017, when the blog took off again:

  1. Germanic–Balto-Slavic and Satem (‘Indo-Slavonic’) dialect revisionism by amateur geneticists, or why R1a lineages *must* have spoken Proto-Indo-European
  2. The renewed ‘Kurgan model’ of Kristian Kristiansen and the Danish school: “The Indo-European Corded Ware Theory”
  3. The new “Indo-European Corded Ware Theory” of David Anthony
  4. Correlation does not mean causation: the damage of the ‘Yamnaya ancestral component’, and the ‘Future American’ hypothesis
  5. The Aryan migration debate, the Out of India models, and the modern “indigenous Indo-Aryan” sectarianism

The most likely reason for the radical increase in this blog’s readership is very simple, then: people want to know what is really happening with the research on ancestral Indo-Europeans and Uralians, and other blogs and forums are not keeping up with that demand, being content with repeating the same ideas again and again (R1a-CWC-IE, R1b-BBC-Vasconic, and N-Comb Ware-Uralic), despite the growing contradictions. As you can imagine, once you have seen the Yamna -> Bell Beaker migration model of North-West Indo-European, with Corded Ware obviously representing Uralic, you can’t unsee it.

The online bullying, personal attacks, and similar childish attempts to silence those who want to talk about this theory elsewhere (while fringe theories like R1a/CHG-OIT, R1b-Vasconic, or the Anatolian/Armenian-CHG hypotheses, to name just a few, are openly discussed) has had, as could be expected, the opposite effect to what was intended. I guess you can say this blog and our projects have profited from the first relevant Streisand effect of population genomics, big time.

If this trend continues this year (and other bloggers’ or forum users’ faith in miracles is not likely to change), I suppose that after the Yamna Hungary samples are published (with the expected results) this blog is going to be the most read in 2020 by a great margin… I can only infer that this tension is also helping raise the interest in (and politicization of) the question, hence probably the overall number of active users and their participation in other blogs and forums is going to increase everywhere in 2019, too, as this debate becomes more and more heated.

So, what I infer from the most popular posts and the numbers is that people want criticism and controversy, and if you want blood you’ve got it. Here it is, my latest addition to the successful series criticizing the “Corded Ware/R1a–Indo-European” pet theories, a post I wrote two-three months ago, slightly updated with the newest comedy, and a sure success for 2019 (already added to the static pages of the menu):

The “Indo-European Corded Ware theory” doesn’t hold water

This is how I feel when I see spikes in visits with more and more returning users linked to my controversial posts 😉

Are you not entertained?! Are you not entertained?! Is this not why you are here?!

ASoSaH Reread (I): Y-DNA haplogroups among Indo-Europeans (apart from R1b-L23)

eneolithic-early-admixture-steppe-ancestry

Given my reduced free time in these months, I have decided to keep updating the text on Indo-European and Uralic migrations and/or this blog, simultaneously or alternatively, to make the most out of the time I can dedicate to this. I will add the different ‘A Song of Sheep and Horses (ASoSaH) reread’ posts to the original post announcing the books. I would be especially interested in comments and corrections to the book chapters rather than the posts, but any comments are welcome (including in the forum, where comments are more likely to stick).

This is mainly a reread of iv.2. Indo-Anatolians and vi.1. Disintegrating Indo-Europeans.

Indo-Anatolians and Late Indo-Europeans

I have often written about R1b-L23 as the majority haplogroup among Late Proto-Indo-Europeans (see my predictions for 2018 and my summary of 2018), but always expected other haplogroups to pop up somewhere along the way, in Khvalynsk, in Repin, in Yamna, and in Bell Beakers (see e.g. the post on common fallacies of R1a/IE-fans).

Luckily enough – for those of us who want precise answers to our previous infinite models of Indo-European language expansions (viz. GAC-associated expansion, IE-speaking Old Europe, Anatolian homeland, Iran homeland, Maykop as Proto-Anatolian, Palaeolithic Continuity Theory, Celtic in the Atlantic façade, etc.) – the situation has been more clear-cut than expected: it turns out that, especially during population expansions, acute Y-chromosome bottlenecks were very common in the past, at least until the Iron Age.

Khvalynsk and Repin-Yamna expansions were no different, and that seems quite natural in hindsight, given the strong familial ties and aversion to foreigners proper of the Late Proto-Indo-European society and culture – probably not really that different from other contemporary societies, like the neighbouring Late Proto-Uralic or Trypillian ones.

y-dna-khvalynsk
Y-DNA samples from Khvalynsk and neighbouring cultures. See full version here.

Y-DNA haplogroups

During the expansion of early Khvalynsk, the most likely Indo-Anatolian culture, the society of the Don-Volga area was probably made up of different lineages including R1b-V1636, R1b-M269, R1a-YP1272, Q1a-M25, and I2a-L699 (and possibly some R1b-V88?), a variability possibly greater than that of the contemporary north Pontic area, probably a sign of this region being a sink of different east and west migrations from steppe and forest areas.

During its expansion, the Khvalynsk society saw its haplogroup variability reduced, as evidenced by the succeeding expansive Repin culture:

Afanasevo, representing Pre-Tocharian (the earliest Late PIE dialect to branch off), expanded with R1b-L23 – especially R1b-Z2103 – lineages, while early Yamna expanded with R1b-L23 and I2a-L699 lineages, which suggests that these are the main haplogroups that survived the Y-DNA bottleneck undergone during the Khvalynsk expansion, and especially later during the late Repin expansion. Nevertheless, other old haplogroups might still pop up during the Repin and early Yamna period, such as the R1b-V1636 sample from Yamna in the Northern Caucasus.

It is still unclear if R1b-L23 sister clade R1b-PF7562 (formed ca. 4400 BC, TMRCA ca. 3400 BC), prevalent among modern Albanians, expanded with Yamna migrants, or if it was part of an earlier expansion of R1b-M269 into the Balkans, and represent thus Indo-Anatolian speakers who later hitchhiked the expansion of the Late PIE language from the north or west Pontic area. The early TMRCA seems to suggest an association with Repin (and therefore Yamna), rather than later movements in the Balkans.

chalcolithic-early-y-dna
Y-DNA samples from Yamnaya and neighbouring cultures. See full version here.

‘Yamnaya’ or ‘steppe’ ancestry?

After the early years when population genetics relied mainly on modern Y-DNA haplogroups, geneticists and amateurs have been recently playing around with testing “ancestry percentages”, based on newly developed free statistical tools, which offer obviously just one among many types of data to achieve a proper interpretation of the past.

Today we have quite a lot Y-DNA haplogroups reported for ancient samples of more recent prehistoric periods, and they seem to offer (at least since the 2015 papers, but more evidently since the 2018 papers on Bell Beakers and Europeans, Corded Ware, or Fennoscandia among others) the most straightforward interpretation of all results published in population genomics research.

NOTE. The finding of a specific type of ancestry in one isolated 40,000-year-old sample from Tianyuan can offer very interesting information on potential population movements to the region. However, the identification of ethnolinguistic communities and their migrations among neighbouring groups in Neolithic or Bronze Age groups is evidently not that simple.

PCA-caucasus-steppe-all
Yamnaya (Indo-European peoples) and their evolution in the steppes, together with North Pontic (eventually Uralic) peoples.Notice how little Indo-European ancestry changes from Khvalynsk (Indo-Anatolian) to Yamna Hungary (North-West Indo-Europeans) Image modified from Wang et al. (2018). See more on the evolution of “steppe ancestry”.

It is becoming more and more clear with each paper that the true “Yamnaya ancestry” – not the originally described one – was in fact associated with Indo-Europeans (see more on the very Yamnaya-like Yamna Hungary and early East Bell Beaker R1b samples, all of quite similar ancestry and PCA cluster before their further admixture with EEF- and CWC-like groups).

The so-called “steppe ancestry”, on the other hand, reflects the contribution of a Northern Caucasus-related ancestry to expanding Khvalynsk settlers, who spread through the steppes more than a thousand years before the expansion of Late Proto-Indo-Europeans with late Repin, and can thus be found among different groups related to the Pontic-Caspian steppes (see more on the emergence and evolution of “steppe ancestry”).

In fact, after the Yamna/Indo-European and Corded Ware/Uralic expansions, it is more likely to find “steppe ancestry” to the north and east in territories traditionally associated with Uralic languages, whereas to the south and west – i.e. in territories traditionally associated with Indo-European languages – it is more likely to find “EEF ancestry” with diminished “steppe ancestry”, among peoples patrilineally descended from Yamna settlers.

Y-DNA haplogroups, the only uniparental markers (see exceptions in mtDNA inheritance) – unlike ancestry percentages based on the comparison of a few samples and flawed study designs – do not admix, do not change, and therefore they do not lend themselves to infinite pet theories (see e.g. what David Reich has to say about R1b-P312 in Iberia directly derived from Yamna migrants in spite of their predominant EEF ancestry): their cultural continuity can only be challenged with carefully threaded linguistic, archaeological, and genetic data.

Related

A very “Yamnaya-like” East Bell Beaker from France, probably R1b-L151

bell-beaker-expansion

Interesting report by Bernard Sécher on Anthrogenica, about the Ph.D. thesis of Samantha Brunel from Institut Jacques Monod, Paris, Paléogénomique des dynamiques des populations humaines sur le territoire Français entre 7000 et 2000 (2018).

NOTE. You can visit Bernard Sécher’s blog on genetic genealogy.

A summary from user Jool, who was there, translated into English by Sécher (slight changes to translation, and emphasis mine):

They have a good hundred samples from the North, Alsace and the Mediterranean coast, from the Mesolithic to the Iron Age.

There is no major surprise compared to the rest of Europe. On the PCA plot, the Mesolithic are with the WHG, the early Neolithics with the first farmers close to the Anatolians. Then there is a small resurgence of hunter-gatherers that moves the Middle Neolithics a little closer to the WHGs.

From the Bronze Age, they have 5 samples with autosomal DNA, all in Bell Beaker archaeological context, which are very spread on the PCA. A sample very high, close to the Yamnaya, a little above the Corded Ware, two samples right in the Central European Bell Beakers, a fairly low just above the Neolithic package, and one last full in the package. The most salient point was that the Y chromosomes of their 12 Bronze Age samples (all Bell Beakers) are all R1b, whereas there was no R1b in the Neolithic samples.

Finally they have samples of the Iron Age that are collected on the PCA plot close to the Bronze Age samples. They could not determine if there is continuity with the Bronze Age, or a partial replacement by a genetically close population.

PCA-caucasus-yamna
Image modified from Wang et al. (2018). Samples projected in PCA of 84 modern-day West Eurasian populations (open symbols). Previously known clusters have been marked and referenced. Marked and labelled are interesting samples; In red, likely position of late Yamna Hungary / early East Bell Beakers An EHG and a Caucasus ‘clouds’ have been drawn, leaving Pontic-Caspian steppe and derived groups between them. See the original file here. To understand the drawn potential Caucasus Mesolithic cluster, see above the PCA from Lazaridis et al. (2018).

The sample with likely high “steppe ancestry“, clustering closely to Yamna (more than Corded Ware samples) is then probably an early East Bell Beaker individual, probably from Alsace, or maybe close to the Rhine Delta in the north, rather than from the south, since we already have samples from southern France from Olalde et al. (2018) with high Neolithic ancestry, and samples from the Rhine with elevated steppe ancestry, but not that much.

This specific sample, if confirmed as one of those reported as R1b (then likely R1b-L151), as it seems from the wording of the summary, is key because it would finally link Yamna to East Bell Beaker through Yamna Hungary, all of them very “Yamnaya-like”, and therefore R1b-L151 (hence also R1b-L51) directly to the steppe, and not only to the Carpathian Basin (that is, until we have samples from late Repin or West Yamna…)

NOTE. The only alternative explanation for such elevated steppe ancestry would be an admixture between a ‘less Yamnaya-like’ East Bell Beaker + a Central European Corded Ware sample like the Esperstedt outlier + drift, but I don’t think that alternative is the best explanation of its position in the PCA closer to Yamna in any of the infinite parallel universes, so… Also, the sample from Esperstedt is clearly a late outlier likely influenced by Yamna vanguard settlers from Hungary, not the other way round…

Unexpectedly, then, fully Yamnaya-like individuals are found not only in Yamna Hungary ca. 3000-2500 BC, but also among expanding East Bell Beakers later than 2500 BC. This leaves us with unexplained, not-at-all-Yamnaya-like early Corded Ware samples from ca. 2900 BC on. An explanation based on admixture with locals seems unlikely, seeing how Corded Ware peoples continue a north Pontic cluster, being thus different from Yamna and their ancestors since the Neolithic; and how they remained that way for a long time, up to Sintashta, Srubna, Andronovo, and even later samples… A different, non-Indo-European community it is, then.

olalde_pca2
Image modified from Olalde et al. (2018). PCA of 999 Eurasian individuals. Marked is the Espersted Outlier with the approximate position of Yamna Hungary, probably the source of its admixture. Different Bell Beaker clines have been drawn, to represent approximate source of expansions from Central European sources into the different regions. In red, likely zone of Yamna Hungary and reported early East Bell Beaker individual from France.

Let’s wait and see the Ph.D. thesis, when it’s published, and keep observing in the meantime the absurd reactions of denial, anger, bargaining, and depression (stages of grief) among BBC/R1b=Vasconic and CWC/R1a=Indo-European fans, as if they had lost something (?). Maybe one of these reactions is actually the key to changing reality and going back to the 2000s, who knows…

Featured image: initial expansion of the East Bell Beaker Group, by Volker Heyd (2013).

Related

“Steppe ancestry” step by step: Khvalynsk, Sredni Stog, Repin, Yamna, Corded Ware

dzudzuana_pca-large

Wang et al. (2018) is obviously a game changer in many aspects. I have already written about the upcoming Yamna Hungary samples, about the new Steppe_Eneolithic and Caucasus Eneolithic keystones, and about the upcoming Greece Neolithic samples with steppe ancestry.

An interesting aspect of the paper, hidden among so many relevant details, is a clearer picture of how the so-called Yamnaya or steppe ancestry evolved from Samara hunter-gatherers to Yamna nomadic pastoralists, and how this ancestry appeared among Proto-Corded Ware populations.

anatolia-neolithic-steppe-eneolithic
Image modified from Wang et al. (2018). Marked are in orange: equivalent Steppe_Maykop ADMIXTURE; in red, approximate limit of Anatolia_Neolithic ancestry found in Yamna populations; in blue, Corded Ware-related groups. “Modelling results for the Steppe and Caucasus cluster. Admixture proportions based on (temporally and geographically) distal and proximal models, showing additional Anatolian farmer-related ancestry in Steppe groups as well as additional gene flow from the south in some of the Steppe groups as well as the Caucasus groups.”

Please note: arrows of “ancestry movement” in the following PCAs do not necessarily represent physical population movements, or even ethnolinguistic change. To avoid misinterpretations, I have depicted arrows with Y-DNA haplogroup migrations to represent the most likely true ethnolinguistic movements. Admixture graphics shown are from Wang et al. (2018), and also (the K12) from Mathieson et al. (2018).

1. Samara to Early Khvalynsk

The so-called steppe ancestry was born during the Khvalynsk expansion through the steppes, probably through exogamy of expanding elite clans (eventually all R1b-M269 lineages) originally of Samara_HG ancestry. The nearest group to the ANE-like ghost population with which Samara hunter-gatherers admixed is represented by the Steppe_Eneolithic / Steppe_Maykop cluster (from the Northern Caucasus Piedmont).

Steppe_Eneolithic samples, of R1b1 lineages, are probably expanded Khvalynsk peoples, showing thus a proximate ancestry of an Early Eneolithic ghost population of the Northern Caucasus. Steppe_Maykop samples represent a later replacement of this Steppe_Eneolithic population – and/or a similar population with further contribution of ANE-like ancestry – in the area some 1,000 years later.

PCA-caucasus-steppe-samara

This is what Steppe_Maykop looks like, different from Steppe_Eneolithic:

steppe-maykop-admixture

NOTE. This admixture shows how different Steppe_Maykop is from Steppe_Eneolithic, but in the different supervised ADMIXTURE graphics below Maykop_Eneolithic is roughly equivalent to Eneolithic_Steppe (see orange arrow in ADMIXTURE graphic above). This is useful for a simplified analysis, but actual differences between Khvalynsk, Sredni Stog, Afanasevo, Yamna and Corded Ware are probably underestimated in the analyses below, and will become clearer in the future when more ancestral hunter-gatherer populations are added to the analysis.

2. Early Khvalynsk expansion

We have direct data of Khvalynsk-Novodanilovka-like populations thanks to Khvalynsk and Steppe_Eneolithic samples (although I’ve used the latter above to represent the ghost Caucasus population with which Samara_HG admixed).

We also have indirect data. First, there is the PCA with outliers:

PCA-khvalynsk-steppe

Second, we have data from north Pontic Ukraine_Eneolithic samples (see next section).

Third, there is the continuity of late Repin / Afanasevo with Steppe_Eneolithic (see below).

3. Proto-Corded Ware expansion

It is unclear if R1a-M459 subclades were continuously in the steppe and resurged after the Khvalynsk expansion, or (the most likely option) they came from the forested region of the Upper Dnieper area, possibly from previous expansions there with hunter-gatherer pottery.

Supporting the latter is the millennia-long continuity of R1b-V88 and I2a2 subclades in the north Pontic Mesolithic, Neolithic, and Early Eneolithic Sredni Stog culture, until ca. 4500 BC (and even later, during the second half).

Only at the end of the Early Eneolithic with the disappearance of Novodanilovka (and beginning of the steppe ‘hiatus’ of Rassamakin) is R1a to be found in Ukraine again (after disappearing from the record some 2,000 years earlier), related to complex population movements in the north Pontic area.

NOTE. In the PCA, a tentative position of Novodanilovka closer to Anatolia_Neolithic / Dzudzuana ancestry is selected, based on the apparent cline formed by Ukraine_Eneolithic samples, and on the position and ancestry of Sredni Stog, Yamna, and Corded Ware later. A good alternative would be to place Novodanilovka still closer to the Balkan outliers (i.e. Suvorovo), and a source closer to EHG as the ancestry driven by the migration of R1a-M417.

PCA-sredni-stog-steppe

The first sample with steppe ancestry appears only after 4250 BC in the forest-steppe, centuries after the samples with steppe ancestry from the Northern Caucasus and the Balkans, which points to exogamy of expanding R1a-M417 lineages with the remnants of the Novodanilovka population.

steppe-ancestry-admixture-sredni-stog

4. Repin / Early Yamna expansion

We don’t have direct data on early Repin settlers. But we do have a very close representative: Afanasevo, a population we know comes directly from the Repin/late Khvalynsk expansion ca. 3500/3300 BC (just before the emergence of Early Yamna), and which shows fully Steppe_Eneolithic-like ancestry.

afanasevo-admixture

Compared to this eastern Repin expansion that gave Afanasevo, the late Repin expansion to the west ca. 3300 BC that gave rise to the Yamna culture was one of colonization, evidenced by the admixture with north Pontic (Sredni Stog-like) populations, no doubt through exogamy:

PCA-repin-yamna

This admixture is also found (in lesser proportion) in east Yamna groups, which supports the high mobility and exogamy practices among western and eastern Yamna clans, not only with locals:

yamnaya-admixture

5. Corded Ware

Corded Ware represents a quite homogeneous expansion of a late Sredni Stog population, compatible with the traditional location of Proto-Corded Ware peoples in the steppe-forest/forest zone of the Dnieper-Dniester region.

PCA-latvia-ln-steppe

We don’t have a comparison with Ukraine_Eneolithic or Corded Ware samples in Wang et al. (2018), but we do have proximate sources for Abashevo, when compared to the Poltavka population (with which it admixed in the Volga-Ural steppes): Sintashta, Potapovka, Srubna (with further Abashevo contribution), and Andronovo:

sintashta-poltavka-andronovo-admixture

The two CWC outliers from the Baltic show what I thought was an admixture with Yamna. However, given the previous mixture of Eneolithic_Steppe in north Pontic steppe-forest populations, this elevated “steppe ancestry” found in Baltic_LN (similar to west Yamna) seems rather an admixture of Baltic sub-Neolithic peoples with a north Pontic Eneolithic_Steppe-like population. Late Repin settlers also admixed with a similar population during its colonization of the north Pontic area, hence the Baltic_LN – west Yamna similarities.

NOTE. A direct admixture with west Yamna populations through exogamy by the ancestors of this Baltic population cannot be ruled out yet (without direct access to more samples), though, because of the contacts of Corded Ware with west Yamna settlers in the forest-steppe regions.

steppe-ancestry-admixture-latvia

A similar case is found in the Yamna outlier from Mednikarovo south of the Danube. It would be absurd to think that Yamna from the Balkans comes from Corded Ware (or vice versa), just because the former is closer in the PCA to the latter than other Yamna samples. The same error is also found e.g. in the Corded Ware → Bell Beaker theory, because of their proximity in the PCA and their shared “steppe ancestry”. All those theories have been proven already wrong.

NOTE. A similar fallacy is found in potential Sintashta→Mycenaean connections, where we should distinguish statistically that result from an East/West Yamna + Balkans_BA admixture. In fact, genetic links of Mycenaeans with west Yamna settlers prove this (there are some related analyses in Anthrogenica, but the site is down at this moment). To try to relate these two populations (separated more than 1,000 years before Sintashta) is like comparing ancient populations to modern ones, without the intermediate samples to trace the real anthropological trail of what is found…Pure numbers and wishful thinking.

Conclusion

Yamna and Corded Ware show a similar “steppe ancestry” due to convergence. I have said so many times (see e.g. here). This was clear long ago, just by looking at the Y-chromosome bottlenecks that differentiate them – and Tomenable noticed this difference in ADMIXTURE from the supplementary materials in Mathieson et al. (2017), well before Wang et al. (2018).

This different stock stems from (1) completely different ancestral populations + (2) different, long-lasting Y-chromosome bottlenecks. Their similarities come from the two neighbouring cultures admixing with similar populations.

If all this does not mean anything, and each lab was going to support some pre-selected archaeological theories from the 1960s or the 1980s, coupled with outdated linguistic models no matter what – Anthony’s model + Ringe’s glottochronological tree of the early 2000s in the Reich Lab; and worse, Kristiansen’s CWC-IE + Germano-Slavonic models of the 1940s in the Copenhagen group – , I have to repeat my question again:

What’s (so much published) ancient DNA useful for, exactly?

Related

Early Iranian steppe nomadic pastoralists also show Y-DNA bottlenecks and R1b-L23

New paper (behind paywall) Ancient genomes suggest the eastern Pontic-Caspian steppe as the source of western Iron Age nomads, by Krzewińska et al. Science (2018) 4(10):eaat4457.

Interesting excerpts (emphasis mine, some links to images and tables deleted for clarity):

Late Bronze Age (LBA) Srubnaya-Alakulskaya individuals carried mtDNA haplogroups associated with Europeans or West Eurasians (17) including H, J1, K1, T2, U2, U4, and U5 (table S3). In contrast, the Iron Age nomads (Cimmerians, Scythians, and Sarmatians) additionally carried mtDNA haplogroups associated with Central Asia and the Far East (A, C, D, and M). The absence of East Asian mitochondrial lineages in the more eastern and older Srubnaya-Alakulskaya population suggests that the appearance of East Asian haplogroups in the steppe populations might be associated with the Iron Age nomads, starting with the Cimmerians.

scythian-cimmerian-sarmatian-y-dna-mtdna

#UPDATE (5 OCT 2018): Some Y-SNP calls have been published in a Molgen thread, with:

  • Srubna samples have possibly two R1a-Z280, three R1a-Z93.
  • Cimmerians may not have R1b: cim357 is reported as R1a.
  • Some Scythians have low coverage to the point where it is difficult to assign even a reliable haplogroup (they report hg I2 for scy301, or E for scy197, probably based on some shared SNPs?), but those which can be reliably assigned seem R1b-Z2103 [hence probably the use of question marks and asterisks in the table, and the assumption of the paper that all Scythians are R1b-L23]:
    • The most recent subclade is found in scy305: R1b-Z2103>Z2106 (Z2106+, Y12538/Z8131+)
    • scy304: R1b-Z2103 (M12149/Y4371/Z8128+).
    • scy009: R1b-P312>U152>L2 (P312+, U152?, L2+)?
  • Sarmatians are apparently all R1a-Z93 (including tem002 and tem003);
  • You can read here the Excel file with (some probably as speculative as the paper’s own) results.

    About the PCA

    1. Srubnaya-Alakulskaya individuals exhibited genetic affinity to northern and northeastern present-day Europeans, and these results were also consistent with outgroup f3 statistics.
    2. The Cimmerian individuals, representing the time period of transition from Bronze to Iron Age, were not homogeneous regarding their genetic similarities to present-day populations according to the PCA. F3 statistics confirmed the heterogeneity of these individuals in comparison with present-day populations
    3. The Scythians reported in this study, from the core Scythian territory in the North Pontic steppe, showed high intragroup diversity. In the PCA, they are positioned as four visually distinct groups compared to the gradient of present-day populations:
      1. A group of three individuals (scy009, scy010, and scy303) showed genetic affinity to north European populations (…).
      2. A group of four individuals (scy192, scy197, scy300, and scy305) showed genetic similarities to southern European populations (…).
      3. A group of three individuals (scy006, scy011, and scy193) located between the genetic variation of Mordovians and populations of the North Caucasus (…). In addition, one Srubnaya-Alakulskaya individual (kzb004), the most recent Cimmerian (cim357), and all Sarmatians fell within this cluster. In contrast to the Scythians, and despite being from opposite ends of the Pontic-Caspian steppe, the five Sarmatians grouped close together in this cluster.
      4. A group of three Scythians (scy301, scy304, and scy311) formed a discrete group between the SC and SE and had genetic affinities to present-day Bulgarian, Greek, Croatian, and Turkish populations (…).
      5. Finally, one individual from a Scythian cultural context (scy332) is positioned outside of the modern West Eurasian genetic variation (Fig. 1C) but shared genetic drift with East Asian populations.
    scythian-cimmerian-pca
    Radiocarbon ages and geographical locations of the ancient samples used in this study. Figure panels presented (Left) Bar plot visualizing approximate timeline of presented and previously published individuals. (Right) Principal component analysis (PCA) plot visualizing 35 Bronze Age and Iron Age individuals presented in this study and in published ancient individuals (table S5) in relation to modern reference panel from the Human Origins data set (41).

    Cimmerians

    The presence of an SA component (as well as finding of metals imported from Tien Shan Mountains in Muradym 8) could therefore reflect a connection to the complex networks of the nomadic transmigration patterns characteristic of seasonal steppe population movements. These movements, although dictated by the needs of the nomads and their animals, shaped the economic and social networks linking the outskirts of the steppe and facilitated the flow of goods between settled, semi-nomadic, and nomadic peoples. In contrast, all Cimmerians carried the Siberian genetic component. Both the PCA and f4 statistics supported their closer affinities to the Bronze Age western Siberian populations (including Karasuk) than to Srubnaya. It is noteworthy that the oldest of the Cimmerians studied here (cim357) carried almost equal proportions of Asian and West Eurasian components, resembling the Pazyryks, Aldy-Bel, and Iron Age individuals from Russia and Kazakhstan (12). The second oldest Cimmerian (cim358) was also the only one with both uniparental markers pointing toward East Asia. The Q1* Y chromosome sublineage of Q-M242 is widespread among Asians and Native Americans and is thought to have originated in the Altai Mountains (24)

    Scythians

    In contrast to the eastern steppe Scythians (Pazyryks and Aldy-Bel) that were closely related to Yamnaya, the western North Pontic Scythians were instead more closely related to individuals from Afanasievo and Andronovo groups. Some of the Scythians of the western Pontic-Caspian steppe lacked the SA and the East Eurasian components altogether and instead were more similar to a Montenegro Iron Age individual (3), possibly indicating assimilation of the earlier local groups by the Scythians.

    Toward the end of the Scythian period (fourth century CE), a possible direct influx from the southern Ural steppe zone took place, as indicated by scy332. However, it is possible that this individual might have originated in a different nomadic group despite being found in a Scythian cultural context.

    scythian-alakul-variation
    Genetic diversity and ancestral components of Srubnaya-Alakulskaya population.(here called “Srubnaya”): (Left) Mean f3 statistics for Srubnaya and other Bronze Age populations. Srubnaya group was color-coded the same as with PCA. (Right) Pairwise mismatch estimates for Bronze Age populations.

    Comments

    I am surprised to find this new R1b-L23-based bottleneck in Eastern Iranian expansions so late, but admittedly – based on data from later times in the Pontic-Caspian steppe near the Caucasus – it was always a possibility. The fact that pockets of R1b-L23 lineages remained somehow ‘hidden’ in early Indo-Iranian communities was clear already since Narasimhan et al. (2018), as I predicted could happen, and is compatible with the limited archaeological data on Sintashta-Potapovka populations outside fortified settlements. I already said that Corded Ware was out of Indo-European migrations then, this further supports it.

    Even with all these data coming just from a north-west Pontic steppe region (west of the Dnieper), these ‘Cimmerians’ – or rather the ‘Proto-Scythian’ nomadic cultures appearing before ca. 800 BC in the Pontic-Caspian steppes – are shown to be probably formed by diverse peoples from Central Asia who brought about the first waves of Siberian ancestry (and Asian lineages) seen in the western steppes. You can read about a Cimmerian-related culture, Anonino, key for the evolution of Finno-Permic peoples.

    Also interesting about the Y-DNA bottleneck seen here is the rejection of the supposed continuous western expansions of R1a-Z645 subclades with steppe tribes since the Bronze Age, and thus a clearest link of the Hungarian Árpád dynasty (of R1a-Z2123 lineage) to either the early Srubna-related expansions or – much more likely – to the actual expansions of Hungarian tribes near the Urals in historic times.

    NOTE. I will add the information of this paper to the upcoming post on Ugric and Samoyedic expansions, and the late introduction of Siberian ancestry to these peoples.

    A few interesting lessons to be learned:

    • Remember the fantasy story about that supposed steppe nomadic pastoralist society sharing different Y-DNA lineages? You know, that Yamna culture expanding with R1b from Khvalynsk-Repin into the whole Pontic-Caspian steppes and beyond, developing R1b-dominated Afanasevo, Bell Beaker, and Poltavka, but suddenly appearing (in the middle of those expansions through the steppes) as a different culture, Corded Ware, to the north (in the east-central European forest zone) and dominated by R1a? Well, it hasn’t happened with any other steppe migration, so…maybe Proto-Indo-Europeans were that kind of especially friendly language-teaching neighbours?
    • Remember that ‘pure-R1a’ Indo-Slavonic society emerged from Sintashta ca. 2100 BC? (or even Graeco-Aryan??) Hmmmm… Another good fantasy story that didn’t happen; just like a central-east European Bronze Age Balto-Slavic R1a continuity didn’t happen, either. So, given that cultures from around Estonia are those showing the closest thing to R1a continuity in Europe until the Iron Age, I assume we have to get ready for the Gulf of Finland Balto-Slavic soon.
    • Remember that ‘pure-R1a’ expansion of Indo-Europeans based on the Tarim Basin samples? This paper means ipso facto an end to the Tarim Basin – Tocharian artificial controversy. The Pre-Tocharian expansion is represented by Afanasevo, and whether or not (Andronovo-related) groups of R1a-Z645 lineages replaced part or eventually all of its population before, during, or after the Tocharian expansion into the Tarim Basin, this does not change the origin of the language split and expansion from Yamna to Central Asia; just like this paper does not change the fact that these steppe groups were Proto-Iranian (Srubna) and Eastern Iranian (Scythian) speakers, regardless of their dominant haplogroup.
    • And, best of all, remember the Copenhagen group’s recent R1a-based “Indo-Germanic” dialect revival vs. the R1b-Tocharo-Italo-Celtic? Yep, they made that proposal, in 2018, based on the obvious Yamna—R1b-L23 association, and the desire to support Kristiansen’s model of Corded Ware – Indo-European expansion. Pepperidge Farm remembers. This new data on Early Iranians means another big NO to that imaginary R1a-based PIE society. But good try to go back to Gimbutas’ times, though.
    olander-classificatoin
    Olander’s (2018) tree of Indo-European languages. Presented at Languages and migrations in pre-historic Europe (7-12 Aug 2018)

    Do you smell that fresher air? It’s the Central and East European post-Communist populist and ethnonationalist bullshit (viz. pure blond R1a-based Pan-Nordicism / pro-Russian Pan-Slavism / Pan-Eurasianism, as well as Pan-Turanism and similar crap from the 19th century) going down the toilet with each new paper.

    #EDIT (5 OCT 2018): It seems I was too quick to rant about the consequences of the paper without taking into account the complexity of the data presented. Not the first time this impulsivity happens, I guess it depends on my mood and on the time I have to write a post on the specific work day…

    While the data on Srubna, Cimmerians, and Sarmatians shows clearer Y-DNA bottlenecks (of R1a-Z645 subclades) with the new data, the Scythian samples remain controversial, because of the many doubts about the haplogroups (although the most certain cases are R1b-Z2103), their actual date, and cultural attribution. However, I doubt they belong to other peoples, given the expansionist trends of steppe nomads before, during, and after Scythians (as shown in statistical analyses), so most likely they are Scythian or ‘Para-Scythian’ nomadic groups that probably came from the east, whether or not they incorporated Balkan populations. This is further supported by the remaining R1b-P312 and R1b-Z2103 populations in and around the modern Eurasian steppe region.

    scythian-peoples-balkans
    Early Iron Age cultures of the Carpathian basin ca. 7-6th century BC, including steppe groups Basarabi and Scythians. Ďurkovič et al. (2018).

    You can find an interesting and detailed take on the data published (in Russian) at Vol-Vlad’s LiveJournal (you can read an automatic translation from Google). I think that post is maybe too detailed in debunking all information associated to the supposed Scythians – to the point where just a single sample seems to be an actual Scythian (?!) -, but is nevertheless interesting to read the potential pitfalls of the study.

    Related

    Modern Sardinians show elevated Neolithic farmer ancestry shared with Basques

    sardinia-europe-relation

    New paper (behind paywall), Genomic history of the Sardinian population, by Chiang et al. Nature Genetics (2018), previously published as a preprint at bioRxiv (2016).

    #EDIT (18 Sep 2018): Link to read paper for free shared by the main author.

    Interesting excerpts (emphasis mine):

    Our analysis of divergence times suggests the population lineage ancestral to modern-day Sardinia was effectively isolated from the mainland European populations ~140–250 generations ago, corresponding to ~4,300–7,000 years ago assuming a generation time of 30 years and a mutation rate of 1.25 × 10−8 per basepair per generation. (…) in terms of relative values, the divergence time between Northern and Southern Europeans is much more recent than either is to Sardinia, signaling the relative isolation of Sardinia from mainland Europe.

    We documented fine-scale variation in the ancient population ancestry proportions across the island. The most remote and interior areas of Sardinia—the Gennargentu massif covering the central and eastern regions, including the present-day province of Ogliastra— are thought to have been the least exposed to contact with outside populations. We found that pre-Neolithic hunter-gatherer and Neolithic farmer ancestries are enriched in this region of isolation. Under the premise that Ogliastra has been more buffered from recent immigration to the island, one interpretation of the result is that the early populations of Sardinia were an admixture of the two ancestries, rather than the pre-Neolithic ancestry arriving via later migrations from the mainland. Such admixture could have occurred principally on the island or on the mainland before the hypothesized Neolithic era influx to the island. Under the alternative premise that Ogliastra is simply a highly isolated region that has differentiated within Sardinia due to genetic drift, the result would be interpreted as genetic drift leading to a structured pattern of pre-Neolithic ancestry across the island, in an overall background of high Neolithic ancestry.

    sardinia-pca
    PCA results of merged Sardinian whole-genome sequences and the HGDP Sardinians. See below for a map of the corresponding regions.

    We found Sardinians show a signal of shared ancestry with the Basque in terms of the outgroup f3 shared-drift statistics. This is consistent with long-held arguments of a connection between the two populations, including claims of Basque-like, non-Indo-European words among Sardinian placenames. More recently, the Basque have been shown to be enriched for Neolithic farmer ancestry and Indo-European languages have been associated with steppe population expansions in the post-Neolithic Bronze Age. These results support a model in which Sardinians and the Basque may both retain a legacy of pre-Indo-European Neolithic ancestry. To be cautious, while it seems unlikely, we cannot exclude that the genetic similarity between the Basque and Sardinians is due to an unsampled pre-Neolithic population that has affinities with the Neolithic representatives analyzed here.

    density-nuraghi-sardinia-genetics
    Left: Geographical map of Sardinia. The provincial boundaries are given as black lines. The provinces are abbreviated as Cag (Cagliari), Cmp (Campidano), Car (Carbonia), Ori (Oristano), Sas (Sassari), Olb (Olbia-tempio), Nuo (Nuoro), and Ogl (Ogliastra). For sampled villages within Ogliastra, the names and abbreviations are indicated in the colored boxes. The color corresponds to the color used in the PCA plot (Fig. 2a). The Gennargentu region referred to in the main text is the mountainous area shown in brown that is centered in western Ogliastra and southeastern Nuoro.
    Right: Density of Nuraghi in Sardinia, from Wikipedia.

    While we can confirm that Sardinians principally have Neolithic ancestry on the autosomes, the high frequency of two Y-chromosome haplogroups (I2a1a1 at ~39% and R1b1a2 at ~18%) that are not typically affiliated with Neolithic ancestry is one challenge to this model. Whether these haplogroups rose in frequency due to extensive genetic drift and/or reflect sex-biased demographic processes has been an open question. Our analysis of X chromosome versus autosome diversity suggests a smaller effective size for males, which can arise due to multiple processes, including polygyny, patrilineal inheritance rules, or transmission of reproductive success. We also find that the genetic ancestry enriched in Sardinia is more prevalent on the X chromosome than the autosome, suggesting that male lineages may more rapidly trace back to the mainland. Considering that the R1b1a2 haplogroup may be associated with post-Neolithic steppe ancestry expansions in Europe, and the recent timeframe when the R1b1a2 lineages expanded in Sardinia, the patterns raise the possibility of recent male-biased steppe ancestry migration to Sardinia, as has been reported among mainland Europeans at large (though see Lazaridis and Reich and Goldberg et al.). Such a recent influx is difficult to square with the overall divergence of Sardinian populations observed here.

    sardinian-admixture
    Mixture proportions of the three-component ancestries among Sardinian populations. Using a method first presented in Haak et al. (Nature 522, 207–211, 2015), we computed unbiased estimates of mixture proportions without a parameterized model of relationships between the test populations and the outgroup populations based on f4 statistics. The three-component ancestries were represented by early Neolithic individuals from the LBK culture (LBK_EN), pre-Neolithic huntergatherers (Loschbour), and Bronze Age steppe pastoralists (Yamnaya). See Supplementary Table 5 for standard error estimates computed using a block jackknife.

    Once again, haplogroup R1b1a2 (M269), and only R1b1a2, related to male-biased, steppe-related Indo-European migrations…just sayin’.

    Interestingly, haplogroup I2a1a1 is actually found among northern Iberians during the Neolithic and Chalcolithic, and is therefore associated with Neolithic ancestry in Iberia, too, and consequently – unless there is a big surprise hidden somewhere – with the ancestry found today among Basques.

    NOTE. In fact, the increase in Neolithic ancestry found in south-west Ireland with expanding Bell Beakers (likely Proto-Beakers), coupled with the finding of I2a subclades in Megalithic cultures of western Europe, would support this replacement after the Cardial and Epi-Cardial expansions, which were initially associated with G2a lineages.

    I am not convinced about a survival of Palaeo-Sardo after the Bell Beaker expansion, though, since there is no clear-cut cultural divide (and posterior continuity) of pre-Beaker archaeological cultures after the arrival of Bell Beakers in the island that could be identified with the survival of Neolithic languages.

    We may have to wait for ancient DNA to show a potential expansion of Neolithic ancestry from the west, maybe associated with the emergence of the Nuragic civilization (potentially linked with contemporaneous Megalithic cultures in Corsica and in the Balearic Islands, and thus with an Iberian rather than a Basque stock), although this is quite speculative at this moment in linguistic, archaeological, and genetic terms.

    Nevertheless, it seems that the association of a Basque-Iberian language with the Neolithic expansion from Anatolia (see Villar’s latest book on the subject) is somehow strengthened by this paper. However, it is unclear when, how, and where expanding G2a subclades were replaced by native I2 lineages.

    Related

    Common pitfalls in human genomics and bioinformatics: ADMIXTURE, PCA, and the ‘Yamnaya’ ancestral component

    invasion-from-the-steppe-yamnaya

    Good timing for the publication of two interesting papers, that a lot of people should read very carefully:

    ADMIXTURE

    Open access A tutorial on how not to over-interpret STRUCTURE and ADMIXTURE bar plots, by Daniel J. Lawson, Lucy van Dorp & Daniel Falush, Nature Communications (2018).

    Interesting excerpts (emphasis mine):

    Experienced researchers, particularly those interested in population structure and historical inference, typically present STRUCTURE results alongside other methods that make different modelling assumptions. These include TreeMix, ADMIXTUREGRAPH, fineSTRUCTURE, GLOBETROTTER, f3 and D statistics, amongst many others. These models can be used both to probe whether assumptions of the model are likely to hold and to validate specific features of the results. Each also comes with its own pitfalls and difficulties of interpretation. It is not obvious that any single approach represents a direct replacement as a data summary tool. Here we build more directly on the results of STRUCTURE/ADMIXTURE by developing a new approach, badMIXTURE, to examine which features of the data are poorly fit by the model. Rather than intending to replace more specific or sophisticated analyses, we hope to encourage their use by making the limitations of the initial analysis clearer.

    The default interpretation protocol

    Most researchers are cautious but literal in their interpretation of STRUCTURE and ADMIXTURE results, as caricatured in Fig. 1, as it is difficult to interpret the results at all without making several of these assumptions. Here we use simulated and real data to illustrate how following this protocol can lead to inference of false histories, and how badMIXTURE can be used to examine model fit and avoid common pitfalls.

    admixture-protocol
    A protocol for interpreting admixture estimates, based on the assumption that the model underlying the inference is correct. If these assumptions are not validated, there is substantial danger of over-interpretation. The “Core protocol” describes the assumptions that are made by the admixture model itself (Protocol 1, 3, 4), and inference for estimating K (Protocol 2). The “Algorithm input” protocol describes choices that can further bias results, while the “Interpretation” protocol describes assumptions that can be made in interpreting the output that are not directly supported by model inference

    Discussion

    STRUCTURE and ADMIXTURE are popular because they give the user a broad-brush view of variation in genetic data, while allowing the possibility of zooming down on details about specific individuals or labelled groups. Unfortunately it is rarely the case that sampled data follows a simple history comprising a differentiation phase followed by a mixture phase, as assumed in an ADMIXTURE model and highlighted by case study 1. Naïve inferences based on this model (the Protocol of Fig. 1) can be misleading if sampling strategy or the inferred value of the number of populations K is inappropriate, or if recent bottlenecks or unobserved ancient structure appear in the data. It is therefore useful when interpreting the results obtained from real data to think of STRUCTURE and ADMIXTURE as algorithms that parsimoniously explain variation between individuals rather than as parametric models of divergence and admixture.

    For example, if admixture events or genetic drift affect all members of the sample equally, then there is no variation between individuals for the model to explain. Non-African humans have a few percent Neanderthal ancestry, but this is invisible to STRUCTURE or ADMIXTURE since it does not result in differences in ancestry profiles between individuals. The same reasoning helps to explain why for most data sets—even in species such as humans where mixing is commonplace—each of the K populations is inferred by STRUCTURE/ADMIXTURE to have non-admixed representatives in the sample. If every individual in a group is in fact admixed, then (with some exceptions) the model simply shifts the allele frequencies of the inferred ancestral population to reflect the fraction of admixture that is shared by all individuals.

    Several methods have been developed to estimate K, but for real data, the assumption that there is a true value is always incorrect; the question rather being whether the model is a good enough approximation to be practically useful. First, there may be close relatives in the sample which violates model assumptions. Second, there might be “isolation by distance”, meaning that there are no discrete populations at all. Third, population structure may be hierarchical, with subtle subdivisions nested within diverged groups. This kind of structure can be hard for the algorithms to detect and can lead to underestimation of K. Fourth, population structure may be fluid between historical epochs, with multiple events and structures leaving signals in the data. Many users examine the results of multiple K simultaneously but this makes interpretation more complex, especially because it makes it easier for users to find support for preconceptions about the data somewhere in the results.

    In practice, the best that can be expected is that the algorithms choose the smallest number of ancestral populations that can explain the most salient variation in the data. Unless the demographic history of the sample is particularly simple, the value of K inferred according to any statistically sensible criterion is likely to be smaller than the number of distinct drift events that have practically impacted the sample. The algorithm uses variation in admixture proportions between individuals to approximately mimic the effect of more than K distinct drift events without estimating ancestral populations corresponding to each one. In other words, an admixture model is almost always “wrong” (Assumption 2 of the Core protocol, Fig. 1) and should not be interpreted without examining whether this lack of fit matters for a given question.

    admixture-pitfalls
    Three scenarios that give indistinguishable ADMIXTURE results. a Simplified schematic of each simulation scenario. b Inferred ADMIXTURE plots at K= 11. c CHROMOPAINTER inferred painting palettes.

    Because STRUCTURE/ADMIXTURE accounts for the most salient variation, results are greatly affected by sample size in common with other methods. Specifically, groups that contain fewer samples or have undergone little population-specific drift of their own are likely to be fit as mixes of multiple drifted groups, rather than assigned to their own ancestral population. Indeed, if an ancient sample is put into a data set of modern individuals, the ancient sample is typically represented as an admixture of the modern populations (e.g., ref. 28,29), which can happen even if the individual sample is older than the split date of the modern populations and thus cannot be admixed.

    This paper was already available as a preprint in bioRxiv (first published in 2016) and it is incredible that it needed to wait all this time to be published. I found it weird how reviewers focused on the “tone” of the paper. I think it is great to see files from the peer review process published, but we need to know who these reviewers were, to understand their whiny remarks… A lot of geneticists out there need to develop a thick skin, or else we are going to see more and more delays based on a perceived incorrect tone towards the field, which seems a rather subjective reason to force researchers to correct a paper.

    PCA of SNP data

    Open access Effective principal components analysis of SNP data, by Gauch, Qian, Piepho, Zhou, & Chen, bioRxiv (2018).

    Interesting excerpts:

    A potential hindrance to our advice to upgrade from PCA graphs to PCA biplots is that the SNPs are often so numerous that they would obscure the Items if both were graphed together. One way to reduce clutter, which is used in several figures in this article, is to present a biplot in two side-by-side panels, one for Items and one for SNPs. Another stratagem is to focus on a manageable subset of SNPs of particular interest and show only them in a biplot in order to avoid obscuring the Items. A later section on causal exploration by current methods mentions several procedures for identifying particularly relevant SNPs.

    One of several data transformations is ordinarily applied to SNP data prior to PCA computations, such as centering by SNPs. These transformations make a huge difference in the appearance of PCA graphs or biplots. A SNPs-by-Items data matrix constitutes a two-way factorial design, so analysis of variance (ANOVA) recognizes three sources of variation: SNP main effects, Item main effects, and SNP-by-Item (S×I) interaction effects. Double-Centered PCA (DC-PCA) removes both main effects in order to focus on the remaining S×I interaction effects. The resulting PCs are called interaction principal components (IPCs), and are denoted by IPC1, IPC2, and so on. By way of preview, a later section on PCA variants argues that DC-PCA is best for SNP data. Surprisingly, our literature survey did not encounter even a single analysis identified as DC-PCA.

    The axes in PCA graphs or biplots are often scaled to obtain a convenient shape, but actually the axes should have the same scale for many reasons emphasized recently by Malik and Piepho [3]. However, our literature survey found a correct ratio of 1 in only 10% of the articles, a slightly faulty ratio of the larger scale over the shorter scale within 1.1 in 12%, and a substantially faulty ratio above 2 in 16% with the worst cases being ratios of 31 and 44. Especially when the scale along one PCA axis is stretched by a factor of 2 or more relative to the other axis, the relationships among various points or clusters of points are distorted and easily misinterpreted. Also, 7% of the articles failed to show the scale on one or both PCA axes, which leaves readers with an impressionistic graph that cannot be reproduced without effort. The contemporary literature on PCA of SNP data mostly violates the prohibition against stretching axes.

    pca-how-to
    DC-PCA biplot for oat data. The gradient in the CA-arranged matrix in Fig 13 is shown here for both lines and SNPs by the color scheme red, pink, black, light green, dark green.

    The percentage of variation captured by each PC is often included in the axis labels of PCA graphs or biplots. In general this information is worth including, but there are two qualifications. First, these percentages need to be interpreted relative to the size of the data matrix because large datasets can capture a small percentage and yet still be effective. For example, for a large dataset with over 107,000 SNPs for over 6,000 persons, the first two components capture only 0.3693% and 0.117% of the variation, and yet the PCA graph shows clear structure (Fig 1A in [4]). Contrariwise, a PCA graph could capture a large percentage of the total variation, even 50% or more, but that would not guarantee that it will show evident structure in the data. Second, the interpretation of these percentages depends on exactly how the PCA analysis was conducted, as explained in a later section on PCA variants. Readers cannot meaningfully interpret the percentages of variation captured by PCA axes when authors fail to communicate which variant of PCA was used.

    Conclusion

    Five simple recommendations for effective PCA analysis of SNP data emerge from this investigation.

    1. Use the SNP coding 1 for the rare or minor allele and 0 for the common or major allele.
    2. Use DC-PCA; for any other PCA variant, examine its augmented ANOVA table.
    3. Report which SNP coding and PCA variant were selected, as required by contemporary standards in science for transparency and reproducibility, so that readers can interpret PCA results properly and reproduce PCA analyses reliably.
    4. Produce PCA biplots of both Items and SNPs, rather than merely PCA graphs of only Items, in order to display the joint structure of Items and SNPs and thereby to facilitate causal explanations. Be aware of the arch distortion when interpreting PCA graphs or biplots.
    5. Produce PCA biplots and graphs that have the same scale on every axis.

    I read the referenced paper Biplots: Do Not Stretch Them!, by Malik and Piepho (2018), and even though it is not directly applicable to the most commonly available PCA graphs out there, it is a good reminder of the distorting effects of stretching. So for example quite recently in Krause-Kyora et al. (2018), where you can see Corded Ware and BBC samples from Central Europe clustering with samples from Yamna:

    NOTE. This is related to a vertical distorsion (i.e. horizontal stretching), but possibly also to the addition of some distant outlier sample/s.

    pca-cwc-yamna-bbc
    Principal Component Analysis (PCA) of the human Karsdorf and Sorsum samples together with previously published ancient populations projected on 27 modern day West Eurasian populations (not shown) based on a set of 1.23 million SNPs (Mathieson et al., 2015). https://doi.org/10.7554/eLife.36666.006

    The so-called ‘Yamnaya’ ancestry

    Every time I read papers like these, I remember commenters who kept swearing that genetics was the ultimate science that would solve anthropological problems, where unscientific archaeology and linguistics could not. Well, it seems that, like radiocarbon analysis, these promising developing methods need still a lot of refinement to achieve something meaningful, and that they mean nothing without traditional linguistics and archaeology… But we already knew that.

    Also, if this is happening in most peer-reviewed publications, made by professional geneticists, in journals of high impact factor, you can only wonder how many more errors and misinterpretations can be found in the obscure market of so many amateur geneticists out there. Because amateur geneticist is a commonly used misnomer for people who are not geneticists (since they don’t have the most basic education in genetics), and some of them are not even ‘amateurs’ (because they are selling the outputs of bioinformatic tools)… It’s like calling healers ‘amateur doctors’.

    NOTE. While everyone involved in population genetics is interested in knowing the truth, and we all have our confirmation (and other kinds of) biases, for those who get paid to tell people what they want to hear, and who have sold lots of wrong interpretations already, the incentives of ‘being right’ – and thus getting involved in crooked and paranoid behaviour regarding different interpretations – are as strong as the money they can win or loose by promoting themselves and selling more ‘product’.

    As a reminder of how badly these wrong interpretations of genetic results – and the influence of the so-called ‘amateurs’ – can reflect on research groups, yet another turn of the screw by the Copenhagen group, in the oral presentations at Languages and migrations in pre-historic Europe (7-12 Aug 2018), organized by the Copenhagen University. The common theme seems to be that Bell Beaker and thus R1b-L23 subclades do represent a direct expansion from Yamna now, as opposed to being derived from Corded Ware migrants, as they supported before.

    NOTE. Yes, the “Yamna → Corded Ware → Únětice / Bell Beaker” migration model is still commonplace in the Copenhagen workgroup. Yes, in 2018. Guus Kroonen had already admitted they were wrong, and it was already changed in the graphic representation accompanying a recent interview to Willerslev. However, since there is still no official retraction by anyone, it seems that each member has to reject the previous model in their own way, and at their own pace. I don’t think we can expect anyone at this point to accept responsibility for their wrong statements.

    So their lead archaeologist, Kristian Kristiansen, in The Indo-Europeanization of Europé (sic):

    kristiansen-migrations
    Kristiansen’s (2018) map of Indo-European migrations

    I love the newly invented arrows of migration from Yamna to the north to distinguish among dialects attributed by them to CWC groups, and the intensive use of materials from Heyd’s publications in the presentation, which means they understand he was right – except for the fact that they are used to support a completely different theory, radically opposed to those defended in Heyd’s model

    Now added to the Copenhagen’s unending proposals of language expansions, some pearls from the oral presentation:

    • Corded Ware north of the Carpathians of R1a lineages developed Germanic;
    • R1b borugh [?] Italo-Celtic;
    • the increase in steppe ancestry on north European Bell Beakers mean that they “were a continuation of the Yamnaya/Corded Ware expansion”;
    • Corded Ware groups [] stopped their expansion and took over the Bell Beaker package before migrating to England” [yep, it literally says that];
    • Italo-Celtic expanded to the UK and Iberia with Bell Beakers [I guess that included Lusitanian in Iberia, but not Messapian in Italy; or the opposite; or nothing like that, who knows];
    • 2nd millennium BC Bronze Age Atlantic trade systems expanded Proto-Celtic [yep, trade systems expanded the language]
    • 1st millennium BC expanded Gaulish with La Tène, including a “Gaulish version of Celtic to Ireland/UK” [hmmm, dat British Gaulish indeed].

    You know, because, why the hell not? A logical, stable, consequential, no-nonsense approach to Indo-European migrations, as always.

    Also, compare still more invented arrows of migrations, from Mikkel Nørtoft’s Introducing the Homeland Timeline Map, going against Kristiansen’s multiple arrows, and even against the own recent fantasy map series in showing Bell Beakers stem from Yamna instead of CWC (or not, you never truly know what arrows actually mean):

    corded-ware-migrations
    Nørtoft’s (2018) maps of Indo-European migrations.

    I really, really loved that perennial arrow of migration from Volosovo, ca. 4000-800 BC (3000+ years, no less!), representing Uralic?, like that, without specifics – which is like saying, “somebody from the eastern forest zone, somehow, at some time, expanded something that was not Indo-European to Finland, and we couldn’t care less, except for the fact that they were certainly not R1a“.

    This and Kristiansen’s arrows are the most comical invented migration routes of 2018; and that is saying something, given the dozens of similar maps that people publish in forums and blogs each week.

    NOTE. You can read a more reasonable account of how haplogroup R1b-L51 and how R1-Z645 subclades expanded, and which dialects most likely expanded with them.

    We don’t know where these scholars of the Danish workgroup stand at this moment, or if they ever had (or intended to have) a common position – beyond their persistent ideas of Yamnaya™ ancestral component = Indo-European and R1a must be Indo-European – , because each new publication changes some essential aspects without expressly stating so, and makes thus everything still messier.

    It’s hard to accept that this is a series of presentations made by professional linguists, archaeologists, and geneticists, as stated by the official website, and still harder to imagine that they collaborate within the same professional workgroup, which includes experienced geneticists and academics.

    I propose the following video to close future presentations introducing innovative ideas like those above, to help the audience find the appropriate mood:

    Related

    On the origin of haplogroup R1b-L51 in late Repin / early Yamna settlers

    steppe-eneolithic-migrations

    A recent comment on the hypothetical Central European origin of PIE helped me remember that, when news appeared that R1b-L51 had been found in Khvalynsk ca. 4250-4000 BC, I began to think about alternative scenarios for the expansion of this haplogroup, with one of them including Central Europe.

    Because, if YFull‘s (and Iain McDonald‘s) estimation of the split of R1b-L23 in L51 and Z2103 (ca. 4100 BC, TMRCA ca. 3700 BC) was wrong, by as much as the R1a-Z645 estimates proved wrong, and both subclades were older than expected, then maybe R1b-L51 was not part of the Yamna expansion, but rather part of an earlier expansion with Suvorovo-Novodanilovka into central Europe.

    That is, R1b-L51 and R1b-Z2103 would have expanded wih Khvalynsk-Novodanilovka migrants, and they would have either disappeared among local populations, or settled and expanded with successful lineages in certain regions. I think this may give rise to two potential models.

    A hidden group in the European east-central steppes?

    Here is what Heyd (2011), for example, has to say about the effect of the Khvalynsk-Novodanilovka expansion in the 4th millennium BC, with the first Kurgan wave that shuttered the social, economic, and cultural foundations of south-eastern Europe (before the expansion of west Yamna migrants in the region):

    indo-european-anatolian-uralic-migrations
    Proto-Anatolian migrations with Khvalynsk-Novodanilovka expansion, including ADMIXTURE data from Wang et al. (2018).

    As the Boleraz and Baden tumuli cases in Serbia and Hungary demonstrate, there are earlier, 4th millennium cal. B.C. round tumuli in the Carpathian basin. There are also earlier north-Pontic steppe populations who infiltrated similar environments west of the Black Sea prior to the rise of the Yamnaya culture. This situation can be traced back to the 2nd half of the 5th millennium cal. B.C. to a group of distinct burials, zoomorphic maceheads, long flint blades, triangular flint points, etc., summarized under the term Suvurovo-Novodanilovka (Govedarica 2004; Rassamakin 2004; Anthony 2007; Heyd forthcoming 2011). They also erected round personalized tumuli, though smaller in size and height, above inhumations of single individuals. Suvorovo and Casimcea are the key examples in the lower Danube region of Romania. In northeast Bulgaria, the primary grave of Polska Kosovo (ochre-stained supine extended body position: information communicated by S. Alexandrov) can also be seen as such, as should the Targovishte-“Gonova mogila” primary grave 1 in the Thracian plain with a burial arranged in a supine position with flexed legs, southeast-northwest orientated, and strewed with ochre (Kanchev 1991 , p. 56- 57; Ivanova Gaydarska 2007). In addition to the many copper and shell beads, the 17.4cm long obsidian blade is exceptional, which links this grave to the Csongrád-“Kettoshalom” grave in the south Hungarian plain (Ecsedy 1979). It also yielded an obsidian blade ( 13.2cm long) and copper, shell and limestone beads.

    suvorovo-novodanilovka-expansion-europe
    The Southeast European distribution of graves of the Suvorovo-Novodanilovka group and such unequipped ones mentioned in the text which can be attributed by burial custom and stratigraphic position in the barrow, plus zoomorphic and abstract animal head sceptres as well as specific maceheads with knobs as from Decea Maresului (mid-5th millennium until around 4000 BC). Heyd (2016).

    However, no traces of a tumulus have been recorded above the Kettoshalom tomb. Conventionally, it is dated to the Bodrogkeresztur-period in east Hungary, shortly after 4000 cal. B.C., which would correspond very well with the suggested Cernavodă I (or its less known cultural equivalent in the Thracian plain) attribution for the “Gonova mogila” grave, a cultural background to which the Csongrád grave should have also belonged. Bodrogkeresztur and Cernavodă I periods are not the only examples of 4th millennium cal. B.C. tumuli and burials displaying this steppe connection. Indeed we can find this early steppe impact throughout the 4th millennium cal. B.C. These include adscriptions to the Horodiștea II (Corlateni-Dealul Stadole, grave I: Burtanescu l 998, p. 37; Holbocai, grave 34: Coma 1998, p. 16); to Gordinești-Cernavodă 11 (Liești-Movila Arbănașu, grave 22: Brudiu 2000); to Gorodsk-Usatovo (Corlăteni Dealul Cetăţii, grave I: Comșa 1998, p. 17- 18, in Romania; Durankulak, grave 982: Vajsov 2002, in Bulgaria); and to Cernavodă III(Golyama Detelina, tum. 4: Leshtakov, Borisov 1995), and early (end of 4th millennium cal. B.C.) Ezero in Ovchartsi, primary grave (Kalchev 1994, p. 134-138) and Golyama Detelina, tum. 2 (Kanchev 1991) in Bulgaria. Also the Boleráz and Baden tumuli of Banjevac-Tolisavac and Mokrin in the south Carpathian basin account for this, since one should perhaps take into account primary grave 12 of the Sárrédtudavari-Orhalom tumulus in the Hungarian Alfold: a left-sided crouched juvenile ( 15- 17 y) individual in an oval, NW-SE orientated grave pit 14C dated to 3350-3100 cal. B.C. at 2 sigma (Dani, Ncpper 2006). Neither the burial custom (no ochre strewing or depositing a lump of ochre has been recorded), nor date account for its ascription to the Yamnaya!

    All of these tumuli and burials demonstrate, though, that there is already a constant but perhaps low-level 4th millennium cal. B.C. steppe interaction, linking the regions of the north of the Black Sea with those of the west, and reaching deep into the Carpathian basin. This has to be acknowledged. even if these populations remain small, bounded to their steppe habitat with an economy adapted to this special environment, and are not always visible in the record. Indirect hints may help in seeing them, such as the frequent occurrence of horse bones, regarded as deriving from domesticated horses, in Hungarian Baden settlements (Bokonyi 1978; Benecke 1998), and in those of the south German Cham Culture (Matuschik 1999, p. 80-82) and the east German Bernburg Culture (Becker 1999; Benecke 1999). These occur, however, always in low numbers, perhaps not enough to maintain and regenerate a herd. Does this point us towards otherwise archaeologically hidden horsebreeders in the Carpathian basin, before the Yamnaya? In any case, I hope to make one case clear: these are by no means Yamnaya burials in the strict definition! Attribution to the Yamnaya in its strict definition applies.

    pit-graves-central-europe
    Distribution of Pit-Grave burials west of the Black Sea likely dating to the 2nd half of the 4th millennium BC (triangles: side-crouched burials; filled circles: supine extended burials; open circles: suspected). In Alin Frînculeasa, Bianca Preda, Volker Heyd, Pit-Graves, Yamnaya and Kurgans along the Lower Danube.

    Also, about the expansion of Yamna settlers along the steppes:

    However, it should have been made clear by the distribution map of the Western Yamnaya that they were confining themselves solely to their own, well-known, steppe habitat and therefore not occupying, or pushing away and expelling, the locally settled farming societies. Also, living solely in the steppes requires another lifestyle, and quite different economic and social bases, most likely very different to the established farming societies. Although surely regarded as incoming strangers, they may therefore not have been seen as direct competitors. This argument can be further enforced when remembering that the lowlands and the steppes in the southeast of Europe had already been populated throughout the 4th millennium cal. B.C., as demonstrated above, by societies with a similar north-Pontic steppe origin and tradition, albeit in lower numbers. It is only for these groups that the Yamnaya may have become a threat, but their common origin and perhaps a similar economic/ social background with comparable lifestyles would surely have assisted to allow rapid assimilation. More important, though, is that farming societies in this region may therefore have been accustomed to dealing and interacting with different people and ethnic strangers for a long time. (…)

    When assessing farming and steppe societies’ interaction from a general point of view, attitudes can diverge in three main directions:

    1. the violent one; with raids, fights, struggles, warfare, suppression and finally the superiority and exploitation of the one over the other;
    2. the peaceful one; with a continuous exchange of gifts, goods, work, information and genes in a balanced reciprocal system, leading eventually to the merging of the two societies and creation of a new identity;
    3. the neutral one; with the two societies ignoring each other for a long time.

    What we see from trying to understand the record of the Yamnaya, based on their tumuli and burials, and the local and neighbouring contemporary societies, based on their settlements, hoards, and graves, is likely a mixture of all three scenarios, with the balance perhaps more towards exchange in a highly dynamic system with alterations over time. However, violence and raids cannot be ruled out; they would be difficult to see in the archaeological record; or only indirectly, such as the building of hill forts, particularly the defence-like chain of Vucedol hillforts along the south shore of the Danube on the Serbian/Croatian border zone (Tasic 1995a), and the retreat of people into them (Falkenstein 1998, p. 261-262), with other interpretations also possible. And finally, we are dealing here with very different local and neighbouring societies, as well as with more distant contemporary ones, looking, in reality, rather like a chequer board of societies and archaeological cultures (see Parzinger 1993 for the overview). These display different regional backgrounds and traditions leading to different social and settlement organizations, different economic bases and material cultures in the wide areas between Prut and Maritza rivers, and Black Sea and Tisza river. They surely found their individual way of responding to the incoming and settling Yamnaya people.

    yamna-tumuli-west-carpathians
    Yamnaya tumuli signalling the expansion of West Yamna from ca. 3100 BC (especially after ca. 2950 BC). Heyd (2011).

    The best data we have about this potential non-Yamna origin of R1b-L51 – and thus in favour of its admixture in the Carpathian basin – lies in:

    1. The majority of R1a-Z2103 subclades found to date among Yamna samples.
    2. The presence of R1b-Z2103 in the Catacomb culture – in the Northern Caucasus and in Ukraine.
    3. The limited presence of (ancient and modern) R1b-L51 in eastern Europe and India, whose isolated finds are commonly (and simplistically) attributed to ‘late migrations’.
    4. The presence of R1b-L51 (xZ2103) in cultures related to the ‘Yamna package’, but supposedly not to Yamna settlers. So for example I7043, of haplogroup R1b-L151(xU106,xP312), ca. 2500-2200 BC from Szigetszentmiklós-Üdülősor, probably from the Bell Beaker (Csepel group), but maybe from the early Nagýrev culture.
    5. The expansion of its subclades apparently only from a single region, around the Carpathian basin, in contrast to R1b-Z2103.
    6. The already ‘diluted’ steppe admixture found in the earliest samples with respect to Yamna, which points to the appearance after the Yamna admixture with the local population.
    7. Ukrainian archaeologists (in contrast to their Russian colleagues) point to the relevance of North Pontic cultures like Kvitjana and Lower Mikhailovka in the development of Early Yamna in the west, and some eastern European researchers also believe in this similarity.
    8. If R1b-Z2103 and R1b-L51 had expanded with Suvorovo-Novodanilovka migrants to the west, and had admixed later as Hungary_LCA-LBA-like peoples with Yamna migrants during the long-term contacts with other ‘kurganized cultures’ ca. 2900-2500 BC in the Great Hungarian Plains, it could explain some peculiar linguistic traits of North-West Indo-European, and also why R1b-Z2103 appears in cultures associated with this earlier ‘steppe influence’ (i.e. not directly related to Yamna) such as Vučedol (with a R1b-Z2103 sample, see below). That could also explain the presence of R1b-L151(xP312, xU106) in similar Balkan cultures, possibly not directly related to Yamna.
    PCA-r1b-l51
    Image modified from Wang et al. (2018). PCA of ancient and modern samples. Red circle in dashed line around Varna, Greece Neolithic, and (approximate position of) Smyadovo outliers, part of Khvalynsk-Novodanilovka settlers.

    A hidden group among north or west Pontic Eneolithic steppe cultures?

    The expansion of Khvalynsk as Novodanilovka into the North Pontic area happened through the south across the steppe, near the coast, with the forest-steppe region working as a clear natural border for this culture of likely horse-riding chieftains, whose economy was probably based on some rudimentary form of mobile pastoralism.

    Although archaeologists are divided as to the origin of each individual Middle Eneolithic group near the Black Sea after the end of the Khvalynsk-Novodanilovka period, it seems more or less clear that steppe cultures like Cernavodă, Lower Mikhailovka, or Kvitjana are closer (or “more archaic”) in their steppe features, which connects them to Volga–Ural and Northern Caucasus cultures, like Northern Caucasus, Repin or Khvalynsk.

    On the other hand, forest-steppe cultures like Dereivka (including Alexandria) show innovative traits and contacts with para- or sub-Neolithic cultures to the north, like Comb-Pit Ware groups, apart from corded decoration influenced by Trypillian groups to the west, especially in their later (‘Proto-Corded Ware‘) stage after ca. 3500 BC.

    If Ukrainian researchers like Rassamakin are right, Early Yamna expanded not only from Repin settlers, but also from local steppe cultures adopting Repin traits to develop an Early Yamna culture, similar to how eastern (Volga–Ural groups) seem to have synchronously adopted Early Yamna without massive affluence of Repin settlements.

    Furthermore, local traits develop in southern groups, like anthropomorphic stelae (shared with Kemi-Oba, direct heir of Lower Mikhailovka), and rich burials featuring wagons. These traits are seen in west Yamna settlers.

    north-pontic-kvityana-dereivka-repin
    Modified from Rassamakin (1999), adding red color to Repin expansion. The system of the latest Eneolithic Pointic cultures and the sites of the Zhivotilovo-Volchanskoe type: 1) Volchanskoe; 2) Zhivotilovka; 3) Vishnevatoe; 4) Koisug.

    Problems of this model include:

    1. On the North Pontic area – in contrast to the Volga–Ural region – , there was a clear “colonization” wave of Repin settlers, also supported by Ukrainian researchers, based on the number of new settlements and burials, and on the progressive retreat of Dereivka, Kvitjana, as well as (more recent) Maykop- and Trypillia-related groups from the North Pontic area ca. 3350/3300 BC. It seems unlikely that these expansionist, semi-nomadic, cattle-breeding, patrilineally-related steppe clans that were driving all native populations out of their territories suddenly decided, at some point during their spread into the North Pontic area ca. 3300-3100 BC, to join forces with some foreign male lineages from the area, and then continue their expansion to the west…
    2. Similar to the fate of R1b-P297 subclades in the Baltic after the expansion of Corded Ware migrants, previous haplogropus of the North Pontic region – such as R1a, R1b-V88, and I2 subclades basically disappeared from the ancient DNA record after the expansion of Khvalynsk-Novodanilovka, and then after the expansion of Yamna, as is clear from Yamna, Afanasevo, and Bell Beaker samples obtained to date. This, in combination with what we know about Y-chromosome bottlenecks in post-Neolithic expansions, leaves little space to think that a big enough territorial group with a majority of “native” haplogroups could survive later expansions (be it R1b-L51 or R1a-Z645).
    3. Supporting an expansion of the same male (and partly female) population, the Yamna admixture from east to west is quite homogeneous, with the only difference found in (non-significant) EEF-like proportion which becomes elevated in distant areas [apart from significant ‘southern’ contribution to certain outlier samples]. Based on the also homogeneous Y-DNA picture, the heterogeneity must come, in general, from the female exogamy practiced by expanding groups.
    4. There is a short period, spanning some centuries (approximately 3300-2700 BC), in which the North Pontic area – especially the forest-steppe territories to the west of the Dnieper, i.e. the Upper Dniester, Boh, and Prut-Siret areas – are a chaos of incoming and emigrating, expanding and shrinking groups of different cultures, such as late Trypillian groups, Maykop-related traits, TRB, GAC, (Proto-)Corded Ware, and Early Yamna settlements. No natural geographic frontier can be delimited between these groups, which probably interacted in different ways. Nevertheless, based on their cultural traits, admixture, and especially on their Y-DNA, it seems that they never incorporated foreign male lineages, beyond those they probably had during their initial expansion trends.
    5. The further expansionist waves of Early Yamna seen ca. 3100 BC, from the Danube Delta to the west, give an overall image of continuously expanding patrilineal clans of R1b-M269 subclades since the Khvalynsk-Novodanilovka migration, in different periodic steps, mostly from eastern Pontic-Caspian nuclei, usually overriding all encountered cultures and (especially male) populations, rather than showing long-term collaboration and interaction. Such interaction is seen only in exceptional cases, e.g. the long-term admixture between Abashevo and Poltavka, as seen in Proto-Indo-Iranian peoples and their language.
    PCA-Ukraine-r1b-l51
    Image modified from Wang et al. (2018). PCA of ancient and modern samples. Arrows depicting Khvalynsk -> Yamna drift (blue), and hypothetic approximate Ukraine Eneolithic -> Yamna drift accompanying R1b-L51 (red).

    Consequences

    We are living right now an exemplary ego-, (ethno-)nationalism-, and/or supremacy-deflating moment, for some individuals of eastern and northern European descent who believed that R1a or ‘steppe ancestry proportions’ meant something special. The same can be said about those who had interiorized some social or ethnolinguistic meaning for the origin of R1b in western Europe, N1c in north-eastern Europe, as well as Greeks, Iranians, Armenians, or Mediterranean peoples in general of ‘Near Eastern’ ancestry or haplogroups, or peoples of Near Eastern origin and/or language.

    These people had linked their haplogroups or ancestry with some fantasy continuity of ‘their’ ancestral populations to ‘their’ territories or languages (or both), and all are being proven wrong.

    Apart from teaching such people a lesson about what simplistic views are useful for – whether it is based on ABO or RH group, white skin, blond hair, blue eyes, lactase persistence, or on the own ancestry or Y-DNA haplogroup -, it teaches the rest of us what can happen in the near future among western Europeans. Because, until recently, most western Europeans were comfortably settled thinking that our ancestors were some remnant population from an older, Palaeolithic or Mesolithic population, who acquired Indo-European languages by way of cultural diffusion in different periods, including only minor migrations.

    Judging by what we can see now among some individuals of Northern and Eastern European descent, the only thing that can worsen the air of superiority among western Europeans is when they realize (within a few years, when all these stupid battles to control the narrative fade) that not only are they the cultural ‘heirs’ of the Graeco-Roman tradition that began with the Roman Empire, but that most of them are the direct patrilineal descendants of Khvalynsk, Yamna, Bell Beaker, and European Bronze Age peoples, and thus direct descendants of Middle PIE, Late PIE, and NWIE speakers.

    steppe-chalcolithic-migrations
    Steppe-related migrations ca. 3100-2600 BC with tentative linguistic identification.

    The finding of R1b-L51 and R1b-Z2103 among expanding Suvorovo-Novodanilovka chieftains, with pockets of R1b-L51 remaining in steppe-like societies of the Balkans and the Carpathian Basin, would have beautifully complemented what we know about the East Yamna admixture with R1a-Z93 subclades (Uralic speakers) ca. 2600-2100 BC to form Proto-Indo-Iranian, and about the regional admixtures seen in the Balkans, e.g. in Proto-Greeks, with the prevalent J subclades of the region.

    It would have meant an end to any modern culture or nation identifying themselves with the ‘true’ Late PIE and Yamna heirs, because these would be exclusively associated with the expansion of R1b-Z2103 subclades with late Repin, and later as the full-fledged Late PIE with Yamna settlers to south-east and central Europe, and to the southern Urals. The language would have had then obviously undergone different language changes in all these territories through long-lasting admixture with other populations. In that sense, it would have ended with the ideas of supremacy in western Europe before they even begin.

    The most likely future

    However limited the evidence, it seems that R1b-L51 expanded with Yamna, though, based on the estimates for the haplogroups involved, and on marginal hints at the variability of L23 subclades within Yamna and neighbouring populations. If R1b-L51 expanded with West Repin / Early Yamna settlers, this is why they have not yet been found among Yamna samples:

    steppe-eneolithic-migrations
    Simplified map of Repin expansions from ca. 3500/3400 BC.
    • The subclade division of Yamna settlers needs not be 50:50 for L51:Z2103, either in time or in space. I think this is the simplistic view underlying many thoughts on this matter. Many different expanding patrilineal clans of L23 subclades may have been more or less successful in different areas, and non-Z2103 may have been on the minority, or more isolated relative to Z2103-clans among expanding peoples on the steppe, especially on the east. In fact, we usually talk in terms of “Z2103 vs. L51” as if
      1. these two were the only L23 subclades; and
      2. both had split and succeeded (expanding) synchronously;

      that is, as if there had not been multiple subclades of both haplogroups, and as if there had not been different expansion waves for hundreds of years stemming from different evolving nuclei, involving each time only limited (successful) clans. Many different subclades of haplogroups L23 (xZ2103, xL51), Z2103, and L51 must have been unsuccessful during the ca. 1,500 years of late Khvalynsk and late Repin-Early Yamna expansions in which they must have participated (for approximately 60-75 generations, based on a mean 20-25 years).

    • If we want to imagine a pocket of ‘hidden’ L51 for some region of the North Pontic or Carpathian region, the same can be imagined – and much more likely – for any unsampled territory of expanding late Repin/Early Yamna settlers from the Lower Don – Lower Volga region (probably already a mixed society of L51 and Z2103 subclades since their beginning, as the early Repin culture, ca. 3800 BC), with L51 clans being probably successful to the west.
    • The Repin culture expanded only in small, mobile settlements from the Lower Don – Lower Volga to the north, east, and south, starting ca. 3500/3400 BC, in the waves that eventually gave a rather early distant offshoot in the Altai region, i.e. Afanasevo. Starting ca. 3300 BC in the archaeological record, the majority of R1b-Z2103 subclades found to date in Afanasevo also supports either
      • a mixed Repin society, with Z2103-clans predominating among eastern settlers; or
      • a Repin society marked by haplogroup L51, and thus a cultural diffusion of late Repin/Early Yamna traits among neighbouring (Khvalynsk, Samara, etc.) groups of essentially the same (early Khvalynsk-Novodanilovka) genetic stock in the Volga–Ural region.

      Both options could justify a majority of Z2103 in the Lower Volga–Ural region, with the latter being supported by the scattered archaeological remains of late Repin in the region before the synchronous emergence of Early Yamna findings in the whole Pontic-Caspian steppe.

    • Most Z2103 from Yamna samples to date are from around 3100 BC (in average) onward, and from the right bank of the Lower Don to the east, particularly from the Lower Volga–Ural area (especially the Samara region), which – based on the center of expansion of late Repin settlers – may be depicting an artificially high Z2103-distribution of the whole Yamna community.
    repin-expansion-khvalynsk-cultures
    Repin expansion into the Volga–Ural region from ca. 3500/3400 BC. Map made by me based on maps and data from Morgunova (2014, 2016). Lopatino is marked with number 64.
    • Yamna sample I0443, R1b-L23 (Y410+, L51-), ca. 3300-2700 BCE from Lopatino II, points to an intermediate subclade between L23 and L51, near one of the supposed late Repin sites (based on kurgan burials with late Repin cultural traits) in the Samara region.
    • Other Balkan cultures potentially unrelated to the Yamna expansion also show Z2103 (and not only L51) subclades, like I3499 (ca. 2884-2666 calBC), of the Vučedol culture, from Beli Manastir-Popova zemlja, which points to the infiltration of Yamna peoples in other cultures. In any case, the appearance of R1b-L23 subclades in the region happens only after the Yamna expansion ca. 3100 BC, probably through intrusions into different neighbouring regions, if these Balkan cultures are not directly derived from Yamna settlements (which is probably the case of the Csepel Bell Beaker or early Nagýrev sample, see above).
    • The diversity of haplogroups found in or around the Carpathian Basin in Late Chalcolithic / Early Bronze Age samples, including L151(xP312, xU106), P312, U106, Z2103, makes it the most likely sink of Yamna settlers, who spread thus with expanding family clans of different R1b-L23 subclades.
    • Even though some Yamna vanguard groups are known to have expanded up to Saxony-Anhalt before ca. 2700 BC, haplogroup Z2103 seems to be restricted to more eastern regions, which suggests that R1b-L51 was already successful among expanding West Yamna clans in Hungary, which gave rise only later to expanding East Bell Beakers (overwhelmingly of L151 subclades). The source of R1b-L51 and L151 expansion over Z2103 must lie therefore in the West Yamna period, and not in the Bell Beaker expansion.
    indo-european-uralic-migrations-yamna-gac
    Yamna migrants ca. 3300-2600. Most likely site of admixture with GAC circled in red.
    • The R1b-Z2103 found in Poltavka, Catacomb, and to the south point to a late migration displacing the western R1b-L51, only after the late Repin expansion. This is also seen in the steppe ancestry and R1b-Z2103 south of the Caucasus, in Hajji Firuz, which points to this route as a potential source of the supposed “Earliest Proto-Indo-Iranian” (the mariannu term) of the Near East. A similar replacement event happened some centuries later with expanding R1a-Z93 subclades from the east wiping out haplogroup R1b-Z2103 from the Pontic-Caspian steppe.
    • Many ancient samples from Khvalynsk, Northern Caucasus, Yamna, or later ones are reported simply as R1b-M269 or L23, without a clear subclade, so the simplistic ‘Yamna–Z2103’ picture is not real: if one takes into account that Z2103 might have been successful quite early in the eastern region, it is more likely to obtain a successful Y-SNP call of a Z2103 subclade in the Volga–Ural region than a xZ2103 one.
    • There are some modern samples of R1b-L51 in eastern Europe and Asia, whose common simplistic attribution to “late expansions” is usually not substantiated; and also ancient R1b-L51 samples might be confirmed soon for Asia.
    • ‘Western’ features described by archaeologists for West Yamna settlers, associated with Kemi Oba and southern Yamna groups in the North Pontic area – like rich burials with anthropomorphic stelae and wagons – are actually absent in burials from settlers beyond Bulgaria, which does not support their affiliation with these local steppe groups of the Black Sea. Also, a mix with local traditions is seen accross all Early Yamna groups of the Pontic-Caspian steppe, and still genetics and common cultural traits point to their homogeneization under the same patrilineal clans expanding continuously for centuries. The maintenance of local traditions (as evidenced by East Bell Beakers in Iberia related to Iberian Proto-Beakers) is often not a useful argument in genetics, especially when the female population is not replaced.
    yamna-settlers-hungary
    Yamna settlers in the Great Pannonian Plain, showing only kurgans of Hungary ca. 2950-2500 BC. Yamna Hungary was one of the biggest West Yamna provinces. From Hórvath et al. (2013).

    Conclusion

    This is what we know, using linguistics, archaeology, and genetics:

    • Middle Proto-Indo-European expanded with Khvalynsk-Novodanilovka after ca. 4800 BC, with the first Suvorovo settlements dated ca. 4600 BC.
    • Archaic Late Proto-Indo-European expanded with late Repin (or Volga–Ural settlers related to Khvalynsk, influenced by the Repin expansion) into Afanasevo ca. 3500/3400 BC.
    • Late Proto-Indo-European expanded with Early Yamna settlers to the west into central Europe and the Balkans ca. 3100 BC; and also to the east (as Pre-Proto-Indo-Iranian) into the southern Urals ca. 2600 BC.
    • North-West Indo-European expanded with Yamna Hungary -> East Bell Beakers, from ca. 2500 BC.
    • Proto-Indo-Iranian expanded with Sintashta, Potapovka, and later Andronovo and Srubna from ca. 2100 BC.

    It seems that the subclades from Khvalynsk ca. 4250-4000 BC were wrongly reported – like those of Narasimhan et al. (2018). However, even if they are real and YFull estimates have to be revised, and even if the split had happened before the expansion of Suvorovo-Novodanilovka, the most likely origin of R1b-L51 among Bell Beakers will still be the expansion of late Repin / Early Yamna settlers, and that is what ancient DNA samples will most likely show, whatever the social or political consequences.

    The only relevance of the finding of R1b-L51 in one place or another – especially if it is found to be a remnant of a Middle PIE expansion coupled with centuries of admixture and interaction in the Carpathian Basin – is the potential influence of an archaic PIE (or non-IE) layer on the development of North-West Indo-European in Yamna Hungary -> East Bell Beaker. That is, more or less like the Uralic influence related to the appearance of R1a-Z93 among Proto-Indo-Iranians, of R1a-Z284 among Pre-Germanic peoples, and of R1a-Z282 among Balto-Slavic peoples.

    I think there is little that ancient DNA samples from West Yamna could add to what we know in general terms of archaeology or linguistics at this point regarding Late PIE migrations, beyond many interesting details. I am sure that those who have not attributed some random 6,000-year-old paternal ancestor any magical (ethnic or nationalist) meaning are just having fun, enjoying more and more the precise data we have now on European prehistoric populations.

    As for those who believe in magical consequences of genetic studies, I don’t think there is anything for them to this quest beyond the artificially created grand-daddy issues. And, funnily enough, those who played (and play) the ‘neutrality’ card to feel superior in front of others – the “I only care about the truth”-type of lie, while secretly longing for grandpa’s ethnolinguistic continuity – are suffering the hardest fall.

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