Analysis of R1b-DF27 haplogroups in modern populations adds new information that contrasts with ‘steppe admixture’ results

R1b-DF27-iberia

New open access article published in Scientific Reports, Analysis of the R1b-DF27 haplogroup shows that a large fraction of Iberian Y-chromosome lineages originated recently in situ, by Solé-Morata et al. (2017).

Abstract

Haplogroup R1b-M269 comprises most Western European Y chromosomes; of its main branches, R1b-DF27 is by far the least known, and it appears to be highly prevalent only in Iberia. We have genotyped 1072 R1b-DF27 chromosomes for six additional SNPs and 17 Y-STRs in population samples from Spain, Portugal and France in order to further characterize this lineage and, in particular, to ascertain the time and place where it originated, as well as its subsequent dynamics. We found that R1b-DF27 is present in frequencies ~40% in Iberian populations and up to 70% in Basques, but it drops quickly to 6–20% in France. Overall, the age of R1b-DF27 is estimated at ~4,200 years ago, at the transition between the Neolithic and the Bronze Age, when the Y chromosome landscape of W Europe was thoroughly remodeled. In spite of its high frequency in Basques, Y-STR internal diversity of R1b-DF27 is lower there, and results in more recent age estimates; NE Iberia is the most likely place of origin of DF27. Subhaplogroup frequencies within R1b-DF27 are geographically structured, and show domains that are reminiscent of the pre-Roman Celtic/Iberian division, or of the medieval Christian kingdoms.

Some people like to say that Y-DNA haplogroup analysis, or phylogeography in general, is of no use anymore (especially modern phylogeography), and they are content to see how ‘steppe admixture’ was (or even is) distributed in Europe to draw conclusions about ancient languages and their expansion. With each new paper, we are seeing the advantages of analysing ancient and modern haplogroups in ascertaining population movements.

Quite recently there was a suggestion based on steppe admixture that Basque-speaking Iberians resisted the invasion from the steppe. Observing the results of this article (dates of expansion and demographic data) we see a clear expansion of Y-DNA haplogroups precisely by the time of Bell Beaker expansion from the east. Y-DNA haplogroups of ancient samples from Portugal point exactly to the same conclusion.

The situation of R1b-DF27 in Basques, as I have pointed out elsewhere, is probably then similar to the genetic drift of Finns, mainly of N1c lineages, speaking today a Uralic language that expaned with Corded Ware and R1a subclades.

The recent article on Mycenaean and Minoan genetics also showed that, when it comes to Europe, most of the demographic patterns we see in admixture are reminiscent of the previous situation, only rarely can we see a clear change in admixture (which would mean an important, sudden replacement of the previous population).

Equating the so-called steppe admixture with Indo-European languages is wrong. Period.

The following are excerpts from the article (emphasis is mine):

Dates and expansions

The average STR variance of DF27 and each subhaplogroup is presented in Suppl. Table 2. As expected, internal diversity was higher in the deeper, older branches of the phylogeny. If the same diversity was divided by population, the most salient finding is that native Basques (Table 2) have a lower diversity than other populations, which contrasts with the fact that DF27 is notably more frequent in Basques than elsewhere in Iberia (Suppl. Table 1). Diversity can also be measured as pairwise differences distributions (Fig. 5). The distribution of mean pairwise differences within Z195 sits practically on top of that of DF27; L176.2 and Z220 have similar distributions, as M167 and Z278 have as well; finally, M153 shows the lowest pairwise distribution values. This pattern is likely to reflect the respective ages of the haplogroups, which we have estimated by a modified, weighted version of the ρ statistic (see Methods).

Z195 seems to have appeared almost simultaneously within DF27, since its estimated age is actually older (4570 ± 140 ya). Of the two branches stemming from Z195, L176.2 seems to be slightly younger than Z220 (2960 ± 230 ya vs. 3320 ± 200 ya), although the confidence intervals slightly overlap. M167 is clearly younger, at 2600 ± 250 ya, a similar age to that of Z278 (2740 ± 270 ya). Finally, M153 is estimated to have appeared just 1930 ± 470 ya.

Haplogroup ages can also be estimated within each population, although they should be interpreted with caution (see Discussion). For the whole of DF27, (Table 3), the highest estimate was in Aragon (4530 ± 700 ya), and the lowest in France (3430 ± 520 ya); it was 3930 ± 310 ya in Basques. Z195 was apparently oldest in Catalonia (4580 ± 240 ya), and with France (3450 ± 269 ya) and the Basques (3260 ± 198 ya) having lower estimates. On the contrary, in the Z220 branch, the oldest estimates appear in North-Central Spain (3720 ± 313 ya for Z220, 3420 ± 349 ya for Z278). The Basques always produce lower estimates, even for M153, which is almost absent elsewhere.

R1b-DF27-tree
Simplified phylogenetic tree of the R1b-M269 haplogroup. SNPs in italics were not analyzed in this manuscript.

Demography

The median value for Tstart has been estimated at 103 generations (Table 4), with a 95% highest probability density (HPD) range of 50–287 generations; effective population size increased from 131 (95% HPD: 100–370) to 72,811 (95% HPD: 52,522–95,334). Considering patrilineal generation times of 30–35 years, our results indicate that R1b-DF27 started its expansion ~3,000–3,500 ya, shortly after its TMRCA.

As a reference, we applied the same analysis to the whole of R1b-S116, as well as to other common haplogroups such as G2a, I2, and J2a. Interestingly, all four haplogroups showed clear evidence of an expansion (p > 0.99 in all cases), all of them starting at the same time, ~50 generations ago (Table 4), and with similar estimated initial and final populations. Thus, these four haplogroups point to a common population expansion, even though I2 (TMRCA, weighted ρ, 7,800 ya) and J2a (TMRCA, 5,500 ya) are older than R1b-DF27. It is worth noting that the expansion of these haplogroups happened after the TMRCA of R1b-DF27.

R1b-DF27-PCA
Principal component analysis of STR haplotypes. (a) Colored by subhaplogroup, (b) colored by population. Larger squares represent subhaplogroup or population centroids.

Sum up and discussion

We have characterized the geographical distribution and phylogenetic structure of haplogroup R1b-DF27 in W. Europe, particularly in Iberia, where it reaches its highest frequencies (40–70%). The age of this haplogroup appears clear: with independent samples (our samples vs. the 1000 genome project dataset) and independent methods (variation in 15 STRs vs. whole Y-chromosome sequences), the age of R1b-DF27 is firmly grounded around 4000–4500 ya, which coincides with the population upheaval in W. Europe at the transition between the Neolithic and the Bronze Age. Before this period, R1b-M269 was rare in the ancient DNA record, and during it the current frequencies were rapidly reached. It is also one of the haplogroups (along with its daughter clades, R1b-U106 and R1b-S116) with a sequence structure that shows signs of a population explosion or burst. STR diversity in our dataset is much more compatible with population growth than with stationarity, as shown by the ABC results, but, contrary to other haplogroups such as the whole of R1b-S116, G2a, I2 or J2a, the start of this growth is closer to the TMRCA of the haplogroup. Although the median time for the start of the expansion is older in R1b-DF27 than in other haplogroups, and could suggest the action of a different demographic process, all HPD intervals broadly overlap, and thus, a common demographic history may have affected the whole of the Y chromosome diversity in Iberia. The HPD intervals encompass a broad timeframe, and could reflect the post-Neolithic population expansions from the Bronze Age to the Roman Empire.

While when R1b-DF27 appeared seems clear, where it originated may be more difficult to pinpoint. If we extrapolated directly from haplogroup frequencies, then R1b-DF27 would have originated in the Basque Country; however, for R1b-DF27 and most of its subhaplogroups, internal diversity measures and age estimates are lower in Basques than in any other population. Then, the high frequencies of R1b-DF27 among Basques could be better explained by drift rather than by a local origin (except for the case of M153; see below), which could also have decreased the internal diversity of R1b-DF27 among Basques. An origin of R1b-DF27 outside the Iberian Peninsula could also be contemplated, and could mirror the external origin of R1b-M269, even if it reaches there its highest frequencies. However, the search for an external origin would be limited to France and Great Britain; R1b-DF27 seems to be rare or absent elsewhere: Y-STR data are available only for France, and point to a lower diversity and more recent ages than in Iberia (Table 3). Unlike in Basques, drift in a traditionally closed population seems an unlikely explanation for this pattern, and therefore, it does not seem probable that R1b-DF27 originated in France. Then, a local origin in Iberia seems the most plausible hypothesis. Within Iberia, Aragon shows the highest diversity and age estimates for R1b-DF27, Z195, and the L176.2 branch, although, given the small sample size, any conclusion should be taken cautiously. On the contrary, Z220 and Z278 are estimated to be older in North Central Spain (N Castile, Cantabria and Asturias). Finally, M153 is almost restricted to the Basque Country: it is rarely present at frequencies >1% elsewhere in Spain (although see the cases of Alacant, Andalusia and Madrid, Suppl. Table 1), and it was found at higher frequencies (10–17%) in several Basque regions; a local origin seems plausible, but, given the scarcity of M153 chromosomes outside of the Basque Country, the diversity and age values cannot be compared.

Within its range, R1b-DF27 shows same geographical differentiation: Western Iberia (particularly, Asturias and Portugal), with low frequencies of R1b-Z195 derived chromosomes and relatively high values of R1b-DF27* (xZ195); North Central Spain is characterized by relatively high frequencies of the Z220 branch compared to the L176.2 branch; the latter is more abundant in Eastern Iberia. Taken together, these observations seem to match the East-West patterning that has occurred at least twice in the history of Iberia: i) in pre-Roman times, with Celtic-speaking peoples occupying the center and west of the Iberian Peninsula, while the non-Indoeuropean eponymous Iberians settled the Mediterranean coast and hinterland; and ii) in the Middle Ages, when Christian kingdoms in the North expanded gradually southwards and occupied territories held by Muslim fiefs.

DF27-iberia-france
Contour maps of the derived allele frequencies of the SNPs analyzed in this manuscript. Population abbreviations as in Table 1. Maps were drawn with SURFER v. 12 (Golden Software, Golden CO, USA).

I wouldn’t trust the absence of R1b-DF27 outside France as a proof that its origin must be in Western Europe – especially since we have ancient DNA, and that assertion might prove quite wrong – but aside from that the article seems solid in its analysis of modern populations.

Related:

Text and figures from the article, licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Something is very wrong with models based on the so-called ‘steppe admixture’ – and archaeologists are catching up

steppe-admixture

Russian archaeologist Leo Klejn has published an article Discussion: Are the Origins of Indo-European Languages Explained by the Migration of the Yamnaya Culture to the West?, which includes the criticism received from Wolfgang Haak, Iosif Lazaridis, Nick Patterson, and David Reich (mainly on the genetic aspect), and from Kristian Kristiansen, Karl-Göran Sjögren, Morten Allentoft, Martin Sikora, and Eske Willerslev (mainly on the archaeological aspect).

I will not post details of Klejn’s model of North-South Proto-Indo-European expansion – which is explained in the article, and relies on the north-south cline of ‘steppe admixture’ in the modern European population -, since it is based on marginal anthropological methods and theories, including glottochronological dates, and archaeological theories from the Russian school (mainly Zalyzniak), which are obviously not mainstream in the field of Indo-European Studies, and (paradoxically) on the modern distribution of ‘steppe admixture’…

The most interesting aspects of the article are the reactions to the criticism, some of which can be used from the point of view of the Indo-European demic diffusion model, too. It is sad, however, that they didn’t choose to answer earlier to Heyd’s criticism (or to Heyd’s model, which is essentially also that of Mallory and Anthony), instead of just waiting for proponents of the least interesting models to react…

The answer by Haak et al.:

Klejn mischaracterizes our paper as claiming that practitioners of the Corded Ware culture spoke a language ancestral to all European Indo-European languages, including Greek and Celtic. This is incorrect: we never claim that the ancestor of Greek is the language spoken by people of the Corded Ware culture. In fact, we explicitly state that the expansion of steppe ancestry might account for only a subset of Indo-European languages in Europe. Klejn asserts that ‘a source in the north’ is a better candidate for the new ancestry manifested in the Corded Ware than the Yamnaya. While it is indeed the case that the present-day people with the greatest affinity to the Corded Ware are distributed in north-eastern Europe, a major part of the new ancestry of the Corded Ware derives from a population most closely related to Armenians (Haak et al., 2015) and hunter-gatherers from the Caucasus (Jones et al., 2015). This ancestry has not been detected in any European huntergatherers analysed to date (Lazaridis et al., 2014; Skoglund et al., 2014; Haak et al., 2015; Fu et al., 2016), but made up some fifty per cent of the ancestry of the Yamnaya. The fact that the Corded Ware traced some of its ancestry to the southern Caucasus makes a source in the north less parsimonious.

In our study, we did not speculate about the date of Proto-Indo-European and the locations of its speakers, as these questions are unresolved by our data, although we do think the genetic data impose constraints on what occurred. We are enthusiastic about the potential of genetics to contribute to a resolution of this longstanding issue, but this is likely to require DNA from multiple, as yet unsampled, ancient populations.

Klejn response to that:

Allegedly, I had accused the authors of tracing all Indo-European languages back to Yamnaya, whereas they did not trace all of them but only a portion! Well, I shall not reproach the authors for their ambiguous language: it remains the case that (beginning with the title of the first article) their qualifications are lost and their readers have understood them as presenting the solution to the whole question of the origins of Indo-European languages.

(…) they had in view not the Proto-Indo-European before the separation of the Hittites, but the language that was left after the separation. Yet, this was still the language ancestral to all the remaining Indo-European languages, and the followers of Sturtevan and Kluckhorst call only this language Proto-Indo-European (while they call the initial one Indo-Hittite). The majority of linguists (specialists in Indo-European languages) is now inclined to this view. True, the breakup of this younger language is several hundred years more recent (nearly a thousand years later according to some glottochronologies) than the separation of Anatolian languages, but it is still around a thousand years earlier than the birth of cultures derived from Yamnaya.
More than that, I analysed in my criticism both possibilities — the case for all Indo-European languages spreading from Yamnaya and the case for only some of them spreading from Yamnaya. In the latter case, it is argued that only the languages of the steppes, the Aryan (Indo- Iranian) are descended from Yamnaya, not the languages of northern Europe. Together with many scholars, I am in agreement with the last possibility. But, then, what sense can the proposed migration of the Yamnaya culture to the Baltic region have? It would bring the Indo-Iranian proto-language to that region! Yet, there are no traces of this language on the coasts of the Baltic!

My main concern is that, to my mind, one should not directly apply conclusions from genetics to events in the development of language because there is no direct and inevitable dependence between events in the life of languages, culture, and physical structure (both anthropological and genetic). They can coincide, but often they all follow divergent paths. In each case the supposed coincidence should be proved separately.

The authors’ third objection concerns the increase of the genetic similarity of European population with that of the Yamnaya culture. This increases in the north of Europe and is weak in the south, in the places adjacent to the Yamnaya area, i.e. in Hungary. This gradient is clearly expressed in the modern population, but was present already in the Bronze Age, and hence cannot be explained by shifts that occurred in the Early Iron Age and in medieval times. However, the supposed migration of the Yamnaya culture to the west and north should imply a gradient in just the opposite direction!

Regarding the arguments of Kristiansen and colleagues:

[They argue that] in two early burials of the Corded Ware culture (one in Germany, the other in Poland) some single attributes of Yamnaya origin have been found.

(…) if this is the full extent of Yamnaya infiltration into central Europe—two burials (one for each country) from several thousands (and from several hundreds of early burials)—then it hardly amounts to large-scale migration.

Quite recently we have witnessed the success of a group of geneticists from Stanford University and elsewhere (Poznik et al., 2016). They succeeded in revealing varieties of Y-chromosome connected with demographic expansions in the Bronze Age. Such expansion can give rise to migration. Among the variants connected with this expansion is R1b, and this haplogroup is typical for the Yamnaya culture. But what bad luck! This haplogroup connected with expansion is indicated by the clade L11, while the Yamnaya burials are associated with a different clade, Z2103, that is not marked by expansion. It is now time to think about how else the remarkable results reached by both teams of experienced and bright geneticists may be interpreted.

Regarding the work of Heyd,

(…) with regard to the barrow burials of the third millennium BC in the basin of the Danube, although they have been assigned to the Yamnaya culture, I would consider them as also belonging to
another, separate culture, perhaps a mixed culture: its burial custom is typical of the Yamnaya, but its pottery is absolutely not Yamnaya, but local Balkan with imports of distinctive corded beakers (Schnurbecher). I would not be surprised if
Y-chromosome haplogroups of this population were somewhat similar to those of the Yamnaya, while mitochondrial groups were indigenous. As yet, geneticists deal with great blocks of populations and prefer to match them to very large and generalized cultural blocks, while archaeology now analyses more concrete and smaller cultures, each of which had its own fate.

Iosif Lazaridis shares more thoughts on the discussion in his Twitter account:

As we mentioned in Haak, Lazaridis et al. (2015), the Yamnaya are the best proximate source for the new ancestry that first appears with the Corded Ware in central Europe, as it has the right mix of both ANE (related to Native Americans, MA1, and EHG), but also Armenian/Caucasus/Iran-like southern component of ancestry. The Yamnaya is a westward expansive culture that bears exactly the two new ancestral components (EHG + Caucasus/Iran/Armenian-like).
As for the Y-chromosome, it was already noted in Haak, Lazaridis et al. (2015) that the Yamnaya from Samara had Y-chromosomes which belonged to R-M269 but did not belong to the clade common in Western Europe (p. 46 of supplement). Also, not a single R1a in Yamnaya unlike Corded Ware (R1a-dominated). But Yamnaya samples = elite burials from eastern part of the Yamnaya range. Both R1a/R1b found in Eneolithic Samara and EHG, so in conclusion Yamnaya expansion still the best proximate source for the post-3,000 BCE population change in central Europe. And since 2015 steppe expansion detected elsewhere (Cassidy et al. 16, Martiniano et al. 17, Mittnik et al. 17, Mathieson et al. 17, Lazaridis et al. 2016 (South Asia) and …?…

I love the smell of new wording in the morning… viz. Yamnaya best proximate source for Corded Ware, Corded Ware might account for only a subset of Indo-European languages, Corded Ware representing Aryan languages (probably Klejn misinterprets what the authors mean, i.e. some kind of Indo-Slavonic or Germano-Balto-Slavic group)…

We shall expect more and more ambiguous rewording and more adjustments of previous conclusions as new papers and new criticisms appear.

Related:

Featured image from the article: Distribution of the ‘Yamnaya’ genetic component in the populations of Europe (data taken from Haak et al., 2015). The intensity of the colour corresponds to the contribution of this component in various modern populations

Neolithic and Bronze Age Basque-speaking Iberians resisted invaders from the steppe

gaul-asterix

Good clickbait, right? I have received reports about this new paper in Google Now the whole weekend, and their descriptions are getting worse each day.

The original title of the article published in PLOS Genetics (already known by its preprint in BioRxiv) was The population genomics of archaeological transition in west Iberia: Investigation of ancient substructure using imputation and haplotype-based methods, by Martiniano et al. (2017).

Maybe the title was not attractive enough, so they sent the following summary, entitled “Bronze Age Iberia received fewer Steppe invaders than the rest of Europe” (also in Phys.org. From their article, the only short reference to the linguistic situation of Iberia (as a trial to sum up potential consequences of the genetic data obtained):

Iberia is unusual in harbouring a surviving pre-Indo-European language, Euskera, and inscription evidence at the dawn of history suggests that pre-Indo-European speech prevailed over a majority of its eastern territory with Celtic-related language emerging in the west. Our results showing that predominantly Anatolian-derived ancestry in the Neolithic extended to the Atlantic edge strengthen the suggestion that Euskara is unlikely to be a Mesolithic remnant. Also our observed definite, but limited, Bronze Age influx resonates with the incomplete Indo-European linguistic conversion on the peninsula, although there are subsequent genetic changes in Iberia and defining a horizon for language shift is not yet possible. This contrasts with northern Europe which both lacks evidence for earlier language strata and experienced a more profound Bronze Age migration.

Judging from the article, more precise summaries of potential consequences would have been “Proto-Basque and Proto-Iberian peoples derived from Neolithic farmers, not Mesolithic or Palaeolithic hunter-gatherers”, or “incomplete Indo-European linguistic conversion of the Iberian Peninsula” – both aspects, by the way, are already known. That would have been quite unromantic, though.

Their carefully selected title has been unsurprisingly distorted at least as “Ancient DNA Reveals Why the Iberian Peninsula Is So Unique“, and “Ancient Iberians resisted Steppe invasions better than the rest of Europe 6,000 years ago“.

So I thought, what the hell, let’s go with the tide. Using the published dataset, I have also helped reconstruct the original phenotype of Bronze Age Iberians, and this is how our Iberian ancestors probably looked like:

Typical Iberian village during the Steppe invasion, according to my phenotype study of Martiniano et al. (2017). Notice typical invaders to the right.

And, by the way, they spoke Basque, the oldest language. Period.

Now, for those new to the article, we already knew that there is less “steppe admixture” in Iberian samples from southern Portugal after the time of east Bell Beaker expansion.

portugal-bronze-age-admixture
(A) PCA estimated from the CHROMOPAINTER coancestry matrix of 67 ancient samples ranging from the Paleolithic to the Anglo-Saxon period. The samples belonging to each one of the 19 populations identified with fineSTRUCTURE are connected by a dashed line. Samples are placed geographically in 3 panels (with random jitter for visual purposes): (B) Hunter-gatherers; (C) Neolithic Farmers (including Ötzi) and (D) Copper Age to Anglo-Saxon samples. The Portuguese Bronze Age samples (D, labelled in red) formed a distinct population (Portuguese_BronzeAge), while the Middle and Late Neolithic samples from Portugal clustered with Spanish, Irish and Scandinavian Neolithic farmers, which are termed “Atlantic_Neolithic” (C, in green).

However, there is also a clear a discontinuity in Neolithic Y-DNA haplogroups (to R1b-P312 haplogroups). That means obviously a male-driven invasion, from the North-West Indo-European-speaking Bell Beaker culture – which in turn did not have much “steppe admixture” compared to other north-eastern cultures, like the Corded Ware culture, probably unrelated to Indo-European languages.

portugal-bronze-age-haplogroup
Summary of the samples sequenced in the present study.

As always, trying to equate steppe or Yamna admixture with invasion or language is plainly wrong. Doing it with few samples, and with the wrong assumptions of what “steppe admixture” means, well…

Proto-Basque and Proto-Iberian no doubt survived the Indo-European Bell Beaker migrations, but if Y-DNA lineages were replaced already by the Bronze Age in southern Portugal, there is little reason to support an increased “resistance” of Iberians to Bell Beaker invaders compared to other marginal regions of Europe (relative to the core Yamna expansion in eastern and central Europe).

As you know, Aquitanian (the likely ancestor of Basque) and Iberian were just two of the many non-Indo-European languages spoken in Europe at the dawn of historical records, so to speak about Iberia as radically different than Italy, Greece, Northern Britain, Scandinavia, or Eastern Europe, is reminiscent of the racism (or, more exactly, xenophobia) that is hidden behind romantic views certain people have of their genetic ancestry.

Some groups formed by a majority of R1b-DF27 lineages, now prevalent in Iberia, spoke probably Iberian languages during the Iron Age in north and eastern Iberia, before their acculturation during the expansion of Celtic-speaking peoples, and later during the expansion of Rome, when most of them eventually spoke Latin. In Mediaeval times, these lineages probably expanded Romance languages southward during the Reconquista.

Before speaking Iberian languages, R1b-DF27 lineages (or older R1b-P312) were probably Indo-European speakers who expanded with the Bell Beaker culture from the lower Danube – in turn created by the interaction of Yamna with Proto-Bell Beaker cultures, and adopted probably the native Proto-Basque and Proto-Iberian languages (or possibly the ancestor of both) near the Pyrenees, either by acculturation, or because some elite invaders expanded successfully (their Y-DNA haplogroup) over the general population, for generations.

Maybe some kind of genetic bottleneck happened, that expanded previously not widespread lineages, as with N1c subclades in Finland.

There is nothing wrong with hypothetic models of ancient genetic prehistory: there are still too many potential scenarios for the expansion of haplogroup R1b-DF27 in Iberia. But, please, stop supporting romantic pictures of ethnolinguistic continuity for modern populations. It’s embarrassing.


Featured image from Wikipedia, and Pinterest, with copyright from Albert Uderzo and publisher company Hachette.

Images from the article, licensed CC-by-sa, as all articles from PLOS.

How to do modern phylogeography: Relationships between clans and genetic kin explain cultural similarities over vast distances

yakut-phylogeography

A preprint paper has been published in BioRxiv, Relationships between clans and genetic kin explain cultural similarities over vast distances: the case of Yakutia, by Zvenigorosky et al (2017).

Abstract:

Archaeological studies sample ancient human populations one site at a time, often limited to a fraction of the regions and periods occupied by a given group. While this bias is known and discussed in the literature, few model populations span areas as large and unforgiving as the Yakuts of Eastern Siberia. We systematically surveyed 31,000 square kilometres in the Sakha Republic (Yakutia) and completed the archaeological study of 174 frozen graves, assembled between the 15th and the 19th century. We analysed genetic data (autosomal genotypes, Y-chromosome haplotypes and mitochondrial haplotypes) for all ancient subjects and confronted it to the study of 190 modern subjects from the same area and the same population. Ancient familial links and paternal clan were identified between graves up to 1500 km apart and we provide new data concerning the origins of the contemporary Yakut population and demonstrate that cultural similarities in the past were linked to (i) the expansion of specific paternal clans, (ii) preferential marriage among the elites and (iii) funeral choices that could constitute a bias in any ancient population study.

Even if you are not interested in the cultural and anthropological evolution of this Turkic-speaking people of the Russian Far Eastern region, the method used is an excellent example of how to use archaeology and genetics (especially Y-DNA and mtDNA data) to obtain meaningful results when investigating ancient populations.

For quite some time, probably since the first renown admixture analyses of ancient DNA samples were published, we have been living under the impression that phylogeography, or simply archaeogenetics as it was called back in the day, is not needed.

Cavalli-Sforza’s assertion that the study of modern populations could offer a clear picture of past population movements is now considered wrong, and the study of Y-DNA and mtDNA haplogroups is today mostly disregarded as of secondary importance, even among geneticists. Whole genomic investigation (and especially admixture analyses) have been leading the new wave of overconfidence in genetic results, tightly joint with the ignorance of its shortcomings (and commercial interests based on desires of ethnic identification), and haplogroups are usually just reported with other, not entirely meaningful aspects of ancient DNA analyses.

While it is undeniable that admixture analyses are offering quite interesting results, they must be carefully balanced against known archaeological and linguistic knowledge. Phylogeography – and especially Y-DNA haplogroup assessment – is quite interesting in investigating kinship and clans in patrilocal communities – i.e. most communities in prehistoric and historic periods, unless proven otherwise.

Luckily enough, there are those researchers who still strive to obtain meaningful information from haplotypes. The article referenced in this post is quite interesting due to its phylogeographic method’s applicability to ancient cultures and peoples.

When some geneticists look at simplistic prehistoric maps, like those depicting Yamna, Afanasevo, Corded Ware, and Bell Beaker cultures together, they forget that 1) cultural regions are selected more or less arbitrarily (we only have certain scattered sites for each of these cultures); 2) economic or population contacts are difficult to ascertain and to represent graphically; and 3) time periods for archaeological sites are important – in fact, they are probably THE most important aspect in assessing how accurate a map (and its “arrows” of migration or exchange) represents reality.

A careful, detailed study like this one, if applied to the Pontic-Caspian steppe, would probably reveal how R1b subclades dominated steppe clans, beginning at least during the Suvorovo-Novodanilovka expansion to the west, and certainly representing the vast majority of lineages during the internal expansion in the Early Yamna period and its later expansion east and west of the steppe…

Featured image from the article, summing up Geography, Archaeology, and Genetics of Yakutia – including Y-DNA and mtDNA haplogroups from ancient populations.

Related:

Germanic–Balto-Slavic and Satem (‘Indo-Slavonic’) dialect revisionism by amateur geneticists, or why R1a lineages *must* have spoken Proto-Indo-European

haplogroup-R1a

I feel there has recently been an increase in references to quite old – and generally outdated – terms, such as Germano-Balto-Slavic and “Indo-Slavonic” (i.e. Satem), described as Late Indo-European dialects. This is happening in forums and blogs that deal with “Indo-European genetics”, and only marginally (if at all) with the main anthropological subjects that form Indo-European studies, that is Linguistics and Archaeology.

Firstly, let me go apparently against the very aim of this post, by supporting the common traits that these dialects actually share.

Satem Indo-European or Indo-Slavonic

Balto-Slavic is a complex dialect, whose known proto-history and history offers already a difficult picture. Contrary to the opinion of many, there is no single document that can identify the terms Antes, Sklavenes, and Venedi with the cultures that are usually identified as speaking languages ancestral to East Slavic, South Slavic, and West Slavic . These names were used interchangeably in the Byzantine Empire, which was obviously not involved in classifying Slavic peoples by their linguistic branches… For more on the historical identification of Slavic tribes, read Florin Curta‘s The Making of the Slavs: History and Archaeology of the Lower Danube Region, c. 500-700 A.D. On the identification of potential candidates for early Slavic and Baltic cultures, you can read the appropriate entries in the Encyclopedia of Indo-European Culture, by Mallory & Adams.

Baltic and Slavic tribes seem to have a too recently recorded history to be able to confidently trace back their cultural predecessors. In its recent history, close to the formation of its community, Proto-Slavic must have had intense contacts with Iranian-speaking peoples. Also, previously, if R1a-M417 subclades are in fact the most common lineages expanded with the Corded Ware culture (as it seems now), they have no doubt shared a common language, most likely a non-Indo-European one. Not Indo-European in the strict sense, at least, since it formed part most likely of the Indo-Uralic continuum that must have been spoken during the Mesolithic in Eastern Europe, and a language probably nearer to Uralic than to classic Indo-European.

A strong connection between Balto-Slavic and Indo-Iranian in a common Satem branch, as supported by Kortlandt (see e.g. Balto-Slavic and Indo-Iranian 2016, or a reconstruction of Schleicher’s Fable in PIE branches), would imply that a Corded Ware culture from the Dnieper-Donets – speaking a Graeco-Aryan dialect – interacted for centuries with Uralic and other Graeco-Aryan languages, only later influenced by North-West Indo-European (as late as its contact with East Germanic during the Barbarian migration). This model cannot justify the shared traits of Balto-Slavic with North-West Indo-European, unless a third, substrate language – like Holzer’s (1989) Temematic proposal – is added to the equation. Such models are not impossible, but seem too complex.

On the other hand, linguistically Balto-Slavic seems to have split in its known branches quite early, and traits such as the satemization trend appear to have affected each main dialect (Baltic and Slavic) differently, as attested in the different ruki development, hence the assumption of its early but different influence of the trend to both Indo-Iranian and Balto-Slavic (or, more exactly, Indo-Iranian, Baltic, and Slavic). Also, the common North-West Indo-European vocabulary, as well as morphological trends shared by NW IE dialects, clearly affects the oldest layer of both languages (hence the parent Proto-Balto-Slavic too), which predates thus the satemization trend, and further contributes to the idea of a common root between West Indo-European (or Italo-Celtic), Northern Indo-European (the language ancestral to Pre-Germanic), and Proto-Balto-Slavic.

Germano-Balto-Slavic or North European

A common group between Germanic and Balto-Slavic is justified by the presence of certain common isoglosses, such as the famous shared oblique cases in *-m- instead of *-bh-, and support for such a group is found recently e.g. in Gramkelidze-Ivanov (1993-1994) – who nevertheless support a North-West Indo-European continuum -, or in Jasanoff, for whom both languages (regarding phonological traits) “began their post-IE history together”.

proto-indo-european-language-tree
Proto-Indo-European language tree, including early (Indo-Hittite) and late (European) stages by Trager & Smith (1950). From the paper On the Origin of North Indo-European, Gimbutas (1952)

On the other hand, such shared traits could have derived either from old contacts – supported traditionally because of their proximity -, or by a common substrate to both without a need for direct contacts, as supported by Kortlandt in Baltic, Slavic, Germanic (2016), among others).

The fact that there might have been a different, third language involved – the hypothetic Temematic substrate language to Balto-Slavic, potentially nearer to Baltic because of the stronger superstrate influence in Slavic – further complicates the dialectal identification of Baltic and Slavic – that is, if one supports a common Germanic and Balto-Slavic group.

This Northern group was supported by Gimbutas (1952) based on a previous linguistic paper by Trager & Smith (1950) – published in the infancy of dialectal PIE differentiation -, but this model is not mainstream nowadays. The linguistic model followed by Anthony (based on Ringe, Warnow, and Taylor 2002), did not link Germanic to Balto-Slavic (or to Italo-Celtic, for that sake) more than to any other dialect, but it seems that the three might have spread from the same western (Repin-derived) Yamna region, according to their maps. See for example their recent article The Indo-European Homeland from Linguistic and Archaeological Perspectives, which sums up and partly corrects Anthony’s detailed account of steppe migrations in the already classic book The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World (2007). Dialectal groups and implications are unclear from their publications, with changing linguistic schemes since 2007, but with a quite stable archaeological framework.

Dialectal Late Indo-European

I am not implying that a common group of Balto-Slavic with Indo-Aryan (or of Germanic with Balto-Slavic) is fully discarded by linguistics: history and archaeology can indeed support a close interaction between these languages, and there has been historically some support to the inclusion of Balto-Slavic within a Graeco-Aryan group. However, Linguistics and Archaeology are each day more supportive of the association of Italo-Celtic with Germanic in a North-West Indo-European group, and Balto-Slavic with them (Oettinger 1997). See for example any recent article or book by Mallory, Adams, Beekes, Adrados, etc., or if you prefer, refer to the mainstream models followed by scholars in the German, Spanish, Leiden, or American schools. As you probably know, Clackson for the British school supports an abstract “constellation analogy” model for the language reconstruction, and the French school is dominated by archaeologist Jean Paul Demoule’s rejection of a Proto-Indo-European community; both schools, as you can imagine, will have to revise their theories in light of recent genetic studies…

Regarding Archaeology, North-West Indo-European must have expanded with the westward Yamna expansion, i.e. associated with the Bell Beaker expansion. That was supported in mainstream Archaeology before the most recent genetic studies.

Even Anthony (2007), who has related the Corded Ware culture to the expansion of Indo-European languages through cultural diffusion, recognizing the expansion of Yamna migrants to the west (identifying them with Italo-Celtic and Proto-Greek speakers), has to offer two or three separate cultural diffusion events (!), whereby Pre-Germanic, Proto-Balto-Slavic, and Proto-Indo-Iranian had been learned by the influence of the Yamna culture on neighbouring (unrelated) peoples of Corded Ware cultures: in Central European – Single Grave culture (from Pre-Germanic Usatovo), Middle Dnieper culture (from Balto-Slavic in the Contact Zone), and Potapovka (from Poltavka) cultures, respectively. No actual spread or migration from Yamna into Corded Ware has been supported since Gimbutas.

Balto-Slavic is indeed a complex group of languages – with some supporting (since Toporov and Ivanov proposal in the 1960s) three dialectal groups, composed of East Baltic, West Baltic, and Slavic branches (thus implying an older split of Baltic). Because of the close interaction of eastern Europe with Eurasian invasions, the nature of their language won’t probably ever be solved. Genetics is not the savior that overcomes these difficulties; so long it has only brought more (albeit no doubt interesting) questions, and even though their correct interpretation might offer some new light, we will be far from obtaining a clear picture of the cultural and linguistic development of Proto-Baltic and Proto-Slavic communities.

What I am criticizing here, therefore, is this recent revisionist trend whereby PIE must have been spoken by R1a-Z645 lineages, a trend found not only among amateur geneticists. I am beginning to think – judging from online comments, posts or tweets – that this trend is becoming stronger as a reaction to the fact that not a single R1a-Z645 sample has been found in Yamna or its expansion. These new revisionist models depict a common group of R1a-Z645 lineages hidden somewhere in the steppe, sharing some sort of Indo-Germanic (??) group, or argue for a shared Late PIE community without dialectal divisions, to justify its potential find somewhere marginal to the PIE territory, and then a later development of Corded Ware into Bell Beaker cultures (and, it is implied, peoples).

While not impossible, these are unlikely models, not based on knowledge but on wishes, since linguistic data strongly suggest a North-West Indo-European dialect including Italo-Celtic, Germanic, and (at the very least in its substrate and thus western R1a lineages) Balto-Slavic, and archaeological findings don’t show any meaningful population exchange between Corded Ware and Yamna… That is, it hadn’t until after the first famous papers on the so-called ‘steppe admixture’ of 2015, when (surprise!) Kristiansen has already jumped on the bandwagon (and Anthony seems to be beginning to suggest the same) of previously discarded Yamna -> Corded Ware, and Corded Ware -> Bell Beaker migrations.

Not a single serious researcher can deny that a hidden community of R1a-417 in Yamna is possible. But no one should support that it is the most likely explanation to the current genetic picture, whether based on Linguistic, Archaeology, Anthropology, or Genetics (be it phylogeography or admixture analyses).

I think this recent trend must therefore be the fruit of the influence of previous, deeply entrenched concepts regarding the Corded Ware culture and its link with Proto-Indo-European. These concepts are based on Gimbutas’ Kurgan model, Anthony’s revision of it – explaining the expansion as multiple cultural diffusions (thus renewing Gimbutas’ claim) -, and early studies of modern populations’ haplogroups. Apart from those trends, especially worrying for the future of the field (if it is to be taken seriously), is the interest of some pressure groups, including especially eastern Slavic peoples of R1a lineages, and Finnic speakers of N1c lineages, who are linking some fantastic ancient ethnolinguistic community to their modern national pride.

kurgan-expansion-europe
“European dialect” expansion of Proto-Indo-European according to The Indo-Europeans: Archeological Problems, Gimbutas (1963). Observe the similarities of the western European expansion to the recently proposed expansion of R1b lineages with western Yamna and Bell Beaker.

Adapting to reality

You can find support for anything you like in anthropology: there is certainly a paper out there that apparently supports your personal view on prehistoric ethnolinguistic Europe. You only have to do a quick search in Academia.edu, and you can justify whatever new genetic results you personally obtained playing with the freely available datasets and open source software – e.g. from Reich’s lab, or the famous ADMIXTURE. If you are one of those few interested in the field who haven’t tried it out yet, Razib Khan helps introduce you to DIY Genetics, so you can show off some graphics and proportions, like most popular bloggers and forum users are doing. Then you can also publish your results in BioRxiv, just to try it out.

So there is no merit at all in justifying these genetic results by supporting a potential anthropological scenario for it. Heck, you can invent it! Here, I said it. Anyone can do Anthropology. In fact, it seems that everyone does Human Evolutionary Genetics nowadays, no matter their background. Some lab knowledge and experience in doctoral research seems to be enough.

Admixture analyses are obtained using one or more algorithms, which have a limited potential to inform of possible migrations (its ultimate objective, at least regarding its complementary function to Archaeology within Indo-European studies). Such algorithms invariably have:

  • Intrinsic constraints: You have to understand each algorithm’s intrinsic limitations to be able to apply them correctly, and to derive meaningful but cautious conclusions. Using software commands and obtaining graphics and percentages does not imply you understand the constraints at stake. If you have tried them out, you have seen their great limitations; if you don’t see them, you certainly realize how little you understand of them.
  • Extrinsic constraints. Most are known, and often mentioned explicitly in research papers:
    • Few DNA samples, from limited sites.
    • Scarce and variable material recovered from these samples.
    • Quality of the retrieval, human errors, etc.
    • Lack of precise anthropological context.

Admixture results (whether by professionals or amateurs) are nevertheless often illustrated with tailored anthropological models: in case of the renown papers most likely because of ignorance of anthropological context, broad (philosophical or theoretic) and precise (historical), or lack of sufficient understanding of the different fields involved, and in case of many amateur geneticists also (often) to justify a desire for a prehistoric ethnolinguistic identification similar to their social or political agendas, in a new Kossinnian trend.

Admixture analyses are not wrong per se. It is wrong to trust them to inform you of something they can’t; because they need context, and ancient samples need ancient context, which in prehistoric times is obviously quite limited. If you don’t know as much as possible about the ancient context (i.e. Linguistics, Archaeology, Anthropology), you get the wrong conclusions. Period. If you look for papers on ancient context expecting to find whichever model fits your results (or worse, your wish), that is called bias. Don’t expect to get the right conclusions doing that, either. If you find it, that’s called confirmation bias. Such results are not useful. For anyone, not even you, you just deceive yourself and maybe others.

Some apparently think that a group of geneticists can achieve a meaningful interpretation of data just by adding one or more archaeologists to the research group – or as ‘co-authors’ of individual research papers. Wrong again. Ten people with IQ 20 don’t make the reasoning of a person with IQ 200 (not that I believe in measuring intelligence, but you get the point). Similarly, twenty researchers, each one with knowledge exclusively (or almost exclusively) of their own field, can’t achieve a meaningful explanation for the data obtained. Geneticists look for an anthropological model that coherently fits their results. Archaeologists will look for a model known to them that fits the genetic results (or more likely the interpretations thereof) they are given. That way, when working together, they can achieve a common ground. If neither of them understands the complexities and shortcomings of the others’ materials and methods (and their whole background), the results will be formally correct, but still wrong. They need to know all aspects involved in the others’ fields in great detail, to understand all potential implications of new data.

Since the advent of ancient DNA samples and especially PCA analyses, phylogeography (leaning predominantly on Y chromosomes) has been relegated to a (probably deserved) second place in assessing DNA samples. However, as Razib Khan states, “in the scaffold of the ancient DNA framework it can resolve some issues”. I think this is one of those issues, an issue that is not trivial at all – in that it affects migration models from the steppe at a critical period of linguistic expansion -, and the shortcomings of not relying on it are becoming quite evident with each new publication.

Many amateur geneticists that support the mainstream genetic models of the past two years don’t like the ad hoc explanations that others have been constantly giving to support their previous theories. After all, it seems unfair that some people would reject data that offers an obvious prehistoric picture of populations, because of the unwillingness to change one’s own preconceptions, right? For example, against the mainstream steppe migration theory, we have those who support that R1b must have been western European (Palaeolithic or Mesolithic) hunter-gatherers expanded from Iberia; or those who want R1a to have expanded from India. No matter how strong the evidence is against those models, some groups harbour a desire to fit anything in one’s previous image of reality.

However, some people who can’t stand those absurd ad hoc explanations and rationalisations, are quite ready to embrace the idea that, somehow, during the Chalcolithic expansion of Yamna, an imaginary community was formed where communities of divergent lineages R1a-Z645 (found mostly north of the steppe and later in Corded Ware cultures) and R1b-M269 (found mostly in the steppe and later in the cultures known to have evolved from Yamna, like Afanasevo, Vučedol, and Bell Beaker) lived together and spoke the same language for centuries, or even millennia. And that community would have existed after a Late Neolithic westward expansion of the Khvalynsk culture, and another westward expansion of the Repin culture, both of which probably reduced the diversity of Y-DNA lineages within Yamna: the first to R1b-M269 lineages, the second to R1b-L23 subclades.

Both communities of R1a and R1b lineages, described then as united until the Yamna expansion (although no sample of R1a-Z645 subclade has been ascribed to any steppe expansion) would have expanded somehow separately, R1a-M417 exclusively to the north into Corded Ware – without any migratory connection found between Yamna and Corded Ware in mainstream Archaeology -, and forming thus dialectal groups (like “Germano-Balto-Slavic” or “Indo-Slavonic”) that are not supported by mainstream linguistics.

On the other hand, R1b-Z2103 and R1b-L51 lineages, which were already separated within Yamna and probably forming different communities, are known to have spread to the west with the Yamna expansion, in some places and cultures they are found together (like Bell Beaker), which would be expected in a common migration of separate groups. No single R1b-L23 sample has been found in the Corded Ware expansion, no single R1a-M417 individual in the Yamna expansion.

These convoluted explanations of how R1a lineages must have spoken Indo-European are based on the assumption that admixture analyses (from the current limited data, with the current wrong interpretation of their context) necessarily means that Corded Ware peoples spread as Yamna migrants – hence R1a lineages must come from Yamna – and then spread into Bell Beaker.

It is possible, and in my opinion expected, that eventually some R1a-M417 subclade will be found in Yamna samples (east or west), and some haplogroup R1b-M269 (especially R1b-L23 and subclades) will be found in samples from Corded Ware cultures (west or east). Indeed, there must have been close contacts between both cultures (between Yamna–Southeast Europe–East Bell Beaker and Corded Ware), and not only through female exogamy. It would be quite strange not to find a single R1b-L23 sample in Corded Ware cultures, or an R1a-M417 sample in Late Proto-Indo-European-speaking territories. Those scattered samples, whenever they are found, will probably not change the data: but they might give a reason for some to keep supporting a model that is not the most likely one. It won’t still be the most reasonable, the simplest model that explains all data.

What it means to be an ‘ethnic’ Balt or Slav

Older models – older even than Gimbutas’ kurgan model of the 1950s, as you can see -, by presupposing an instant breakup of a unitary Proto-Indo-European language into different linguistic communities without previous dialectal relation with each other, cannot explain our common European linguistic heritage. More recent models based on recent genetic studies (and on outdated or newly invented linguistic and archaeological theories), by trying to connect genetically (directly) modern eastern Europeans with Proto-Indo-Europeans, are in fact disconnecting Balto-Slavic peoples from the rest of Europe for three thousand years, and connecting them either with Uralic or with Indo-Iranian speakers. Ethnolinguistic identification, however, is not about genetics – and it has never been, and I hope it will never be -; it is related to self-identification into groups, and more broadly to a common culture, and often specifically a common language.

In terms of language, it makes sense to support a situation where Balto-Slavic was a North-West Indo-European dialect (sharing a common language ancestral to Germanic and Italo-Celtic too), with certain ancient (Uralic?) innovative traits shared with Indo-Iranian and partly with Germanic (but with no direct contacts necessary between these branches). Its recent transition to a Baltic and Slavic proto-languages, already by eastern European groups, shows their strong external influence from Uralic and Iranian, respectively, so an identification of Balto-Slavic with the expansion of R1a lineages is probably to be found in a western group of R1a-Z282 subclades expanding eastwards between the Bronze Age and the Iron Age.

Eastern Europe’s Indo-European heritage (Balto-Slavic) is therefore connected to the western European one (Italo-Celtic and Germanic), each with its own linguistic substrate and influences, but with a common, shared ancient language. North-West Indo-European derived in turn from Late Indo-European, a language ancestral to Indo-Iranian and Palaeo-Balkan languages, the latter showing continued contacts with western Europe for millennia.

In the minimum-case scenario – for supporters of a Satem proto-language like Kortlandt – the language substrate to Baltic and Slavic must be a North-West Indo-European language (to fit its shared traits with North-West Indo-European), like Holzer’s Temematic (a hypothesis which Kortlandt seems to support) that would have then been recently absorbed by Satem speakers of Eastern Europe. In that context, central European R1a-Z282 lineages (which form the majority of West Slavic lineages) would have spoken that NWIE language for millennia , until proto-historic times, when a cultural diffusion of a Graeco-Aryan dialect (mainly spoken by R1a-Z93 or eastern European R1a-Z282 lineages, then) would have happened in eastern Europe, and then a cultural diffusion (or demic diffusion?) of Slavic-speaking peoples would have happened to the west, into central Europe.

In none of these scenarios is any sort of Proto-Indo-European -> Balto-Slavic ethnolinguistic, genetic, or territorial continuity to be seen. The former model is not only the simpler explanation for Slavic and Baltic, but it is also the communis opinio today by most Indo-Europeanists, it is supported by Archaeology, and Genetics is likely to keep supporting it with each new paper. I don’t find anything shameful, or that could diminish modern Baltic and Slavic identities a bit, by accepting any of those models, so I don’t understand the imperative need some people seem to have of identifying R1a lineages with the Yamna expansion and thus Proto-Indo-European.

For those who will still be vying for a more prominent role of haplogroup R1a in the Proto-Indo-European ethnogenesis, there are alternative older scenarios to the arrival of Proto-Indo-European to the steppe, as there are older models for an Anatolian origin of PIE. So, for example I already laid out the possibility that the invasion of R1a-M417 brought Indo-European (or, more precisely, Indo-Uralic) to eastern Europe – as part of a Uralo-Yukaghir or Paleo-Siberian group -, while R1b communities may have originally been speakers of Afroasiatic (cf. R1b-V88 and the potential Afroasiatic homeland in Lake Megachad), and R2 would have been associated with the spread of Dravidian (and maybe Kartvelian and Altaic), all of them departing from a common Nostratic associated with haplogroup R. This model could find support in genetics in the link found between Mesolithic Northeast Europeans and Neolithic Siberians, from an Ancient North Eurasian (ANE) population probably rich in Y-chromosome haplogroup R1a.

This is just one of many highly hypothetic ancient scenarios, and it requires more assumptions than a continuity of Indo-Uralic (or even Indo-Uralic and Afroasiatic) with R1b lineages – R1a potentially marking the spread of Paleo-Siberian languages -, and above all it is based on controversial linguistic macrofamilies, not (yet?) supported by mainstream anthropological disciplines. It is nevertheless one theory certain romantics can place their hopes in, as R1b communities of the steppe become accepted as those originally speaking (Middle and Late) Proto-Indo-European in the steppe.

Wrap-up

I am not saying I am right. There is still too much to be said and corrected. In fact, I could be wrong, and we may lack a lot of interesting data: there might have been a late R1a-R1b North-West Indo-European-speaking community within western Yamna, and we might need to revise what we knew about Archaeology yet again (and maybe even Linguistics!) before admixture algorithms; then maybe geneticists have come to save the day after all. However, all anthropological evidence points strongly (and genetic studies more strongly with each new study) to the image we had previous to the first genetic data based on haplogroups.

I think it is preposterous of some researchers (no matter if professional or amateur geneticists, or archaeologists, or even linguists) to think algorithms can beat more than two hundred years and thousands of works on this matter. In Academia, mathematics rarely revolutionize a field; it could usually help, but it can just make you sound scientifish, and point in the wrong direction.

And no, I am not smarter than the rest, I can only judge from what I know, and that is always too little, far less than I would like to. But maybe I am in a more neutral position regarding the end result, given my renewed skepticism in revolutionary methods to solve academic problems, and my indifference as to a western European or eastern European origin of R1b or R1a lineages. And I am not alone in my lack of confidence in the interpretation of recent genetic admixture results – read Voker Heyd’s papers, for example, if you want the view of a renown and experienced archaeologist who was in the field of Indo-European studies earlier than any of those now popular geneticists.

In fact, I also fell for the R1a-Corded Ware expansion of Late Indo-European, and before many in the Anthropological fields, and with even less proof, back when we only had haplogroups of modern populations and the promises of Cavalli-Sforza. When I decided to publish a grammar to learn Indo-European as a modern language, the aim was to offer a mainstream reconstruction of Late Proto-Indo-European without adding my own contributions; despite this, I added the newly, archaeogenetically-supported Corded Ware migration model (see A Grammar of Modern Indo-European, Third Edition, pp. 74 and ff.).

I guess I liked the picture of an old romantic Europe, divided in western Vasconic (R1b) and eastern Uralic (N1c) hunter-gatherers (and later farmers) being invaded by warring kurgan-makers from the steppe (R1a) … And I really liked the article of Haak et al. (2015) – the first one I read on this subject -, which I saw, like everyone else, as supporting what many of us already believed about a single, common expansion of North-West Indo-European into western Europe. It also made our life – regarding the linguistic unity of Balto-Slavic with the West Indo-European core – much easier…

calcolithic-expansion
Chalcolithic expansion from Yamna into Corded Ware (as early North-West Indo-European dialects), as interpreted in the second edition of A Grammar of Modern Indo-European.

Recent papers, when compared to what linguists and archaeologists had been saying for years – before even Y-DNA haplogroup was a thing for any of these now popular genetic labs (not to speak about internet geneticists) -, leave little space for doubt right now. I embraced the results of haplogroup analysis of modern populations, which seemed to support an expansion of Proto-Indo-European R1a-lineages with the Corded Ware culture, and dismissed thus Gimbutas’ and Anthony’s model (of a Yamna -> Bell Beaker expansion of Italo-Celtic). I also embraced the results of the publications on genetics of 2015 with open arms.

But, I was able to change my mind when the careful observation of individual samples of these recent studies began to contradict what we thought, and I did so publicly only recently (publishing the Indo-European demic diffusion model), and more strongly after the latest papers (publishing the updated second edition), without remorse. And I will reverse that decision again if needed, and change it again and again as I feel necessary, no matter how many times. In Science, to adapt to new data does not make you a brownnoser, it makes you a scientist. Not to adapt to new data does not make you a man of firm ideals, or any chivalrous concept you might have about that, it makes you look ignorant and biased. It’s that simple.

Some of you may think that there is a third way: to keep an old, now unlikely idea you have supported in the past, but not bragging about it in the meantime until it is proven fully wrong, just in case it is demonstrated to be right in the end – because then you might claim you were right all along, like you had some magic understanding or hidden data the rest of us didn’t. I don’t think that’s the correct way to behave in a scientific environment, either. That makes you a coward. And you wouldn’t have been right all along: you would have been right, then wrong, then right again. Everybody can see that, and so do you.

Geneticists working on future publications should be planning ahead of what might happen. The overconfidence of Haak et al. (2015), Mathieson et al. (2015), and Allentoft et al. (2015), including Lazaridis et al. (2016), in supporting a Yamna -> Corded Ware migration, and a Corded Ware -> Bell Beaker migration are understandable in a rapidly growing field that didn’t leave enough time to study complex anthropological questions. The recent errors of following that simplistic and wrong model in Mathieson et al. (2017), and Olalde et al. (2017), coupled with Kristiansen’s (2017) and Anthony’s (2017) new interpretations (to fit the conclusions of those genetic studies), can be forgiven, because of all the fuss created around the Steppe admixture concept, and the desire of journals to publish popular papers, and of researchers to go with the tide and gain some popularity along the way.

From now on, however, if the evidence keeps pointing in the same direction, a lack of attention to anthropological detail will be simple wishful ignorance, and that cannot be forgiven in any field that strives to ascertaining the truth. If continued, this trend will damage the field of Human Evolutionary Biology for years – at least in the view of anthropologists, who are the real filter of this field’s conclusions -, when its current results prove wrong. Genetic studies will be banished from anthropological studies, dismissed as a pseudo-science, and avoided by any scientific or academic journal worthy of a minimum self-respect.

To regain trust in a field that purportedly uses “more scientific methods” but is nonetheless proven that wrong for years in its essential assumption (a Yamna -> Corded Ware migration model), and especially when it is associated with the traditionally despised ‘Kossinnian trends‘, will be a hard task for those involved. So many postdoc offers in so many labs being created right now will vanish, as the interest in publishing papers of this discredited field will disappear. This could also threaten the recently renewed impulse by archaeologists and linguists of migration models, which had been rejected for a long time, giving impulse to those who deny them ( e.g. in the UK and in France), or who just don’t want to see Archaeology or Linguistics get involved with such a controversial question, or even between each other.

High-impact factor journals like Nature, Science, PNAS, and those not so famous, as well as their reviewers and readers, are doing a disservice to the endeavour of ascertaining the historical truth, if they allow this to happen without protesting. But such consequences for the field will be their making, and not that of suspicious anthropologists, who do well in distrusting any revolutionary results published by overconfident researchers from newly developed and too broadly defined subfields.

Related:

(Note: featured image is licensed CC-by-sa 4.0 from crates at Wikipedia)

Indo-European and Central Asian admixture in Indian population, dependent on ethnolinguistic and geodemographic divisions

indian-population-genetics

Preprint paper at BioRxiv, Dissecting Population Substructure in India via Correlation Optimization of Genetics and Geodemographics, by Bose et al. (2017), a mixed group from Purdue University and IBM TJ Watson Research Center. A rather simple paper, which is nevertheless interesting in its approach to the known multiple Indian demographic divisions, and in its short reported methods and results.

Abstract:

India represents an intricate tapestry of population substructure shaped by geography, language, culture and social stratification operating in concert. To date, no study has attempted to model and evaluate how these evolutionary forces have interacted to shape the patterns of genetic diversity within India. Geography has been shown to closely correlate with genetic structure in other parts of the world. However, the strict endogamy imposed by the Indian caste system, and the large number of spoken languages add further levels of complexity. We merged all publicly available data from the Indian subcontinent into a data set of 835 individuals across 48,373 SNPs from 84 well-defined groups. Bringing together geography, sociolinguistics and genetics, we developed COGG (Correlation Optimization of Genetics and Geodemographics) in order to build a model that optimally explains the observed population genetic sub-structure. We find that shared language rather than geography or social structure has been the most powerful force in creating paths of gene flow within India. Further investigating the origins of Indian substructure, we create population genetic networks across Eurasia. We observe two major corridors towards mainland India; one through the Northwestern and another through the Northeastern frontier with the Uygur population acting as a bridge across the two routes. Importantly, network, ADMIXTURE analysis and f3 statistics support a far northern path connecting Europe to Siberia and gene flow from Siberia and Mongolia towards Central Asia and India.

Among the most interesting results (emphasis mine):

Our meta-analysis of the ADMIXTURE output shows that the IE and DR populations across castes shared very high ancestry, indicating the autochthonous origin of the caste system in India (Figure 2). f3 statistics show that most of the castes and tribes in India are admixed, with contributions from other castes and/or tribes, across languages affiliations (Supplementary Table 4 and Supplementary Note). The geographically isolated Tibeto-Burman tribes and the Dravidian speaking tribes appear to be the most isolated in India. Linear Discriminant Analysis on the normalized data set clearly supports genetic strati cation by castes and languages in the Indian sub-continent

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Our meta-analysis of the ADMIXTURE plot in Figure 4A quantifies the ADMIXTURE results (darker colors indicate higher pairwise shared ancestry). Indian populations show a greater proportion of shared ancestry with the so-called Indian Northwestern Frontier populations, namely the tribal populations spanning Afghanistan and Pakistan. Central Asian populations share higher degrees of ancestry with IE and DR Froward castes. Uygurs share high degrees of ancestry with Indian populations.

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f3 statistics (all negative Z-scores are shown) indicate Chinese and Siberian ancestry contributing to the Tibeto-Burman tribal speakers. On the other hand, the Mongols and the Europeans have contributed significant amounts of ancestry to the Indo-European and Tibeto-Burman forward castes. F3 statistics also show that the Central Asians are an admixed population with signs of admixture from Caucasus and other parts of Europe.

Among the results for proportions of shared ancestry between Indians and Eurasians (FIG. 4), there is an obvious influence of European admixture (Caucasus, and Southern, Central, and Northern EU), potentially from the Yamna-Corded Ware expansion, in IE_ForwardCaste, which is lessened in IE_BackwardCaste and also in IE_Tribal, while DR_ForwardCaste shows again more admixture than IE_Tribal, but diminishing with lower castes and quite low in DR_Tribal.

Ancestry from Central Asia is strong with a similar pattern, which hints at the influence of Sintashta, Andronovo, and BMAC influence in the expansion of the Steppe component, even more than a later Turkic component.

On the other hand, the influence from Turkey is difficult to assess, given the complex genetic history of Anatolia, but the map contained in Fig. 6 doesn’t feel right, not only from a genetic viewpoint, but also from linguistic and archaeological points of view. This is the typical map created with admixture analyses that is wrong because of not taking into account anthropological theories.

Quite interesting is then the influence of admixture in these different ethnolinguistic groups, Indo-European and Dravidic, which points to an initially greater expansion of Indo-European speakers, and later resurge of Dravidian languages.

Featured image contains simplified origin and data of samples studied, from the article.

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