Forces driving grammatical change are different to those driving lexical change

Grammar change

A new paper at PNAS, Evolutionary dynamics of language systems, by Greenhill et al. (2017).

Significance

Do different aspects of language evolve in different ways? Here, we infer the rates of change in lexical and grammatical data from 81 languages of the Pacific. We show that, in general, grammatical features tend to change faster and have higher amounts of conflicting signal than basic vocabulary. We suggest that subsystems of language show differing patterns of dynamics and propose that modeling this rate variation may allow us to extract more signal, and thus trace language history deeper than has been previously possible.

Abstract

Understanding how and why language subsystems differ in their evolutionary dynamics is a fundamental question for historical and comparative linguistics. One key dynamic is the rate of language change. While it is commonly thought that the rapid rate of change hampers the reconstruction of deep language relationships beyond 6,000–10,000 y, there are suggestions that grammatical structures might retain more signal over time than other subsystems, such as basic vocabulary. In this study, we use a Dirichlet process mixture model to infer the rates of change in lexical and grammatical data from 81 Austronesian languages. We show that, on average, most grammatical features actually change faster than items of basic vocabulary. The grammatical data show less schismogenesis, higher rates of homoplasy, and more bursts of contact-induced change than the basic vocabulary data. However, there is a core of grammatical and lexical features that are highly stable. These findings suggest that different subsystems of language have differing dynamics and that careful, nuanced models of language change will be needed to extract deeper signal from the noise of parallel evolution, areal readaptation, and contact.

This is in line with the studies by Bendt, like Adaptive Communication: Languages with More Non-Native Speakers Tend to Have Fewer Word Forms, which suggest a simplification of grammar with language contact.

It might then give further support to my proposal of Uralic as the Corded Ware substrate – common to Balto-Slavic and Indo-Iranian -, since they are the only Late Indo-European branches that clearly retain the grammatical complexity in word forms, which – together with their shared phonetic isoglosses (also present partially between Balto-Slavic and Germanic) -, put them nearer to a complex, potentially related Uralic (or other Indo-Uralic) branch.

On the other hand, the finding of a greater stability of lexicon gives further support to the concept of a North-West Indo-European group, since one of its foundations (the main one originally) is the shared vocabulary between Italo-Celtic, Germanic, and Balto-Slavic.

Featured image: from the article (copyrighted), “Map showing locations of languages in this study. The phylogenies show the maximum clade credibility tree of the Austronesian languages in our sample. Each phylogeny is colored by the average rate of change, with branches showing more change colored redder, while bluer branches show reductions in rate. Branches with significant shifts are annotated with an asterisk, and the languages showing significantly different rates of change in their grammatical data are located on the map”.

Related:

C.C. Uhlenbeck on the Proto-Indo-European homeland in the 19th century

yamna-expansion-europe

Michiel de Vaan, from the University of Lausanne, has recently uploaded three of his papers published in recent years in the JIES on the works of Dutch linguist C.C. Uhlenbeck:

1. The Early C. C. Uhlenbeck on Indo-European, JIES 44/1-2, 2016, p. 73-80

Christianus Cornelius Uhlenbeck (1866–1951) was one of the leading Dutch linguists between the 1880s and the 1940s. He made his mark on a number of disciplines in descriptive and comparative linguistics, such as Basque, the indigenous languages of North America, Old Germanic and Sanskrit. In 2008, a special issue of the Canadian Journal of Netherlandic Studies (Genee & Hinrichs 2008) was devoted to his memory, the contents of which can be read online.

Uhlenbeck’s work and thinking on the Indo-European language family, and, in particular, on the original habitat of its speakers, have been discussed by Kortlandt 2010, who concluded that Uhlenbeck had remarkably advanced views for his time. The first two journal articles in which Uhlenbeck (1895, 1897) sets forth his views were published in Dutch. During the academic year 2013/14, I had the opportunity to read a number of articles on the question of the Indo-European homeland problem with my students at Leiden University. I provided Uhlenbeck’s Dutch articles from 1895 and 1897 with an English translation which I hereby submit to all colleagues

On Anthony and Haarman:

Anthony focuses on the socioeconomic changes that took place in the fifth and fourth millennium BC, when the Indo-European steppe peoples entered into contact with the sedentary, agricultural population of Southeast-Europe, also termed Old European or Palaeo-European. Importantly, Anthony dismantles the monolithic view of a single “steppe pastoralism”, and instead stresses that the steppe economy itself went through various developmental phases, which might be linked to different periods of expansion of Indo-European into Europe. Haarmann zooms in on the sociocultural effects of the Indo-European expansion(s). Since language contact will often heavily influence the languages which are in contact, he sets out to look for traces of the language of the Old Europeans in the surviving Indo-European languages, first of all, in Ancient Greek. As many scholars before him have also realized, there is a thick layer of non-Indo-European words in Greek in fields such as agriculture, wine production, weaving, metallurgy, religion and mythology, building techniques, and local flora and fauna. Even the Greeks themselves acknowledged the presence of a “Pelasgian” substratum in their own language. Haarmann concludes (2012: 119): “Despite the fact that Indo-Europeans exercised political power and promoted their language as the common vehicle, they were nevertheless impressed by the achievements of the Old Europeans to the extent that the dominant language of the élite absorbed manifold influences from the local language(s).”

2. Where was the Indo-European proto-language spoken?, by C.C. Uhlenbeck (1895), translation by Michiel de Vaan, JIES 44/1-2, 2016, p. 181-185.

It cannot be objected that the eastern and the western Iranians differed much in their dialects, for the PIE language itself must have been split in a number of fairly different dialects. There has never been in the world a language without dialect differences, larger or smaller, depending on the geographic distance. That is why, in the beginning of this piece, I spoke not of one original language, but of a group of closely cognate dialects. Since the linguistic area of PIE was probably very large, it is certainly possible that part of it lay in the steppes, another part in the mountains, and yet another part in the fertile plains. If so, the fauna and the flora of the homeland cannot have been the same in different areas. And this is an argument, which the linguistic prehistorician must not lose sight of!

On the necessary natural (geographic and stage) division of PIE, he made apparently a dialectal division into a European group (including Greek?), a Balkan-Balto-Slavic group, and Indo-Iranian.

3. The prehistory of the Indo-European peoples, by C.C. Uhlenbeck (1897), translation by Michiel de Vaan, JIES 44/1-2, 2016, 186-212.

The following excerpt is probably not the most interesting one (check out the different aspect of prehistoric life described through linguistics), but it is fun to be able to support the same arguments today:

Does linguistics provide us with the means to indicate a smaller region as the center of expansion of the Indo-European languages and peoples? Hardly. After all, it is far from certain that the people who speak Indo-European languages are also ethnologically more closely related to each other than to peoples with languages very different from ours. If the homeland of the Indo-European languages does not coincide with that of the Indo-European peoples, it becomes impossible to determine either one. In reality, if the Indo-European speaking peoples do not form an ethnological unity, we have not the slightest reason to suppose that they all hail from a single region. The use of a common language can just as well be explained by a powerful, prehistoric cultural influence, as by common ancestry. The unknown, unknowable origin of that cultural force is then, in a certain sense, the homeland of our language family. Searching a homeland of the Indo-Europeans or of the Indo-European dialects is like taking a wild stab, something which all who understand history must abhor. If Schrader regards as the homeland the Pontic steppes, if Hirt regards the coasts of Lithuania as such, this is based on insufficient and partially judged data. Still, the large agreement in vocabulary between Indo-European and Egypto-Semitic remains a remarkable fact, which Friedrich Delitzsch first illustrated in a truly scientific way.

(…)

If we stick to the facts, and refrain from bottomless speculations, we will find no other homeland than the area indicated above, which encompasses half of Europe and a part of Asia.

Spread of Indo-European folktale traditions related to cultural and demic diffusion (using genomic data)

folktale-genomics

New article at PNAS, Inferring patterns of folktale diffusion using genomic data, by Bortoloni et al. (2017).

Abstract:

Observable patterns of cultural variation are consistently intertwined with demic movements, cultural diffusion, and adaptation to different ecological contexts [Cavalli-Sforza and Feldman (1981) Cultural Transmission and Evolution: A Quantitative Approach; Boyd and Richerson (1985) Culture and the Evolutionary Process]. The quantitative study of gene–culture coevolution has focused in particular on the mechanisms responsible for change in frequency and attributes of cultural traits, the spread of cultural information through demic and cultural diffusion, and detecting relationships between genetic and cultural lineages. Here, we make use of worldwide whole-genome sequences [Pagani et al. (2016) Nature 538:238–242] to assess the impact of processes involving population movement and replacement on cultural diversity, focusing on the variability observed in folktale traditions (n = 596) [Uther (2004) The Types of International Folktales: A Classification and Bibliography. Based on the System of Antti Aarne and Stith Thompson] in Eurasia. We find that a model of cultural diffusion predicted by isolation-by-distance alone is not sufficient to explain the observed patterns, especially at small spatial scales (up to ~4,000 km). We also provide an empirical approach to infer presence and impact of ethnolinguistic barriers preventing the unbiased transmission of both genetic and cultural information. After correcting for the effect of ethnolinguistic boundaries, we show that, of the alternative models that we propose, the one entailing cultural diffusion biased by linguistic differences is the most plausible. Additionally, we identify 15 tales that are more likely to be predominantly transmitted through population movement and replacement and locate putative focal areas for a set of tales that are spread worldwide.

I am very interested in folktales and their origins within Proto-Indo-European culture, so the title alone was an immediate click-bait for me. It did, as always, disappoint in its methods and conclusions, but just the idea it proposes is of great interest for future studies.

There are gross limitations in assessing folktales using simply the Aarne-Thompson-Uther Classification without further analysis or explanation, apart from a summary of tales in the supplementary materials.

But their maps and simplistic hypothesized waves of diffusion (‘African origin’, ‘northern Eurasian’, ‘Eastern European’, or ‘Middle-Eastern/Caucasian’) seem to me as if they try to swim with the tide of the current literature regarding the identification of Proto-Indo-European demic diffusion with “steppe admixture” distribution (and ancient language family diffusion in general through admixture), and as such it can only be wrong.

If you just look at actual folktale distribution (black dots) and compare them with prehistoric cultures and ancient Y-DNA distribution, you realize their maps don’t make much sense, and more complex methods (and a clearer idea of what admixture represents) are needed.

If their intention was to get published in a journal of high impact factor, they succeeded, so good for them. I am glad this subject gets more attention. Of course, their conclusions are kept formally in line with the many limitations of their methods, and are the most interesting aspect of the article:

By correcting for the presence of ethnolinguistic barriers, we find that the null model of cultural diffusion predicted by IBD alone cannot explain the observed distribution of folktales across Eurasia. Instead, beyond ~4,000 km, cultural diffusion biased by linguistic barriers exhibits the highest correlation at all geographic bins. At small geographic bins (<4,000 km), population movements and linguistic barriers may be more relevant than geographic proximity, pointing once again at the possible importance of small-scale processes of cultural transmission for testing more specific hypotheses when using genetic evidence. In addition, processes other than simple cultural diffusion may be more relevant for a smaller group of tales shared by pairs of populations that are genetically closer than populations not exhibiting those tales. Looking for smaller packages of tales or individual tales and their variants can be useful to shed light on the formation process of this vast body of popular knowledge. The long-range patterns detected by our analyses may complement this picture by suggesting a more ancient origin of some of these folktales (SI Appendix). On a broader level, these results can be used in the future to infer directional trends of cultural dispersal as well as to test for the emergence of systematic social biases [such as prestige bias, conformism/anticonformism, heterophily, and content-dependent biases] or cultural barriers different from linguistic ones, which have a chronology that may be independently ascertained.

If you are interested in studies about folktales, and especially those related to Indo-European traditions, you can check out the following articles I found interesting in the past:

Related:

Featured image (featured also in the article): Possible focal area and dispersion pattern for tale ATU313 “The Magic Flight,” one the most popular folktales in this dataset, which may have been additionally spread through population movement and replacement. It is interesting to note how this tale reached locations that are far from its putative origin (such as Japan and southeastern Africa), whereas it was not retained by many populations located in between (gray dots).

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/.

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.

Another hint at the role of Corded Ware peoples in spreading Uralic languages into north-eastern Europe, found in mtDNA analysis of the Finnish population

corded-ware-migration-yamna

Open article at Scientific Reports (Nature): Identification and analysis of mtDNA genomes attributed to Finns reveal long-stagnant demographic trends obscured in the total diversity, by Översti et al. (2017).

Of special interest is its depiction of Finland’s past as including the expansion of Corded Ware population of mtDNA U5b1b2 (and probably Y-DNA R1a-M417 subclades), most likely Uralic speakers of the Forest Zone, to the north of the Yamna culture (where Late Proto-Indo-European was spoken).

A later expansion of other subclades – particularly Y-DNA N1c -, was probably associated with the later western expansion of the Eurasian Seima-Turbino phenomenon, and its current prevalence in Finnish Y-DNA haplogroups might have been the consequence of the population decline ca. 1500 BC, and later Iron Age population bottleneck (with the population peak ca. 500 AD) described in the article.

That would more naturally explain the ‘cultural diffusion’ of Finnic languages into invading eastern N1c lineages, a diffusion which would have been in fact a long-term, quite gradual replacement of previously prevalent Y-DNA R1a subclades in the region, as supported by the prevalent “steppe” component in genome-wide ancestry of Finns.

Therefore, there were probably no sudden, strong population (and thus cultural) changes associated with the arrival of N1c lineages, like the ones seen with R1a (Corded Ware / Uralic) and R1b (Yamna / Proto-Indo-European) expansions in Europe.

How the Saami fit into this scheme is not yet obvious, though.

Abstract:

In Europe, modern mitochondrial diversity is relatively homogeneous and suggests an ubiquitous rapid population growth since the Neolithic revolution. Similar patterns also have been observed in mitochondrial control region data in Finland, which contrasts with the distinctive autosomal and Y-chromosomal diversity among Finns. A different picture emerges from the 843 whole mitochondrial genomes from modern Finns analyzed here. Up to one third of the subhaplogroups can be considered as Finn-characteristic, i.e. rather common in Finland but virtually absent or rare elsewhere in Europe. Bayesian phylogenetic analyses suggest that most of these attributed Finnish lineages date back to around 3,000–5,000 years, coinciding with the arrival of Corded Ware culture and agriculture into Finland. Bayesian estimation of past effective population sizes reveals two differing demographic histories: 1) the ‘local’ Finnish mtDNA haplotypes yielding small and dwindling size estimates for most of the past; and 2) the ‘immigrant’ haplotypes showing growth typical of most European populations. The results based on the local diversity are more in line with that known about Finns from other studies, e.g., Y-chromosome analyses and archaeology findings. The mitochondrial gene pool thus may contain signals of local population history that cannot be readily deduced from the total diversity.

From its results:

In general, there appears to be two loose and largely overlapping clusters among the Finn-characteristic haplogroups: the first between 1,000–2,000 ybp and the second around 3,300–5,500 ybp. The age of the older cluster coincides temporally with the arrival of the Corded-Ware culture and, notably, the spread of agriculture in Finland. The arrival and spread of agriculture, temporally corresponding with the age estimates for most of the haplogroups characteristic of Finns, might be a sign of population size increase enabled by the new mode of subsistence, resulting in reduced drift and accumulation of genetic diversity in the population.

(…)

Another insight in the past population sizes in Finland is based on radiocarbon-dated archaeological findings in different time periods. These analyses suggest two prehistoric population peaks in Finland, the Stone Age peak (c. 5,500 ybp) and the Metal Age peak (~1,500 ybp). Both of these peaks were followed by a population decline, which appears to have reached its ebb around 3,500 ybp. These developments are not distinguishable in the BSPs. However, these ages correspond well to the two haplogroup age clusters described above. The presumably less severe Iron Age population bottleneck seen in the archaeological data, 1,500–1,300 ybp, temporally coincides with the population size reduction visible for the Finn-characteristic subhaplogroups.

Related:

Discovered via Eurogenes.