The population turnover in westernmost Europe over the last 8,000 years

The figure above is from The genomic history of the Iberian Peninsula over the past 8000 years. If you had seen something like this five years ago, you’d be gobsmacked. But today this is not atypical, especially in light of the fact that Spain seems to harbor many good sites in relation to the preservation of ancient DNA. In the figure above you see an excellent representation of the different streams of ancestry and settlement within Spain over the last 8,000 years. You can conclude from it, for example, that only a small proportion of the ancestry of modern Spaniards derives from people who were residents of the peninsula during the Pleistocene. Similarly, you can also conclude that a minority, though non-trivial, proportion of the ancestry of modern-day Spaniards derives from people who arrived during Classical Antiquity and the Moorish period.

And, confirming earlier work, the Basques seem to be relatively untouched by these later gene flow events. To some extent, we all knew that, as the Basques were famously exempt from limpieza de sangre, the blood purity laws of medieval Spain. But importantly, the Basques have a substantial amount of ancestry from peoples whose heritage goes back to Central Europe, and to a great extent, the forest-steppe of far eastern Europe. This is a huge change from what was understood fifteen years ago. As the Basques speak a clearly non-Indo-European language, many scholars hypothesized that they were remnants of hunter-gatherer peoples, who had been resident in the Iberian peninsula since the Pleistocene.

But the reality is that the origin of the Basques is likely in the arrival of Near Eastern farmers. The Basques share a strong genetic affinity with the peoples of Sardinia, who are the closest proxies in modern European populations for this group. Importantly, the Basque difference from Sardinians is their much greater proportion of Central European/steppe-like ancestry. How did they get this ancestry?

One of the major results of this paper is that a particular branch of R1b came to dominate Spain around 4,000 years ago. Before this period the dominant Y chromosomal lineages in the Iberian peninsula were those associated with the farmer populations. The frequency of R1b is above 80% in Basque males. This is one reason that earlier scholarship assumed that R1b was associated with European hunter-gatherers (the Basque being the descendants of those people). Today, we know that both branches of R1 seem to have expanded ~4,000 years ago and that the most common lineages in western and southern Eurasia seem to go back to the steppe peoples.

It may be that the Basque language actually derives from the steppe as non-Indo-European peoples expanded along with the Indo-Europeans, adopting similar cultural habits and characteristics. This is not a crazy position. The Magyars, for example, are not Turkic or Indo-European, but they adopted a lifestyle associated earlier and simultaneously with Turkic and Indo-European pastoralists. But let’s set this possibility aside. Another option is that the Basque descend from one of the post-Cardial cultures of southwest Europe. That is, their language has roots in the dialects of the early Anatolian farmers. Unlike other peoples, they absorbed the influx of Indo-Europeans, and culturally assimilated them.

This too is not crazy. But how might they have absorbed the Indo-Europeans? In the paper above they tentatively argue, from some of their results, that the Indo-European influx was more male than female. There are suggestions that Basque society may have had matrilineal aspects. This does not entail that they were “matriarchal,” but rather, that inheritance passed through the maternal line. Matrilineal societies are not necessary pacific. The Iroquois are a case in point. And, they have a natural way of assimilating warbands of alien males: these men could become integrated into the preexistent kinship networks.

How might the rise of R1b lineages have occurred so fast? One could posit those young men with Indo-European fathers may have had connections to hostile Indo-European tribes that their cousins with non-Indo-European fathers lacked. If the Indo-Europeans were patrilineal, as seems likely, and the proto-Basques were matrilineal, then these men would have been well placed to better protect the cultural integrity and political independence of their maternal heritage through connections of their paternal lineage.

I have an explicit model here: the intermarriage of European trappers in the American West with native women. In many cases, the children of these men would be raised within a native context, and so served as a bridge of sorts. And, there is another analogy: the frequency of R1a is quite high in some non-Indo-European groups in South Asia. It will turn out, I believe, that Southern Europe and India share many similarities, as the Indo-Europeans encountered people in these regions with rich and complex societies.

Several years ago, A recent bottleneck of Y chromosome diversity coincides with a global change in culture, was published. The authors note there was an explosive growth several Y chromosomal lineages, including R1b and R1a, on the order of 4,000 years ago. Recently the evolutionary anthropologist Joe Henrich stated that “Religion is a technology for scaling up human societies.” With this in mind, I will state here that patriarchy is a technology for swallowing up human societies. The distribution of Y chromosomal lineages associated with early Indo-European extends outside of the boundaries of Indo-European languages. In fact, the expansion of I1, concordant with R1b, suggests that non-Indo-European lineages were assimilated into expanding Indo-European groups.

There is, of course, a debate whether this expansion was violent or not. I suggest above a way in which Indo-European lineages, at least by origin, could become pervasive in a non-Indo-European society. But, it does seem to more plausible that more direct forms of marginalization were likely. In a pre-modern environment not far from the Malthusian limit it wouldn’t take much for certain male lineages to replace themselves, while others to die out. The descent from antiquity project in Europe is difficult because there does seem to have been an elite paternal lineage rupture with the fall of Rome. Many modern noble families are traceable to the centuries after the fall of Rome, but none of them clearly are linked to before the fall of Rome. This does not mean that there was a massacre of those lineages, but that elite lineages which lost their rents would quickly lose their status.

I do think what we call war was part of the expansion. But war was likely simply one of the many manifestations of the power of rise of these bands of brothers.

8 thoughts on “The population turnover in westernmost Europe over the last 8,000 years

  1. Ancient Basque matrilineality or matriolocality usually seems to come back to Strabo – “for instance, it is the custom among the Cantabrians for the husbands to give dowries to their wives, for the daughters to be left as heirs, and the brothers to be married off by their sisters. The custom involves, in fact, a sort of woman-rule — but this is not at all a mark of civilisation”. Is there much more evidence for it?

    (who also said of the Gauls for instance: “Their custom relating to the men and the women (I mean the fact that their tasks have been exchanged, in a manner opposite to what obtains among us), it is one which they share in common with many other barbarian peoples.”)

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    Anyway, one (more) good thing about adna is that this can actually be tested – do the Iberian sites in this paper suggest that local burials share a matriline or that males share a patriline? If there is closer relatedness between multi-generational males at the site than female, then that suggests patrilocality and patrilineality. We could get some direct evidence either way, rather than relying on what is effectively this single reference. I might have a look and see if the evidence in the paper suggests anything.

    You could also look at clustering of patrilines among Basques today, or medieval Basque cemetaries. If patrilines cluster at a location with high time depth, then that’s some evidence against matrilocality ever being true for them.

    Patrilocality is of course the modal world pattern, relative to matrilocality (somewhat idealised; most marriages don’t involve village swapping, but relatively this holds true for those that do). Adjusting for subsistence pattern probably means a stronger association of patrilocality with plow agriculture.

  2. 1. Some IE mannerbund encountered a settlement much larger than their group, maybe something like 10 times more people. Could have been less or more.
    2. They’ve managed to slaughter all their males
    3. There were too many females still
    4. They got swamped and absorbed culturally, language and customs
    5. They didn’t abide of one thing though: teaching their male children the ancient steppe warrior ways
    6. Descendents of this group would invade Iberia later, bringing Proto-Basque with them.
    7. The Vasconic hypothesis might be corrected here, as we don’t precisely know where this language shift happened. But it was certainly outside of Iberia, and where Farmers still maintained their complex societies.
    8. It might be the case that THE FIRST wave of Steppe expansions into Europe got their language shifted because they encountered robust EEF societies.
    9. The following waves would retain their IE language because there would be no such barriers anymore, with only sparse micro villages elsewhere to pillage.
    10. So, it could be that the Beaker Vanguard spoke Proto-Basque, and the Rearguard spoke IE.
    11. The same Vanguard effect wouldn’t apply to the Eastern expansion because Central Asia was much less populated, much more sparsely so. They also avoided some more sedentary settlements by taking a detour through the Mountain Ranges.
    12. Still this happened, and I believe the same offshot effect of mannerbunds attacking larger settlements that they can handle happened. The genetic shift would happen, they would become an elite of sorts, but, by the sheer size of the conquered settlement, the mannerbund guys would be the ones absorbing the culture.

    Things were rudimentary at the time, I don’t believe in lack of violence or culturally transmitted ways. Things were pragmatic, done by convenience or force.

  3. I realize the graphic above shows the Basque as an isolated genetic group over the past 2,000 years, with no more inputs from other ethnicities, and that is surely the case for the most part. But in 2018, we found a rare example of a Basque-Jewish DNA link: a Basque person whose ancestors in recent centuries lived in the area of the town of Falces, Navarre, in northern Spain is a valid match on an autosomal DNA segment to many Ashkenazic Jews, 3 Mexicans, a Puerto Rican, and Argentinian, and a Brazilian. It is likely that the common ancestor of this segment was a Sephardic Jew instead of a Spaniard or a Basque, but there are traces of Iberian DNA in modern Sephardic Jews so that possibility can’t be ruled out.

  4. I would love to see an update of this graph but with widths scaled to estimated population sizes over the years, a bit like Minard’s flow graph. Maybe then the neolithic replacement would look more like a neolithic addition that explodes in size.

    @Kevin brook, Basque genetic isolation was always very relative (although it seems that it was enough to keep some genes out for 2ky). And Falces is down south, away from the mountains and the core Basque region, a transition area, lots of mixing with the wider Iberian population. in 1492 Spain made all Jews to emigrate or convert, and later many basques emigrated to South America, so I can think of many plausible stories for this gene segment to end up in all these places (two jewish sisters, one stays and converts and later her family emigrates to South America, the other emigrates to France and marries Askhenazi?)

  5. 1. Another thing to consider concerning the loss of Y-dna HGs: During times of stress females produce more female offspring which makes evolutionary sense. See: Preconception stress and the secondary sex ratio: a prospective cohort study, Chason et al, 2012

    2. Concerning language replacement versus adoption in migration and/or invasion models: The Philistines are believed to have come to Canaan from Crete but after arriving, their Iron-Age inscriptions were written in the local Semitic language {akin to Hebrew}. There are grounds to infer that the Israelites incorporated Hurrian and other elements who adopted the Canaanite language {sometimes with difficulty, see “Shibboleth”}. I suppose the difference between invasion versus migration would depend on the size of the invaders, or intruders versus the size of the local population. In the case of Europe and the Basques a “First-Wave” effect does make sense.

  6. It may be that the Basque language actually derives from the steppe as non-Indo-European peoples expanded along with the Indo-Europeans

    The Iberian speakers (along the Mediterranean coast of the peninsula) may have lost their language by the II c. AD because their more accessible and more desirable lands were subject to much greater migration pressures from the other shores of the sea (as the graph suggests). But in the Iron Age and in the beginning of the Roman era, the Iberian peoples spoke non-Indo-European languages as well (and used Phoenician-related semi-syllabulary for writing). Importantly, their poorly deciphered languages had a number of close parallels to Basque (including exactly the same numerals – the entire system of numerals! – and highly similar suffixes / morphology) so the linguists always left open a possibility that Iberian and Vasconic languages shared an origin.

    Now we understand that genetically, Iron Age Iberians and Aquitanians (proto-Basques) were of the same stock, too.

    Therefore, one of the two things must be true: either the invading Steppe-related male-dominated groups were originally Indo-European but lost their “father tongue” both among the “stubborn, resilient Basques” and among the soon-to-lose-their-language-to-Phoenicians-and-Romans non-IE Iberians
    or Iberian and Vasconic languages were related, and invasive

    Anyway my point it that the fates of the Basque and Iberian languages were identical before the Roman Era, and it would be a fallacy to assume that there was something unique to the Basques which made them retain a non-IE language through the Late Bronze and Iron Ages.

  7. Modern archaeology tends to underestimate(*) — consistently and grossly, IMHO — the potential speed, scale and raw destructiveness of primitive warfare at a pre-State or early-State level of organization.

    For example, African history in the past few centuries is full of examples of peoples who didn’t even have chieftainship but who were ferociously, aggressively expansive for long periods. The Maasai in East Africa, for example, or the Galla who overran much of Ethiopia from the 16th century on.

    You don’t need big armies or elaborate organization to destroy populations; you just need to be mobile and tactically superior and willing spend a lot of time and effort to attack the food resources of your victims. This makes any area the newcomers can move over uninhabitable. Subsistence economies are never more than a couple of failed harvests away from disaster, and famine and plague synergize naturally.

    Note also that fairly small migrations can have a large cumulative genetic impact if they impose stark differences in reproductive success over time.

    Latin America is full of populations where there was never a mass migration of Spaniards comparable to those of the English to their colonies, but where the present-day populations are mostly Iberian genetically — Mexicans are about 2/3 Spanish genetically, or a tiny bit less, and Chile is similar. Much more than that in the Y-chromosome lines, of course.

    (*) I think for essentially ideological reasons, operating through unconscious mechanisms like confirmation bias and motivated reasoning.

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