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.