The power of ancient DNA in terms of human evolution at this point is to a large extent the ability to understand the arc of human cultural history as reflected in our genealogies. Archaeologists have long attempted to infer aspects of social and cultural practice from material remains. Now, geneticists are getting into this game, with mixed results.
Today the Bradley lab in Ireland published a paper about the genetics of Neolithic Ireland (i.e., before the arrival of Bell Beakers ~2,500 BC). The first author is Lara Cassidy, who I interviewed last year. There is a reason this paper is in Nature.
Let me quote the abstract first:
…The scale and sophistication of megalithic architecture along the Atlantic seaboard, culminating in the great passage tomb complexes, is particularly impressive…Although co-operative ideology has often been emphasized as a driver of megalith construction…the human expenditure required to erect the largest monuments has led some researchers to emphasize hierarchy…Here we present evidence that a social stratum of this type was established during the Neolithic period in Ireland. We sampled 44 whole genomes, among which we identify the adult son of a first-degree incestuous union from remains that were discovered within the most elaborate recess of the Newgrange passage tomb. Socially sanctioned matings of this nature are very rare, and are documented almost exclusively among politico-religious elites—specifically within polygynous and patrilineal royal families that are headed by god-king…We identify relatives of this individual within two other major complexes of passage tombs 150 km to the west of Newgrange, as well as dietary differences and fine-scale haplotypic structure (which is unprecedented in resolution for a prehistoric population) between passage tomb samples and the larger dataset, which together imply hierarchy. This elite emerged against a backdrop of rapid maritime colonization that displaced a unique Mesolithic isolate population, although we also detected rare Irish hunter-gatherer introgression within the Neolithic population.
There’s a lot of moving parts in this research, and the most interesting element isn’t the genetics, but the social structure that you can infer from the genetics. It seems entirely likely that the “Megalithic civilization” of Atlantic Europe was hierarchal. But this pretty much confirms it. As noted in the paper violations of first-order incest taboos as a cultural norm (as opposed to deviancy) are strongly associated with very stratified preliterate or semiliterate societies (with the possible exception of Zoroastrianism). Additionally, this research highlights that a set of individuals, likely paternally related, seem to be enriched in elite burials.
In a few circles, there are ideas that Neolithic Europeans were peaceful and matrilineal. The existence of stratification like this and the likelihood of ‘god-kings’ makes that very unlikely in Ireland. Though there was no doubt some variation in Neolithic Europe, the existence of “long-houses” in Germany from contemporary cultures is ominous. The matrilineal element is distinct. There are matrilineal societies that are quite warlike (e.g., the Nairs of Kerala or the Iroquois). But the possibility of common Y chromosomes suggests that this was a patrilineal society, which is, on the whole, more common anthropologically.
To me this is the most awesome part of the paper:
The Brú na Bóinne passage tombs appear in Medieval mythology that relates their construction to magical manipulations of the solar cycle by a tribe of gods, which has led to unresolved speculation about the durability of oral traditions across millennia…Although such longevity seems unlikely, our results strongly resonate with mythology that was first recorded in the eleventh century AD, in which a builder-king restarts the daily solar cycle by copulating with his sister…Fertae Chuile, a Middle Irish placename for the Dowth passage tomb (which neighbours Newgrange), is based on this lore, and can be translated as ‘Hill of Sin’ or ‘Hill of Incest’…
This is incredible. Unless you are set in your ways I think it is hard to deny that the medieval Irish were passing on a recollection in their myth from an encounter between Bell Beakers and the late descendants of the Newgrange people. In The Isles Norman Davies argues that the Irish, unlike the English and the British more generally (Brythonic), kept their own mythology, and so have a sense of their past in a way that is uncommon among Northern European peoples. The Irish legends imply that there were multiple waves of people, and it is assumed that the people who live in the great mounds are the Tuatha Dé Danann, who became ancient Irish demigods.
I suspect that the early Bell Beakers viewed the monuments of the Tuatha Dé Danann, the Newgrange people, like how some Americans view “Indian graveyards.” Even among modern people, there is superstition, so what can we expect from the ancients? The Greeks forgot their heritage and assumed that the cyclopean citadels of their ancestors were built by giants. No doubt agro-pastoralist Bell Beakers looked at the massive ruins, and perceived the work of the gods.
And we shouldn’t underestimate the ability of oral tradition to recall events for premodern people. Mount Mazama blew 7,700 years ago, but native people in the area have legends of that explosion. Australian Aboriginals have myths that clearly outline and detail landmarks that are now underwater due to rising sea levels. The point is that it’s plausible that facts that are 3,000 years old could persist down to Christian Ireland, and be recorded by priests.
There are lots more I could say about this paper in the details. They found an infant with Down syndrome! They show recent introgression of hunter-gatherer ancestry into some Neolithic individuals. Also, they show hunter-gatherer substructure (Irish hunter-gatherers do not have ancestry from Magdelanian populations, only Villabruna). But the biggest aspect here is that this paper now sets a standard for how you can synthesize ancient DNA with archaeology and mythology.