The hot topic at the moment is social inequality in Bronze Age Europe, thanks to a new paper by Mittnik et al. at
Science. The full article is sitting behind an exceedingly robust paywall
here.
However, the genotype dataset from the paper is freely available at the Max Planck Society's Edmond data repository
here. Below is my Principal Component Analysis (PCA) of ancient West Eurasian genetic variation featuring 41 of the highest quality ancients from the new dataset. Almost all of them are from the Lech Valley in the Bavarian Alps, covering the period from the Bell Beaker culture (BBC) to the Middle Bronze Age (MBA). Two of the samples are from a mass Corded Ware culture (CWC) burial in the more northerly Tauber Valley.
I've also highlighted other ancients on the plot associated with the BBC and CWC from present-day Netherlands and Germany, respectively. The relevant PCA datasheet can be downloaded
here.
Social stratification in ancient Europe is a fascinating topic, and it's an issue that I've started looking at myself (see
here). However, I can't see any correlation between the inferred social standing of the individuals from the Lech and Tauber valleys and their positions in my PCA.
Nevertheless, the PCA is interesting in that it highlights considerable genetic heterogeneity within the Lech Valley BBC population. Indeed, how is this heterogeneity even possible, if, as per Mittnik et al., ancient DNA "has shown that the spread of the BBC throughout continental Europe did not involve large-scale migrations"?
Below is another version of my PCA, but this time focusing on three males: Lech Valley Beakers UNTA58_68Sk1 and WEHR_1192SkA, as well as ALT_4 from the aforementioned mass CWC grave in the Tauber Valley. Note that UNTA58_68Sk1 and WEHR_1192SkA represent genetically the most southern and northern, respectively, Lech Valley BBC samples that had enough data to be run in my analysis. I chose to focus on males because they carry the Y-chromosome, which can be informative about male-mediated ancient population expansions.
The PCA outcomes for these individuals are generally in line with their results in other types of genetic analyses, including those based on formal statistics. For instance, compared to the other two, ALT_4 harbors excess early steppe herder ancestry, UNTA58_68Sk1 excess early European farmer ancestry, and WEHR_1192SkA excess European hunter-gatherer ancestry. Moreover...
- UNTA58_68Sk1 shows a non-local isotopic signature and belongs to Y-haplogroup G2a, a marker essentially missing from BBC populations north of the Alps, and is best modeled as a two-way mixture between Bronze Age populations from the Balkans and the Pontic-Caspian steppe (see here), which probably means that he was a migrant to the Lech Valley from south of the Alps
- importantly, UNTA58_68Sk1 is not an isolated case, at least in the sense that several other BBC individuals from Bavaria, Bohemia, Hungary and Poland show varying ratios of Balkan-related ancestry, although almost all of these people are women
- WEHR_1192SkA is very similar to Bell Beakers from the northern Netherlands with whom he shares the R1b-P312 Y-haplogroup, suggesting that he was part of a population that moved into the Lech Valley from potentially as far away as the North Sea coast
- although ALT_4 probably shares the R1b-L51 Y-haplogroup with WEHR_1192SkA and many other BBC and Bronze Age individuals from the Bavarian Alps and surrounds, this can't be used as evidence of significant local genetic continuity after the CWC period, especially considering the comparatively eastern genome-wide structure of ALT_4.
Of course, archeological data suggest that the BBC was influenced in some important ways by the Copper and Bronze Age cultures of the Balkans and Carpathian Basin. So much so, in fact, that Marija Gimbutas, author of
The Civilization of the Goddess, believed that the BBC originated in the Balkans from a synthesis of the local Vucedol culture and the intrusive Yamnaya culture from the Pontic-Caspian steppe.
Considering the ancient DNA evidence, however, the main demographic center of the early BBC could not have been south of the Alps.
Rather, it appears that early BBC and even CWC groups from north of the Alps moved into the Balkans and Carpathian Basin, where they may have established contacts with the local elites. If so, this might explain the significant southern cultural influences on the BBC, but limited accompanying genetic impact. This scenario also has support from archeological data (for instance, see
here).
See also...
Is Yamnaya overrated?
The Boscombe Bowmen
Single Grave > Bell Beakers