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Tuesday, June 21, 2022

My take on the Erfurt Jews


I had a quick look at the genotype data from the recent Waldman et al. preprint focusing on the ancestry of early Jews from Erfurt, Germany. My impression is that the genetic origins of these Jews are somewhat more complex than claimed in the manuscript.

Indeed, I'd say the Waldman et al. characterization of the Erfurt Jews as a three-way mixture between populations similar to present-day Lebanese, South Italians and Russians doesn't exactly reflect reality.

Unlike Waldman et al., I designed an ADMIXTURE analysis that separated East Asian ancestry into East Asian and Siberian clusters, and also included Mediterranean and North African clusters. The output is available in a spreadsheet HERE. Below is a bar graph based on some of the output.
Now, keeping in mind that ADMIXTURE is not a formal mixture test, and that it estimates ancestry proportions from inferred populations, as opposed to ancient groups that actually existed, here are some key observations:

- in terms of fine scale ancestry, the Erfurt Jews show enough variation to be divided into three or four clusters, as opposed to just two as per Waldman et al.

- some of the Erfurt Jews show excess "Mediterranean" ancestry, while others excess "North African" ancestry, and this cannot be explained with ancestral populations similar to Lebanese and/or South Italians, but rather with significant gene flow from the western Mediterranean and possibly North Africa

- several of the Erfurt Jews show relatively high levels of "East Asian" ancestry that cannot be explained by admixture from Russians, or even any Russian-like populations, because such populations almost lack this type of ancestry, and instead show significant "Siberian" admixture

- as far as I can see, there are no correlations between any of the observations above and the quality of the samples. That is, low coverage doesn't appear to be causing the aforementioned excess "Mediterranean", "North African" and/or "East Asian" ancestry proportions.

Investigating this in more detail with, say, formal statistics will take some time. But I was able to reproduce the results from the above ADMIXTURE run using several somewhat different datasets, so that's something.

It seems to me that Waldman et al. want a simple and elegant model to explain the data, which is understandable, but I do think they should at least expand their ADMIXTURE analysis to include "Siberian", "Mediterranean" and "North African" clusters, and go from there depending on what they find.

Citation...

Waldman et al., Genome-wide data from medieval German Jews show that the Ashkenazi founder event pre-dated the 14th century, bioRxiv, posted May 16, 2022, doi: https://doi.org/10.1101/2022.05.13.491805

Saturday, June 18, 2022

David Reich on the origin of the Yamnaya people (!?)


Harvard's David Reich is doing a talk next month about the genetic history of West Asia and nearby parts of Europe. This is a quote from an online abstract of the talk (found here).

The impermeability of Anatolia to exogenous migration contrasts with our finding that the Yamnaya had two distinct gene flows, both from West Asia, suggesting that the Indo-Anatolian language family originated in the eastern wing of the Southern Arc and that the steppe served only as a secondary staging area of Indo-European language dispersal.

If this is actually what David Reich is going to claim then I'd say his team has a lot of work to do before they put out their paper on the topic.

First of all, Yamnaya did not have two distinct gene flows from West Asia. I don't even know what that means exactly, but there's no way that this statement is correct no matter how one interprets it.

In fact, the Yamnaya population formed on the Pontic-Caspian steppe from earlier groups native to this part of Eastern Europe, such as the people associated with the Sredny Stog culture.

That is, there were no migrations from West Asia into Eastern Europe that can be claimed to have been instrumental in the emergence of the Yamnaya population. On the other hand, Yamnaya may have been significantly influenced by cultural impulses from West Asia, but this is nothing new.

In terms of deep population structure, the Yamnaya genotype can be described as a mixture between Eastern European and West Asian-related genetic components. However, these Asian-related components were already in Europe thousands of years before Yamnaya came into existence.

Indeed, soon to be published ancient DNA shows that hunter-gatherers very similar to the Yamnaya people, packing quite a lot of West Asian-related ancestry, lived in the Middle Don region (just north of the Pontic-Caspian steppe) well before 5,000 BCE (see here).

So, did the West Asian ancestors of these Middle Don hunter-gatherers speak Proto-Indo-European, or, as David Reich calls it, Indo-Anatolian? Keep in mind that most linguists put the birth of Indo-Anatolian around 4,000 BCE, which is actually the Sredny Stog period.

Moreover, in underlining Anatolia's supposed impermeability to exogenous migration, David Reich is arguing against things that no one worth their salt ever claimed. That's because the spread of Indo-Anatolian speakers into Anatolia has never really been described by archeologists and linguists as a massive migration, but rather as an infiltration into lands already heavily populated by the Hattians (for instance, see here).

We may have already seen the genetic evidence of this infiltration in the presence of steppe Y-chromosome haplogroup R-V1636 in a Chalcolithic burial at Arslantepe (see here and here). Let's wait and see what else crops up over the next few years as many more ancient Anatolian genomes are sequenced by David Reich and colleagues.

See also...