Tag: Ashkenazi Jews

Cryptic Ashkenazi ancestry across Eastern Europe

Posted on by Razib Khan

One of the great things about the spread of ‘direct to consumer’ genomics is that it’s increasing sample size in countries where for various reasons there isn’t much coverage. It was brought to my attention that My Heritage DNA results have been analyzed by the company, and yielded the surprising result that Hungary has been most impacted by Ashkenazi Jewish admixture in the Diaspora. This is surprising since it is well known that the United States of America is home to the second-largest Jewish community in the world, with more than 90 percent of that being Ashkenazi.

The main issue here is the distinction between genetic and cultural definitions. Ashkenazi Jews are a coherent population genetic classification, emerging out of a series of admixtures during the medieval period as a strong endogamous group. This means that this community has a distinctive genetic profile, just as Finns or Cambodians have distinctive genetic profiles. But Ashkenazi Jews are also a cultural and religious entity. Because of social and cultural constraints imposed by Christian societies, Jews could leave their religious identity, but Christians could not become Jewish.

In the United States, the massive wave of Jewish migration occurred around 1900. This is not so many generations in the past, so not too many people have very distant Jewish ancestry. Additionally, anti-Semitism has been a more marginal factor on the American landscape, so Jewish ancestry has been less hidden (though not always).

The situation in Eastern Europe is very different. A massive wave of demographic expansion occurred among Ashkenazi Jews after 1500. In the 18th-century Jewish fertility was far greater than gentile fertility in Poland. This resulted in an increase in the Jewish proportion over time, but likely also assimilation of some Jews into Christian society. The “Jewish Enlightenment”, spanning the 100 years between 1780 and 1880, was also a period when massive defections occurred from the more integrated elements of the Central European Jewry. Moses Mendelssohn’s last male descendant to practice Judaism died in 1871, after one century of assimilation and conversion.

Overall, this result confirms what history would suggest to us. I believe if My Heritage DNA looks specifically at IBD tracts they will see that an early peak of admixture would center around 1830, during the height of the Jewish Enlightenment, in Central Europe. The admixture will be later further east in Europe, due to the later period of assimilation of Jews in those societies. In contrast, in the USA exogamy rates for Jews remained at 10% as late as 1960. Only in the past few generations have been risen to around 50% or more.

The origin of the Ashkenazi Jews in early medieval Europe

Posted on by Razib Khan


Last year’s The time and place of European admixture in Ashkenazi Jewish history is very close to the last word on the genetics of the ethnogenesis of Ashkenazi Jews. Here’s the author summary:

The Ashkenazi Jewish population has resided in Europe for much of its 1000-year existence. However, its ethnic and geographic origins are controversial, due to the scarcity of reliable historical records. Previous genetic studies have found links to Middle-Eastern and European ancestries, but the admixture history has not been studied in detail yet, partly due to technical difficulties in disentangling signals from multiple admixture events. Here, we present an in-depth analysis of the sources of European gene flow and the time of admixture events by using multiple new and existing methods and extensive simulations. Our results suggest a model of at least two events of European admixture. One event slightly pre-dated a late medieval founder event and was likely from a Southern European source. Another event post-dated the founder event and likely occurred in Eastern Europe. These results, as well as the methods introduced, will be highly valuable for geneticists and other researchers interested in Ashkenazi Jewish origins.

Roughly the Ashkenazi Jews are a half and half mix of a Middle Eastern population and various European groups. The majority of the European ancestry is “Southern European,” probably something like Italian. But, a minority of the European ancestry is like “Eastern European.” Additionally, the former admixture pre-dated the bottleneck, and probably dates to ~1000 A.D., while the latter event post-dates the bottleneck.

For years I had thought that Isaac Bashevis Singer’s excellent novel The Slave was interesting but implausible. The reason being that Ashkenazi Jews and their gentile neighbors did not mix by this time, as the European ancestry in Ashkenazi Jews dates to the Roman period.

These results reject that model…the tract-length evidence is persuasive to me that admixture with Slavs did occur.  Some Italian groups are more north shifted, but the most parsimonious explanation while the Eastern European like ancestry came in later is that it tracks Jewish migration into Germany and Poland-Lithuania later.

The dating of admixture is something I’m less sure of. At 625 to 1,250 years before the present, it puts the emergence of the Ashkenazi community firmly in the Christian era. I don’t want to get into too many details, but from what I have read the Church and local authorities frowned on Jews owning Christians slaves, and tried to suppress instances where Christian slave women became concubines to Jewish men or even Judaized.

I had long assumed that these records reflect elite paranoia. If the dates of admixture are right they may reflect a real concern and a phenomenon (the Y and mtDNA evidence strongly point to the likelihood that the pattern was generally partnerships between Jewish men and gentile women).

And to be frank they tell us less about Jews than they do about the nature of “Christian Europe” in the early medieval period. There is one school of Reform Protestant which takes a dim view of how deeply Christian medieval Europe ever was. I think these results support the thesis that Christianity was an elite religion whose grasp upon the masses was more tenuous and illusory than we might imagine. There is also the reality that the feudal Christian state never had totalitarian authority over the population.

In theory Jewish assimilation of Christians to their identity, Judaizing, could be a capital crime. But if these results are correct it was quite common in the formation of the early Ashkenazi community before it moved north and then east. This decentralization and relative weakness of the early medieval Church and state, the superficially of mass Christianity, might also explain how vast regions of France defected from orthodox Christianity for decades in the 12th century during the ascendancy of the Cathars.

On a final note, I decided to do a little probing on the Middle Eastern forebears of the Askhenazi. The paper says that Levantine populations are the most likely source, which is entirely expected. But I wanted more detail, so I used the Human Origins Array dataset. You can see on the PCA above that the Ashkenazi Jews are shifted toward the European (Basque) population away from Middle Easterners, but if you project the line outward it lands on Christian and Muslim Lebanese. Haber et al. last year showed that there was continuity between the modern Lebanese and Caananites, and the Jews were likely originally a form of Canaanite. Curiously, Palestinian samples in the data are strongly shifted away for the Lebanese, toward groups like Saudis.

I understand it’s a hot potato politically, but if I didn’t have a dog in this fight I’d say that the contention that Palestine and Jordan (look at the Jordanian sample positions) underwent some population turnover is likely true (though I’d be curious about the data on Palestinian Christians).