A new study on Jewish genetics

Kevin MacDonald:  Gil Atzmon and colleagues have come out with the largest study yet comparing Jewish and non-Jewish populations. (See here and here.) Ted Sallis will be coming out with a longer summary for TOO, but I thought I would highlight a couple points.

The study is remarkable for the number of genetic loci studied (3904 SNPs) and the number of people sampled (273 Jews from 7 different Jewish groups (Ashkenazi, Iranian, Syrian, Iraqi, Italian; Greek; Turkish) and 418 people from 16 non-Jewish groups).  As in previous studies, the main message is that Jewish populations do cluster together and are different from the populations they have lived among for hundreds of years.  The 7 Jewish populations divided into a European/Syrian group with a relatively high degree of genetic admixture with European non-Jews (30-60%) and a Middle Eastern group (Iraqi and Iranian Jews). The estimate of 60% overlap between Ashkenazi populations and Europeans indicates that Ashkenazi Jews are an intermediary population with genetic interests that overlap significantly with Europeans.

The new findings were seen as support for the idea that there was significant admixture with non-Jews in Greco-Roman times. This is based on the clustering of the European/Syrian Jews  and the fact that these groups have been separated since ancient times. The authors argue that the data are consistent  with historical accounts of proselytism and large-scale conversions to Judaism in ancient times.  When I reviewed the historical data in A People That Shall Dwell Alone (Ch. 4, pp. 62-78), I ended up rejecting this theory, coming down on the side of historians who doubted how important conversion really was. One thing that convinced me was that there was a lot of evidence for biases against converts. For example, once they converted they were regarded as very undesirable marriage partners and that a pure Jewish genealogy was a very big asset in the marriage market. Families keep their genealogies for generations, and there is a lot of evidence for hostility toward converts. Contrary to Atzmon et al., conversion is not required to explain the large numbers of Jews in the ancient world.

There was also a very pronounced apologetic tone to Jewish advocates of high levels of prosetlytism. But now it looks like they may have been right because the greatest admixture among the European/Syrian groups comes from the Mediterranean area: French, Northern Italian, and Sardinians. It’s hard to see how that could have happened without the admixture occurring in the ancient world. It’s also worth noting that, once again, the data are not compatible with a major role for the Khazars.

In any case, there certainly were elaborate cultural barriers against intermarriage throughout very long stretches of Jewish history, resulting in genetically different populations with substantially different genetic interests. That’s the point of the group evolutionary strategy idea: Admixture would have been much higher without barriers.

And of course, genetic overlap is not the same thing as a psychological sense of common interest. Following John Murray Cuddihy, I have often stressed the hostility and sense of historical grievance that Jews have had toward the Europeans they have lived among for centuries. Psychological attitudes do not necessarily match up one-to-one with genetic distance. Attitudes are affected not only by genetic similarity but are at least partly affected by ingroup/outgroup psychology which is known to be fairly insensitive to genetic distance: People can develop great hatreds toward the fans of different football teams.

The point is that it’s quite possible that Jewish hostility toward Europeans and their culture is not really warranted by the recent findings on genetic distance–an intriguing possibility to say the least.