On the genetics of Jewishness

One more before I unchain myself from the home office desk, and switch off this wretched machine and its incessantly chattering hard drives…

Scientific papers on population genetics tend to be hard going for this non-biologist, but to me the subject is so fascinating that I do my best to keep up with developments in the field.

It is always a pleasure for me to read a well-drafted science paper, and especially so in such a difficult topic. So it is with great delight that I highlight here an article on the genomic structure of the Jewish people, published recently in the journal Nature by a team of researchers led by Karl Skorecki, director of the Rappaport Institute in Haifa.

I shall begin by quoting directly from the very first paragraph of the paper…

“Contemporary Jews comprise an aggregate of ethno-religious communities whose worldwide members identify with each other through various shared religious, historical and cultural traditions. Historical evidence suggests common origins in the Middle East, followed by migrations leading to the establishment of communities of Jews in Europe, Africa and Asia, in what is termed the Jewish Diaspora. This complex demographic history imposes special challenges in attempting to address the genetic structure of the Jewish people.”

In their paper, first author Doron Behar and his colleagues show that the various communities of the Jewish diaspora have maintained strong genetic links despite thousands of years of separation from their Levantine source. Their work gives the lie to claims from the ‘Back to Brooklyn’ crowd that the Jews have no common origin.

In their research, Behar and his coworkers took DNA samples from 121 people living in 14 Jewish communities in Israel, North Africa, Europe, Central Asia and India, and compared these with samples from 1,166 individuals in 69 non-Jewish populations, including in those regions in which there is a surviving Jewish community. To this analytical pot the researchers added some 16,000 samples of the Y chromosome (male only), and of mitochondrial DNA, which is passed down the maternal line.

As well as confirming the common, Middle Eastern origins of the Jewish people as a whole, this latest study has revealed the surprising fact that the genetic markers known as single nucleotide polymorphisms are in Jewish communities closer to those of Cypriots and Druze than of other Middle Eastern populations.

The most significant finding concerns the close genetic similarities between Europe’s two major Jewish communities: the Ashkenazim and Sephardim. Ashkenazi Jews formed the majority in northern and eastern Europe until the Holocaust, while in the late fifteenth century the Sephardim were exiled from the Iberian peninsula to the Ottoman Empire, north Africa and the low countries of northern Europe.

If you have access to Nature, do have a look at the Behar et al. paper. Also worth perusing is Nicholas Wade’s commentary in the New York Times on this and a related research paper on “Abraham’s Children”.

Further reading

Behar et al., “The genome-wide structure of the Jewish people”, Nature (2010)

Atzmon et al., “Abraham’s children in the genome era: major Jewish diaspora populations comprise distinct genetic clusters with shared Middle Eastern ancestry”, AJHG 86, 850 (2010)