Share DNA between Jews and Arabs

Genetic ancestry : Abraham's children

One trunk, several main branches and plenty of branches. That is the picture that two studies paint of the genetic origins and development of the Jews living today. The scientists found that today's Jews inherited many genes from an original Jewish population who lived in the Middle East, in the eastern Mediterranean known as the Levant, around 3,000 years ago. This means that the 13 million Jews living today are not only connected to one another by culture and religion, but also by a shared biological heritage.

This common origin had been questioned again and again, most recently by the Israeli historian Shlomo Sand in his book "The Invention of the Jewish People". At the same time, the Jews living today also have strong genetic connections to non-Jewish groups, especially to Italians in Europe and to Druze, Bedouins and Palestinians in the Middle East.

The researchers used the DNA chip or "microarray" technique. With this procedure it is possible to compare the genetic material of different people in great detail, starting with individual "letters" of the genetic information DNA up to longer sections. Studies based on DNA chips allow more extensive statements than previous studies. Previously, the male Y chromosome and the genome of the mitochondria, which were only passed on from mothers, had been used to trace the genealogy of the Jews.

Harry Ostrer of New York University examined the DNA of 237 people whose families have been Jewish for generations and who represent the large groups of the diaspora: the Ashkenazi, who were native to northern and eastern Europe before the war and the Holocaust and who are now predominantly in the USA and Israel live; the Sephardi, who lived in Spain (until 1492) and Portugal (until 1497) and later came to the Ottoman Empire, North Africa and the Netherlands; and finally the oriental Jews.

Ostrer compared their genetic information with that of 2,800 non-Jews, as he reports in the American Journal of Human Genetics. In the study by Doron Behar from the Rambam Medical Center in Haifa, published in the journal “Nature”, fewer people took part, but more population groups were considered.

In both studies it turned out that the Jews of the three diaspora groups are genetically closer to each other than non-Jews of the same region. Within each group, individuals were as related as second to fifth degree cousins.

Scientists were surprised by the proximity between present-day Ashkenazi and Sephardi - unexpected because the two branches separated a long time ago. Both groups inherited between 30 and 60 percent of their genome from Europeans. They could be descended from Jews who were native to northern Italy before 800 AD and who mingled with Italians here. This is supported by the fact that the genome of the Sephardi and Ashkenazi clearly corresponds to that of the Italian Jews.

The oriental Jews are relatively isolated. Its origin is believed to be in Persia and Babylon about 2500 years ago. They separated themselves from the ancestors of the other two diaspora groups 100 to 150 generations ago, the researchers calculate, sometime in the last millennium BC.

There are probably several reasons for the large proportion of non-Jewish Europeans in the genome of today's Ashkenazi in particular. On the one hand, Jews evangelized in antiquity, especially in the Roman Empire, as a result of which Judaism spread strongly. Mass conversions resulted in up to ten percent of the Roman population practicing the Jewish religion.

So it is not surprising that the Ashkenazi and Sephardi are the closest genetically to southern Europeans. In addition, between the 15th and 19th centuries there was a strong rapprochement between the Jewish and non-Jewish population in Europe. During this time the number of Jews in Europe rose from around 50,000 to five million. The originally “Jewish” part of the genome has shrunk.

"Our research supports the idea of ​​a Jewish people linked by a common genetic history," said study director Harry Ostrer. "But mixing with people of European origin explains why so many European and Syrian Jews have blue eyes and blonde hair." The study shows how genetics reflect history. "We actually see the events of the Jewish diaspora in the genome of Jewish people."

However, there are doubts as to how far historical events can be reconstructed using genetic analyzes. "You have to make too many assumptions," said geneticist David Goldstein of Duke University in Durham, the journal "Nature". "In genetics we do not yet have the accuracy to precisely determine the point in time of events."

The studies are not able to say exactly how it was - but they do allow pretty reliable statements about how it was not. The historian Sand assumes that it was not people from the Levant but converted Khazars from the Black Sea who were the ancestors of the Ashkenazi - one of his proofs that a genuinely “Jewish people” is an invention.

But with Sands' argument, the geneticists can do away with it. Although there are indications of a genetic intermingling with the Khazars in the last millennium, this influence is very limited. That strengthens Sand's critics. “These results confirm what the Jewish folk wisdom always knew,” said the historian Anita Shapira from Tel Aviv University to the journal “Science”: that the Jews had a common origin in the Middle East. "It's nice to be supported by modern genetics."

Shlomo Sand, on the other hand, considers the idea of ​​a “genetic identity” for the Jews to be absurd. "No study has ever found a genetic mark that is typical only for Jews," "Science" quotes the historian. “It is a bitter irony that, of all people, the descendants of Holocaust survivors want to find a biologically based Jewish identity. Hitler would certainly be very pleased. "

With this fundamental criticism, the cornered sand is likely to overshoot the mark. Genetic findings are not easy to ignore. But of all people, Doron Behar, head of the “Nature” study, is a bit in the sand's notch. It is not necessarily the genes that make a Jew, he argues. There is no “metaphysical” difference between someone who was born Jewish and someone who converted to Judaism. Genes have their limits.

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