The word diaspora means a scattering of seeds. The Jewish Diaspora began 2600 years ago when the Babylonians exiled Jews from the Kingdom of Judah, and has continued through the centuries, with Jewish communities frequently being uprooted and scattered around the world.
It’s remarkable that Jews have maintained a tangible cultural identity through those 26 centuries of dispersion, and perhaps even more remarkable that genetic studies now show they have maintained a substantial genetic identity as well.
Genetic Links to the Levant
Two new studies have clarified the extent of Jewish genetic continuity across continents and centuries while also bringing some of the finer details into focus for the first time.
Doron Behar, at the Rambam Health Care Campus in Haifa, Israel, leads a research team - itself scattered from Tartu, Estonia to Tucson, Arizon - that has completed the most comprehensive study to date comparing the entire genomes of a number of Jewish and non-Jewish populations. The team’s findings appeared June 9, 2010 in the journal Nature.
The team’s whole-genome comparisons of 14 Jewish and 69 non-Jewish groups found that despite being separated for more than 2500 years, most Jews show a strong genetic link to specific non-Jewish populations in the Levant (the Eastern Mediterranean region that includes modern-day Lebanon, Syria, Israel, Jordan, the Palestinian territories, Cyprus and parts of Iraq).
“Most Jewish samples form a remarkably tight subcluster that overlies Druze and Cypriot samples but not samples from other Levantine populations or paired Diaspora host populations,” the researchers write. (The Druze are a religious community found largely in Israel, Syria, Lebanon and Jordan. Their religion stems from Islam, but incorporates other beliefs as well).
Behar’s findings support the idea that most Jews alive today descend from ancient Hebrews or Israelites who lived in the Levant during Biblical times.
The extent to which Jewish communities have maintained genetic continuity can be seen in the Jews of Bukhara, now the capital of Uzbekistan, in central Asia. By oral tradition, the Bukhara Jewish community traces its roots to the 8th Century BCE, when the Jews of the Northern Kingdom of Israel were exiled by the Assyrians. Despite being cut off from the rest of the Jewish world for two millennia, the current study shows that Bukharan Jews remain genetically close to other contemporary Jewish populations, but not to their geographic neighbors.
The study also showed that Ashkenazim (Jews with roots in Central and Eastern Europe) and Sephardim (Jews whose ancestors lived in Spain and Portugal prior to 1492) show a high degree of genetic overlap and genetic ties back to the Levant.
Karl Skorecki, Director of the Rappaport Research Institute in Haifa and co-author of the Nature paper, says that although earlier studies of mitochondrial and Y-chromosome DNA had shown links to the Levant, the new findings using the entire genome are surprising. “It was still quite remarkable to observe such a striking degree of genome-wide relatedness of DNA markers among Jews from communities that have been historically and geographically dispersed,” he said. “In addition, the remaining very strong overlap in this genome-wide signal with a Levantine Near East signature was also more striking than we might have expected.”
Exceptions to the Rule
Two Jewish communities - Ethiopian and Indian Jews - showed a very different pattern. These groups turned out to be genetically much closer to their neighbors, although Y-chromosome studies do show links back to the Levant along the male line. It’s likely that the history of these groups involved much more genetic and religious interchange with neighboring groups than was true for most other groups.
Connections Confirmed
A separate study headed by Dr. Harry Ostrer at New York University’s Langone Medical Center reached similar conclusions. As reported in the June 3, 2010 issue of the American Journal of Human Genetics, Ostrer’s group also studied the entire genomes of a variety of Jewish and non-Jewish groups, and found a high degree of relatedness that can be traced back to the Middle East.
The determined that the genetic divergence of European Jews from the Middle East dates back approximately 2500 years, again supporting the theme of historical identity flowing from Biblical times.
“We have shown that Jewishness can be identified through genetic analysis, so the notion of a Jewish people is plausible,” says Dr. Ostrer. “Yet the genomes of the Jewish Diaspora groups have distinctive features that are representative of each group’s genetic history.”
It appears that most of the seeds scattered throughout the world during the 26 centuries of the Jewish Diaspora have in fact not fallen far from the tree.
Journal reference: Doron Behar et al., "The Genome-wide structure of the Jewish people," Nature, 9 June, 2010 (doi: 10.1038/nature09103).
Robert Adler - Robert Adler is a science and technology reporter and book author. He divides his time between Santa Rosa, California and Oaxaca, ...
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