90% of living Jews are European (Askenazi) Jews. There are two theories of the origin of European Jewry: the Rhineland Hypothesis contends that European Jews fled Palestine after the Roman destruction of the Temple in 70 A.D. or after the Muslim conquest of Palestine in 637 A.D., migrated into Europe via Italy and Spain, then settled along the Rhine, before being driven eastward by persecution. The use of Yiddish, a High German dialect, by Ashkenazi Jews provides substantive support for their origin somewhere in Germany.
The alternative Khazar Hypothesis, popularized by Arthur Koestler, argues that nearly all European Jews really descend from the Khazars, a Turkish-speaking people, who converted to Judaism en masse in the 8th century.
New genetic evidence produced by a study by Geneticist Eran Elhaik of the Johns Hopkins School of Public Health in Baltimore, published in the British journal Genome Biology and Evolution, on The Missing Link of Jewish European Ancestry: Contrasting the Rhineland and the Khazarian Hypotheses provides strong support for the Khazar Hypothesis.
Thus far… the Khazars’ contribution has been estimated only empirically, as the absence of genome-wide data from Caucasus populations precluded testing the Khazarian hypothesis. Recent sequencing of modern Caucasus populations prompted us to revisit the Khazarian hypothesis and compare it with the Rhineland hypothesis. We applied a wide range of population genetic analyses to compare these two hypotheses. Our findings support the Khazarian hypothesis and portray the European Jewish genome as a mosaic of Near Eastern-Caucasus, European, and Semitic ancestries, thereby consolidating previous contradictory reports of Jewish ancestry. We further describe a major difference among Caucasus populations explained by the early presence of Judeans in the Southern and Central Caucasus.
In the same issue, Danielle Venton summarized the conclusion of “the first scientific paper to prove the Khazarian Hypothesis and reject the Rhineland Hypothesis.”
When Behar et al. published “The genome-wide structure of the Jewish people” in 2010, Elhaik decided to investigate the question that had intrigued him for so long. Using data published by Behar, he calculated seven measures of ancestry, relatedness, and geographical origin. Though he used some of the same statistical tests as prior studies, he chose different comparisons.
“Results in the current literature are tangled,” Elhaik says. “Everyone is basically following the same assumption: Ashkenazi Jews are a population isolate, so they are all similar to one another, and this is completely incorrect.”
Previous studies had, for example, combined the question of similarity among and between Jewish populations and the question of ancestry and relatedness to non-Jewish populations. Elhaik viewed these questions separately. Jewish communities are less homogeneous than is popularly thought, he says, with Jewish communities along the former Khazarian border showing the most heterogeneity.
His second question centered on ancestry: When comparing Jewish communities to their non-Jewish neighbors, Caucasus or Levant (Middle Eastern) populations—which is the closest to Jews? “All Eurasian Jewish communities are closer to Caucasus populations,” he writes, with Central European Jews closer to Italian non-Jews as the exception. Not one of the eight evaluated Jewish populations were closer to Levant populations.