Genetic studies of DNA
See also: Y-chromosomal Aaron, Genealogical DNA test, and Matrilineality
Despite the evident diversity displayed by the world's distinct Jewish populations, both culturally and physically, genetic studies have demonstrated most of these to be genetically related to one another, having ultimately originated from a common ancient Israelite population that underwent geographic branching and subsequent independent evolutions.[24]
A study published by the National Academy of Sciences found that "the paternal gene pools of Jewish communities from Europe, North Africa, and the Middle East descended from a common Middle Eastern ancestral population", and suggested that "most Jewish communities have remained relatively isolated from neighboring non-Jewish communities during and after the Diaspora".[24] Researchers expressed surprise at the remarkable genetic uniformity they found among modern Jews, no matter where the diaspora has become dispersed around the world.[24]
Moreover, DNA tests have demonstrated substantially less inter-marriage in most of the various Jewish ethnic divisions over the last 3,000 years than in other populations.[25] The findings lend support to traditional Jewish accounts accrediting their founding to exiled Israelite populations, and counters theories that many or most of the world's Jewish populations were founded by entirely gentile populations that adopted the Jewish faith, as in the notable case of the historic Khazars.[25][26] Although groups such as the Khazars could have been absorbed into modern Jewish populations — in the Khazars' case, absorbed into the Ashkenazim — it is unlikely that they formed a large percentage of the ancestors of modern Ashkenazi Jews, and much less that they were the genesis of the Ashkenazim.[27]
Even the archetype of Israelite-origin is also beginning to be reviewed for some Jewish populations amid newer studies. Previously, the Israelite origin identified in the world's Jewish populations was attributed only to the males who had migrated from the Middle East and then forged the current known communities with "the women from each local population whom they took as wives and converted to Judaism".[28] Research in Ashkenazi Jews has suggested that, in addition to the male founders, significant female founder ancestry might also derive from the Middle East, with about 40% of the current Ashkenazi population descended matrilineally from just four women, or "founder lineages", that were "likely from a Hebrew/Levantine mtDNA pool" originating in the Near East in the first and second centuries CE.[28]
Points in which Jewish groups differ is largely in the source and proportion of genetic contribution from host populations.[29][30] For example, Teimanim differ from other Mizrahim, as well as from Ashkenazim, in the proportion of sub-Saharan African gene types which have entered their gene pools.[29] Among Yemenites, the average stands at 35% lineages within the past 3,000 years.[29] Yemenite Jews, as a traditionally Arabic-speaking community of local Yemenite and Israelite ancestries,[30] are included within the findings, though they average a quarter of the frequency of the non-Jewish Yemenite sample.[29] The proportion of male indigenous European genetic admixture in Ashkenazi Jews amounts to around 0.5% per generation over an estimated 80 generations, and a total admixture estimate "very similar to Motulsky's average estimate of 12.5%."[24]
DNA analysis further determined that modern Jews of the priesthood tribe — "Kohanim" — share a common ancestor dating back about 3,000 years.[31] This result is consistent for all Jewish populations around the world.[31] The researchers estimated that the most recent common ancestor of modern Kohanim lived between 1000 BCE (roughly the time of the Biblical Exodus) and 586 BCE, when the Babylonians destroyed the First Temple.[32] They found similar results analyzing DNA from Ashkenazi and Sephardi Jews.[32] The scientists estimated the date of the original priest based on genetic mutations, which indicated that the priest lived roughly 106 generations ago, between 2,650 and 3,180 years ago depending whether one counts a generation as 25 or 30 years.[32]
Beyond intra-Jewish genetic interrelationships, other findings show that by the yardstick of the Y chromosome, the world's Jewish communities are closely related to Arab Israelis and Palestinians,[33][34] who together as a single population also represent modern "descendants of a core population that lived in the area since prehistoric times", albeit religiously Christianized and later largely Islamized, and both ultimately culturally Arabized.[33] The authors of one of the studies wrote that "the extremely close affinity of Jewish and non-Jewish Middle Eastern populations observed ... supports the hypothesis of a common Middle Eastern origin".[24]
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