SCIENCE: Jews as Part of the Genetic Landscape of the Middle East

  • mwolverine

    Posts: 5411

    Mar 05, 2018 6:37 PM GMT
    The Y Chromosome Pool of Jews as Part of the Genetic Landscape of the Middle East

    A sample of 526 Y chromosomes representing six Middle Eastern populations (Ashkenazi, Sephardic, and Kurdish Jews from Israel; Muslim Kurds; Muslim Arabs from Israel and the Palestinian Authority Area; and Bedouin from the Negev) was analyzed for 13 binary polymorphisms and six microsatellite loci. The investigation of the genetic relationship among three Jewish communities revealed that Kurdish and Sephardic Jews were indistinguishable from one another, whereas both differed slightly, yet significantly, from Ashkenazi Jews. The differences among Ashkenazim may be a result of low-level gene flow from European populations and/or genetic drift during isolation. Admixture between Kurdish Jews and their former Muslim host population in Kurdistan appeared to be negligible. In comparison with data available from other relevant populations in the region, Jews were found to be more closely related to groups in the north of the Fertile Crescent (Kurds, Turks, and Armenians) than to their Arab neighbors. The two haplogroups Eu 9 and Eu 10 constitute a major part of the Y chromosome pool in the analyzed sample. Our data suggest that Eu 9 originated in the northern part, and Eu 10 in the southern part of the Fertile Crescent. Genetic dating yielded estimates of the expansion of both haplogroups that cover the Neolithic period in the region. Palestinian Arabs and Bedouin differed from the other Middle Eastern populations studied here, mainly in specific high-frequency Eu 10 haplotypes not found in the non-Arab groups. These chromosomes might have been introduced through migrations from the Arabian Peninsula during the last two millennia.

    Previous investigations based on binary Y chromosome polymorphisms suggested a common origin for Jewish and non-Jewish populations living in the Middle East (Santachiara-Benerecetti et al. 1993; Hammer et al. 2000). Our recent study of high-resolution microsatellite haplotypes demonstrated that a substantial portion of Y chromosomes of Jews (70%) and of Palestinian Muslim Arabs (82%) belonged to the same chromosome pool (Nebel et al. 2000). Of those Palestinian chromosomes, approximately one-third formed a group of very closely related haplotypes that were only rarely found in Jews. Altogether, the findings indicated a remarkable degree of genetic continuity in both Jews and Arabs, despite their long separation and the wide geographic dispersal of Jews.

    In the present study, we examined the genetic relationship among three Jewish communities, the Ashkenazi, Sephardic, and Kurdish Jews, who were geographically separated from each other for many centuries. By comparing data from these groups with data from other relevant populations, we looked for information about how the Y chromosomes of Jews fit into the genetic landscape of the Middle East.

    Eu 10 was the most frequent haplogroup among Palestinian Arabs and Bedouin (table 1), with a low haplotype diversity (h=.82) in both populations. Forty-two percent of the haplotypes and 47% of the chromosomes in Eu 10 were only observed in the two Arab populations. Palestinians had ∼42% of their Eu 10 chromosomes in common with Bedouin but had only 11% in common with the other four populations. The commonalities with the other four populations resulted from the sharing of low-frequency haplotypes. In contrast, in all the other haplogroups (except Hg 7, which was observed in only two Palestinian individuals in the present study), Palestinians shared 20%–46% of their chromosomes with the four non-Arab populations. Thus, the genetic distinctiveness of the Palestinian Arabs is mainly seen in the presence of specific high-frequency Eu 10 haplotypes not found in non-Arab groups.

    the majority of contemporary Jews descended from the ancient Israelites that had lived in the historic land of Israel until ∼2000 years ago. Many of the Jewish diaspora communities were separated from each other for hundreds of years. Therefore, some divergence due to genetic drift and/or admixture could be expected. However, although Ashkenazi Jews were found to differ slightly from Sephardic and Kurdish Jews, it is noteworthy that there is, overall, a high degree of genetic affinity among the three Jewish communities. Moreover, neither Ashkenazi nor Sephardic Jews cluster adjacent to their former host populations, a finding that argues against substantial admixture of males. These findings are in accordance with those described by Hammer et al. (2000).

    Kurdish Jews are not closer to Muslim Kurds than are Sephardim or Ashkenazim, suggesting that reciprocal male gene flow between Jews in Kurdistan and their Muslim host population was below the detectable level. The acceptance of Judaism by the rulers and inhabitants of the Kurdish Kingdom of Adiabene in the first century of the Common Era resulted in the assimilation of non-Jews into the community (Brauer 1993). This recorded conversion does not appear to have had a considerable effect on the Y chromosome pool of the Kurdish Jews.

    Iraqi and North African Jews are both considered to belong to the ethnically heterogeneous group of Sephardim, although the two communities were probably separated for 1,000 years. The Jewish community in Iraq was formed by deportees during the Assyrian and Babylonian exiles (723 and 586 b.c.) and by waves of immigrants in subsequent centuries. Communities in various North African countries and in the Iberian Peninsula were established primarily in the course of the Muslim conquest in the seventh and eighth centuries. After their expulsion from Spain in 1492 a.d., Jews were dispersed in North Africa and Southern Europe (Ben-Sasson 1976). The two Sephardic communities and Kurdish Jews are very closely related to each other. Thus, these populations seem to have preserved, to a large extent, their original Y chromosome pools.

    Jews and Palestinian Arabs share a large portion of their Y chromosomes, suggesting a common ancestry (Nebel et al. 2000). Surprisingly, in the present study, Jews were found to be even closer to populations in the northern part of the Middle East than to several Arab populations. It is worth mentioning that, on the basis of protein polymorphisms, most Jewish populations cluster very closely with Iraqis (Livshits et al. 1991) and that the latter, in turn, cluster very closely with Kurds (Cavalli-Sforza et al. 1994).

    The Y chromosome variation of Muslim Kurds falls within the spectrum observed in other populations (Turks and Armenians) living in the same region. The three populations are closer to Jews and Arabs than to Europeans.
  • mwolverine

    Posts: 5411

    Mar 05, 2018 6:39 PM GMT
    Palestinian Arabs and Bedouin

    Bedouin are largely nomadic Arab herders, with a tribal organization. They live in all Arab countries, constituting about one tenth of the population (Cavalli-Sforza et al. 1994). The Bedouin population of the Negev desert was found to be most distant from Jews and Muslim Kurds and to be closely related only to Palestinians. Both these Arab populations differ from the other Middle Eastern groups sampled for the present study, mainly in having a higher frequency of Eu 10 chromosomes, the majority of which they share with each other.

    the Y chromosomes in Palestinian Arabs and Bedouin represent, to a large extent, early lineages derived from the Neolithic inhabitants ["∼10,500 years ago"] of the area and additional lineages from more-recent population movements. The early lineages are part of the common chromosome pool shared with Jews (Nebel et al. 2000). According to our working model, the more-recent migrations were mostly from the Arabian Peninsula, as is seen in the Arab-specific Eu 10 chromosomes that include the modal haplotypes observed in Palestinians and Bedouin.

    Historical records describe tribal migrations from Arabia to the southern Levant in the Byzantine period, migrations that reached their climax with the Muslim conquest 633–640 a.d.; Patrich 1995). Indeed, Arab-specific haplotypes have been observed at significant frequencies in Muslim Arabs from Sena (56%) and the Hadramaut (16%) in the Yemen (Thomas et al. 2000). Thus, although Y chromosome data of Arabian populations are limited, it seems very likely that populations from the Arabian Peninsula were the source of these chromosomes. The genetic closeness, in classical protein markers, of Bedouin to Yemenis and Saudis (Cavalli-Sforza et al. 1994) supports an Arabian origin of the Bedouin. The alternative explanation for the distribution of the Arab-specific haplotypes (i.e., random genetic drift) is unlikely. It is difficult to imagine that the different populations in the Yemen and the southern Levant, in which Arab-specific chromosomes have been detected at moderate-to-high frequencies, would have drifted in the same direction.


    The high degree of genetic similarity of the Middle Eastern populations studied here is not reflected in linguistic affinity. The Kurdish language is related to Persian and belongs to the Indo-European family, which sets the Kurds apart from the Semitic-speaking Jews and Arabs and from the Turkic speakers in Turkey (Pelletiere 1984). Like Kurdish, the Armenian language is also of Indo-European origin, but it forms a separate branch within the western group of this family. The high genetic affinity across major language divisions therefore suggests that the Y chromosome pool of Middle Eastern populations is ancient and predates the emergence or introduction of different languages into the region.

    In conclusion, the present study shows that the Middle Eastern populations we analyzed are closely related and that their Y chromosome pool is distinct from that of Europeans. Genetic dating performed in the present study, together with age estimates reported elsewhere (reviewed by Bosch et al. 1999), suggests that the major haplogroups observed in our sample are much older than the populations in which they are found. Thus, the common genetic Middle Eastern background predates the ethnogenesis in the region. The study demonstrates that the Y chromosome pool of Jews is an integral part of the genetic landscape of the region