Two major groups of living Jews (Atzmon et al. 2010)

(Last Update Jun 10)

More on this paper as soon as I read it carefully. Nature News has an overview of the research. This study addresses my question about the extent of Southern vs. Central/European ancestry in Jews.

It is also entirely consistent with my theory that Diaspora Jews are to a certain extent descended from Italian-Balkan-Anatolian groups, among which they lived in Hellenistic-Roman-Late Antique times; my guess is that Middle-Eastern Jews form a distinct group in relation to European/Syrian ones because, unlike them, they had a smaller opportunity of absorbing Euranatolians, and their admixture -if any- came from linguistically (and probably genetically) related Semitic groups.

UPDATE I (Jun 4)

It is a bit frustrating how the authors did not limit themselves to HGDP but also included a wide variety of populations from POPRES, which they bundled together in a fairly arbitrary way:

Next, each of 2407 European subjects was assigned into one of 10 groups based on geographic region: South:Italy, Swiss-Italian; Southeast: Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Greece, Kosovo, Macedonia, Romania, Serbia,Slovenia, Yugoslavia; Southwest: Portugal, Spain; East: CzechRepublic, Hungary; East-Southeast: Cyprus, Turkey; Central:Austria, Germany, Netherlands, Swiss-German; West: Belgium,France, Swiss-French, Switzerland; North: Denmark, Norway,Sweden; Northeast: Finland, Latvia, Poland, Russia, Ukraine;Northwest: Ireland, Scotland, UK.

I don't know exactly why Switzerland should be bundled with Belgium, while Austria with Netherlands, or that Finns would be bundled with Poles, or Albanians, Greeks, and Slavs would be bundled in a broad "Southeast" group. Anyway, the authors don't use this POPRES sample much in their actual paper, although they present some results in the supplement, so I won't dwell on it further.

UPDATE II (Jun 4)

On the left we have panel B from Figure 1 in the paper, which shows the first two principal components in a regional context. Capitalized labels represent Jewish groups. Note that Iranian and Iraqi Jews don't show a particular relationship to Arabs (Bedouins and Palestinians). It would be interesting to see if there is a relationship with Iraqis or Iranians, which might indicate whether admixture with these local groups is responsible for Iranian/Iraqi Jewish distinctiveness. As in previous studies, most other Jews, including Syrian Jews, are located between Europeans and Druze; the lack of non-Jewish Euranatolian populations is especially baffling.

I am particularly interested in the seemingly very close relationship between Greek, Turkish, and Italian Jews. The GRK-TUR relationship is not that puzzling, as these are mostly Ottoman Jews who found themselves on different sides of national borders, and we would not expect them to be any different. But, why would they be so similar to Italian Jews? Speaking of Greek Jews, how many of them are of Romaniote and how many of Sephardic extraction?

UPDATE III (Jun 4)

The STRUCTURE analysis is also quite interesting. Jews seem to lack appreciable levels of East Asian (orange) or Sub-Saharan African (yellow) admixture, or of Central/South Asian admixture (green). The lack of E/C/S Asian admixture is especially damning of the Khazar hypothesis.

We should probably not interpret the three main visible components ("European" blue, "Mozabite" purple, "Near Eastern" pink) as representing ancestral proportions of European, North African, and Near Eastern elements. For example, Mongoloids have some "purple" while it is unlikely that they have North African admixture; so, while purple has an obvious relationship to Mozabites, it is not a good fit for an ancestral population group. Its substantial presence in the Near East also precludes such an easy interpretation.

Nor can we easily infer the percentage of "European" and "Near Eastern" admixture in Jews. The "Pink" element seems to grade from prominence among Iranian Jews to insignificance among Basques, but what did the original European and Jewish groups look like? Depending on how close they were to the Basque and Iranian Jewish end of the gradient, quite different admixture proportions would arise.

In more mathematical terms, a gradient can be represented as a single variable x going from 0 to 1, e.g., pink/(pink+blue) in the STRUCTURE analysis or relative position between Basques and Druze in the PCA figure above. But x can be expressed in an infinite number of ways as a weighted summation of two other numbers between 0 and 1. If ancestral groups were exactly like Basques and Druze or they were exactly pure blue and pure pink, then we could arrive at exact ancestral proportions for living Jews, but unfortunately, unlike situations where clear-cut well-differentiated ancestral groups exist to act as yardsticks, this does not appear -as of yet- to be the case for intra-Caucasoid variation.

UPDATE IV (Jun 4)

From the paper:

Admixture with local populations, including Khazars and Slavs, may have occurred subsequently during the 1000 year (2nd millennium) history of the European Jews. Based on analysis of Y chromosomal polymorphisms, Hammer estimated that the rate might have been as high as 0.5% per generation or 12.5% cumulatively (a figure derived from Motulsky), although this calculation might have underestimated the influx of European Y chromosomes during the initial formation of European Jewry. Notably, up to 50% of Ashkenazi Jewish Y chromosomal haplogroups (E3b, G, J1, and Q) are of Middle Eastern origin,15 whereas the other prevalent haplogroups (J2, R1a1, R1b) may be representative of the early European admixture. The 7.5% prevalence of the R1a1 haplogroup among Ashkenazi Jews has been interpreted as a possible marker for Slavic or Khazar admixture because this haplogroup is very common among Ukrainians (where it was thought to have originated), Russians, and Sorbs, as well as among Central Asian populations, although the admixture may have occurred with Ukrainians, Poles, or Russians, rather than Khazars. In support of the ancestry observations reported in the current study, the major distinguishing feature between Ashkenazi and Middle Eastern Jewish Y chromosomes was the absence of European haplogroups in Middle Eastern Jewish populations.

I would not be so quick to assign haplogroups to European or Middle Eastern origin. For example, G seems to have originated in the Middle East, but it is quite plentiful in substantial parts of Europe. So, while its ultimate origins may be West Asian (it arose in a man who lived in West Asia thousands of years ago), its proximate origin may be European in some particular case.

As I have argued before, I doubt E3b (or E1b1b) was an original Jewish lineage, J2 probably represents Iranian/Euranatolian admixture in Jews, while J1 (or a subset thereof) has strong Semitic connotations.

UPDATE V (Jun 10):

Another paper by Behar et al. (2010) on the same topic.

AJHG doi:10.1016/j.ajhg.2010.04.015

Abraham's Children in the Genome Era: Major Jewish Diaspora Populations Comprise Distinct Genetic Clusters with Shared Middle Eastern Ancestry

Gil Atzmon et al.

Abstract

For more than a century, Jews and non-Jews alike have tried to define the relatedness of contemporary Jewish people. Previous genetic studies of blood group and serum markers suggested that Jewish groups had Middle Eastern origin with greater genetic similarity between paired Jewish populations. However, these and successor studies of monoallelic Y chromosomal and mitochondrial genetic markers did not resolve the issues of within and between-group Jewish genetic identity. Here, genome-wide analysis of seven Jewish groups (Iranian, Iraqi, Syrian, Italian, Turkish, Greek, and Ashkenazi) and comparison with non-Jewish groups demonstrated distinctive Jewish population clusters, each with shared Middle Eastern ancestry, proximity to contemporary Middle Eastern populations, and variable degrees of European and North African admixture. Two major groups were identified by principal component, phylogenetic, and identity by descent (IBD) analysis: Middle Eastern Jews and European/Syrian Jews. The IBD segment sharing and the proximity of European Jews to each other and to southern European populations suggested similar origins for European Jewry and refuted large-scale genetic contributions of Central and Eastern European and Slavic populations to the formation of Ashkenazi Jewry. Rapid decay of IBD in Ashkenazi Jewish genomes was consistent with a severe bottleneck followed by large expansion, such as occurred with the so-called demographic miracle of population expansion from 50,000 people at the beginning of the 15th century to 5,000,000 people at the beginning of the 19th century. Thus, this study demonstrates that European/Syrian and Middle Eastern Jews represent a series of geographical isolates or clusters woven together by shared IBD genetic threads.

Link