Ashkenazi Jews are not inbred

By Razib Khan | July 20, 2012 9:59 am

Jews, and Ashkenazi Jews in particular, are very genetically distinctive. A short and sweet way to think about this population is that they’re a moderately recent admixture between a Middle Eastern population, and Western Europeans, which has been relatively isolated due to sociocultural forces. As far as their inbreeding, well, here’s one recent paper, Signatures of founder effects, admixture, and selection in the Ashkenazi Jewish population: To explore the amount of genetic variation within the AJ and European populations, we first measured the mean heterozygosity. Surprisingly, we found a higher level of heterozygosity among AJ individuals compared with Europeans…confirming speculation made in one recent report and a trend seen in another…Although this difference may appear small, it is highly statistically significant because of the large number of individuals and markers analyzed, even after pruning SNPs that are in high LD. The higher diversity in the AJ population was paralleled by a lower inbreeding coefficient, F, indicating the AJ population is more outbred than Europeans, not inbred, as has long been assumed…The greater genetic variation among the AJ population was further confirmed using a pairwise identity-by-state (IBS) permutation test, which showed that average pairs of AJ individuals have significantly less genome-wide IBS sharing than pairs of EA or Euro individuals…Thus, our results show that the AJ population is more genetically diverse than Europeans. How could Ashkenazi Jews be more diverse? Look at what I wrote above, and what most people intuitively assume: Ashkenazi Jews are an admixed population, so they likely carry the alleles unique to both Western Europeans and Middle Eastern peoples! On the other hand, Ashkenazi Jews do have a lot of the genome identical by descent, as befits a population which has long been endogamous, and entered into a recent population expansion from a more modest base.

Image credit: Georges Beard.

  • simplicio

    Could periodic migrations be an explanation? The Ashkenazi moved from elsewhere in the Roman empire to Northern Europe in the late Roman early medieval period, then from Western Europe/Germany to Eastern Europe and Russia in the late Medieval period and then to Israel and the US during the 20th century.

    I imagine even if they bred primarily within their own village between migrations, each migration would “mix” the various villages together to form new communities and lead to less “inbred” genome.

  • toto

    they’re a moderately recent admixture between a Middle Eastern population, and Western Europeans,

    I thought the recent papers had shown that the European component was actually South-East European (Greece/Italy)? Or did I just misread it?

    The paper you linked to has the Ashkenazi sitting between Levant and Southeast Europe (Figure 2). However, maybe it just means a small West European component with a large Levant component, with the weighted average falling over the Mediterranean by chance?

    You know what would be awesome though? Doing the same with Muslims. Not just the Sayyeds, everyone. A big STRUCTURE plot showing a thin component that would connect South Asian and Moroccan Muslims, but not Hindus or Moroccan Jews, and that would grow bigger as you get closer to Hijaz. Voila, 2 billion “para-Sayyeds”! Sons of the desert arise!

    Hell, I’m pretty sure that could get funding from some bored Saudi royal.

  • http://jaymans.wordpress.com/ JayMan

    As populations tend to do, I’d imagine that Jews picked up genes from where ever they went (or at least many such places), because it seems that Ashkenazi Jews seem to have physical features similar to those peoples in the area from they originate (i.e., Jews from Western Europe have Germanic features, and Jews from Eastern Europe have Slavic features, for example).

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    #2, i include italy as western europe. i’ve proposed the sayyed project. interesting idea of getting funding. someone should do it.

  • qohelet

    JayMan: As the genetic results would suggest, there are plenty of Ashkenazim who look Mediterranean/West Asian and plenty who look Western European, but not all that many who look Slavic. Maybe among recent Russian “Jewish” types who made it to Israel via Law of Return, but not in general.

  • Bolek

    #5 “not all that many who look Slavic”

    Some do look Slavic. Natalie Portman pictured here for example has Polish/Russian/East European roots and looks very Slavic.

  • http://forwhattheywereweare.blogspot.com/ Maju

    I don’t see any strong European admixture signature among Ashkenazim (there is some but it’s low-level) when Anatolian (or nearby) populations are included in the comparison. Only when an artificial blank is left between the Levant and Europe then Ashkenazim appear as “intermediate” but in fact they (and other Western Jews: Sephardites, Moroccan Jews) are essentially as intermediate as Cypriots or Turks are themselves and actually cluster extremely well with Cypriots specially (followed by Turks, Armenians…)

    Refs. Bauchet 2007 (Ashkenazim cluster with Greeks and Armenians vs. other Europeans), Atzmon 2010 (Western Jews cluster with Turks and Cypriots, specially Cypriots, Ashkenazim show at best a very weak tendency towards Europeans) and Behar 2010 (Western Jews show nearly identical Admixture signature to Cypriots, with Ashkenazi being only slightly more European than other Western Jews).

    However when I tried to compare Western Jews with various West Asians (Turks, Cypriots and four Levant peoples) I found that both Ashkenazim and Moroccan Jews quickly converged to their own distinct clusters (what I attributed to inbreeding or maybe very intense founder effect in the Middle Ages, something like Northern and Western Roma maybe who descend of some one thousand founders), so I could not work with them and had to limit myself to work with Sephardites, who are less homogeneous but again show a Cypriot (and to lesser extent Turkish) genetic signature.

    But I guess that strong Medieval founder effect could have caused this kind of genetic “compaction”, while still being able to retain or restore genetic diversity by means of admixture with different populations (Europeans and also Mediterranean Jews surely). My best guess because it’s not a simple problem, still comparing only with Europeans (as Bray did) is not really too informative in any case.

  • qohelet

    Besides evidence from the maternal side of extensive European admixture and strong paternal similarities to Levantine populations (intermediate J1/J2 ratio, high E-M34), the circumstantial fact is that too many Ashkenazim are light-featured for the shift to be mostly Anatolian, Aegean, or Italian.

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    #7, LD in the follow up post is evidence of admixture between two distinct populations. #8, how about selection? i agree that it is hard to see how so many ashk jews can be as fair featured as they are being a combination of tuscans + assyrians (a good approximation).

  • qohelet

    The selection hypothesis hasn’t been explored enough – to that end, there are always claims about an elusive study claiming Holocaust survivors were lighter-featured than European Jews on average – but the amount of time Ashkenazim spent in France and Germany shouldn’t be discounted. Also, why Assyrians rather than Palestinians or Lebanese? I think uniparentals help clarify things a lot in this case.

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    why Assyrians rather than Palestinians or Lebanese? I think uniparentals help clarify things a lot in this case.

    i am convinced by various lines of evidence that christian and jewish middle eastern populations are much better proxies for pre-islamic populations in that region. in particular, there’s now good evidence that muslim populations in the fertile crescent have had substantial arabian and african input (you can see the african pretty clearly in the HGDP palestinian and bedouin samples; far less in the druze).

  • Luke Raines

    Weren’t the Jews involved in the slave trade? Couldn’t the European genes be the result of Jewish slave owners mating with their female gentile slaves?

  • Grey

    “the circumstantial fact is that too many Ashkenazim are light-featured for the shift to be mostly Anatolian, Aegean, or Italian.”

    Unless the Levantines / Anatolians were originally lighter (not saying they were just the logic of it).

    #

    “not all that many who look Slavic”

    I always thought Paul Newman looked Slavic but that may just have been me.

    #

    “Couldn’t the European genes be the result of Jewish slave owners mating with their female gentile slaves?”

    There’s a lot of possibilities but if the root movement was related to banking and money lending then if a group of Jewish money-lenders moved to a new region from the Levant to open up a new franchise then one easy way to compete with the local money-lending families would have been to marry into those familes first and then go back to endogamy once the process was complete. Repeat with each new region / country.

  • Joe Q.

    #13, the “root movement” would have been related more to persecution or expulsion than anything else, and Jews did not really get involved in finance until maybe the 16th century at the earliest — by which time Jewish settlement patterns in Europe were pretty stable.

    Remember also that miscegenation was rare because of religious law on both sides. Conversion to Judaism was considered apostasy in both Christian and Muslim law, the child of an un-converted non-Jewish mother would not have been considered Jewish, regardless of paternity.

  • Kaleberg

    The Jews weren’t big money lenders until the Middle Ages when a lot of other occupations were closed to them. (Of course, this depends on what part of Europe you are talking about.)

  • qohelet

    Not sure about Anatolians, but it’s a fair guess that classical Levantines were lighter than modern-day Levantines. But very unlikely light enough to account for the proportion of light hair and eyes among Ashkenazim.

    Also, Newman’s mother was an ethnic Slovak. His profoundly un-Jewish features are the subject of a great self-referential scene in Exodus, actually.

  • idurar

    It’s funny to see again the bias about modern Levantines being different from the ancient ones. There are certainly several influences in modern populations since the Arabo-Islamic era, from Arabia/North Africa, Eurasia and Sub-Saharan Africa but it does not explain the specificity of the Levant: in any case, ancient Levantine populations were not Anatolians nor Northern Mesopotamians (as modern-day “Assyrians”).

    As for Western Jews (Ashkenazis, Sephardis etc), it’s pretty clear they have European ancestry, more so than Cypriots in various ADMIXTURE analyses. So it’s there, although minor, considering the ratio with the West Asian and Southwest Asian components, the latter being quite high, even for Anatolians for instance, which in my opinion discard the Anatolian hypothesis. Another point is the “Africanity” of the Western Jews: excluding groups with North African ancestry, there are still some hints of African affinity (lineages and autosomally) that are barely present in Assyrians and non-existant further north (Anatolia/Caucasus) and East (Iranic populations).

  • Dm

    Doesn’t identity-by-state permutations test reflect a counterbalance of admixture vs. inbredness + drift? Rather than just the degree of inbreeding? Since the population has strong admixture effects, a low IBS doesn’t exclude strong inbreeding, does it?

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    ancient Levantine populations were not Anatolians nor Northern Mesopotamians (as modern-day “Assyrians”).

    provide a citation for what you’re talking about here or i’ll ban you (i’ll wait 24 hours). i’m specifically looking for statistical genetic validation here.

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    #18, good points.

  • http://discovermagazine.com john lovar

    So you don’t look Jewish!!!! I will admit I laugh when I hear this. Seems like Jewish means not so good looking or just shy of good looking. I guess i’m not Jewish. LOL Seriously, I wanted to know how the millions of eastern Europeans and Russian Jews could have descended from the the relatively small number of Sephardi migrating across western Europe. Where did all these people migrate from? Is there any evidence of a large pool of people in Central Asia or Caucasus? I have looked at migration maps and its not at all clear why the largest single population of Jews doesn’t seem to have a equally significant source.

  • Karl Zimmerman

    Although the thread might have moved on…

    There are comparably large sub-populations in the Levant which presumably had little recent SSA admixture. Not only the Druze and the Samaritans, but the various Arab Christian populations in Lebanon and Syria. They might have gotten some admixture, particularly in the Mount Lebanon region, from crusaders, but if anything this should have lightened them compared to the Roman-era population, not darkened them.

    For that matter, it wouldn’t be surprising that the Alawites were relatively unadmixed, as until late Ottoman times they were basically a poor, isolated quasi-ethnic group which had little dealings with the greater Islamic world.

    A bit of an aside, but has anyone looked at admixture in the Copts versus Muslim Egyptians?

  • evodevo

    In early Roman republic/empire and Greco-Roman times there were huge Jewish quarters in most cities around the Mediterranean, especially Alexandria in Egypt and in various Greek and Turkish cities. The great diaspora following the unsuccessful second Jewish rebellion in 134-5 was when a large part of the Palestinian Jewish population dispersed out of Judea. I imagine there was at least some admixture going on in those colonies, which would confuse the genetic picture before medieval times.

  • https://plus.google.com/109962494182694679780/posts Razib Khan

    #23, there are references in the NT to mixed people in the jewish communities. in fact, the talmud itself makes reference to proselytes.

  • TD

    Ashkenazi Jews are genetically diverse ofcourse. For a modern day Semitic-Mediterranean population thats a given, considering the opportunity Jews have long had to mingle with their Mizrahi brethren and the limited, though significant waves of back and forth conversions to Judaism in North Africa and Iberia, attracting possibly gentiles thought to be converso’s. Its expected that through acquiring a minority of Berber admixture through proselytism in North Africa that they would be more genetically diverse than Northern Europeans and majority of Southern Europeans, in the same way Sicilians are. Their East-African affinity too is likely a byproduct of their genetic continuity since being formed by god-fearers in the Levant and Egypt particularly, prior to their expulsion. (the Druze and Samaritans also share this affinity) This too only makes them further genetically diverse.

    A population can still be genetically diverse and relatively more recently inbred. The post 13th century explosion of Ashkenazi Jewish population numbers, exceeding Sephardim and Mizrahim rapidly and the fact that they demonstrage great IBD sharing with non-Mizrahi Jews certainly suggests inbreeding of a selective sort. This does not mean they are the definition of ‘inbred’, though alike Israeli-Bedouins, they are consequently more susceptible to a greater variety of rarer diseases.

    The way in which Ashkenazim often deviate from Sephardim in West-Eurasian plots towards West Slavs IMO might hint at the possibility of very minor recent admixture. Going off oracle results produced by an amaeture anthropologist, this cannot be more than ten percent, if you were to assume the Ashkenazim are an off-shoot of the Italian Jews (similar genetic profile to Eastern Sephardim) namely from Atzmon study, who we know they share great IBD with.

    ‘However when I tried to compare Western Jews with various West Asians (Turks, Cypriots and four Levant peoples) I found that both Ashkenazim and Moroccan Jews quickly converged to their own distinct clusters (what I attributed to inbreeding or maybe very intense founder effect in the Middle Ages, something like Northern and Western Roma maybe who descend of some one thousand founders), so I could not work with them and had to limit myself to work with Sephardites, who are less homogeneous but again show a Cypriot (and to lesser extent Turkish) genetic signature.’

    I remember looking at this blog post. The data output was great, though I disagreed with a few of your conclusions and discussion of those findings. If you limit yourself to using just Anatolian and Levantine samples, this biases your findings by not exploring their source of Mediterranean ancestry, better captured with the inclusion of North Africans and Southern Europeans. The greater genetic diversity of these Levantine populations, which demonstrated the same stubborness as the MAJ and AJ in your analysis also inherently flawed the experiment, since this cannot be factored out using either admixture or structure. Its all relative, you can say they are an East-Mediterranean population (something I can agree with) due to their similarity with Cypriots, though if you perform continental and not regional admixture analyses, you will find Cypriots are more similar to the Druze than say Turks or Armenians. The hypothesis for a profoundly Anatolian origin of the Jews is unlikely, as they deviate from Europeans more towards populations like the Druze, Iraqi Jews, some Syrians and Lebanese.

    ‘i agree that it is hard to see how so many ashk jews can be as fair featured as they are being a combination of tuscans + assyrians (a good approximation).’

    If Ashkenazi Jews were to be split in 50/50, with a European average and a Middle Eastern average, going off the oracle results I have saved, this approximation is not far off, if I use only those from the Harappa oracle tool . . . This was the best and first 50/50 result found.

    [33,] “53.7% druze_hgdp_42 + 46.3% spaniard_1000genomes_98″ “2.5185”

    These were the top 10

    HarappaOracle(“ashkenazy-jew_behar_21″,k=500,mixedmode=T)
    [,1] [,2]
    [1,] “ashkenazy-jew_behar_21″ “0”
    [2,] “25% bulgarian_yunusbayev_13 + 75% sephardic-jew_behar_19″ “1.0377”
    [3,] “65.5% ashkenazi_harappa_4 + 34.5% sephardic-jew_behar_19″ “1.0691”
    [4,] “24.6% romanian_behar_16 + 75.4% sephardic-jew_behar_19″ “1.1884”
    [5,] “41.2% lebanese_behar_7 + 58.8% tuscan_1000genomes_11″ “1.5613”
    [6,] “11.9% russian_behar_2 + 88.1% sephardic-jew_behar_19″ “1.6507”
    [7,] “72.2% ashkenazi_harappa_4 + 27.8% morocco-jew_behar_15″ “1.7084”
    [8,] “42.4% lebanese_behar_7 + 57.6% tuscan_hgdp_8″ “1.7455”
    [9,] “87% sephardic-jew_behar_19 + 13% ukranian_yunusbayev_20″ “1.8247”
    [10,] “43.5% lebanese_behar_7 + 56.5% tuscan_hapmap_102″ “1.8514”

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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