Thursday, May 14, 2015

New Paper on Ashkenazi Jews: We should wait for ancient samples from the Levant

Seems as though we're in for a new paper on the ancestry of Ashkenazi Jews which seems to posit that they do indeed have European admixture but mostly of Southern European/ Italic origins.

It seems to be a rather valiant effort, mind you and even finds some Eastern European ancestry in Ashkenazi Jews but I must agree with David Wesolowski over at Eurogenes (the blog's author); this paper looks to be on to something but there's one key flaw; it's using modern populations and not ancient samples to make its inferences. This is relevant because if we're learning one thing through the constant sampling of ancient remains across Europe is that "Modern Populations Ancient Populations". 

This principal seems to even ring true for some ancient populations that existed as early as ~2,500 years ago. They've sampled three ancient Etruscans from about ~2,500 years in the past and surprisingly enough; they do not seem to be well-represented by modern day Tuscans in Italy despite modern Tuscany and surrounding parts of the Italian peninsula corresponding well with where the Etruscans once were. [1]

Modern populations in my humble opinion are simply not a viable proxy for the peoples who lived where they now toil away a few or several thousand years ago. They're surely descended from those people to some great extent but clearly not a frozen image of said ancient group's genome. 

And herein lies the problem; we lack ancient genomes from the Levant. And therefore we honestly lack a true proxy for what could be an ancient Levantine. David voices this concern on his blog; posting that he believes the ancient Near East wasn't genetically what it is now. And he's probably right. We can't be sure exactly how Southern European Ashkenazi Jews are because we lack an example of what a "pure" pre-Western Jew exodus and even pre-Arabization/ Arabian conquest Levantine looked like so we lack something concrete to compare them to and see just how much they've shifted away from what Yahudim were like before their exodus.

Modern Arabs in the Levant are mostly the Arabized descendants of former Aramaic speakers who do seem to clearly have some Peninsula Arabian genetic input as can be surmised from their
Haplogroups as you can see for example through the J1 Project. This effect seems to be greater for example in Muslim Levantines who prove somewhat distinct from their Christian neighbors though not at all by any note worthy amount. [2]

Cypriots may prove a good example of the ancient Levant perhaps because they're an island population given that Sardinians; a fellow island population come out to be a genetic isolate in Europe [3] [4], predominantly descended from Early European Farmers with very little Steppe derived ancestry. Islanders can at times prove a preservation of what close by mainland populations used to be like as they could have avoided whatever land expansion affected their mainland kin. 

However Cypriots who speak Greek for example could very well have Southern European admixture due to becoming Hellenized and shifting to Greek linguistically. Though any reader reading this must forgive me as I'm not too knowledgeable about Cypriot genetics other than that Cypriots seem to look like a Levantine population (similar to Western Jews and Arab Levantines more than anything else) especially in terms of their fundamental ancestral components and the proportions they have them at (Eurogenes K=8).


Other groups like Samaritans may prove to be reliable genetic isolates of the Levant but still; we're learning via Europe time and time again that assuming modern populations are a perfect example of their ancient predecessors is a slippery way of seeing things. 

Suppose Levantines from ~2,000 years ago or from right before the ancestors of Ashkenazi Jews departed prove to actually carry a notable amount of Western European Hunter-Gatherer and Early European Farmer-esque ancestry. Wouldn't that prove the results of this paper (the exact proportions of Italic-esque ancestry in Ashkenazis) to be incorrect? And Ashkenazim would suddenly look a lot more Near Eastern.

I'm doing a lot of blabbering here to say something quite simple in truth. We lack ancient samples from the Levant and neither Western Jews nor Arab Levantines are to be taken as a trustworthy example of the ancient Levant as both groups have seemingly experienced non-Levantine gene flow, one from Europe (mostly from Southern Europe) and the other from the Arabian Peninsula. Until we have ancient individuals from the Levant to compare these populations to; we should remain cautious about trusting how non-Levantine either group is.

However I do not at all doubt the core of what this paper will be preaching (I did once though...) which is that Ashkenazim do seemingly have some substantial non-Levantine admixture mostly of a Mediterranean European nature and also a much much smaller amount of Eastern European admixture.


Reference List




 

6 comments:

  1. The Rhineland valley hypothesis is the most regarded amongst Historians so far. One of the first prominent Jewish family of Germany , Kalonymos , were from Toscany. Jews in Italy could have come from various places such as neighbouring Greece and Anatolia for instance Jews of Cyprus were expelled and formed a large community ! As slaves and merchants from Levant and Alexandria heck we got the whole picture ! They certainly would not have gotten in Italy from Khazaria !! You said it with the best word sur : We need ancient aDNa from the Levant to get a better understanding of the Master Piece! Cheers !!

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  2. In Carmi et. al.'s 2014 paper, Iraqi Jews plot very close to Palestinians - who, in turn, plot closer to Iraqi Jews than to Bedouins. This would appear to weigh against any drastic genetic change in the sedentary population of the southern Levant as a result of the Arab Muslim conquest.

    The 50-50 estimate for Levantine and Southern European contributions to the Ashkenazi gene pool is, therefore, probably correct. It also makes good sense from what we know about the history of Jews in the Greco-Roman world.

    There may well be a smattering of genes in East European Jews derived from the mixed Khazar populace - just as there are a smattering of Yiddish words derived from an apparently Altaic source. But the Rome-to-Rhineland sequence makes much better sense of the big picture.

    Of course, one could argue that we won't know for sure until we've excavated Khazar skeletons and extracted DNA from them. But when that happens, I suspect it will look more like DNA from Crimean Tatars or Chuvash, not people from the Caucasus.

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    Replies
    1. "In Carmi et. al.'s 2014 paper, Iraqi Jews plot very close to Palestinians - who, in turn, plot closer to Iraqi Jews than to Bedouins. This would appear to weigh against any drastic genetic change in the sedentary population of the southern Levant as a result of the Arab Muslim conquest."


      The Iraqi Jews in Carmi et al. don't seem to cluster too grossly different from how Iraqi Jews normally cluster.


      Eurogenes:

      http://oi62.tinypic.com/30m4em9.jpg


      Carmi et al. :

      http://oi61.tinypic.com/2efumo7.jpg


      Those are two distinct kinds of PCAs however (keep that in mind). But nevertheless-> Iraqi Jews are a generally well understood population at this point from what I know and they're not at all anything like Palestinians despite the close clustering. Iraqi and Iranian Jews are more or less "Mesopotamian" (nearly indistinguishable from Assyrians or Iraqi Mandaeans) but share IBD segments with Ashkenazi and Sephardi Jews demonstrating ancient shared ancestry between them and "Western Jews".



      Here's an example of Levantines, Arabian Bedouin and "Mesopotamians" via Eurogenes K=8:

      https://docs.google.com/spreadsheets/d/1Zs2DKkkHpShin-u1OCHd7t2Y_ygnGNl3yhIyB5csvHE/pubchart?oid=597357883&format=interactive


      Notice the distinction between Iraqi Jews and Palestinians and Iraqi Jews' extreme similarity to Assyrians. Iraqi and Iranian Jews mostly look like a Jewish population that's mixed so heavily with Mesopotamian populations that they've become nearly indistinguishable from them hence they too are not to be taken as representative of the ancient Levant tbh.


      "This would appear to weigh against any drastic genetic change in the sedentary population of the southern Levant as a result of the Arab Muslim conquest. "

      At this point it really is fairly obvious that Levantine Arabs are Peninsula Arabian admixed, I really see no denying this... It's noticeable
      via their uniparentals for example (consult the J1 Project)...


      --

      Side note:

      http://www.forumbiodiversity.com/showthread.php/41453-Eurogenes-v3?p=1192646&highlight=#post1192646

      ^ The guy's an Assyrian, observe his "best fits"...

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  3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3032072/#bib20
    Gives paternal estimate for Ashkenazi Y-DNA as being at most 50%. However, this looks very much contrary to the paper they themselves reference:
    http://www.pnas.org/content/97/12/6769.full
    According to the above, >80% of paternal Ashkenazi lineage is non-mixed.
    Interestingly, according to:
    Igor Lipovsky's "Early Israelites: Two Peoples, One History" there is small but real Indo-European component of likely Achaean origin (coming via tribe of Dan and from the Philistines), that ought to be included in consideration of what got mixed in into Judean DNA pre-2nd AD. Hence, it's possible to be bold in saying that somewhere above 90% of Ashkenazi DNA is from Judea/Palestinian province.

    As to maternal DNA, due to discussion here:
    https://westhunt.wordpress.com/2013/10/08/jewish-moms/
    it appears that Behar's conclusions included in the paper regarding mtDNA is incorrect/misleading. Maternal contribution in Ashkenazim attributable to Levant is no more than 10%.

    Hence it does seem that 90% and 10% figure is equivalent, on average, to the 50-50 estimate, though of course the latter hides the supreme importance of paternal contribution in maintaining the genetic-cultural identity.

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  4. Northeast African Jews are often left out. The spread of WHG type ancestry in much of the Middle East, for both christians and muslims, could suggest that it was well diffused in the past, with consideration of most Jews. Then, it could be a relic of Hellenization, or North African ancestry (spike in East and West African components + WHG) between Arabs. It is also possibly all of the factors (a legacy of Hellenization in Jews, and a legacy of slave trade, pan-Arab admixture, and Indo-European contact in Arabs.)

    But the Jews of Northeast Africa significantly resemble Palestinian Christians. Jewish communities in Northeast Africa are arguably among the most ancient. Their host populations like Libyans and Tunisians are very much different than Levantines, so it is possible that they are the best representation of ancient Judeans among Jews. Palestinian Christians are pretty similar to Samaritans. When you take the J2 man from Britian into account (my opinion is that he is our first ancient southern Levantine), the Levant may not be so different. David of Eurogenes also mentioned that he likely belonged to a similar endogamous population.

    European Jews and Cypriots both probably have significant Southeast European ancestry.

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