This podcast is brought to you by the Albany Public Library main branch and the generosity of listeners like you. What is a podcast? God daddy, these people talk as much as you do! Razib Khan's Unsupervised Learning
Hey, everybody, this is Razib Khan with the Unsupervised Learning Podcast. I'm here to talk about Ashkenazi Jewish genetics with my friend, Josh Lipson, Josh, can you introduce yourself to the listeners?
Sure thing. So I am not a professional geneticist or historian, but basically grew up intellectually fascinated by the birth of this new genetics, history, linguistics, synthesis, and reading a lot of Razib' s blog, and some of the other now defunct blogs about that. I am currently clinical psychology PhD student, but I have a bachelor's degree in Middle Eastern history, both Arab and Jewish history in the in the more specific sense. And I've been working for the last two years with a number of other I guess you could call us euphemistically citizen scien ntists, on a deep dive into the Y chromosomal makeup of Ashkenazi and Sephardic Jews and how that synchronizes with what we know about historical demographics and in some ways, introduces entirely new side stories that no one would have ever guessed from any other source. So yeah, that's pretty much me thrilled to be here.
Yeah, I mean, I'm excited. So you know, to give the readers a little bit more context, as Josh is, you know, one of my longtime correspondents, whenever Jewish genetics comes up, you know, he's, he's passionate about the topic. He's pretty knowledgeable, and I want to talk to him partly because, you know, he's kept track of the details and the weeds for a while now. And we have some, you know, maybe not necessarily disagreements, but just like the minor issues we want to talk about in relation to where Ashkenazi Jewish genetics is today. And so many of you will probably have read a piece that I wrote on substack, about Ashkenazi Jewish genetics. The title is actually "Ashkenazi Jewish genetics, a match made in the Mediterranean". So I wrote this piece and it got a lot of attention. But um, to some extent, it's it's kind of sad that it got the attention it did, because the results that I talked about are pretty well known. It's just that they haven't been popularized very much for whatever reason. So let me just review it. You know, I know there have been books that have been written about this topic, I think, you know, David Goldstein wrote a book, I think John Entine, and also wrote a book. I mean, there's, there's a bunch of books on Jewish genetics, but they're a little out of date now. So just to give a capsule summary, Ashkenazi Jews are the Jews of basically North Central Europe, North of the Alps. And they're the Jews of the German speaking world. Yiddish is the traditional language of these Jews, they're, you know, united by this common language and social heritage, and a particular Ashkenazi religious liturgy. And unlike Sephardic Jews, Ashkenazi Jews are actually genetically pretty coherent. So if you run a principal component analysis, or any kind of genetic clustering, Ashkenazi Jews come out to be basically very similar and a very, very clear and distinct cluster on the map, you know, are on the plot. And in terms of their origins, there's always been controversies or they converted people or the Khazar. You know, are they 100% Middle Eastern? And I think in the broad sketches, we kind of know who and what they are.
And you know, there were a couple of papers around 2010 Doran Behar, Israeli geneticists led one of them, and they established that Ashkenazi Jews are kind of a population between Europeans and Middle Eastern people. And this is in line with other things that we know about both the mitochondrial DNA and the Y chromosomes, the Y chromosomes, the paternal lineage of Ashkenazi Jews, does seem to be overwhelmingly Middle Eastern, for you haplo nerds out there, you know, we're talking haplogroup J, I think J1, some J2, but a lot of E as well. And then there is a minority who are Levites who are r1a, but this looks like to be a Middle Eastern r1a. There's other non middle eastern lineages in there. So for example, the European variant of r1b I believe is like 10% of Ashkenazi Jews. So you know, there's been some admixture in the mitochondrial DNA, the maternal lineage is actually quite different. Because there's a lot more ambiguity here, partly due to the less clear separation between populations of mtdna. But it looks like a lot of the mtdna is actually, I guess we could say Mediterranean European, a lot of it might be old, early European farmer lineages that came out of Anatolia with agriculture, probably from the southwest Mediterranean, probably from probably from, you know, Italy, Spain, that area. So you have the maternal lineage and the paternal lineage, and these two are fusing together, it overall on the principal component analysis, we're talking about a 50/50 split now, you know, depending on your parameter settings, the Ashkenazi can be 40%, Middle Eastern, or 55%. Middle Eastern, there are more precise estimates. But I think it's really plausible just to say, you know what, it's about a 50/50 split. These populations went through the Rhineland. And they expanded demographically in the middle ages, from a very small population to a very big population. And a small population is evident in their genomes, where Ashkenazi Jews tend to be distantly related to each other, because they have an X number of ancestral, you know, ancestors that coalesce back to this common population. You know, I recently quoted a paper from Shai Carmi, 2017. He said, you know, his, his group's methods had 300 people, other people have said 500, the point is, is small. Now, it's not so small that the Ashkenazi Jewish population is highly inbred. I think that's a little bit of an exaggeration. That would be frankly, a population smaller than 100. You don't need that large of a population to actually maintain genetic diversity in population genetics. There's diminishing marginal returns here. So I want people to keep that perspective. But if you do have on the order of 500, common ancestors in the year 1250 AD, you're all gonna see very genetically homogenous and similar to each other. So Ashkenazi Jews tend to get results from a lot of the direct to consumer genetic testing that they're Oh 95% 99% Ashkenazi Jewish. There's not that much variation within people with for Jewish grandparents, because they all share the same ancestors. Right. And so you know, that's where we are right now. There have been earlier, there have been more advanced methods that have tried to estimate when these admixtures happen. And that's kind of a little bit of a point of a dispute between Josh and I are not much dispute, but really discussion, and I want to open that up. So Carmi's group using segment length analysis. They estimated there's wide interval here, but they estimated that the admixture between the Middle Eastern component which is like Levantine population is exactly what you would expect. And Southwest European component happened around 750 AD. And then they estimated that there was a later Northern European probably Slavic admixture, a small component after 1250 AD. So you know, setting aside the last, which, you know, I think, is actually kind of plausible, considering the history and also some of the phenotype like just the physical appearance of some Ashkenazi Jews.
Let's talk about the 750 AD number, because it's a little weird. We know that there was a lot of Roman Jews in the classical empire in places like Rome, obviously in Spain, because there were Jews when the Visigoths showed up, and Jews when the Muslims conquered Spain. And these, these Roman Jews were presumed, till recently, I guess, until this paper to be the ancestors of Ashkenazi Jews in terms of migrating north, you know, Italian Jews, for example, are very common candidate, Italian Jews are kind of an ancient Jewish community, that might not be either Sephardic or Ashkenazi. Or it could be a combination. It's kind of confused, but maybe Josh can speak to that more. But so we have the situation where we get an estimate of a late arrival. So here's my hypothesis. My hypothesis was Ashkenazi Jews descended from people who arrived, say during the Islamic period, probably males, and they intermarried with local Italian women around 750 AD. And what happened to the earlier Jewish populations in the western Mediterranean? Well, my hypothesis was going by recent work on ancient DNA in the western Mediterranean, that they were predominately urban and urban populations tend to demographically collapse and disappear. And so those Jews did exist. But they didn't leave as much of a legacy because they lived in urban areas. The Jews that, you know, came to the Western Mediterranean, after the fall of Rome, in contrast, expanded and moved north and demographically radiated and they were the ones who led to the Ashkenazi Jews, they probably recapitulated many of the same dynamics as the earlier Jewish populations in the western Mediterranean in terms of intermarrying with local populations. And also, it could be that we are looking at a pan Mediterranean Jewish population. And so it could be that these later Ashkenazi Jews actually are not that distantly related from or not the Ashkenazi Jews, but these later like Roman Jews, are not that distantly related from the Jews that were the Italian peninsula, because there could have been reciprocal gene flow for the western to the eastern Mediterranean. So could be that we're looking at a pan Mediterranean Jewish population that eventually moved northward. So I think that's a reasonable hypothesis. We don't know the details of the timing of the admixture yet - we just know I think pretty assuredly that there was an admixture. So Josh, I guess I'll let you have the floor now.
Hey, yeah, Razib. So that's a really good summary and hearing you and some other people recently bring back that particular aspect of Carmi's paper from a few years ago, has definitely, definitely been a thought provoking experience for me, because it kind of runs counter to what my hypothesis, and I think, a more generally popular hypothesis in sort of the amateur, but well read, world of Jewish genetics and history have embraced over the last few years. I want to start with your comment about pan Mediterranean Jewish genetic profile or gene pool or cultural world. I think that is probably a key place where we agree as a starting point, but the details of that dynamic might make a big difference here. So you know, I remember learning from your reporting back in 2010, about this distinction that I don't think anyone really knew about in clear terms till DNA studies started coming out between Western and Eastern Jews genetically, you know, the word Mizrahi in, in modern Israeli usage does not mean genetically Eastern Jews, it's actually basically a synonym for Sephardi. And so I don't think anyone would have necessarily guessed that Moroccan Jews genetically are closer to Ashkenazi, and than they are to Iraqi and Iranian Jews. But you know, we've we've known for at least a decade, that there's this primary split between Jews who lived in the Greco-Roman world, in classical times and Jews who lived in the greater Babylonian and Persian world. So one thing I'll say is that I think the genetic evidence precludes the idea completely, that if this is the case, that the admixture happened in 750 CE that the Near Eastern source was Babylonian Jews. That just doesn't line up. Babylonian Jews, Iraqi Iranian Jews are genetically pretty distinct from the Near Eastern 40-50 whatever percentage that contributes to Ashkenazi Jews, which is much more like Samaritans or Lebanese Christians or Palestinian Christians. Babylonian Jews were demographically the lion's share of Jews in late antiquity and the early medieval period are probably something like half Mesopotamian, at least and and that different shows up. Yeah, so all of this is to say that, in the case that Razib's hypothesis based on Carmi's methodology, is the main story of Ashkenazi Jewish origins. The Origin has got to be in Palestine, Byzantine or early Arab Palestine, or somewhere else in the East Mediterranean. Now, the problem with say, locating another place in the East Mediterranean is that if you look at the genetics of other Jewish communities in the eastern Mediterranean, that have very little Sephardic admixture that are mostly descended from Jews who've been there since classical times, presumably, like Libyan Jews, for example, or the least Sephardic admixed Syrian Jews, there is still evidence of like Greco Roman type ancestry in them. So so that's also foreshadowing my point that I think Greco Roman type ancestry has been in Mediterranean Jewry for a long time, and has probably been in Ashkenazi Jews or in their gene pool for something like almost 2000 years. But anyway, to steal ....
Right right - you throw a lot out there. I do want to clarify for listeners here. So you're talking about Libyan Jews and Syrian Jews. I didn't get into it in the piece, but I will in the future of the term Sephardic Jews, you know, in a modern parlance is used very broadly basically just to mean not 100%, but mostly non Ashkenazi Jews. But you know, as you apply here, that's not really true. So Sephardic Jews, so these are the Jews that were very populous in the Iberian Peninsula, up until, you know, basically the 15th century expelled at the end of the 15th century, large numbers obviously converted, but the ones that didn't convert were expelled, they went to the Ottoman Empire, they settled in Morocco. They settled in Egypt, they settled in what is today modern Turkey, they settled in Greece, they settled in Syria. So in some of these areas, so for example, in Thessaloniki in Greece, there are Romaniad Jews who are descended from quote "Roman Jews" were indigenous Greek speaking Jews, and other Sephardic Jewish community in Thessaloniki, or there was before the Holocaust, unfortunately, the Sephardic Jews, you know, were originally from Spain, at least notionally speaking Ladino, the romance language, right? In Turkey, you have I think it's mostly a Sephardic community. In Syria, you had indigenous Syrian Jews, but they were culturally assimilated by the Sephardic Jews. And from what I know the Syrian liturgy disappeared in the 19th century, and then you have other pockets here in North Africa. The Moroccan Jews are Sephardic Jews, but when I look at the genetics, I'll say someone like the pollster, David Dhore, an analyst, he has clear Berber shift, which is just notable in all the Moroccan Jews. They're not mostly Berber, but they definitely have Berber Berber admixture. And then you talked with the Libya Jews, there's Jews in Tunisia. So can you break down for us these various groups of Sephardim, which I know we want to talk about Ashkenazi Jews here, but we can't really talk about just Ashkenazi Jews to really understand what's going on here. Right?
Yeah, yeah. So it's interesting. And I think so, you know, you have a continuum. And this has been known for almost a decade to among North African Jews from basically most Sephardic to least running from west to east, you know, Moroccan Jews, or Moroccan Jews or some substantial level of Sephardic obviously, they absorbed a heavily Berber admixed, pre Sephardic Jewish substrate, you get to Tunisia, and there were actually two separate communities, basically, through the 20th century, one small one with ties to very close ties to the Sephardic, the Portuguese Sephardic community of Livorno in Italy, who called themselves the Grana and then the native Tunisian Jews were called the Twansa. And in Libya, I don't think it was organized so formally, but the two... Libya and Tunisia are basically in Jewish cultural geography and tradition, one land, and you do see Jews with a little bit of Sephardic ancestry there. It's definitely prestigious, but generally speaking, they look like they're some mix between Levantine - basically, Greco, Roman and Berber, and actually, probably the largest share of that is Levantine. And they're less Berber than then a lot of Moroccan Jews for whatever reason. But um, my point is being that outside of Europe, even there's considerable evidence that Greek and Roman colonization during a time when Judaism was still a more proselytizing religion, when Helene's and Romans were pagan, that Jewish communities outside of Europe, we're probably absorbing Greek and Roman type ancestry. So that's something we need to take into account. And there's also interesting evidence, I like to talk about my Y chromosome lineage a lot that that links Ashkenazi Jews and pre Sephardic Jews in places like Tunisia and Libya, going back probably to late classical times, and the sight of that common connection is an open question for now. But it suggests to me that there's continuity of Jewish roots in the central Mediterranean in a place like Italy, going back to classical times, but we'll, we'll dive into that a little later. I guess the point I just wanted to make is that, you know, got a little sidetracked but at the end of the day, if we're steel-manning, this late arrival from the Near East, to It'll be theory, I think the only location that makes sense for it is Palestine, Judea, Israel, because Jews farther, just anywhere out in the East Mediterranean, we're probably already substantially hellenized, including genetically, and Jews to the east were a very different genetic character. So I read a blog post that came out after the Carmi paper initially did it was very amateurish, and I'm, I think the person might have had some unsavory motives. But he said, a possible explanation for this dating is the Jewish revolt against Heraclitus, during the Byzantine-Sassanian War of the seventh century. It was basically the last Jewish revolt in Palestine, the Land of Israel, against Imperial authority. I mean, we're talking half a millennium after Titus. And that apparently, the the Jews of Palestine, who were still a very substantial, very religiously important community got crushed, and that this might potentially be a source of Jewish migrants to the west, later on. So that's the thought...
Yeah, I mean, you put a lot out there. And so let me just kind of like review it and, you know, repeat some of some of what you said, just to make it clear for the listener, because I think some of the stuff that we take for granted is pretty surprising and exotic to the listeners from what I can gather. So, you know, in the Carmi paper he used, you know, Palestinians, I think some Lebanese, you know, as his Levantine source populations, he had other populations in there to just test like Iranians and whatnot, as you as you would, as you basically have said, the eastern Jewish populations, these Mizrahi Jewish populations, as they're called today - Iraqis, Persian Jews. They are Middle Eastern, but they are quite different. Well, not quite, but they are noticeably different from people from the Levant. So they're more like, you know, I've written about this years ago, they're more like Assyrian Christians, for example, who have lived in the same area for many, many 1000s of years, they all come out of these common ancestral populations. And, you know, it's hard to like, tease apart the differences, sometimes with the earlier methods, but the newer methods, you can usually tell if the source population was very similar to Mizrahi Jews, it would be very, very clear, if the source population was shifted more towards Iran and Iraq. I think Carmi's methods could have definitely detected it. And I, myself, when I've looked at the data have seen the differences between these various groups. It does seem like yes, the ancestral population from the Middle East, that gave rise to the Ashkenazi Jews are from the eastern Mediterranean shores from the Levant from where they are technically supposed to be, according to kind of like the the textual evidence, right. But you know, what we're pointing out here is in the Roman period, especially before Christianity, but even after Christianity to some extent, because the process of christianization took centuries, to interpenetrate. And like to go from top to the bottom of society, the boundary between the Jews and the non Jews was partly ethnic, but it was partly just a simple religious difference. There were some listeners know, a group in the Roman Empire called God-fearers, who were monotheists. And were quite sympathetic to Jews, but they tend to be Gentiles, they were Gentiles, usually. And they did not follow the Jewish law, they did not want to follow the Jewish law, they just wanted to worship the Jewish God. And they're the hypothesis that early Christianity as a transformed itself from a Jewish sect, to a Gentile sect to drew upon large numbers of God-fearer converts, who were able to participate in the worship of the Jewish God without having to partake of the Jewish law. But you know, among the Jews themselves, proselytes were well known, and they are recorded in antiquity. I believe... Josh, you can correct me I believe Rabbi Akiva was descended from a convert actually, but not 100%. Sure, I know that some of the rabbis mentioned in classical antiquity, it is noted that they are descended from converts. And I don't think it's in a pejorative way. I think it's kind of showing that, you know, Judaism and the Jewish life were already attractive, even then to pagans in the Roman Empire. And so it would be entirely expected and unsurprising that Jews would have Gentile ancestry quote, unquote, because you know, some of these Gentiles are gonna be very similar to choose anyways, like in the Levant in the Middle East, other Gentiles Greeks in the western Mediterranean Romans there are going to be somewhat different, and then you have the confound that there is going to be some gene flow from the Western Roman Empire into the Levant populations in general. So when we're using these modern populations to make these calculations of these estimates, we need to be careful because these modern populations have changed. Really the brass tacks of like how we can figure this out would be really good ancient DNA sources. And I think that'll probably come online in the next 10 years. With the Max Planck group, they're really, really going towards antiquity and trying to nail down some details. So I think we'll know about that. But I think your overall point that you're seeing some lineages that do seem older, and that are hard to attribute to the 750, The Late Late date of admixture. Can you can you unpack that a little bit for us?
Yeah, I'd be happy to. So again, you know, we're talking about several different methodologies that can give us convergent or divergent results. And so I'm intrigued by this theory that you're presenting because I'm not technically familiar with this segment, analysis IBD based stuff. But one thing that I've enjoyed a lot and found very valuable is digging into the uniparental lineage data, and specifically the the Y stuff, which over the last five, six years, there's been a Cambrian explosion in our understanding of Y chromosome DNA phylogeny structure. And because the Y chromosome doesn't recombine, and because it mutates at a pretty steady rate, though, that exact rate is debated. You know, we can we can date the age the coalescence date of y DNA lineages, pretty precisely. Um, anyway, so you know, I'm this is probably my main wheelhouse when it comes to Jewish genetics. I'm - I've worked on a project that's still in beta, I guess we've finished with the results. You know, where we've basically catalogued and estimated the size of every Y DNA lineage in Ashkenazi Jews. Unsurprisingly, a lot of them coalesce to a single individual who lived, you know, between 750 and 1000 CE he just around the time that the Ashkenazi Jewish community began to form. But what's interesting is some coalesce to an earlier date, or split from non Ashkenazi branches at an earlier date. And I think that in a lot of cases, this is evidence that a lineage that is found in Ashkenazi Jews has an older origin, an older ancestral presence in the west or central Mediterranean. I'll give you an example. The best examples are the ones that are of obvious European origin. So we, there there's a famous Cohen modal haplotype thing, about 50% of Ashkenazi Cohanim belong to a branch that is almost certainly from ancient Israel, very well studied, but the third largest Y DNA branch among Ashkenazi Cohanim Cohen's priests, is actually a European variety of haplogroup J to be that almost certainly descends, based on a finding from the Antonio paper in 2019. From Etruscans or central Italians, and that Ashkenazi lineage coalesces back - It's basically a few cousin lineages - to about 200 to 300 CE I mean, the fact that it's an Italian origin already points in the direction of a really early entry into the Ashkenazi population. But um, that dating really shows that we're talking about an Italian originbranch that entered a, an Ashkenazi, pre Ashkenazi source population in Italy. During the time of the Roman Empire full stop. There's another one that's also probably of Italian origin that is estimated to be a little bit younger than that called RL4, which is a sub branch of italic r1b-u152. Also found in Ashkenazi Jews also coalesces back to like 300 to 500 CE, I can think of a few other examples and there are also
branches that are likely of Middle Eastern origin But their structure tells a story that roots them deep in the West Mediterranean so that this will be my last specific example. But yeah, it's near and dear to my heart because it's my own lineage. I descend from an Ashkenazi branch of E, that's almost certainly of Levantine eastern Mediterranean origin that connects to four other cousin branches that have been found in Sephardic Jews, North African Jews, Hispanics, Sicilians, and we all share a common father, around 350 to 400 CE this date is established by multiple estimation methods. But the question is, what's more parsimonious? Did five cousin branches with a common origin around 300 or 400 CE all separately migrate to Spain, France, Italy, Tunisia, Germany, a few 100 years later, or did they have a common origin, somewhere closer, like in Rome, or southern Italy, or even Tunisia around the end of the Western Roman Empire and spread out from there, you know, which would be proof of continuity of Western Roman Jewish populations into later Ashkenazi. So that's, that's one line of evidence that I think is pretty strong.
Okay, um, yeah, so I guess, again, like, this is, you know, you obviously know the Y chromosome stuff like inside out, like, Oh, you know, way better than me, and probably most of the listeners. And you know, it's important when understanding and kind of estimating these probabilities, you know, the modern distributions, you know, where the branches are, you know, where the coalescence is, are. And I haven't, you know, boned up on all these details. So I don't have like a immediate response. I guess my big question is always, okay, is the modern distribution reflecting the ancient distribution? And how can we possibly interpret it in light of possible pan Mediterranean dynamics with some of these populations? And so I guess the key question is like, going back to the segment length, which, which you alluded to, you know, let me unpack it for the listeners who are not familiar with how genomic inference of this sort operates, because I think most people are not. So what Carmi et al. - what their group basically did, is like a standard thing, where you estimate like along the segment of DNA, you can estimate where that DNA originated from. And so if you have really, really long segments that have the same ancestry, that means mixture of the source population into the target population was relatively recent. And a concrete example I think I gave my piece was black Americans. They have really, really long segments of European ancestry in their genome average is about 20%. The segments are long, because recombination cuts apart only one to three points along each chromosome every generation. So if you think 100 generations 1 to 3 cuts, every generation, that chromosome is going to be chopped up in so many different ways as mixed and matched with the other chromosomes, that you're going to see lots of alternating stretches of ancestry on that chromosome. If it's only two to three generations, you're not going to see alternating stretches. So for example, My children are half European, half South Asian, and they have two physical chromosomes, where the homologues where, you know, say on chromosome 20, they have one South Asian one, they have one European one. There's no alternation because there's no recombination that's happened. Now, when they have children, they're going to be recombination between their chromosomes. And their children will inherit whatever their children's other ancestry is, their children were 100%, I guarantee inherit segments of chromosomes that have South Asian stretches that alternate with European stretches. And so what they did is they looked at this Southern European Southwest European ancestry in the Ashkenazi genome, and they looked at the length distribution of those segments. And using a model of X number of recombination events per generation a generation time, they estimated a good value for when the admixture would have started in a pulse between Southern Europeans and a Levintine population that's the other presumable source population or maybe it is in their model. They estimated to like 750 AD with with a pretty wide confidence window. You know, obviously like you know, there's imprecision here, but It seemed definitely to be dated after the Roman Empire. And so that indicates that the admixture must have happened relatively late. So this presents a problem for the idea that they were, you know, descended from Roman era Jews. So one thing that I will say is I do wonder
of their statistical power. You know, they tried to check for this, they said they only saw one event, but their statistical power of being able to detect multiple admixtures. So sometimes what happens is multiple admixtures can average to one single admixture, or the smaller admixtures can be totally ignored in the analyses. So I think the Carmi model is where I would start, but you know, talking to you is not necessarily where I would end. And we obviously need to get historians involved in this. People who are versed in textual analysis, and who can shed some light on you know, what was going on in the post Roman world, as well as the Roman world. So for example, um, you know, you're familiar with Jewish history, genetic history and stuff. What's going on with like, the Jews in Spain, like why were there so many Jews in Spain? Like, do we know why, I mean, I know that they were present when the Muslims conquered Spain, and there was what I've read is that there was some tolerance during the Visigothic period when they were Aryan Christians, which was a heretical sect of Christianity. And the rulers were a minority religion, and so they tolerated other minority religions. And then then we became Catholic about 600 AD, they started persecuting the Jews. And so after a long period of toleration, they suffered persecution. And then the arrival of Muslims obviously allowed some more toleration for a while. So can you speak a little bit to that for the listener? Because I think that that's, that's something that's kind of perplexed me.
Yeah, I mean, frankly, I think the story of the origins of the Jews of Spain is at least as murky, if not murkier, than the story of the origins of the Jews of Ashkenaz. I mean, there's evidence that there was never a break in Jewish settlement from classical times into the early medieval period in Italy, basically from Rome, down, as well as pockets of Spain and, and maybe the southern French coast, too. But what's interesting is that my understanding is that the Jewish settlement density through all this period was much higher in central - and well, Rome, in southern Italy, then in Iberia. So the question of how Iberia kind of overnight, around the time of the arrival of the Arabs became such a hub of Jewish life and Jewish demographic weight is really interesting. And so you've got to wonder, I mean, how much of that is the result of - and this is kind of a direct parallel to the conversation we're having about Ashkenazim - How much of that phenomenon is the result of continuity of Jews who lived under Roman and then Visigothic rule, versus Jews who arrived with Arab and Berber conquerors. But I think once again, if you look at Sephardim they have as much European ancestry pretty much as Ashkenazi - the composition isn't exactly the same. But actually, a better fit than calling it mostly Iberian is one that looks at Italians and Greeks as a source of admixture. So this, again, makes me makes me think that continuity from that period might be underrated as a possibility. Does that kind of get it what you were wondering about?
Yeah, yeah. So I mean, you're thinking I mean, it sounds like well, talking to you, you're thinking there was a large admixed East Mediterranean, you know, central to East Mediterranean Jewish population, you know, that lived in the cities of the European side of the Mediterranean. And this is the source for a lot of other populations. Is that what I'm getting from you?
That's, that's my impression. But obviously, it's a very murky period in time, especially the transition between these two eras between Empire and the emergence of groups we would call Ashkenazi and Sephardic.
Yeah, I mean, one of the things that I kind of alluded to in the peace of mind, let's explore this a little bit. Obviously, there's Judah Halevy. You know, there's Moses Maimonides. There's some Sephardim of the Sephardim - Sephardic Jews that are prominent in the Middle Ages, you know, there's Rashi, the rabbi, I think from Trier, you know, for the Ashkenazim early on 1000 AD, but um, I feel to a great extent that aside from mention, you know, aside from like, kind of like offhand mentions by secular like, you know, Christian rulers or Muslims. And then, of course, Jewish religious tradition of commentary and exposition, that, to a great extent Jews kind of fall off the radar, you know, for for really like over 1000 years in many ways, except for maybe in Spain to some extent where they got involved in secular affairs pretty intensely in much of the Christian and Muslim world. And they have their own community, their own history. And I think that this caused - this is causing some problems and in our attempt to understand what's going on, because, you know, there's extensive commentary that Jews have on religious matters within their own community. But there's no Josephus, really, for the medieval Jews. There's no Philo, there are not as many Jews who are commenting on themselves as a nation, among other people's and what's going on with those interactions, because their primary goal was just not to interact, it was just to, like, live in their own communities, practice their own law, probably wait for the Messiah, and try to survive. What do you think of that assertion by me?
I think that that's right, in the broad outlines. I - It's interesting, yeah, there, there is a long period of silence. And even though the classical era - Yeah, had had its fair share of Jewish historians, there's really, there's really no analog to that, that I know of, in the Western world, at least during this period of silence. And so there are, there are multiple steps that, you know, between these two eras that seem to be lost to the mists of time, but once again, you know, for example, I think that multiple methods from population genetics can help elucidate them again, it's, it's kind of remarkable that if you look at the big Ashkenazi founding, Y chromosomal branches, they tend to coalesce to exactly the period that we believe Ashkenazi Jews to have originated in another line of evidence, I want to talk about that, especially in the context of Ashkenazim, is even in non historical non narrative texts. Historians have been able to salvage going back to the 11th century, because, um, and this is pretty morbid, but there are large lists of the martyrs who were either killed by Crusaders in in Germany during the First Crusade or who committed mass suicide. And there's a lot of onomastic evidence that tells us about the at least proximate cultural background and origins of Ashkenazi Jews. And also a lot of this evidence is kind of woven into the linguistic fabric of Yiddish, which is a language I don't know how to speak, but that I've, I've studied from a linguistic perspective, because I think it's one of our best lines of evidence and understanding what kind of environment Ashkenazi Jews emerged out of.
Yeah, so can you can you talk about these martyrs? I mean, I think people know in the generality, like what, you know, what's going on during that period - But what was their background? I know that there are, there are there are Spanish Jews who, for example, moved into the world of the Ashkenazim, even the Ashkenazi Jews, some of them can trace their descent to that, but, I mean, how heterogeneous were they?
So this is a great question. And I, I feel pretty secure in saying that, you know, there's been a lot of research on, I think, especially from a linguistic perspective, but also from just a textual historical perspective. And I also think that genetics is beginning to line up with this, that Jews in the Rhineland, who are the best documented Jewish population north of the Alps. In the early medieval period, we're the largest but not the exclusive demographic source of Ashkenazi Jews. So we know that in the 10th century, at least, and then more fully in the 11th century, there were established Jewish communites in three cities along the Rhine River; Mainz, Worms, and Speyer , you know, the Ashkenazi last name Shapiro, that comes from Speyer which is in...
I did not know that I did not know that the more you know.
Yeah, exactly. It sounds a little bit, uh, you know, romanced maybe but no, it comes from a, the name of a German city. And those Jewish communities, you know, we even know the names of the biggest families who live there, and some of their specific locations of origin in the generations before in Italy and France. So that's huge. And people people don't actually know about that. There were like 5, 6, 7 big families in the 11th 12th century Rinus Jewish communities and we know where some of them came from in Italy and France. But also what's really interesting is that, at the same time, there were Jewish communities that emerged - I'm talking as early as the 10th century, a few 100 miles east on the Germanic Slavic frontier, which to the best of our knowledge, were... grew continuously in places like Regensburg in Bavaria, in Prague, in Magdeburg in Saxony. And what's interesting is that the Yiddish language really seems to be mostly derived from southeastern and Eastern German dialects. And also Eastern Yiddish has a strong, apparently Czech substrate and we know that Jews living in early medieval Prague, spoke aJewish dialect of Czech. So the origins of Eastern Ashkenazi Jews who today are the overwhelming majority of Ashkenazi Jews, I mean, not Henry Kissinger, but but most of us, emerges out of this world primarily - not not that we aren't also descended from Jews in the Rhineland. But evidence from the onamastics. From the Yiddish linguistics really points to the importance of basically another zone, which probably had partly separate origins. There, there's evidence that this more easterly community had origins in Italy, but also in the Balkan and Byzantine world, to say nothing of the fact that there were also Jews farther east, in Eastern Europe, of, of Hellenic Jewish but also probably of Khazar Jewish origin that were in East Slavic lands who made a smaller but unmistakable contribution to Eastern European Jews eventually.
Yeah, I mean, this is, you know, there's so many nuances and details we could go through. I will I will mention, really quickly, that there's a book called "Pity of it all: History of the German..". Yeah, "Pity of it all: a portrait of German Jews 1743 to 1933", by Amos Elon, it's a good book. One thing that he points out, and others have pointed out is even the German Jews, like the Bavarian cattle traders, for example, that were pretty prominent in the 18th century. Some of them might have origins that are pretty deep, because they kept escaping from principality to principality. But the reality is, it looks like demographically, even a lot of the, you know, high, high bourgeois German Jews that were so assimilated, created reformed Judaism, and really ushered in the Jewish enlightenment - They themselves were derived from migrants from the eastern people that you're talking about, basically, the people at the interstices of, of the Germanic and Slavic world, and operating as middlemen minorities there. And this was just a function of demographics. Their population expansion is just incredible. They obviously found a good niche for, you know, being successful. And, you know, I reported it in my piece, you know, we're talking hundreds of 1000s and eventually millions, by the, by the, you know, 17 and 1800s of Ashkenazi Jews in these in these lands, between core Germany and Russia. And, you know, I think, you know, you're talking about these details of the Rhineland, Jews and possible Hellenic Jews. I think that could culturally be correct. I think the issue that we have, you know, if you're a geneticist looking at the data Is the signal of the Jews of the middle of these Eastern European Jews is so strong that it overwhelms a lot of the other potential signals. What do you what do you think about that assertion?
Yeah, well, I would say that that that's true in the main that differences among different Ashkenazi subgroups are small. I'm forgetting the name of the PI on this paper. But a few years ago, paper came out that I think pretty clearly demonstrated that Western and Eastern Ashkenazim overlap substantially, but there's also a lot of non overlap. And there are a lot of Western Ashkenazi Jews, and there are samples out there specifically of Alsatian Jews who are probably descended heavily from Jews who've been in that Rhineland area for 1000 years, that look, again, they they they are not that far, but that look distinct from Eastern and Central European Jews, specifically, in their absence of Slavic ancestry, and they look actually on a PCA just as close to Sephardic Jews as the eastern Ashkenazi Jews. I'm forgetting the name of the paper, but, you know, this is a small demographic segment but I think there is evidence of substructure
Yes, let's talk about that. Because you you know, fair amount of substructure. What we're talking about here substructure is like variation. And, you know, we've talked about this, but, you know, be curious to your thoughts. You know, so the two biggest groups in modern American Ashkenazi Jewish culture traditionally, were the Litvaks you know, roughly Lithuanian Jews like the northeastern Jews, Lithuania, Belarussia, that area and the Galatians who are from the Galicia region of Poland, like South West Poland, roughly, right? So these are two big groups. stylized fact is the Galician Jews are much more likely, or they were kind of the most enthusiastic adherence of Hasidic Judaism. Whereas the Litvak Jews were more traditionalist in you know, they're more traditionalist, non-Hasidic Haredi Jews. So they're orthodox, very orthodox, they can be ultra orthodox even. But they tend not to have participated in the mystical revival and the you know, frankly, fixation on charismatic leaders rebbes that the Hasidic Jews, the Galician Jews did. And people have told me that there is subtle structure between the Galician Jews and the Litvak Jews like what have you seen?
Yeah. Oh, by the way, I just before I forget, I sent you the link, the paper that showed Western Eastern substructure that's Gladstein and Hammer 2019. But okay, as for the Litvak-Galizianer thing - So a few years ago, when ancestry debuted its genetic communities thing, and there was a paper, I think the lead author was Chinese. That introduced the methodology behind it, which is more of a network based rather than like a principal components based method - showed what I found, interestingly, a clear... again, and they didn't mention this, but if you know the history, and you know the dialect history of Yiddish, and you know, the political history of the Polish Lithuanian Commonwealth, there was clear evidence of a Litvak cluster. And basically an all other Eastern European Jews clusters, so not just Galizianers, but Jews from most of Poland, except for the Northeast, Western Ukraine, Romania, Hungary, Slovakia on one hand, and then Litvaks are basically Lithuanian and Belarusian Jews, some also some adjacent areas. And this map of Jewish ancestral locations by cluster lined up almost perfectly with one the dialect boundary between Northeastern or Litvak Yiddish and the other dialects, and also the boundary after 1569, the internal boundary in the Polish Lithuanian Commonwealth between the Kingdom of Poland and the Duchy of Lithuania. And so why Litvaks are so distinctive, when Galizianers really aren't there. They're just part of this generic non Litvak group is an interesting question. And there are a few possible things that converge with this like there are some Jewish genetic diseases that are primarily Litvak genetic diseases is my understanding. I'm forgetting which And then also, there is some evidence that some of my collaborators, friends from the kind of Jewish genetics underground, have noticed, and I was skeptical at first, a shout out to a friend in Toronto, that Litvak Jews do seem to preserve more of an imprint of pre Ashkenazic Eastern European Jews in the form of elevated like West Asian or Caucasus like ancestry, as well as elevated East Asian ancestry versus Polish Jews versus Jews from Romania. And so, you know, that, that could go back to demographic phenomenon 6-700 years ago.
Yeah, so let me, let me dig a little bit into some of what you're saying and how we can interpret it in light of the genetic tests that a lot of the listeners have probably taken. So a lot of them probably find out, oh, 23andme tells them they're 99.4% Jewish. And so how does this work? At the high level, how it works is you take a training set of people, you identify, and have verified as Ashkenazi Jews, and then you look at your customers, and you see how close they are to these Ashkenazi Jews. And the reality is, as we've been implying, here, Ashkenazi Jews are a pretty coherent population cluster. And so it's not that difficult. Now, I don't know the details, obviously, in the proprietary internal methods. But sometimes there are situations where a population has internal variation, but you elide that internal variation, because that's just considered part of that populations variation. So you can imagine a situation where an algorithm sees that Ashkenazi Jews are, you know, 94 to 100%, of this component, and maybe that variation is noise, or maybe it's real underlying structure. But you know, culturally, you know, that these are all Ashkenazi Jews. And so the algorithm is trained and can see this variation recognizes it and says, you know, let's just decide this is 100% Ashkenazi Jew, because basically, Ashkenazi Jews can be across the interval 94 to 99. And I'm just, you know, given this as a hypothetical, but this is the sort of thing that frankly, does happen. Now, within even that cluster, you moved to East Asian ancestry. Well, there's also evidence of sub Saharan African ancestry among a lot of people in the Mediterranean that goes back to antiquity. It's at very low levels. And so what happens is, since it's widespread, and it's at lower levels, it's baked into the cake of these clustering algorithms. And it doesn't show up separately, but you can see it distinctly when you compare it to say, I don't know, like Natufians from 10,000 years ago, that Middle Eastern populations and Mediterranean populations have a couple of percent of sub Saharan African shift within them. And Ashkenazi Jews have this and this is probably from the Roman period, and it's probably from a pan Mediterranean admixture. And so you don't see this, like Ashkenazi Jews don't come up as 1%. African because all Ashkenazi Jews have it. And also most Mediterranean populations have it, it's just baked into the cake of the training - of the you know, the, the algorithm. And the same with the East Asian ancestry. It has been detected at low levels in Ashkenazi Jews. It's also been detected in some methods - For example, for the nerds out there, the chromopainter fine structure method, but also others, it detects low levels of East Asian admixture across a lot of Eastern European populations. And here, I'm not just talking about Russian - people with Russian Tatar ancestry, which is a known thing. We're talking you know, in Belorussia, even among Lithuanians, Gentile Lithuanians. And so we haven't like talked about this in detail. But, uh, you know, Carmi, et al. detected Northern European ancestry, probably Slavic, although the difference between Slavic and Eastern German is, you know, I mean, we can't figure it out in terms of like, you need really complicated, powerful methods to detect these differences sometimes. So, this seems intuitively obvious, like they were in these regions for not quite 1000 years, but close, you know. And so, of course, there would be some gene flow, like, you know, endogomy is not perfect. I mean, what do you have to say about that, like, what do you know, from the cultural history and the scuttlebutt from the genetic genealogy community?
Yeah, I mean, well, first of all, what's interesting is that the type of East Asian ancestry in Ashkenazi Jews seems to be out of the blue seems not to match any pre existing hypothesis about Khazars about admixture with Slavs which Eastern Ashkenazi Jews are definitely somewhere on the order of Probably 10%, Slavic give or take. I mean there are two, I believe two well documented mitochondrial DNA lineages in Ashkenazi Jews of East Asian origin one of them as as you know, as you know, there's a whole paper about it is probably to be identified with a southern Chinese woman, which is extremely weird. We have no idea how it happened and it's not found in Gentile, Eastern Europeans
Alright, should I say this? Or should this be edited out? Ashkenazi Jews have always loved Chinese food so ...
I'll leave that to your discretion. But anyway, and that, interestingly enough that that particular mitochondrial DNA branch peaks among Litvak Jews, although that's that's a tentative conclusion. But um, as for so if you're asking about the broader question of Slavic admixture, I think there's probably evidence that it entered at multiple periods and multiple locations. There's even a... so most of the Slavic ancestry in Ashkenazim was mediated via women. Some of them might have been slave girls, our ancestors did, unfortunately, participate in the slave trade of pagan, Slavic women, possibly which, which extended into the Mediterranean. And so what's interesting is that it's possible that some of that ancestry entered the Ashkenazi population before they were in Slavic lands - There's one Y chromosome lineage in Ashkenazi that small, have clear Slavic ancestry. It's, it's about like a 10th of the size of the Middle Eastern r1a1, but it's a Slavic r1a branch. And I actually have both of them in my pedigree, and that one coalesces not to 500 years ago, but to 1200 years ago. And so how the hell did a Slavic male lineage, enter the proto Ashkenazic population that early and I'm thinking it might be that Slavic admixture into Ashkenazi Jews started on the Germanic Slavic frontier, but it probably also continued up until you know, the christianization of Lithuania in the 14th century, or maybe even later. So. But that's an interesting one, I would bet that higher resolution segment length analyses could could tease that out and say definitively whether we're talking about one main admixture event or something more continuous.
Well, I mean, there could be a possibility. I mean, there were a lot of Slavic slaves in the Mediterranean after the fall of the Roman Empire, all the way to Spain, but a lot of them in Italy. So that's a potential. So one one thing about with slaves is, you know, christianization, obviously was actually considerably patchier before say, 1000 AD then people would think it was slaves, that is an option where they're pagans, you can't enslave Christians, for example, Muslims can enslave Muslims, Christians can't enslave Christians, they could be Christianized in Islamisized later, obviously. But if you had a pagan slave, and you, you know, freed them, and they assimilate into your community, even if they're male, you know, with women, it's much more obvious, but if they're male, I mean, it makes sense. Whereas, like, if they go from pagan to Jewish, that's more socially acceptable, maybe it wouldn't, you know, warrant attention by the authorities than if it was a Christian. You know, the Judaizing the conversion to Judaism of Christians did happen. But um, you could be you could get in trouble if it came to the authorities attention. Whereas if you're a pagan who converts to Judaism, probably they're not going to encourage it, but it's not a capital crime or anything, right?
Yeah, well, I mean, okay, this brings us around kind of full circle back to this some admixture in two way admixture in Italy, around 750 theory. So my question is, In what world given what we know about the history, the culture, the religious strictures, are we seeing lots of Italian women when Italy is mostly christianized maybe you know, again, in the backwater people were worshipping Roman statues or whatever. But when Italy was at least formally, totally christianized um, you know, In what world are all of these Italian women who are Catholic Christian, either converting to Judaism or marrying Jewish men and informally becoming Jewish, flying under the radar, not receiving condemnation and reprisal from authorities? It's just very hard to imagine versus again, say pagan women 1800 years ago in Italy, marrying into Jewish families.
Yeah, I mean, I think that's a fair point, I think what we would have to ask, though, and wonder, is the extent of rural Christianization, across much of Eastern and Central Europe, in particular, before the counter reformation, or before the Catholic reformation, let me call it the Catholic reformation. So for example, this is outside the purview of this podcast. But there is a there is work that suggests that the last pagan sacred groves in Lithuania were actually burned down during the 16 and 1700s. By - by Catholic priests. And, you know, this was this was done because of the inroads of the Reformation to the West in Poland, and to the north and Latvia and Estonia, which became Lutheran under the Swedes, you know, and so they're called snake groves, they're probably around at least until the 1600s. You know, the issue here is, to a great extent. In some parts of Europe, the nobility just allowed the peasants to do whatever they wanted to do religiously, as long as they came to mass, I think, you know, during Christmas or whatever, like they were periodic points when they had to show they had to signal their Christianity. But the reality is, they often were allowed to conduct their own affairs. These were not totalitarian states. You know, in Western Europe, it was a little different. It wasn't totalitarian, but the state was more bureaucratic- bureaucratized, things like the Inquisition existed, and people would keep track much more closely, what the religious practices were. But in Eastern Europe, I think it was much more patchy. And I can tell you, even into the 1700s, in Prussia, there was a district where the Lutheran pastor was not assigned by the state, mostly for a bureaucratic, bureaucratic reasons for a generation, and they ended up sacrificing a bull to ensure the harvest. And there was an Inquisitor pastor who had interrogated the villagers, like, why are you doing this? Like what's going on here? And the villagers couldn't really give a clear answer. But you may know this, and I know some of the listeners do. This practice of killing and burying bulls is actually a Baltic pagan practice. So someone remembered in their folk memory, and so if they remembered that indicates to me that this practice was occurring, relatively recently, like within, you know, it was probably at least within the century, someone was practicing it or there are like, pretty vibrant stories about the bull sacrifice.
Interesting. I started reading that right when the pandemic blew up - right before it, I started reading a book that you had recommended on your blog, "Europe; was ever really Christian?". And that was - that was really fascinating. I never got to the Eastern Europe Part. I, I have no doubt that that's part of the story of how as much Slavic and Baltic blood got into the eastern Ashkenazi gene pool as it did, but I guess to evaluate, like the historical feasibility of, you know, this Carmi methodology based theory, you know, it would be important to do a deep dive on what was the real religious landscape of Italy around 750 CE and I know that a lot of stuff that went on in rural contexts You know, a lot of stuff that women did, you know, it wasn't poor - isn't well recorded by you know, the mainstream historical sources, but I feel like we have a shot in a place like Italy versus a place like, medieval Lithuania, in in really being able to estimate that again, it's just it's, it's a strange thought to imagine that, you know, Greek and Aramaic speaking Jews who had come straight from Palestine would have hit upon this reserve of secretly pagan Italian women, but we know we know from clear genetic evidence that that things just as strange have happened. So...
Yeah, you know, and I've kept you for a while. I'll let you go soon - I do want to point out Italy... There's just there's just so much like this story of the of the Ashkenazi Jews like traverses so much interesting history for me. So I want to point out, Italy in the seventh and eighth century, was dominated by Lombard Christians and the Lombards, when they arrived into Italy, their elite had nominally converted to Aryan Christianity, they were the last Aryan Christians. And just for the listeners Aryan Christians follow Arias, who was a presbyter, I think, in Alexandria, and they have some differences of detail in regards to how the Trinity works from Nicene Christians, Orthodox Christians, Catholic Christians, as we would understand them today, in any case, but most of them were still pagan when they entered the Italian peninsula around 600 AD. And their pagan practices lasted long enough that Christians - Christians, who were of Lombardy, ancestry themselves, like ministers and whatnot, they could observe them. So the Lombards were conducting pagan rituals authorized by the Duke Romuald late in the six hundreds, okay. And so this is I'm going to read from Wikipedia the entry but this I've read this elsewhere, "they expressed a religious veneration to a golden Viper and prostrated themselves before it, they paid also a superstitious honor to a tree which, on which they hung the skin of a wild beast. And these ceremonies were closed, closed by public games in which the skins serve for a mark on which Bowman shot arrows over their shoulders." So, you know, as late as 700, the Lombard authorities, you know, the ruling class or actually countenancing the practice of pagan rituals, even though they themselves were nominally Christian. And so I mean, this is a situation where you're, you're seeing a very gradual shift and the Italian landscape at the time that this admixture happened, may have been far less, you know, what we would call Christian - Then, you know, then we were expecting, so I want to bring that up. So I, you know, I've talked to you for a while, there's still a lot to explore on this topic. I think, you know, going back to what I said at the beginning, we have a general understanding now the Ashkenazi Jews are a fused people of European and Levantine origin, but the when, the how, I have not closed the case on it. I hope people don't think that my substack piece closed the case on it, it opened the discussion. I do think the Carmi paper that we've alluded to here, from 2017, I think it was a major step forward. And I think it was a necessary step forward to actually get at what happened. But I think to actually understand that we need to do some of the things that Josh is implying here, which is looking at the history, looking at the text, looking at the archaeology, looking at the ethnography looking at the mythology, and also getting as many samples is possible for various other populations. Do I think it's going to be possible in the next decade? Yes, I do think so. And so I think, you know, at some point, I will write an update on the substack if substack is still around, which will actually I think, clarify and shed some more light on what happened. So thank you for your time, Josh. It was really great conversation and I will see you online.
It's been a pleasure. Thanks Razib and looking forward to the reception.