The Puzzle of the Ashkenazic Bottleneck | Jim Stone | TEDxBeaconStreet

Scientists have wondered for many years why Ashkenazic Jews are disproportionally subject to certain genetic diseases.

A geneticist named Shai Carmi found a surprising answer using modern genome analysis tools. Carmi has written that in the fourteenth century the root stock of this now large population consisted of only about 350 breeding individuals. This finding can explain the disease proclivities -- but it contradicts virtually all historical sources.

[warpedcomedy]

I think it's important to note that the figure of 6 million Jews in the Roman Empire includes those still in Judea as well as all throughout the empire. Many of those Jews stayed in places like North Africa and Spain, stayed in Judea (there was a Jewish population of probably hundreds of thousands in the land of Israel up to the Middle Ages), or migrated to Babylon and Persia (lots of Jews went there from the Galilee during the third century), possibly other places like Yemen as well.

Ashkenazi Jews in particular are descendants of Jews who lived in southern Europe, mainly Italy, before migrating north. So the core population was much smaller than 6 million. I think it's quite possible that massacres, especially by Crusaders, as well as the plague may have played a part in the bottleneck though.

[warrenkruger]

I am a geneticist and have given talks on this subject. I have come to the exact same conclusion, i.e. the Medieval Genocide of European Jews was highly effective, and explains the genetic record. One thing however is that Ashkenazi Jews are interesting in that there Genetic makeup indicates that the founding population was a 50:50 mixture of Middle Eastern and European DNA (most similar to Northern Italy). In addition, about half of all Jewish Men's Y-chromosomes have middle-eastern haplotypes. My thinking on this is that the Askenazi Jewish population got started by male Jewish traders settling in Italy and marrying local woman.

[proverbalizer]

10:10 he said if they drifted away there would be something in the oral tradition, then 5 seconds later he said so it must have been mass slaughter... and yet nothing in the oral tradition of the survivors? hmmmm....

[donaldpelles]

Ashkenazi Jews are also very much intermarried. In my family tree there are multiple instances of individuals from different branches marrying. I have heard this anecdotally about Jews in Lithuania, where one of grandfathers came from. I think it was probably true of German Jews as well.

[kingofcelts]

A lot of speculation really, I'm very doubtful about his conclusions..

[JosueLopez-kkus]

he says "jews were treated pretty well in this period, there's no way they were persecuted or converted" and then "there was a lot of intolerance in this period, they were killed in mass murder", I mean which one is going to be? or maybe he wasn't clear about the dates

[scottybottybanana]

I'm not convinced Jim can rule out dispersal that easily, unless you were going to have a large genetic testing of the population. Though, as people are starting to check their DNA on ancestry websites, more people are discovering Ashkenazic ancestry.

[speedylogic]

I'm a fan of genetics and history. This presentation started well yet deteriorated rapidly to myths and legends. A waste of 20 minutes.

[tedgemberling]

I think he is underestimating conversion as a cause. Yes it's true that both Jewish and Christian authorities discouraged mating between the religions, but we know that authorities cannot generally regulate such things very well. If you are attracted to someone you will try to find some way to get close to them.

[MrRhomas]

Rodney Stark in his book "the Rise of Christianity" posits that Jews in the Roman diaspora evolved into a hybrid religious cultural group in that they spoke and many worshipped in Greek, adopted Pagan habits, and when Christianity developed, saw in it a continuity with Judaism and were ripe for conversion. Combine this with the edict to go forth a convert, Christian evangelists from the Holy Land would likely have first gone to Jewish communities in the diaspora where their message was more easily understood. As such, many Jews in the diaspora converted to Christianity which had much more in common than Paganism. Also, he refers to "God-fearers" who were gentiles who admired and followed the monotheism and teaching of Judaism but did not want or were not able to formally convert, as being a large part of the "Jews" in the diaspora and many of the early converts.

[JasonPengo]

It's amazing that the Ashkenazi Jews of today are all descended from 330 people who were alive in 1350 AD.

[FOLIPE]

I don't understand. You test current-day ashkenazi, whose ancestors didn't convert because if so they wouldn't be ashkenazi, and then you ask where are the people who didn't become their ancestors, and say they were killed? Couldn't they simply be the ones that didn't go to Poland, that stayed in the way, and became non-Ashkenazi.

[Liberperlo]

I had my DNA tested by My Ancestry, an Israeli company from my understanding. I am about 85% Ashkenazi, a mixture of Italian, Greek and other South European, and 2% Nigerian/West African(!). My own immediate family are very Reform Jews who came from London and Brooklyn NY. Our parents have passed and were buried as Jews, The only one of my siblings who has children (my niece and nephews) married into a Chinese family. We have hung onto our culture(s) but are not very religious at all.

I'm proud of my Jewish background and actually think it's a shame that the language my grandparents spoke, Yiddish, was specifically not taught to my parents and can now mostly be only heard in Haredi/ultraOrthodox communities that for religious reasons would have nothing to do with me or my family.

The point of all this is that we are all more mixed than we think. I believe that discrimination based on religious traditions, both internal and antisemitism from nonJews, plays a part in the genetic bottleneck. The forces at play are still happening now. Us secular Jews are 'breeding out', meeting Sephardic Jews, or are more tolerant of people not of Ashkenazic background adopting Ashkenazic culture or the Jewish religion. Genetically, this is good as this reduces the impact of Jewish genetic disease.

[bluegalacticmonkey]

Extrapolating from the present attitudes and events to the past colors what one is observing and is not an approach a historian should take in my opinion. Especially considering that no facts other than lack of genetic diversity are actually presented.

[aaronmorein]

Hey, the comments here are pretty critical. A lot of the criticisms are levied against claims that actually make sense, but might require some background info or good notetaking. I heard him make a couple mistakes, but they seem like he misspoke. Academics generally agree with his conclusion.

[SionTJobbins]

I'm not convinced. Not saying it didn't happen, nor can happen, but even in the Middle Ages there would still be some clues - manuscripts written by other states witnessing attrocities; songs; poems; place names. There would also, surely be some reference in Jewish works - where literacy was more widespread.

The figure of 6 million Jews in the Roman Period seems very high too - it would make the population of present day Italy about 60 million. The population of England in 1600 was still only about 3 million; France maybe 6-7million. Seems to me there were fewer Jews to begin with, a long 'uninteresting' and unascribed period of assimilation (which also party explains the non-Jewish DNA in Ashkenazi Jews); conversion (priests and individuals and families turning a blind eye to converting Jews or a Jewish woman, say, marrying into the family) and, of course yes, genocidal killings.

[phishisgrate]

I don't understand. He first argues that it can't be persecution b/c Jews were treated well in the Roman Empire and dark ages but then says it's due to mass slaughter. Those two arguments seem to contradict each other....completely. Unless I'm missing something.

[danielanderson]

From my own research, Stone’s conclusions are a pretty good estimate of what occurred, and align with more recent genetic research. What’s not clear however is how many Jews left Babylonia for Central and Western Europe and eventually Eastern Europe. A million or more sounds huge and unlikely. The conclusions would make more sense if we are talking tens of thousands, many of whom perished through disease, persecution, genetic drift, low birth rates etc. It’s highly unlikely that Jewish communities that spread out across Europe were larger than a few hundred each, many of which were wiped out due to these factors. That’s the only way we could in any way arrive at such a small number of 350 or so Ashkenazim who survived.

[jasminejeanine]

He's missing something super obvious... WHY don't the Ashkenazi jews have a oral tradition and writings talking about what happened? As they're experts at remembering history in general & could read/write and could easily pass messages to OTHER Jews outside the region as this only works if they genocide was 100% & all records were destroyed.

[Vivldi]

I am 8 % Ashkenazi, were are my relatives here?