Ethnogenesis, as the name implies, is the process whereby a new ethnic group is created. An ethnicity is more or less a group with a shared culture, belief in common ancestry, and that preferentially marries within itself rather than outside of itself. Over time, this creates a group that is ethnically distinct from its neighbors, even under conditions of close proximity.
The Amish, for example, after splitting off from the Swiss in the 1600s over religious differences (remember, religion is ethnicity,) arrived in Pennsylvania in the early 1700s, so we may mark Amish ethnogenesis around the mid 1600s or early 1700s People today make fun of Ben Franklin for complaining that the German-speaking immigrants to Pennsylvania were problematic and not integrating with the rest of the population, but you know, the Amish still haven’t integrated. They still speak German, follow their own religion and traditions, and don’t inter-marry with the rest of the Pennsylvania population, such that they are quite ethnically distinct, at least on a genetic level.
The Hui of China are another example; they were not really considered an ethnic group before the establishment of the People’s Republic of China circa 1949. The Chinese decided to just lump all of their Muslim minorities–some of them quite distinct–under one term. (Historically, the term “Hui” also referred to Christians and Jews and was just a general catch-all.) Hui now marry other Hui preferentially enough that the Wikipedia page goes into detail on known cases of inter-marriage with the Han, but a fellow Hui from across the country may be regarded as just another Hui, and so a preferred partner.
Anyway, so that got me thinking about the establishment of Israel. Normally when I think of Jews, I am actually thinking of Askenzim, and you probably are, too. But Israel is actually 61% Mizrahi Jews–Jews from predominantly Muslim countries.
You know the general story: Once upon a time, all of the Jews lived in Israel. These people were probably pretty similar, ethnically, to the Palestinians, assuming the Palestinians are anything like the region’s residents 2000 years ago, and don’t have a massive influx of Turkish DNA or something like that.
Then the Jews got conquered and scattered to the winds. Most famously after the destruction of the Second Temple by the Romans, but also during the Babylonian and Assyrian eras, etc. Anyway, for the past 2000+ years or so, there have been significant Jewish communities in a lot of places that aren’t Israel, eg:
Then in the late 1800s, the Jews–mostly Ashkenazim, I think–got sick of this state of affairs and decided to exit Europe and go back to Israel. Unfortunately, they didn’t really succeed until 1948, at which point Jews from all over the world started pouring in.
Since most people are genetically similar to their neighbors, eg the Palestinians and Syrians, or Han and She, I began wondering how similar Jews were to their neighbors of millenia verses their similarity to each other.
Here’s a graph showing major genetic lineages of a bunch of different ethnic groups, including several Jewish ones:
Broad cultural zones are easily distinguished, like East Asians in yellow, South Asia in greens, Europeans with their large dark blue chunk, Middle Easterners with their big patches of light green and light blue, and the rust-tones in sub-Saharan Africa. This data set is great, because it lets us compare various Jewish groups to their immediate neighbors, eg:
I made a condensed version of the graph that highlights the measured Jewish groups and their neighbors, (sadly, some of the samples are pretty small, making them hard to read):
And an even more condensed version that just compares the Jews to each other:
(Note that the pure green section on the right-hand side is not a Jewish group, but just a chunk of the graph that happened to overlap the text due to the Cochin Jewish section being so small.)
Observations: Most Jewish groups are significantly more similar to their immediate neighbors than they are to other Jewish groups, especially when we look at the furthest-flung folks. Cochin Jews and Ethiopian Jews, for example, show almost no DNA in common (in this graph.)
Given what all Middle Eastern groups look like in the sample, we may speculate that the original Jewish group primarily had a large section of light blue and a slightly smaller section of light green, with probably a smidge of sub-Saharan. Several of the Middle Eastern Jewish groups still have this genetic makeup.
Three Jewish groups show a more European makeup, with a large dark blue chunk characteristic of Europeans and North Africans: the Ashkenazim, Sephardim, and Moroccan Jews. They look closest to Cypriots, though I compared them to Spaniards and Tuscans as their nearest neighbors in the graph.
Since the Ashkenazim are estimated to be about half Italian, it’s not surprising that they have about half as much dark blue as the Italians. Even within European groups, while they look fairly similar at this level of resolution, some groups are quite distinct from each other–Italians and Germans, for example, or Brits and Greeks. Geneticists can determine whether your ancestors were Italians or Germans or Greeks just by looking at your DNA, but those kinds of small details don’t really show up all that well on a graph that is trying to show the differences between Sub-Saharan Africanss and Asians. So while Moroccans, Sephardim, and Ashkenazim all look rather similar here, there may be finer grained differences that just don’t show up at this scale.
What’s up with the Moroccan Jews? They do not look like Moroccans; I therefore speculate a more recent migration of Moroccan Jews from somewhere else that’s not Morocco, like Spain.
The Jews who migrated to the East, however, lost a significant portion–almost all–of their light blue component, replacing it with dark green more typical of Indians and other SE Asian populations.
I don’t think this dataset contains Uzbeki Jews (or the Lemba, who are not Jewish enough to be considered Jewish, but still have a few Jewish traditions and folktales and a bit of Jewish ancestry,) which is sad, but I’d wager the Uzbeki Jews look a lot like other Uzbeks.
One of the things I’ve heard often from Jews is that all Jews are Jews, part of one great big Jewish family descended from Abraham (even the atheist ones!) and thus Jews should always try to be kind to each other, all Jews are welcome in Israel, etc. This is a perfectly sensible philosophy when you’re a peasant in Poland and the only foreign Jews you’ve ever met were from Lithuania. But 2000+ years of diaspora have resulted in far flung groups becoming quite ethnically distinct from each other. Like the Amish, isolated groups in Cochin or Ethiopia have become their own ethnies distinct from their ancestors, but unlike the Amish, they have inter-married significantly with the locals. (The Amish do not marry non-Amish.)
The Roman Exile, therefore, should be regarded as a major ethnogenesis event–the beginning of the creation of most current Jewish ethnic groups.
The creation of the state of Israel constitutes a second major ethnogenesis event, a bringing together of these multiple ethnic groups into one population that views itself as one population. I expect a great deal of mixing between these historically distinct groups into a more homogenous whole, (though some groups may not mix terribly well.)