It’s Rosh Hashanah, the Jewish New Year, and I’m thinking about Jews in Haplogroup G2a3b1 (P303). I’m specifically  thinking about the theory that G2a3b1 might have entered Europe, at least in part, with the Jewish Diaspora. Ray Banks, the Project Administrator for Family Tree DNA’s Haplogroup G Project has been flirting with this theory for some time now. And, I sometimes think there is no end to the number of people who contact me privately about it.

There are plenty of Jews among our distant cousins. Haplogroup G probably originated in the Middle East, perhaps in the area of Lake Van, south of the Caucasus Mountains, so it’s not surprising that Jews (and many other Middle Eastern ethnic groups) are represented. Men from Haplogroup G might have been among the founding populations of ancient Hebrews, or might have been assimilated through conversion and conquest at many later dates.

Most Jews in Haplogroup G are G2c. Approximately 7% of Ashkenazi Jews belong this group (Behar et al., 2004). G2c might (or might not) be a marker for paternal ancestry among the Khazars, a Turkic tribe that converted en masse to Judaism in the 8th century. There are also small clusters of Jews scattered throughout G1 and G2a. Probably most of them descend from converts during the Roman Empire. (See, e.g., Shlomo Sand, The Invention of the Jewish People (2010)).

There is no mystery with any of these groups.

I’m thinking about a a different group — G2a3b1, the overwhelming majority of Haplogroup G in Europe.

Ray Banks recently advanced the theory that G2a spread through Europe, at least in part, with the Radhanites, Jewish merchants who plied the trade routes between the Muslim East and the Christian West about 500 to 1000 CE. A few years ago Ray’s Banks’ Banks DNA Project website speculated that his’ ancestor (in Haplogroup I-P109) might have lived about 600 BCE in Persia (now Iran). I suspect this theory influenced Ray’s later thinking.

The Radhanite theory is a modern incarnation of an older theory that members of Haplogroup G are descended from Jews deported from Judaea as slaves in 135 CE, who ended up in the slave markets of Rome and spread from there.

Why the Jews? A number of reasons. First, Haplogroup G apparently came to Europe from the Middle East. It is somewhat common among Jews, but is relatively rare in Europe. That’s the initial hook.

Second, some of the major European subgroups of G apparently date to about 600 BCE. The date is comfortably close to 538/7 BCE, when Cyrus the Great of Persia ended the Babylonian Captivity and allowed Jews to return to Judah. So we can imagine, if we choose, that our distant ancestors might have been Persian men with Jewish wives, who joined the Return.

Third, there seem to be slightly higher levels of G in the Rhine river valley, in Cologne and Mainz. Those are cities known to have Jewish populations from an early date.

Fourth, the highest concentration of Haplogroup G might be on the Spanish island of Ibiza, which is famous for being a center for the crypto-Jews of Spain.

But the Ibiza Jews are poorly typed, and it seems likely that they might descend from the unusually high number of Jewish converts in Roman Spain. Anecdotal evidence

Today, we find Haplogroup G at higher frequencies in those same areas, but a causal connection would be forced. The Radhanites, for example, are explicitly mentioned primarily in connection with the Rhône River valley, while G2 researchers have suggested a concentration in this Rhine River valley.

Dating by STR mutation rates is rapidly falling out of favor, but it has given us a framework of dates that will be hard to replace. P303, the mutation that defines G2a3b1, is thought to be about 5,000 years old. Coincidentally, that’s roughly the same age (5,000 to 6,100 years) as the Neolithic G2a skeletons found in Europe. This group is found in smaller numbers outside Europe, and might have originated somewhere in the Middle East.

L497 and L42, two significant subgroups of P303, are thought to be about 2,500 years old, which takes us (again) to 500 BCE. These groups almost certainly originated in Europe, judging from the rarity of samples from other areas.

Note: None of these older theories proved out. It’s now (2020) clear European G2a represents a population settled in European since Neolithic times–just as the academics said all along.

Edited to fix broken link.