Monday, September 12, 2022

Remains found in British well provide insight into Ashkenazi genetic 'bottleneck'


Genome analysis of bodies found in a well in Norwich, England provided insight into the start of a genetic "bottleneck" brought on by a repaid shrinking in the population of Ashkenazi Jews. 
Photo by Rob Farrow/Geograph/Creative Commons

Aug. 30 (UPI) -- Genome analysis suggests that human remains recovered from a medieval burial site in Britain may provide insight into the rapid decrease of the population of Ashkenazi Jews, according to a study released Friday.

Researchers in Britain analyzed the DNA of 17 bodies found at the bottom of a medieval well in Norwich, Britain, and found that six of them had "strong genetic affinities with modern Ashkenazi Jews" and that they were likely victims of antisemitic violence during the 12th century, according to findings presented in the journal Current Biology.

"It's been over 12 years since we started looking into who these people are, and the technology finally caught up with our ambition," Ian Barnes, one of the coauthors of the study, told phys.org. "Our main job was to establish the identity of those individuals at the ethnic level."

Radiocarbon dating showed that the bodies were deposited between 1161 and 1216, which aligns with a time frame that includes a historically documented antisemitic massacre in Norwich in 1190.

Analysis of the individuals' DNA found that three were sisters -- one aged 5-10, one aged 10-15 and the third a young adult -- while at least one of the individuals was descended from a recent union between two close relatives.

The DNA analysis also indicated one body belonged to a child that may have been as old as 3 and had had blue eyes and red hair, with the latter associated with historical stereotypes of European Jews.

It further showed the victims were predisposed to genetic conditions that are prevalent in modern Ashkenazi Jews.

Scientists have speculated that an event between 500 and 800 years ago caused a dramatic decline in the Ashkenazi Jewish population, creating a "bottleneck" that can lead to an increase in the frequency of rare genetic variants.

Co-author Mark Thomas, however, said the presence of these genetic predispositions in 12th-century Jews would alter the current timeline.

"The bottleneck that drove up their frequency must be before the [Norwich individuals]," Thomas said. "That puts it back older than the vast majority of estimates of when that bottleneck occurred."

Following the discovery, the local community arranged a formal Jewish burial for the individuals.

"When you study ancient DNA from people who've died hundreds to thousands of years ago, you don't often get to work with a living community at the same time," Barnes said. "It's been really satisfying to work with this community on a story that's so important to them."

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