17 Bodies Found at Mall Construction Site Were Medieval Ashkenazi Jews | Science | In-depth science and technology reporting | DW

In 2004, construction workers constructing a shopping center in Norwich, UK, made a shocking discovery: they found the skeletal remains of seventeen humans at the bottom of a medieval well. The find caught the attention of historians and laypeople alike.

There were indications suggesting that the bodies could have been Jewish.

Now researchers have gotten closer to the bottom of the matter: Through DNA analysis, they have found that the bodies were almost certainly Ashkenazi Jews. This research provides some of the earliest scientific knowledge about the DNA of medieval Ashkenazi Jews and offers key insights into the medical history of the population.

Ashkenazi Jews: A Diaspora Population

Ashkenazi Jews are a population of the Jewish diaspora who settled in Germany on the banks of the Rhine and in Italy some time before the 12th century. Ashkenazi Jews currently make up approximately 80% of the world’s Jewish population.

They are a particularly interesting population to study for geneticists because they have low genetic variability and distinctive characteristics, such as a high prevalence of autosomal recessive diseases, including sickle cell disease and cystic fibrosis, and a high risk of Parkinson’s disease. and breast and ovarian cancer. , for example.

The high frequency of some of the otherwise rare genes in the Ashkenazi Jewish population and the lack of genetic variability in the population itself alludes to what is called the “founder effect”, which describes a genetic phenomenon that occurs when a small group of individuals separates from a larger population.

A population that has experienced a founder effect will exhibit genotypes and physical traits resembling the original group, and these may be very different from the original larger population, explains the National Human Genome Research Institute in the United States.

Demographic bottleneck

Geneticists say founder effects occur for different reasons, but often occur in response to what’s called a “population bottleneck.”

Population bottlenecks occur when the size of an entire population is greatly reduced by a mass extermination event, such as a large volcanic eruption, tsunami, or genocide.

Researchers found evidence of this type of bottleneck in the Ashkenazi Jewish population in a 2014 research paper which found that all Ashkenazi Jews living on Earth today date back to around 350 people who lived there. between 600 and 800 years old.

Ashkenazi Jews have experienced a number of bottlenecks over the past centuries due to anti-Semitic violence, but scientists are particularly interested in this specific bottleneck because it caused genetic variations.

This new research, published August 30 in the journal Current biology, indicates that the event could have occurred earlier in history. Mark Thomas, author of the paper and professor of evolutionary genetics at University College London, said it could have happened in the early Middle Ages.

An Ashkenazi Synagogue in Sarajevo, built in 1902

Genetic testing of skeletal remains

Scientists tested the medieval samples from six individuals found in the well for a range of genetic variants known to exist at a higher frequency in Ashkenazi Jews than in non-Ashkenazi Jews today. They found some of the variations.

To understand the importance of finding these variations, the researchers ran computer simulations, asking the question: how many variations would we expect to find if this population then had the same frequencies of disease variants as Ashkenazi Jews? today ? And how many would we expect to find if they had the same frequency as non-Jewish Europeans today?

“What we saw genetically in these samples is consistent with them coming from a population where the frequency of these Ashkenazi-associated genetic diseases is about the same as today,” Thomas said. “If that’s the case, then the bottleneck that got them to the high frequency must have [happened] before the vast majority of studies are completed.”

Research ethics issues

This is the first time geneticists have analyzed ancient Ashkenazi Jewish DNA in a peer-reviewed paper, as there are ethical prohibitions against disturbing Jewish graves.

Further inferences about the genetic history of the population have been made through the sequencing of surviving Ashkenazi Jewish individuals. This is how the researchers made their first projections about the bottleneck event.

“There’s information about the past looking at DNA today, but it’s not as good as looking at DNA from the past,” Thomas said. “It will always be better to have DNA directly from that time. It’s the same if you look at population history, if you try to look for, for example, signatures of natural selection. We can detect it from modern data, but there’s nothing more powerful than detecting it from ancient DNA data.”

Because the researchers didn’t know anything about the bodies when they started their research, in this case it was okay.

“In our case, we didn’t disturb any Jewish graves,” Thomas said. “These were in the ground from the excavations of a mall development, and we wouldn’t have known they were probably Jewish if not for our work.”

Erfurt scientists have published a pre-printed article with genetic data from 33 Ashkenazi Jews from the 14th century. The article has not been peer reviewed, but they say they have also observed disease variants associated with Ashkenazi populations.

A scientific look at history

While this research doesn’t explain how the 17 people died, or when the bottleneck happened or how, it does help disprove at least one theory about the origins of Ashkenazi Jews: that they descended from the Khazars. , a Turkish people who emigrated to Europe. in the 12th and 13th centuries when their empire collapsed.

The theory was advanced by Arthur Koestler in his 1976 book The Thirteenth Tribe.

“It won’t be true. There’s no way to explain our data on Ashkenazi Jews with this theory, it just doesn’t work. So that’s out the window,” Thomas said.

This is because this UK data is from much earlier.

And as for the bodies themselves: once the local Jewish community learned that the skeletal remains were of Jewish origin, they held a traditional funeral service for them. The researchers worked closely with the office of the local chief rabbi, said Ian Barnes, a molecular evolutionary biologist at the UK’s Natural History Museum. He’s been involved in this case for years.

Published by: Zulfikar Abbey

Edwin S. Wolfe