The study, published this week in the prestigious journal CELL, analyzed DNA from 33 members of the Jewish community who were buried in the 14th century in the city of Erfurt in Germany. Prof. Shai Karmi from the Hebrew University, the leader of the research, found that there was a genetic sequence between the Ashkenazi Jews from the Middle Ages to the present day
A new study, led by Prof. Shai Karmi from the Faculty of Medicine at the Hebrew University and Prof. David Reich from Harvard University, has sequenced the DNA of Ashkenazi Jews from the Middle Ages and improved our understanding of the demographics of the Jews of the time. The DNA was extracted from dental remains that were discovered in the ancient Jewish cemetery in the city of Erfurt in Germany as part of salvage excavations. The findings were published in the prestigious journal Cell.
from Harvard University, sequenced the DNA of Ashkenazi Jews from the Middle Ages and improved our understanding of the demographics of the Jews of the time. The DNA was extracted from dental remains that were discovered in the ancient Jewish cemetery in the city of Erfurt in Germany as part of salvage excavations. The findings were published in the prestigious journal Cell.
The rescue excavations in the medieval Jewish cemetery in the city of Erport were carried out in preparation for the construction of a building on the cemetery site. After the excavation, the Jewish community of the city gave its approval to carry out genetic research on the remains of teeth found and not yet buried. The DNA sequencing of 33 individuals was carried out in Prof. Reich's laboratory, and the data analysis was conducted in Prof. Karmi's laboratory, together with PhD student Shamam Waldman. "The data showed that the Ashkenazi Jews were genetically isolated during the 600 years between the 14th century and the present. Any mixing that occurred with other populations was limited in scope and did not materially affect the genetic makeup today.", Prof. Karmi shares.
A number of researchers have shown in the past that European Jews in the Middle Ages were divided geographically and culturally into two main groups. The present study also revealed the existence of genetically distinct groups. One group from the city of Erfurt, which may represent the Jews of medieval West Germany, was genetically similar to modern populations of Sephardic Jews as well as contemporary Ashkenazi Jews from France and Germany. In the second group evidence of mixing with non-Jewish populations from Central or Eastern Europe was seen. Prof. Karmi adds: "The Western group of Northern European Jews in the Middle Ages lived around the Rhine region in Germany, where the first Ashkenazi communities were established. Eastern Jews lived in East Germany, Austria, the Czech Republic and Poland. The two groups also differed in their language and customs." Findings from the city of Erfurt, located on the border between the areas where the Jews of the West and the East lived, document immigration to the city in the 14th century. The historical, archaeological, and genetic data suggest the hypothesis that Jews from both communities were buried in the city without social separation between them. After the Middle Ages, the communities merged and created one Ashkenazi culture. Accordingly, Ashkenazi Jews today appear to be an almost equal mixture of the two medieval groups.
The study also examined whether the DNA of the Jews of Erfurt shows evidence of the minority of the population and the small number of founders. The researchers discovered that over a third of the Jews sampled carried an identical mitochondrial DNA sequence, which is passed from mother to her offspring (today 20% of Ashkenazi Jews in the world carry such identical DNA sequences). The result means that the population of the first Ashkenazim was so small that a third of the community were descendants from the maternal side of one ancestral woman. Also, genetic variants were found in Arport, some of which cause serious diseases, which are common today in Ashkenazi Jews but rare in other populations. The researchers explain that This is a hallmark of a population with a limited number of founders, because these variants were often carried by a very small number of founders, and became common after the population grew numerically. Prof. Karmi adds: "From the DNA analysis of 16 individuals from the Jews of Erfurt, we saw that almost all of them carried homozygous sequences, meaning identical from both parents. These sequences can be created as a result of kinship between the parents, but in the case of Erfurt, they were most likely created due to distant connections between the parents due to the size of the population that has been kept small for hundreds of years."
By combining DNA data on modern and ancient Ashkenazim, the team of researchers estimated the size of the population in the last 50 generations. It is estimated that the number of ancestors in each generation who contributed genetically to future generations was between 1,000-2,000 people during the entire second half of the Middle Ages. The researchers estimated that the size of the population represented by the Jews of Erfurt was even smaller, up to 3 times compared to the rest of the population, which strengthens the hypothesis that in the Middle Ages there were different genetic groups of Ashkenazi Jews.
According to Prof. Karmi, the current findings still require further research: "This is about one cemetery from one city during only one century, a fact that makes it difficult for us to apply the conclusions with certainty to the entire Ashkenazi Jewish population throughout the Middle Ages". Also, while genetic links were found between the Jews of Erfurt and modern populations from the Middle East, Southern Europe, and Eastern Europe, it was not possible to obtain reliable estimates for the relative part of each source and accurately identify the sources. According to the researchers, there is a need for DNA studies"A. From additional burial sites of Ashkenazi Jews and other populations from the Mediterranean region In order to confirm the results of the research and to better understand the genetic origins of the first Ashkenazim.
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