Ancient DNA from Teeth found in Germany Tells Story of Ashkenazi Jews

The excavation at the medieval Jewish cemetery of Erfurt
(Photo: TLDA Ronny Krause)

New DNA evidence from the Middle Ages studied by scientists from the Hebrew University in Jerusalem is giving the world greater insight into the history of Ashkenazic – European – Jews. The DNA in question was derived by archeologists from teeth that belonged to Jews who lived in the area of modern day Germany in the 14th Century.

For more than a thousand years the Jewish world has been divided into two major groups: Ashkenazic Jews are descended from the European Jewish community and Sephardic Jews come from the Middle East. But in both cases, the names are a misnomer.

Ashkenazi Jews do not come from Germany. In fact, the vast majority came from Eastern Europe, and those Jews’ ancestors probably never lived in Germany at all. They did all at one point, however, speak Yiddish – the Jewish language based on a mixture of Hebrew and German. But Ashkenaz – a Biblical name for a land described as being far away from Israel – became the term used by Jews in the Middle Ages to refer to Germany.

Sephardic Jews, on the other hand, almost all hale from Middle Eastern countries. But the word Sephard – another Biblical name for a faraway land – became the Jewish name for Spain. The Jews of Spain were expelled from that country in 1492 and dispersed throughout the Mediterranean area. So the term came to refer to all Middle Eastern Jews, while most today do not descend from Jews who left Spain and many who truly are descendants of Spanish exiles who lived for centuries in countries like Holland and Italy.

The Ashkenazim eventually eclipsed the Sephardim by far in numbers. But the Holocaust wiped out almost half of all of the world’s Ashkenazic Jews. And after Israel’s independence, Arab nations expelled most of their Jews who largely settled in Israel.

Well, the question now is “where did all of the Ashkenazic Jews really come from?” It is true that Jews in the Middle Ages did first move into Europe by way of settlements in what is now Germany. But many also came to live in what are now Russia and Ukraine by migrating north from places like Babylonia into central Asia while fleeing persecution after the rise of Islam. And in that era Russia had not yet emerged as one kingdom, nor was the area yet fully Christian, so it was easier for Jews to settle there.

There are even theories that suggest that Jews in Eastern Europe converted many locals to Judaism who ate the time were still polytheists.

So, what is the new DNA discovery telling us?

Scientists excavated ancient DNA from teeth, an international group of scientists peered into the lives of a once thriving medieval Ashkenazi Jewish community in Erfurt, Germany and findings shared in the Journal Cell show that the Erfurt Jewish community was more genetically diverse than modern-day Ashkenazi Jews.

This is an interesting finding since one would think that it would be the opposite: that the DNA of Jews would have become more diverse over time because of intermarriage and conversions, etc.

“Today, if you compare Ashkenazi Jews from the United States and Israel, they’re very similar genetically, almost like the same population regardless of where they live,” shared geneticist and co-author Professor Shai Carmi of the Hebrew University of Jerusalem (HU). But unlike today’s genetic uniformity, it turns out that the community was more diverse 600 years ago.

Digging into the ancient DNA of 33 Ashkenazi Jews from medieval Erfurt, the team discovered that the community can be categorized into what seems like two groups. One relates more to individuals from Middle Eastern populations and the other to European populations, possibly including migrants to Erfurt from the East. The findings suggest that there were at least two genetically distinct groups in medieval Erfurt. However, that genetic variability no longer exists in modern Ashkenazi Jews.

The Erfurt medieval Jewish community existed between the 11th and 15th centuries, with a short gap following a 1349 massacre. At times, it was a thriving community and one of the largest in Germany. Following the expulsion of all Jews in 1454, the city built a granary on top of the Jewish cemetery. In 2013, when the granary stood empty, the city permitted its conversion into a parking lot. This required additional construction and an archaeological rescue excavation.

“Our goal was to fill the gaps in our understanding of Ashkenazi Jewish early history through ancient DNA data,” explained Carmi. While ancient DNA data is a powerful tool to infer historical demographics, ancient Jewish DNA data is hard to come by, as Jewish law prohibits the disturbance of the dead in most circumstances. With the approval of the local Jewish community in Germany, the research team collected detached teeth from remains found in a 14th-century Jewish cemetery in Erfurt that underwent a rescue excavation.

The researchers also discovered that the founder event, which makes all Ashkenazi Jews today descendants of a small population, happened before the 14th century. For example, teasing through mitochondrial DNA, genetic materials we inherit from our mothers, they discovered that a third of the sampled Erfurt individuals share one specific sequence. The findings indicate that the early Ashkenazi Jewish population was so small that a third of Erfurt individuals descended from a single woman through their maternal lines.

At least eight of the Erfurt individuals also carried disease-causing genetic mutations common in modern-day Ashkenazi Jews but rare in other populations—a hallmark of the Ashkenazi Jewish founder event.

“Jews in Europe were a religious minority that was socially segregated, and they experienced periodic persecution,” described co-author Harvard University. Although antisemitic violence virtually wiped-out Erfurt’s Jewish community in 1349, Jews returned five years later and flourished into one of the largest in Germany. “Our work gives us direct insight into the structure of this community.”

The team believes the current study helps to establish an ethical basis for studies of ancient Jewish DNA. Many questions remain unanswered, such as how medieval Ashkenazi Jewish communities became genetically differentiated, how early Ashkenazi Jews related to Sephardi Jews, and how modern Jews relate to ones from ancient Judea.

While this is the largest ancient Jewish DNA study so far, it is limited to one cemetery and one period of time. Nevertheless, it was able to detect previously unknown genetic subgroups in medieval Ashkenazi Jews. The researchers hope that their study will pave the way for future analyses of samples from other sites, including those from antiquity, to continue unraveling the complexities of Jewish history.

“This work also provides a template for how a co-analysis of modern and ancient DNA data can shed light on the past,” concluded Reich. “Studies like this hold great promise not only for understanding Jewish history, but also that of any population.”

The research team, of over 30 scientists, included HU’s Shamam Waldman, a doctoral student in Carmi’s group, who performed most of the data analysis.