Ancient DNA reveals the mysterious collapse of Europe's megalith builders

A genetic study of 132 people buried in a large megalithic tomb near Bury, about 50 kilometers north of Paris, has uncovered evidence of a dramatic population collapse and replacement during the Stone Age. The findings, published in Nature Ecology & Evolution, show that the burial site was used during two separate periods, divided by a major population decline around 3000 BC.

DNA analysis revealed that the people buried before and after the collapse were not closely related, indicating that the original population largely disappeared and was replaced by newcomers.

"We see a clear genetic break between the two periods," said Frederik Valeur Seersholm, assistant professor at the Globe Institute at the University of Copenhagen and one of the lead authors of the study.

"The earlier group resembles Stone Age farming populations from northern France and Germany, while the later group shows strong genetic links to southern France and the Iberian Peninsula."

The results suggest that the local population shrank dramatically before new groups migrated north and settled in the region.

Ancient Disease and Signs of Crisis

To investigate what may have caused the decline, the researchers used a DNA technique that examines all genetic material preserved in ancient bones. This allowed them to identify traces of several pathogens, including Yersinia pestis, the bacterium responsible for plague, and Borrelia recurrentis, which causes louse borne relapsing fever.

Although plague was present, the researchers say it does not fully explain what happened.

"We can confirm that plague was present, but the evidence does not support it as the sole cause of the population collapse," said Martin Sikora, associate professor at the University of Copenhagen and senior author of the study. "The decline was likely driven by a combination of disease, environmental stress and other disruptive events."

The skeletal remains also point to an unusually severe crisis. Archaeologists found exceptionally high mortality during the earlier burial period, especially among children and young people.

"The demographic pattern is a strong indicator of crisis," said Laure Salanova, research director at France's National Centre for Scientific Research (CNRS).

DNA Reveals Changes in Stone Age Society

The genetic evidence also shows that the population replacement was accompanied by significant social changes.

During the earlier period, the tomb contained multiple generations of the same extended families, suggesting closely connected communities that buried relatives together over time. In the later period, burials became much more selective and were dominated by a single male lineage, indicating a different social organization.

"This indicates that the population change was accompanied by a shift in how society was structured," Seersholm said.

A Clue to the End of Europe's Megalith Builders

The findings add to growing evidence that the Neolithic population decline affected large parts of northern and western Europe, extending well beyond Scandinavia and northern Germany.

The study may also help explain why the construction of megalithic tombs and other massive stone monuments came to an end across Europe during roughly the same period.

"We now see that end of these monumental constructions coincides with the disappearance of the population that built them," Seersholm said.