A genetic study of 132 people buried in a large megalithic tomb near Berry, about 50 kilometers north of Paris, has revealed evidence of a dramatic population collapse and replacement during the Stone Age. The survey results are natural ecology and evolutionindicating that the burial site was used during two distinct periods separated by a significant decline in population around 3000 BC.
DNA analysis revealed that the people buried before and after the collapse were not closely related, indicating that the original population had all but disappeared and been replaced by new people.
“There is a clear genetic disconnect between these two periods,” said Frederik Valeur-Sielsholm, assistant professor at the Grove Institute at the University of Copenhagen and one of the study’s lead authors.
“Earlier groups resemble the Stone Age farming peoples of northern France and Germany, while later groups show strong genetic links to southern France and the Iberian Peninsula.”
This result suggests that the local population declined dramatically before new groups moved north and settled in the area.
Signs of ancient diseases and crises
To investigate the cause of this decline, researchers used DNA technology to examine all the genetic material preserved in ancient bones. This allowed us to identify traces of several pathogens, including: plague bacteriumthe bacteria that causes plague, and Borrelia recurrentiscausing louse-borne relapsing fever.
Although the plague existed, researchers say it doesn’t fully explain what happened.
“While we can confirm that plague existed, the evidence does not support that plague was the sole cause of the population collapse,” said Martin Sikora, associate professor at the University of Copenhagen and lead author of the study. “This decline may have been caused by a combination of disease, environmental stress, and other destructive events.”
The human remains also show an unusually severe crisis. Archaeologists have found that mortality rates were unusually high during the early burial period, especially among children and young people.
“Demographics are a strong indicator of crisis,” said Laure Salanova, head of research at France’s National Center for Scientific Research (CNRS).
DNA reveals changes in Stone Age society
Genetic evidence also indicates that population turnover was accompanied by significant social changes.
In early times, this tomb contained multiple generations of the same extended family, suggesting a close-knit community that buried relatives together over time. In later periods, burials became more selective and dominated by a single male lineage, indicating the existence of a different social organization.
“This shows that changes in population were accompanied by changes in the structure of society,” Schiersholm said.
Clues to the demise of Europe’s megalithic builders
The discovery adds to the evidence that Neolithic population declines affected much of northern and western Europe, extending far beyond Scandinavia and northern Germany.
The study may also help explain why the construction of megalithic tombs and other large stone monuments stopped across Europe around the same time.
“We now understand that the demise of these monumental structures coincides with the disappearance of the populations that built them,” Schiersholm said.
