Genomes from a French mass grave reveal prehistoric collapse and total population replacement.
Five thousand years ago, the prosperous farming communities of northwestern Europe entered a mysterious demographic decline. You megalithic tumuli that had sheltered generations of the dead were abandoned and, throughout the region, wild forests were slowly regaining the fields that were once cultivated.
Archaeologists have debated the nature of this so-called neolithic declinebut ancient DNA extracted from a mass grave near Paris is finally bringing the crisis to the forefront, says .
By sequencing the genomes of 132 individuals from a single mass grave, scientists discovered a surprising biological chronology. The results were presented in an article published in the journal Nature Ecology & Evolution.
The bones reveal that this was a complete replacement of the population: a vast local clan, deeply interconnected, was fractured by the high mortality and illness, leaving a silence of centuries before an entirely new, genetically distinct people arrived from the south to reclaim the desert landscape.
Just 50 kilometers north of Paris, a large stone tomb in Bury contains the bones of hundreds of early Europeans.
At first glance, this pile of skeletons looks like a single, crowded cemetery. But DNA extracted from his teeth reveals that the tomb was actually used in two distinct occasions, separated by centuries.
“We can observe a clear genetic break between the two burial phases. The people who used the tomb before and after the collapse appear to be two completely different populations,” he said. Frederik Seersholmresearcher at the University of Copenhagen, and first author of the study, in .
“This tells us that something significant happened — like a great disturbance that led to the decline of one population and the arrival of another“, he adds.
During the tomb’s first phase of use, around 3200-3100 BC, the people who lived there they buried their dead, they formed a very united clan. Genomic reconstruction reveals extensive family trees spanning up to five generations.
However, this extended family was in trouble. Bones from this period show an alarming number of young people dying prematurely.
“This type of mortality patternand it is not what we expect in a normal and healthy population”, he stated Laura Salanovafrom the French National Center for Scientific Research. “It suggests that some catastrophic event may have occurred, such as disease, famine or conflict.”
This catastrophic event could have been caused by a disease that has decimated human populations in waves over thousands of years.
In the teeth of several individuals from this first phase, scientists detected the DNA of , the plague bacteria. They also found Borrelia recurrentis, a microorganism that causes recurrent fever transmitted by lice.
“The presence of pathogenic DNA shows that infectious diseases were affecting human populations at this time,” he added. Martin Sikoragenomicist at the University of Copenhagen.
“Although there is no solid argument that the plague alone caused the population collapse, the overall burden of disease could have been one of several contributors,” he added.
A New People and a Reconquered Forest
After the plague and population collapse, Bury’s grave sank into silence. Pollen records from the Paris Basin point to forest regeneration, consistent with reduction in human activity and abandonment of fields agricultural and pastures.
When the tomb finally reopened, centuries laterthe people who deposited their dead there were complete strangers to the original builders. Your DNA was compatible with a long migration from the south of France and the Iberian Peninsula.
This new society brought fundamentally different traditions. Instead of arranging their dead in an extended position, they buried us in the fetal positionwith the body flexed.
The second wave of inhabitants abandoned complex kinship networks of its predecessors. They favored smaller patrilineal lines and a greater proportion of the buried individuals had no kinship relationship with each other.
For these newcomers, it appears that shared culture or social status has become as important as strictly biological ties when deciding who belonged to the group and their place in the collective grave.
Archaeologists just could speculate about the reasons why the first farmers of northwestern Europe suddenly abandoned their huge stone tombs. DNA extracted from Bury’s teeth now gives concrete data about Neolithic decline.
The abrupt end of the megaliths points to a large population replacement, possibly driven by diseasewhich left vast areas of Europe depopulated, which would be occupied by new people.
