Washington (AFP) – Like modern humans and primates, Neanderthals – our closest evolutionary cousins - are thought to live in groups, but their size and composition are difficult to deduce from archeological and fossil remains.
Now, however, scientists are reporting the discovery of 257 prints along the Normandy coast in France, which have been preserved flawlessly for 80,000 years, offering major new clues to the social structures of its prehistoric inhabitants.
Their paper, published in the Proceedings of the National Academy of Sciences on Monday, suggested the group numbered 1
Jeremy Duvo, a doctoral student at the National Museum of Natural History of France and one of the study's co-authors, told AFP that the prints were left in muddy soil, then quickly preserved by sand driven by the wind when the area was part of a system from the dunes, creating a snapshot.
The site of Roselle was discovered by amateur archaeologist Yves Rupin in the 1960s, but it was not until 2012, when he was confronted with the double risk of wind erosion and tides that annual excavations began with government support. .
Tens of meters of sand were extracted with mechanical shovels to reach interesting layers.
The team then switched to brushes to complete the last phase of the delicate excavation work that led to the identification of 257 prints between 2012 and 2017 and hundreds more since then.
The prints were discovered amid what the team called "abundant archaeological material," indicating the butchery's operations and production of stone tools, dating from a time when only Neanderthals, not anatomically modern humans, lived in Western Europe.
– "Miracle" –
Fast-preserved prints offer advertising an advantage over archeological or fossilized bones remains in estimating the size of the group because they can accumulate over time and do not necessarily reflect a single occupation unless a catastrophic event did not kill the entire group at once.
Yet this power is also a footprint, "a major weakness:" They record a peculiar moment in people's lives for a very short period of time, "Duvo says.
"This gives us some idea of the composition of a group, but it is possible that it only represents those members of the group who happened to be on time. "
So the question is: were there so few adult prints because the Neanderthals died young? Or were the adults somewhere else?
Each of the steps is filmed and modeled in three dimensions. For some of them, an elastomer that was less rigid than the plaster was used.
Thanks to the sophisticated new chemical technology available to the 2017 team, hundreds of prints have been lifted from the site to be stored elsewhere.
Those that have not been extracted are "completely wiped out" by the wind, Duvo says.
"Protecting the prints requires a miracle: we must be very, very lucky,"  Prior to Rosell, only nine confirmed Neanderthal prints were discovered in Greece, Romania, Gibraltar and France.
Some of Roselle's castings are already on display, including at the Musee de l'Home in Paris and researchers are looking to find ways to expand the audience through future exhibits.