A clay impression discovered deep inside Bruniquel cave in south-west France could be the kneeprint of a Neanderthal who helped build strange circular structures. Preserved beneath a layer of calcite, the mark is now drawing attention from researchers studying one of Europe’s most unusual prehistoric cave sites.
The possible kneeprint was identified near rings made from broken stalagmites, structures first revealed to the scientific world in a 2016 study. The cave, located near Toulouse, contains hundreds of deliberately arranged stalagmite fragments positioned more than 300 meters from the entrance, in complete darkness.
According toSophie Verheyden from the Royal Belgian Institute of Natural Sciences, the impression may represent a rare form of prehistoric evidence. Human footprints from ancient periods are widely studied, but kneeprints have received little scientific attention so far.
A Kneeprint Preserved Beneath Mineral Deposits
The kneeprint survived because it became covered by a thin layer of calcium carbonate, the same mineral material responsible for the cave’s stalagmites. That natural coating protected the mark while much of the surrounding evidence disappeared over time.
Sophie Verheyden said that cave bears later occupied the site and destroyed many traces left on the floor. A specialist in prehistoric bear prints examined the impression and concluded it was not made by an animal. Researchers remain cautious about identifying it definitively as a human kneeprint.
“It’s just a hypothesis,” Verheyden said during a presentation at the European Geosciences Union meeting in Vienna on May 4. She added that: “To be sure of that, we need a lot of imprints of knees to compare it to.”
The possibility of recovering biological evidence has also emerged. Mareike Stahlschmidt of the University of Vienna noted that DNA can diffuse into calcite and remain preserved there under certain conditions. Scientists believe traces from skin cells, hair, or blood may have survived if the impression mineralized rapidly after it was formed.
Neanderthals Built The Underground Circles
The circular formations inside Bruniquel cave continue to puzzle archaeologists nearly three decades after their rediscovery. The structures were assembled using broken stalagmites, some of them more than 20 centimeters thick at the base, as explained in a study published by Nature.
Verheyden explained that such large formations were unlikely to have been broken accidentally by cave bears. Her team recently located several of the original stalagmite bases and dated their breakage to the same period as the circles themselves.
As mentioned in the latest research, published in Quaternary Science Reviews, the study team used radioactive isotope analysis on calcite deposits to establish the timeline. The dates point to activity around 175,000 years ago. Scientists attribute the structures to Neanderthalsbecause Homo sapiens were not present in Europe at that time.
“We don’t know of any other humans present at that period,” Verheyden said.
Mysterious Structures Found Inside Cave
One of the biggest questions concerns why Neanderthals ventured so far underground to construct the circles. The formations stand in sections of the cave completely deprived of natural light.
“You need to be sure of your light when you go 300 meters underground,” Verheyden noted. The study’s authors also argued that “their presence at 336m from the entrance of the cave indicates that humans from this period had already mastered the underground environment, which can be considered a major step in human modernity.”
Traces of fire found near the structures suggest the area was illuminated during use. Researchers say the circles may not have served as ordinary shelters because of their isolated location deep inside the cave system. The unusual setting has encouraged speculation about cultural or symbolic activities, although the team avoids making firm claims without stronger evidence.
Scientists are now developing methods to identify exactly where each stalagmite originated within the cave.Verheyden said that work may reveal whether the builders selected materials from particular areas rather than simply using the closest available formations.
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