Approximately 175,000 years ago, Neanderthals explored the depths of the Bruniquel Cave in France. They meticulously crushed stalagmites to create enigmatic circular structures, only for a bear to later obliterate most of the evidence of their presence, leaving some clay knee impressions that could potentially belong to a kneeling Neanderthal.

“It’s merely a hypothesis,” states Sophie Verheyden from the Belgian Royal Institute of Natural Sciences. “We require more knee impressions for comparison to validate this theory.”

The stalagmite rings, located in Bruniquel Cave near Toulouse, were discovered in the 1990s and detailed in a 2016 publication by Verheyden and her research team. While human footprints have been thoroughly investigated, ancient knee tracks remain largely unexplored. To initiate this study, Verheyden’s team plans to create knee impressions using individuals kneeling in various clay samples.

Verheyden confidently asserts the ancient nature of the cave remains, preserved beneath a thin calcium carbonate layer, the same substance that formed the stalagmites. Additionally, examination by a bear specialist confirmed the absence of bear footprints in this area.

Potentially, Neanderthal DNA could emerge as compelling evidence tied to those knee impressions. Mareike Stahlschmidt from the University of Vienna demonstrated that DNA can diffuse into calcite, a type of calcium carbonate, and remains preserved. “Bruniquel Cave is a prime candidate for this search,” Stahlschmidt acknowledges.

A forensic analysis of the knee impressions indicates the possibility of DNA from skin cells, hair, and blood, which typically deteriorates swiftly. If the impressions in the cave hardened quickly, some may have been retained.

Given that modern humans (Homo sapiens) were absent from Europe 175,000 years ago, Verheyden concludes, “Neanderthals must be responsible for the construction of the stalagmite circles.”

In a significant discovery this year, the research team indicated that the cave entrance collapsed at least 140,000 years ago, remaining sealed until its rediscovery by cave explorers in 1990. Researchers are confident that all artifacts discovered within are of Neanderthal origin.

Some of the fractured stalagmites were measured to be over 20 centimeters thick, indicating they couldn’t have been broken merely by passing bears. The research team successfully identified several broken stalagmite bases and established they broke during the same time frame as the stalagmite rings, utilizing radioactive isotopic analysis for dating.

“The dating strengthens our understanding, as it coincides with the construction of these intriguing structures,” Verheyden explained while presenting her findings on May 4th at the European Geosciences Union conference in Vienna.

It appears that Neanderthals invested considerable effort into breaking stalagmites to form these circles, with the largest measuring about 7 meters in diameter. This prompts speculation regarding their function, whether as shelter or for cultural or ritualistic purposes, given their location 300 meters deep in total darkness.

“When traversing 300 meters underground, it’s crucial to check your light source,” Verheyden noted. While evidence of fire suggests illumination within the circle, it’s unlikely Neanderthals inhabited this area regularly.

The circle’s placement inspires speculation regarding its potential cultural or religious significance. “It’s tempting to leap to such explanations, but as scientists, we aim for an objective inquiry,” Verheyden stated.

Her team is actively developing a method to “fingerprint” stalagmites based on their mineral composition to determine their source within the cave, offering insight into whether the materials were locally sourced or transported from distant locations.

Verheyden compares this to certain Maya practices, wherein people collect stalagmites from deep within caves to use in fertility rituals. Thus, identifying the origin of a broken stalagmite could yield crucial insights into the intentions behind its construction.

The research team is continually seeking ways to penetrate the calcium carbonate layer covering portions of the cave floor. In the era before bears inhabited the cave, numerous Neanderthal footprints may have existed, now obscured by the calcium carbonate buildup.

“We remain hopeful,” Verheyden expressed. “Every expedition into the cave uncovers new discoveries, even after a decade of exploration.”

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