In 1990, cavers in the the south west of France entered a cave that had been sealed from the outside world for tens of thousands of years by a natural rockslide. 337 metres within the cave, they made a curious find: a mass of broken off stalagmites which seemed to have been arranged into ring or circle shapes on purpose.
In the 1990s archaeologist Francois Rouzard set out to determine whether the constructions in Bruniquel Cave were made by the hands of Neanderthals, but after his premature death from a heart attack in 1999 research ground to halt. But 14 years later, a multi-national team finally did a proper scientific analysis of the structures - and their conclusions are mind-blowing.
Using uranium-series dating of the stalagmite calcite, the researchers found that the structures were built between 175,000 and 177,000 years ago! Neanderthals are believed to have been the only human population living in Europe at this time, and so the researchers have attributed the constructions to them.
Here's the description of the structures:
The arranged structures composed of whole and broken stalagmites, here designated as ‘speleofacts’, are located in the largest chamber of the cave. Our study defines two categories of structures: two annular ones, which are the most impressive, and four smaller stalagmite accumulation structures. The largest annular structure is 6.7 × 4.5 m, and the smaller one is 2.2 × 2.1 m. The accumulation structures consist of stacks of stalagmites and are from 0.55 m to 2.60 m in diameter. Two of them are located in the centre of the larger annular construction, while the other two are outside of it. Overall, about 400 pieces were used, comprising a total length of 112.4 m and an average weight of 2.2 tons of calcite... The stalagmites are well calibrated with a mean length of 34.4 cm for the large (A) and 29.5 cm for the small (B) annular structures, thus strongly suggesting intentional construction.
The annular structures are composed of one to four superposed layers of aligned stalagmites. Notably, some short elements were placed inside the superposed layers to support them. Other stalagmites were placed vertically against the main structure in the manner of stays, perhaps to reinforce the constructions.
Traces of fire were also found to be present on all six of the structures. Carbonized organic material was found, with some of the fragments being the bones of a bear or large herbivore.
The dating of the constructions within Bruniquel Cave is staggering. In terms of megalithic building, Stonehenge dates back around 5000 years; Gobekli Tepe 10,000 years. Completely preserved archaeological sites are rare before 40,000 years ago. And yet here we have a well-preserved site, with signs of intelligent human construction, dating back 175,000 years:
The attribution of the Bruniquel constructions to early Neanderthals is unprecedented in two ways. First, it reveals the appropriation of a deep karst space (including lighting) by a pre-modern human species. Second, it concerns elaborate constructions that have never been reported before, made with hundreds of partially calibrated, broken stalagmites (speleofacts) that appear to have been deliberately moved and placed in their current locations, along with the presence of several intentionally heated zones. Our results therefore suggest that the Neanderthal group responsible for these constructions had a level of social organization that was more complex than previously thought for this hominid species.
For the researchers involved, questions abound. "What was the function of these structures at such a great distance from the cave entrance? Why are most of the fireplaces found on the structures rather than directly on the cave floor? We could assume that they represent some kind of symbolic or ritual behaviour, but could they rather have served for an unknown domestic use or simply as a refuge? Future research will try to answer these questions."