Deep Neanderthal construction
Deep inside Bruniquel Cave in southwestern France, 336 meters from the entrance, lies one of the oldest known human-made constructions. In a large chamber, early Neanderthals built six structures entirely from broken stalagmites. Two are large rings, while the other four are smaller piles or accumulations. The project involved breaking and moving approximately 400 stalagmite pieces, collectively weighing an estimated 2.2 metric tons.
The main ring is an ellipse measuring 6.7 by 4.5 meters, with a smaller ring nearby measuring 2.2 by 2.1 meters. The pieces, technically called "speleofacts," are arranged in up to four stacked layers, reaching a height of about 40 centimeters. The builders deliberately calibrated the pieces, selecting fragments with an average length of about 30-34 centimeters. Some stalagmites were set vertically against the rings, possibly to act as reinforcements. This entire construction effort happened in the phreatic zone, a part of the cave that receives no natural light.
Architects of the dark
Uranium-series dating of the stalagmites and the calcite that later grew over them places the construction at 176,500 years ago, with a margin of error of about 2,000 years. This date confirms the structures were built by early Neanderthals (Homo neanderthalensis), the only hominin species present in Europe at that time. Homo sapiens would not arrive in the region for another 140,000 years.
The construction shows a capacity for group organization and planning previously unknown for such an early period. Evidence of fire is also present. Researchers have identified dozens of reddened or blackened calcite pieces and burnt bone fragments within the structures, showing controlled use of fire for illumination deep underground. The exact purpose of the structures remains unknown. Theories range from a ritual or symbolic function to a more practical use like a shelter from the glacial climate of Marine Isotope Stage 6, but no definitive answer has been reached.