And if Rouzaud’s work made it unlikely that modern humans built the rings, Verheyden’s study grinds that possibility into the dust. Neanderthals must have been responsible. There simply wasn’t any other hominin in that region at that time.
Why did they build the rings and mounds? The structures weren’t foundations for huts; the chamber contains no stone tools, human bones, or any other sign of permanent occupation, and besides, why build shelter inside a cave? “A plausible explanation is that this was a meeting place for some type of ritual social behavior,” says Paola Villa from the University of Colorado Museum.
“When you see such a structure so far into the cave, you think of something cultural or religious, but that’s not proven,” adds Verheyden. Indeed, despite some fanciful speculations about cave bear cults, no one really knows.
Nor is it clear how the Neanderthals made the structures. Verheyden says it couldn’t have been one lone artisan, toiling away in the dark. Most likely, there was a team, and a technically skilled one at that. They broke rocks deliberately, and arranged them precisely. They used fire, too. More than 120 fragments have red and black streaks that aren’t found elsewhere in the chamber or the cave beyond. They were the result of deliberately applied heat, at intensities strong enough to occasionally crack the rock. “The Neanderthal group responsible for these constructions had a level of social organization that was more complex than previously thought,” the team writes.
These discoveries are part of the Neanderthals’ ongoing rehabilitation. Since their discovery, scientists have tried to understand why they died out and we did not, with the implicit assumption that they were inferior in some important way. Indeed, to describe someone as a Neanderthal today is to accuse them of unsophisticated brutishness.
But we now know that Neanderthals made tools, used fire, made art, buried their dead, and perhaps even had language. “The new findings have ushered a transformation of the Neanderthal from a knuckle-dragging savage rightfully defeated in an evolutionary contest, to a distant cousin that holds clues to our identity,” wrote Lydia Pyne in Nautilus.
And now, we have Bruniquel Cave with its structures that are unprecedented in their complexity, antiquity, and depth within the darkness. We know that 400,000 years ago, some ancient hominins chucked their dead into a cave at Sima de los Huesos, but there’s no evidence of the careful constructions in Bruniquel. There’s evidence of painting and sculpture within caves, but none older than 42,000 years. There are signs that Neanderthals used caves, but nothing to suggest that they frequently ventured deeper than sunlight.
“I think we have several lines of evidence showing that the cognitive abilities and behaviors of Neanderthals were complex,” says Marie Soressi from Leiden University. “But we had no direct evidence of their ability to build. That changes the picture for me. It’s puzzling to find such structures so deep inside the cave.”
To solve these puzzles, Verheyden wants to start cutting into the cave’s floor. It has been covered by layers of calcite, which may conceal specimens that hint at the chamber’s purpose. Verheyden also notes that the entrance they’ve been using cannot possibly have been the only one. “We’re crawling through this small thing and there are bear hollows in the cave. I don’t think the bears went in that way!” she says. “There must have been some other passage that collapsed.”
She’s going to find it.