Circles of stalagmite pieces, arranged in a circle 176,500 years ago. (Photo: Etienne FABRE - SSAC)

Approximately 176,500 years ago, in a cave in what is now called France, Neanderthals cut 400 pieces of stalagmite into regular lengths and arranged them in two circles and four piles. In 1990, a teenager and a group of local cavers rediscovered them. Only now, though, have scientists estimated just how old they are—dating well beyond the history of Homo sapiens in this area.

This is one of the earliest examples of construction ever found, and the first example of Neanderthal construction that scientists have dated. It shows that these early homonins explored underground and could use fire and reveals an unknown aspect of their culture. It’s not clear what the circle of stones was used for, but it’s possible it had a ritual function, since there’s no evidence that anyone actually lived in the cave.

The cave, in Bruniquel, France, a small town in the country’s mountainous southwest, was sealed for many years by a rockslide. In 1990, a 15-year-old boy cleared those rocks enough for cavers to slip inside, where they found evidence that bears had once lived there, along with the circles.

One circle is larger than the other. The smaller is about 6.5 feet in diameter; the larger is more oval-shaped, and its diameter ranges from about 13 to 23 feet. The stalagmite pieces used to form these structures are made from the middle of stalagmite pieces and include neither the tip nor root of the stones. They are standardized in size, with one set  averaging about 11.6 inches and the other about 13.5 inches. Some of the stones set in the circles have others propping them up. Two of the four piles of stones are inside the larger circle.

In this area, there are also bones and evidence of fire. One of these bones, a bear bone, was dated closer to when the cave was first discovered and found, with carbon dating, to be about 47,500 years old. But, as the Atlantic explains, carbon dating only works for objects younger than 50,000 years old. When Sophie Verheyden, a scientist specializing in stalagmites, heard about the cave, she wondered if it was possible that the structures might be much older, given the limits of carbon dating. In this new study, published in Nature, she and colleagues dated the stalagmites using uranium levels to get to the much older age of the structure.

Recent discoveries have recalibrated humans’ understanding of Neanderthals, long portrayed as less intelligent and inferior hominins than us very special hominins. But it’s becoming clear that they had a lot going on as well—they made art, used tools, buried their dead, and interbred with humans. This new finding shows that long before Homo sapiens had ever reached Europe, they were hanging out in caves, burning things, and making rock circles. Sounds like a pretty good time.

Bonus find: Sponge as big as a car

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