Archaeologists have reported on an "extraordinary discovery" in France after finding several man-made circular structures, or rings, they say date back 170,000 years to the time Neanderthals lived in the area.
The rings were constructed out of stalagmites from the Bruniquel Cave in France's south, and excavators believe they might have been used for some sort of ritual at the time of their creation.
The 400 stalagmites were presumably broken off from the sides of the cave and arranged in two circles, one larger one and a smaller one, as well as several organized piles throughout the cave.
The discovery was recently reported in Nature, an international journal, which reveals how the discovery sheds light on the life of Neanderthals, who some archaeologists believe lived in France thousands of years before the first humans 140,000 years ago.
Discovering these rings laid out deep in the Bruniquel Cave might give some insight into the daily practices of the Neanderthals. Some of the rings contained charred stalagmites, which suggests they were used for fire.
Because there is no evidence of the Neanderthals living in the cave, researchers argue that the fire might have been used for some sort of ritual, for which Neanderthals ventured 300 meters deep into the cave to partake in.
Emmanuel Discamps, an archaeologist at the University of Bergen in Norway, told the Los Angeles Times that the find is a "truly extraordinary discovery."
"Comparable behavior is known for Upper Paleolithic modern humans — younger than 40,000 years old — so it bridges the gap between 'them' and us," Discamps said.
Geologist Dominique Genty with France's National Center for Scientific Research wrote in the report for Nature that the discovery also details the complexity of Neanderthal society. Before this find, it was not known that Neanderthals had the ability to build.
"We know now," Genty writes, "that they were able to make a sort of elaborate construction."
Additionally, discovering the rings nearly 336 meter from the cave's entrance proves the Neanderthals were familiar with the inner workings of underground living.
"Their presence at 336m from the entrance of the cave indicates that humans from this period had already mastered the underground environment, which can be considered a major step in human modernity," the study reads.
Ultimately, although several theories have been thrown around as to why the species built the rings, archaeologists admit that the true answer remains a mystery.
"The big question is why they made it," Jean-Jacques Hublin, a palaeoanthropologist at the Max Planck Institute for Evolutionary Anthropology, told Nature. "Some people will come up with interpretations of ritual or religion or symbolism. Why not? But how to prove it?"
The Bruniquel Cave was originally discovered in 1990 when a 15-year-old boy dug his way into the cave and discovered the rings. It was later explored by a team of archaeologists in 2013 before this report in the journal Nature was published this month.