Researchers have discovered two mysterious stone rings in a French cave that they believe were created by Neanderthals approximately 176,500 years ago. The findings suggest that the ancient species were capable of behavior that was more advanced than what scientists believed to be possible.

Using hundreds of pillar-shaped mineral deposits called stalagmites, the Neanderthals chopped them to a similar length and created two oval patterns up to 40 centimeters high. Although they were originally discovered back in 1990 after being untouched for tens of thousands of years, nobody thought at the time that it was possible for Neanderthals to have created them.

In the new study, the team used sophisticated dating techniques to determine that the stalagmites were broken off of the ground around 176,500 years ago. Jacques Jaubert of the University of Bordeaux, France, claims that this discovery makes "these edifices among the oldest known well-dated constructions made by humans."

"Their presence at 336 meters (368 yards) 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 researchers wrote in the study.

The team believes that the rings were most definitely not created by chance or constructed by other animals - such as bears and wolves - whose bones were found at the entrance of the cave.

"The origin of the structures is undeniably human," Jaubert said. "It really cannot be otherwise."

Although the purpose of the unique cave structures is still not known, it is possible that they were created for a symbolic or ritual purpose.

"A plausible explanation is that this was a common meeting place for some type of ritual social behavior," said Paola Villa, an archaeologist at the University of Colorado at Boulder who wasn't involved in the study.

Wil Roebroeks, a Neanderthal expert who also wasn't involved in the study, suggests that the finding could be just one of many Neanderthal cultural relics that have yet to be discovered.

"Bruniquel cave (shows) that circular structures were a part of Neanderthals' material culture," he said, calling the rings "an intriguing find, which underlines that a lot of Neanderthal material culture, including their 'architecture,' simply did not survive in the open."

However, given the fact that the unique structures are the first of their kind to be discovered, proving or disproving any theories regarding their creation and purpose is difficult.

"One could even envisage that groups of Neanderthal teenagers explored this underground environment deep in the cave, as teenagers tend to do, building fires, breaking off stalagmites and gradually turning them into the structures that 175,000 years later made it into (the journal) Nature," Roebroeks said.

The findings were published in the May 25 issue of the journal Nature.