Neanderthals Built Mysterious Stone Circles

Rings of stalagmites found in a cave in France suggest that our ancient relatives were surprisingly skilled builders.

By Nadia Drake

Once illuminated by the flickering fires of prehistoric builders, an array of mysterious stone circles hid in darkness for millennia, tucked into the recesses of a cave in France. Now, these ancient structures are again emerging from the shadows.

The strange rings are crafted from stalagmites and are roughly 176,000 years old, scientists reported in Nature. And if the rings were built by a bipedal species, as archaeologists suspect, then they could only be the work of Neanderthals, ancient human relatives that are proving to be much more “human” than anticipated.

“This discovery provides clear evidence that Neanderthals had fully human capabilities in the planning and the construction of ‘stone’ structures, and that some of them penetrated deep into caves, where artificial lighting would have been essential,” says paleoanthropologist Chris Stringer of the Natural History Museum in London.

However, why Neanderthals ventured deep into the darkness and constructed such elaborate structures is an enigma, at least for now.

Sealed since the Pleistocene, Bruniquel Cave is located in southwest France, in a region littered with decorated caves and other Paleolithic sites. In 1990, spelunkers excavated its entrance and squeezed through, finding signs of long-vanished cave bears and other extinct megafauna just inside.

But the cave’s real treasure lay in a damp chamber more than 1,000 feet (330 meters) from the entrance. There, several large, layered ring-like structures protruded from the cave floor, the seemingly unmistakable craftwork of builders with a purpose.

“All visitors have noticed the presence of these structures, from the first speleologists,” says Jacques Jaubert of the University of Bordeaux, a coauthor of the study describing the finding.

It would take decades for scientists to begin deciphering the enigmatic circles, an endeavor slowed by restricted access to the cave and the untimely death of the archaeologist who began work on the site in the 1990s.

In 2013, Jaubert and his team were finally able to bring Bruniquel’s secrets into the light.

“The cave was very well preserved, with very few visits, almost none,” he says, noting that the site is on private property and is regulated by the French government. “The structures are spectacular and have virtually no equivalent for that period, and even for more recent periods.”

The mysterious structures are built from nearly 400 stalagmites—the cone-shaped rock formations that rise from cave floors as dripping, mineral-rich water accumulates over time.

Hewn to roughly the same length, some of the stalagmites were crafted into a large circular structure measuring nearly 22 feet (6.7 meters) across. Others were aligned in a smaller semicircle, and the rest were stacked in heaps.

Cracked areas of red and black discoloration indicate that fires had been lit atop the stalagmites, and charred bits of bone, including the burnt bone of a bear or large herbivore, were found near the smaller circle.

A 3D reconstruction of the structures in Bruniquel Cave.

Even to a trained eye, the scene looked like it could be the work of early modern humans, who first appeared in Europe about 40,000 years ago. But uranium dating of the stalagmites, as well as dates for a mineral cloak that had grown over them and the bone bits, revealed an age the team didn’t expect.

At around 176,000 years old, the structures vastly predate the arrival of Homo sapiens, not just by a smidge, but by more than 100,000 years.

“These must have been made by early Neanderthals, the only known human inhabitants of Europe at this time.” Stringer says.

Neanderthals thrived for 300,000 years, coexisting with and occasionally breeding with modern humans. Like us, they were big-brained and clever, with a mastery of fire. But scientists argue about how similar the two species really were, and debate whether Neanderthals were capable of symbolic thought and ritual behaviors.

Unlike us, Neanderthals didn’t survive, and the reasons why they vanished from the landscape some 30,000 to 40,000 years ago are still a source of contention.

Until now, anthropologists had thought it unlikely that Neanderthals had mastered the art of subterranean living, which is a bit trickier than traipsing around above ground. The Bruniquel cave could prove otherwise.

“The find is solid, and it is an important documentation of the advanced behaviors of the Neanderthals,” says paleoanthropologist Erik Trinkaus of Washington University in St. Louis.

To craft those enormous stone rings, Jaubert and his colleagues argue, the cave’s occupants needed a reliable source of illumination, some kind of social organization, and the ability to conceive of and construct the patterns, which are made from more than two tons of stalagmites.

“This requires the mobilization of people who choose, who lead, who advise, manufacture—and with continuous light,” he says. “All this indicates a structured society.”

That’s one interpretation, but some scientists say it’s too soon to draw these kinds of conclusions about the site. To begin with, it’s not yet clear how widespread such complex behavior may have been among Neanderthals, or if the structures were built by one person or many.

“We don’t know how many people were involved, if the structures were done in one event or during several events, by one person or by several,” says anthropologist Marie Soressi of Leiden University. “I don’t know what to expect, because such a discovery is very unusual.”

Other scientists question the presumed human origin for the structures and instead suggest they could be the work of hibernating cave bears.

“Who in their right minds builds structures 300 meters underground inside of a cave? Seeking refuge in a cave is a way of avoiding having to make an artificial structure,” says paleoanthropologist John Shea of Stony Brook University. “When bears settle in for the winter hibernation, they push all kinds of litter to the side. This looks like a place where cave bears settled in for a nice nap over and over through time.”

But bear dens are generally smaller than the largest ring, Soressi says, and the animals don’t stack stalagmites so much as excavate hollows and brush things aside. Plus, Jaubert notes, “bears do not make fire.”

If the structures are indeed the work of Neanderthals and not cave bears, their purpose is still a mystery. No one knows what the Neanderthals might have been doing in that cave, or how long they used it. Jaubert and his colleagues refuse to speculate about the structures’ purpose until further work at the site tells more of the story.

In the meantime, it’s hard to resist wondering what our ancient relatives were doing deep inside that cavern, with their fire-lit rings of stone.

“The complex Bruniquel structures are well-dated to within a long cold glacial stage, and at that time the cave might have provided a temporary, more temperate refuge,” Stringer says.

“If there is still-buried debris from occupation, it would help us to determine whether this was a functional refuge or shelter, perhaps roofed using wood and skins, or something which had more symbolic or ritual significance.”

Neanderthals Likely Built These 176,000-Year-Old Underground Ring Structures

By Taylor Kubota

About 40,000 years before the appearance of modern man in Europe, Neanderthals in southwestern France were venturing deep into the earth, building some of the earliest complex structures and using fire.

That’s according to new research that more precisely dated bizarre cave structures built from stalagmites, or mineral formations that grow upward from the floor of a cave. Scientists discovered about 400 stalagmites and stalagmite sections that were collected and stacked into nearly circular formations about 1,100 feet (336 meters) from the entrance of Bruniquel Cave, which was discovered in 1990.

Dating these formations to a time when Neanderthals, but not modern humans, were present in Eurasia, makes the finding the oldest directly dated constructions attributed to Neanderthals, according to Marie Soressi, an archaeologist at Leiden University in the Netherlands, who wrote a News and Views article in the same issue of the journal Nature in which the original study is published.

Dating bone
Soot stains, heat fractures and burnt material, including bone, point to the likelihood that these circles were used to contain fires back in the day.

In 1995, some of the burnt bone was dated using carbon-14 dating, a technique that measures the ratio of carbon-14 to carbon-12; that ratio indicates about how long an organism has been dead. It was found to be 47,600 years old — the maximum age carbon-14 dating can attain.

More recently, lead author Jacques Jaubert, of the University of Bordeaux in France, and his colleagues revisited this site, with more advanced surveying and dating technology. Through a technique called uranium-series dating, which relies on the breakdown of uranium to thorium, they were able to estimate when the stalagmites were broken and moved into the circular formations. They found the installations are approximately 176,500 years old (give or take 2,000 years).

Human-made structures
These structures are “among the oldest known well-dated constructions made by humans,” Jaubert and his colleagues wrote in their research paper published yesterday (May 26) in the journal Nature.

Evidence of a human-made structure exists in Olduvai Gorge in Tanzania, dated at over 1 million years old. But this has not been studied extensively, Jaubert said. He added there is similarly little information about a Homo erectus campsite in Bilzingsleben, Germany (about 400,000 years old), early shelters in Terra Amata, France (about 400,000 years old), and the bone and stone materials found in France’s Lazaret cave (around 170,000 years old). Researchers have credited Neanderthals with making a building out of mammoth bone in Ukraine. They believe this is about 40,000 years old.

“In any case, there are many examples of concentrations [of] remains, hearths, lithic [stone] workshops, faunal structures … but never the structures of this magnitude. And in this deep cave context!” Jaubert wrote in an email to Live Science. Before the Bruniquel Cave discovery, the cave paintings of Chauvet, France, were the oldest evidence of cave use by humans or human ancestors. Those date back a mere 38,000 years.

The amazing Bruniquel Cave
The Bruniquel Cave is located on private property, overlooking the Aveyron Valley, near a tributary of the Tarn. This area is rich in Paleolithic sites (dated to about 2.6 million to 10,000 years ago). Near the entrance is another important paleontological site of a similar age or potentially older, Jaubert said. The cave has a narrow entrance and is 33 to 49 feet (10 to 15 meters) wide, 13 to 23 feet (4 to 7 m) high, and — as far as anyone knows — 1,581 feet (482 m) long.

When the cave was first discovered, speleologists (people who study caves) meticulously preserved its natural formations, which aside from the stalagmite circles, include translucent flowstone, an underground lake and calcite rafts, or thin sheets of calcite that formed on the surface of the lake. Calcite is a rock-forming mineral found in limestone and marble. The speleologists also took care to keep Bruniquel’s bone remains and dozens of bear hibernation hollows in pristine condition. A thick layer of calcite had coated all the structures, making dating techniques difficult to perform.

For the next two decades, very few people visited the cave, Jaubert said. He thinks part of this may have been due to the death of the original researcher, archaeologist Francois Rouzaud. Additionally, he said the cave is challenging to access, not only physically but also because it is on private property and there are many conditions that need to be met in order for the owners and the French Ministry of Culture to authorize new research.

In 2013, using 3D-surveying equipment and magnetic measurements that record anomalies caused by heat, researchers were able to map both the stalagmite structures and the burnt remnants. Stalagmite arrangements of this scale are unprecedented, so the research team created the term “speleofacts” to describe each piece of stalagmite used in the structures. They estimate there were about 400 speleofacts total, with a combined weight of between 2.3 and 2.6 tons (2.1 and 2.3 metric tonnes) and a combined length of 367 feet (112 m). Jaubert said the stalagmites were the only raw material available for building in the cave.

Social Neanderthals
Until now, Neanderthals were “presumed by the scientific community not to have ventured far underground, nor to have mastered such sophisticated use of lighting and fire, let alone to have built such elaborate constructions,” according to a statement by the National Center for Scientific Research.

“This type of construction implies the beginnings of a social organization: This organization could consist of a project that was designed and discussed by one or several individuals, a distribution of the tasks of choosing, collecting and calibrating the speleofacts, followed by their transport (or vice versa) and placement according to a predetermined plan,” wrote the researchers in the Naturearticle. The researchers also said this process would have required adequate lighting and determined that the fires in the cave were likely used as light sources.

Given their distance from the cave entrance and daylight, the team said it was unlikely the circles were used as shelters. They didn’t rule out the possibility that they could have been used for technical purposes, such as water storage, or religious or ceremonial purposes. Jaubert said the next steps in studying the cave will include further examination of the structures, a more extensive survey of the cave’s interior to uncover any additional archaeological remains, and a closer look at the cave’s entrance.

The find has added extensively to scientists’ knowledge of Neanderthal social organization and human cave dwelling in prehistory, the researchers said. Even so, they added, the question remains: What were the structures used for?

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Did Neanderthals go extinct because they couldn’t learn to catch rabbits?


Neanderthals became extinct as they were unable to adapt their hunting skills to catch small animals like rabbits, a new study has claimed.

For the study, John Fa of Durrell Wildlife Conservation Trust in Trinity, Jersey, and his colleagues counted skeletons of animals that were found in three excavation sites in Spain and southern France.

The team found that up until 30,000 years ago, the skeletons of larger animals like deer were plentiful in caves.

But around the same time, coinciding with Neanderthals’ disappearance, rabbit skeletons became more abundant.

The team postulated that humans succeeded far more at switching to capturing and eating rabbits than Neanderthals, New Scientist reported.

Fa said that it is still not clear as to why Neanderthals had trouble changing their prey.

He said that maybe the Neanderthals may have been less able to cooperate and rather than using spears, early humans probably surrounded a warren and flushed out rabbits with fire, smoke or dogs.