54,000 Years Ago, Humans and Neanderthals May Have Inhabited Europe Together

Grotte Mandrin isn’t an extensive cave; it’s just a deep overhang in southern France that provides protection from the elements. But the shelter nestled inside a rock outcropping has wide views over a Rhône Valley once teeming with deer, bison and horses. So Neanderthals found the location attractive enough to call it home, seasonally at least, for tens of thousands of years. And they weren’t the only species to move in. A broken molar and sophisticated stone points suggest that Europe’s first known humans may have lived here 54,000 years ago, subsequently alternating occupation with Neanderthals during thousands of years of European prehistory.

Now the striking similarities between these finds and tools from the Near East, published Wednesday in PLOS One, have made Grotte Mandrin the epicenter of an intriguing theory that could write new chapters in the story of how humans inhabited Europe, and what their arrival meant for the continent’s Neanderthal inhabitants.

The provocative new theory suggests modern humans colonized Europe in three distinct waves of migration from the Near East, interacting with Neanderthals intermittently for thousands of years while they attempted to gain a foothold. French archaeologist Ludovic Slimak believes that sophisticated stone tools found in France were produced by systematic technical methods so similar to those seen among Homo sapiens in Lebanon that they must have come from the same culture.

The comparisons of thousands of tools—and a single surprising human tooth—led Slimak to theorize that human migrations from the Near East began about 10,000 years earlier than previously thought. And because tool technologies went through three very similar phases in each region, Slimak believes that they were spread from the Near East to Europe during three distinct waves of migration. It was only after the third wave some 45,000 to 42,000 years ago, he suggests, that Neanderthals began to fade into extinction.

“All this time H. sapiens were there, and we just didn’t see it, because the human remains are absolutely rare,” says Slimak, of the French National Center for Scientific Research. “So we weren’t able to really draw the real history of what happened in that process of migrations and interactions between Homo sapiens and Neanderthals.”

Slimak’s study is sure to spark debate and launch further research efforts that could reveal much about how humans came to take over Europe, what our ancestors’ relations were like with Neanderthals, and why those Neanderthals, Europe’s original inhabitants, eventually disappeared.

“What I propose here is predictive, it’s not a definitive demonstration,” he says, noting that future studies will determine if those predictions are correct.

Since excavations began in 1990, Grotte Mandrin’s dated archaeological layers have produced an intriguing record of the site’s Neanderthal occupation for over 80,000 years. The rock shelter has yielded many tools and nine teeth from at least seven individuals. While most of the teeth are Neanderthal in appearance, one 54,000-year-old molar appears to be distinctly human. That’s surprising, since before that tooth was described in 2022, the earliest widely accepted evidence for modern humans in Europe were tooth and bone fragments from a Bulgarian cave called Bacho Kiro, which yielded human DNA that dates to about 45,000 years ago.

Not everyone is entirely convinced that the Grotte Mandrin tooth is definitively human, rather than perhaps an unusually shaped young Neanderthal’s tooth. “It would be so cool if it were true … but it’s not a slam dunk,” Shara Bailey, a dental paleoanthropologist at New York University, told Science in 2022. And, at least to this point, scientists haven’t been able to recover any DNA that could make the molar’s origin certain.

But the tooth is also from the brief layer in time, about 54,000 years ago, that contains sophisticated stone tools, called Neronian, very different from the typical Neanderthal tools found in surrounding layers both older and younger. Slimak believes the nature of the tools and their systematic production presents an entirely separate line of evidence from the tooth that also points to their human origin.

The small, sophisticated flint points are unlike anything else known during this era in Europe. They show a standardized technical development, unlike Neanderthal tools, which tend to be more unique than uniform. In a 2023 study, Slimak and others even used local flint to create replicas of the various points and tested their effectiveness by using them on dead goats. The smaller ones only proved useful when delivered with the velocity of a bow and arrow, they found, though the next evidence of European archery doesn’t appear until 40,000 years later.

With no prior evidence of humans in France at this date, some had theorized that the region’s Neanderthal population might have included a unique group that adapted to produce these sophisticated implements. But in Harvard University’s Peabody Museum, Slimak encountered a trove of ancient artifacts from Ksar Akil, Lebanon—a key Paleolithic site a few miles outside Beirut—that led him to a very different conclusion.

“You can read a flint like you can read a book,” he says. “It’s not simply the end product, but you can see the technical phases of production. When I opened those boxes, I had a very huge surprise: It was the same technical process. All the phases of production were the same as at Grotte Mandrin.”

There are countless ways to make a point out of flint, and Slimak stresses that the odds of two unrelated groups using the same exact system of steps and techniques are extremely low. “It’s something almost impossible unless you are just the same people,” he says. “It was very clear to me that I was facing the same populations and the same culture.”

“I think the data for this first phase, his connections between the Neronian at Grotte Mandrin and the lower part of the Upper Paleolithic sequence at Ksar Akil, works very well,” says Gilbert Tostevin, an archaeologist at the University of Minnesota not involved in the research.

If the sets of tools from areas some 1,800 miles apart really do evidence the first human migrations to Europe, Slimak further suggests that the later evolution of toolmaking in the same disparate regions is actually also evidence of a second wave of migration. In Ksar Akil, thousands of younger flints known as “backed bladelets” show the same uncanny resemblance to another tool tradition seen from Burgundy to Spain, known as the Châtelperronian, Slimak says. The Châtelperronian industry is often (though not unanimously) considered to be Neanderthal, a level of technical advancement showing that Neanderthals were influenced by the humans who were then beginning to appear in Europe. But Slimak suggests that it correlates so closely with human technology from the Near East that it’s likely also the work of humans—those who migrated to Europe in a second wave. That assertion will likely face challenges.

If the evolving tool technologies, mirroring each other in Europe and the Near East, do evidence a second wave of human migration, the idea could have implications for our theories about how Neanderthals adapted to the arrival of humans. “The way we understand the last Neanderthals is that they adapt to a very different way of life before their disappearance,” says Slimak. But if they didn’t adapt and embrace changes with transitional industries like the Châtelperronian, might that suggest new reasons why they didn’t survive alongside the humans?

Our human ancestors and their Neanderthal relatives not only shared space and time during evolutionary history; they also interbred in various places and times. Today, most humans who live outside of sub-Saharan African carry Neanderthal genes, at 1 to 4 percent. But scientists aren’t sure how often the groups actually came into contact, nor how much they learned from one another at places like Grotte Mandarin where archaeology suggests that they likely met.

Tostevin suggests that while such human-Neanderthal hybridization might or might not have happened at Grotte Mandarin, it’s a key part of dynamics in Paleolithic Europe that isn't acknowledged in the new theory. “After that first phase of modern humans, much of the upper Paleolithic is also being made by hybrids, humans and Neanderthals,” he notes. Tostevin points out that many key European sites from the era have yielded such evidence, from ancient DNA at Bulgaria’s Bacho Kiro and Romania’s “Cave of Bones” to hybrid teeth left on the Channel Islands off the coast of France. “These sites all show individuals that are just a few generations removed from admixture between humans and Neanderthals.”

Other scientists say the new theory presents many opportunities for future research in a number of fields.

“The model is nothing if not provocative,” says Christian Tryon, an anthropologist at the University of Connecticut and the Smithsonian’s Human Origins Program, who was not an author of the new report but was acknowledged by Slimak for his research assistance. “Archaeologists like to connect dots on a map. On these maps there’s a lot of empty space between dots,” says Tryon. “What lines of evidence can we find to actually connect those dots?”

Finding more sites between Lebanon and France may be a challenge, Tryon notes, in part because the world has changed over the past 50,000 years. “One implication to connect those dots in Lebanon and France is that there had to be people hugging Mediterranean coastlines, sea travel that we’re not picking up,” he says. “The problem is that since sea levels rose about 20,000 years ago those key coastal sites could be underwater.”

Other information might come from ancient DNA, a technology that’s advancing quickly. Marie Soressi, an archaeologist at Leiden University in the Netherlands, hopes DNA can help test what she calls an interesting, stimulating and very welcome hypothesis. This week, Soressi and colleagues published a new technique to successfully extract human DNA from 20,000-year-old bone and tooth artifacts, revealing who made and handled them in the ancient past. “Application of this new technique to the time period discussed by Slimak will be of great help to test and develop the theory he has put forward,” she says.

Brian Handwerk | READ MORE

Brian Handwerk is a science correspondent based in Amherst, New Hampshire.