A kid's tooth found in a French cave is the earliest known evidence of modern humans in western Europe, suggesting our species was present there at least 10,000 years earlier than thought. 

The dental fragment indicates that modern humans were living in Western Europe at least 54,000 years ago. Prior to this find, the evidence suggested modern humans arrived in Europe no earlier than around 43,000 years ago. 

The remarkable discovery by an international team of scientists is detailed in a new study published in the journal Science Advances.

The discovery was made at a cave known as Grotte Mandrin in southern France’s Rhône Valley. It’s known that this rock shelter was once inhabited by groups of both Homo sapiens and Neanderthals, our extinct “cousins” who migrated to Europe long before our species made the journey. However, a new look at remains at the cave has revealed the story is much more complicated and intriguing than previously thought 

Dental remains of at least seven different individuals were found within 12 archaeological layers of the cave, each layer representing a different time period. The researchers found that six of these individuals were Neanderthal – but one was a fossil molar belonging to a modern human child dating to approximately 54,000 years old.

Along with the human dental remains, they were also the discovery of stone tools from the unique Neronian industry, typically of the surrounding Rhône Valley. 

Not only is the age of the child’s tooth interesting, but it’s also curious that the human remains were discovered in a layer sandwiched between the Neanderthal layers.

Researchers have long suspected that Grotte Mandrin was a meeting place for Neanderthals and modern humans, since their presence here was just a few years apart. Given that humans and Neanderthals widely interbred with each other, it's not a stretch to believe that inter-species mingling occurred here. 

However, this latest study suggests a clear overlap between the two species; both Neanderthal and modern human populations replaced the other population several times in the same territory. Why this unusual switching and swapping of Neanderthals and humans occurred is a bit of mystery, but the researchers suspect it may have something to do with climate change.

Whatever the reason, the new research is sure to stir up conversation about humanity's migration into Europe and this crucial chapter of our story.

"The new evidence from Mandrin adds to a growing picture of multiple dispersals of early Homo sapiens into Neanderthal territories in Europe prior to 40,000 years ago, at different times and using different technologies," Professor Chris Stringer, study author and Research Leader in Human Evolution at the Natural History Museum in London, told IFLScience.

"These seemingly brief occupations did not establish themselves for longer, and perhaps climate change played a role in their demise. There is a sterile level above Layer E at Grotte Mandrin, suggesting it was abandoned after the early modern human occupation – perhaps a spell of unfavourable conditions kept both populations away, and it was only the Neanderthals who made it back," he explains.

"The discoveries at Grotte Mandrin will stimulate discussions about early genetic and cultural contacts between the Neanderthals and these pioneering modern human groups, as well as attempts to map possible dispersal routes from western Asia to the Rhône Valley along the northern Mediterranean coast, involving sites in regions like Turkey, Greece, Italy and southern France," he added.