A tiny tooth unearthed from a French cave is upending what we know about early humans

The excavation of Grotte Mandrin in France has revealed that early modern humans lived there some 54,000 years ago.

(CNN)A child's tooth unearthed from a French cave has revealed the earliest evidence of humans -- Homo sapiens -- living in western Europe.

The discovery of the molar from Grotte Mandrin, near Malataverne in the Rhône Valley in southern France, along with hundreds of stone tools dating back about 54,000 years ago, suggests that early humans lived in Europe about 10,000 years earlier than archaeologists had previously thought.
What's more, the Homo sapiens tooth was sandwiched between layers of Neanderthal remains, showing that the two groups of humans coexisted in the region. These findings challenge the narrative that the arrival of Homo sapiens in Europe triggered the extinction of Neanderthals, who lived in Europe and parts of Asia for about 300,000 years before disappearing.
    "We've often thought that the arrival of modern humans in Europe led to the pretty rapid demise of Neanderthals, but this new evidence suggests that both the appearance of modern humans in Europe and disappearance of Neanderthals is much more complex than that," said study coauthor Chris Stringer, a professor and research leader in human evolution at the Natural History Museum in London.
      It's the first time archaeologists have found evidence of alternating groups of Homo sapiens and Neanderthals living in the same place, and they rotated rapidly, even abruptly, at least twice, according to the study that published in the journal Science Advances on Wednesday.
      Previously, the arrival of early humans in Europe was dated to between 43,000 and 45,000 years ago, according to remains found in Italy and Bulgaria -- not long before the last surviving Neanderthal remains dating back 40,000 to 42,000 years ago were found. This time frame had led many to think the arrival of Homo sapiens and the disappearance of Neanderthals were inexorably linked.
      Humans and Neanderthals, who we know from genetic analysis encountered one another and had babies, resulting in Neanderthal traces in our DNA, overlapped for a much longer period in Europe, this study suggests.
        The bumps and groves are a bit like fingerprints for archaeologists, giving clues to ancestry and behavior. Level E is the Homo sapien tooth.

        Clues from ancient stone tools

        Did humans and Neanderthals hang out together in this French cave overlooking the Rhône valley? The researchers don't have any hard evidence of interaction between the two groups.
        The tools found in the layers representing the Homo sapiens and Neanderthal occupations are distinct in style and don't show any sign that they taught one another knapping or flaking stonework techniques. The stone tools associated with humans, known as Neronian tools, are smaller than those used by Neanderthals, known as Mousterian tools.
        But the authors feel that it's likely that the two groups must have bumped into one another in the neighborhood -- even if direct contact didn't take place in this particular cave.
        The hundreds of stone tools found at the site suggest that the rock shelter was occupied intensively by both groups of humans -- and was not just a place for an occasional stopover.