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Part of an upper jaw with teeth found in Israel shows that modern humans ventured out of Africa much earlier than previously thought. The find adds to evidence that our species was overlapping with human relatives such as Neanderthals in the crossroads of the Levant for longer than previously realized.
Until recently, the fossil record suggested that our species, Homo sapiens, first appeared in East Africa around 200,000 years ago. While a larger wave of migration didn’t leave the continent until 50,000 to 60,000 years ago, small numbers of modern humans made forays outside of Africa as far back as 120,000 years ago, based on the known fossils. (Explore a map of human migration.)
Then, last June, research on fossils from a site called Jebel Irhoud in Morocco turned conventional wisdom on its head: Those modern-looking humans are up to 350,000 years old, scientists discovered, pushing back the early origins of our species.
The new Middle Eastern discovery, detailed today in Science, complements the Moroccan find by showing that Homo sapiens were also taking initial steps into Eurasia much earlier—around 180,000 years ago.
“This is an exciting discovery that pushes the timing of modern humans leaving Africa back quite a bit,” says Darren Curnoe, an expert on human origins at the University of New South Wales in Sydney, Australia.
“Together with the discovery last year of the earliest modern humans in Africa, our views about our origins are beginning to change very rapidly, after decades of near scientific stagnation.”
The upper jaw fossil was discovered in 2002 during an ongoing archaeological excavation at a site called Misliya, found on Mount Carmel in northern Israel. The site was once a rock shelter frequented by various prehistoric human species over many hundreds of thousands of years.
“Humans like to live in open rock shelters so that they can see if there’s danger or prey moving by, but also to stay dry. It was one of these terraces where they could overlook the landscape in front of them,” says study co-author Rainer Grün, director of the Australian Research Centre for Human Evolution at Griffith University in Queensland.
Researchers carried out a detailed analysis to confirm that the shape of the teeth and jaw are those of a modern human and not a Neanderthal, says Grün. (Find out how Neanderthal genes might be affecting your health.)
Though the fossil was found early on during the excavation, it was not dated until 2014/2015. The initial results were so surprising that the team decided to corroborate them, ultimately using four independent dating methods on the dentine of the teeth, the tooth enamel, sediment attached to the jaw, and stone found beside the fossil.
The methods together yielded an estimated age of 177,000 to 194,000 years, reports the team, led by paleoanthropologist Israel Hershkovitz at Tel Aviv University.
This age range “fits very well in the model that’s now emerging of a very ancient history of our species, much older than we have thought,” says Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who led the team that made the 2017 Jebel Irhoud find.
“The story of the ‘out of Africa’ movement of our species is more complicated that we previously thought.”
With Tools, Too
It’s still unclear whether this was the earliest incursion of Homo sapiens into Eurasia, how far east they went, and why none of the early forays before about 50,000 years ago turned into a bigger wave of migration, Hublin adds.
Over hundreds of thousands of years, there was “a sort of pulsation of this African population to the gate of western Asia,” he argues. These pulses may relate to so-called green Sahara episodes—intermittent periods of moister climate, when the current desert belt across North Africa was vegetated and people could move more freely.
Another interesting aspect of the discovery is the tools found alongside the fossil, says Julia Galway-Witham, a paleoanthropologist at the Natural History Museum in London. The tools were fashioned with a relatively sophisticated method of stone knapping called the Levallois technique, which requires skill and forethought and allows greater control over the resulting scrapers or blades.
“They represent the earliest association of this type of tool with modern humans outside Africa,” she says. “Perhaps the co-occurrence of this tool type with early Homo sapiens at Jebel Irhoud, Morocco—and now with modern humans at Misliya—indicates some association of the development of this technology in Africa and western Asia with the emergence of Homo sapiens in these regions.”
With plenty of ongoing archaeological research in the Levant region, new fossils that can potentially answer the lingering questions about human migration into Asia may soon be found, Grün says.
And the latest genetic work hints that there may have been even earlier treks out of Africa—and into the midst of other human species, adds Hublin. An analysis of ancient DNA in a 124,000-year-old German Neanderthal bone suggests that Neanderthals may have interbred with our own species more than 220,000 years ago.