A human jaw found in a cave collapsed on the western slope of Mount Carmel in Israel could rewrite the history of our species, in fact it belonged to what may have been one of the oldest individuals of a population of Homo sapiens to have left Africa . To reveal it is the study "The earliest modern humans outside Africa" published in Science by a large team of international researchers and right in Science Ann Gibbson writes that
"In a huge cave on the Mediterranean Sea, an ancient people roasted hares, turtles and eggs of ostrich and produced stone tools from flint ".
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The researchers say that the jaw and the tools found in the cave would date back to 177,000 to 194,000 years ago and this would mean that modern humans would have left Africa 40,000 years earlier than previously believed. “The discovery - could have implications on when and how our species was formed and how many waves of the first humans left Africa.”
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Before now, the first fossils of modern humans found outside Africa came from the nearby Skhul Cave on Mount Carmel and from the cave of Qafzeh in Israel, sites dating back between 90,000 and 120,000 years. But, according to the dating in 2017 of a skull found in Morocco, our species was born in Africa about 300,000 years ago, long before the generally accepted date of 200,000 years for the origin of our species, which was based on genetic studies and fossil finds, such as the remains found in the Omo valley, in Ethiopia, dating back to 195,000 years ago. Some researchers had claimed a much more recent exodus from Africa based on fragmentary fossils and stone tools found in the Middle East, Arabia, and China. But outside of Africa there were no safely dated sites, with accepted human fossils.
The upper jaw described in Science was discovered in 2002 by students digging the floor of the Misliya Cave, 12 kilometers south of Haifa, as soon as they saw this upper jaw, which keeps a full row of teeth on the left side, the researchers they understood that it belonged to a specimen of our species, the Homo sapiens :
"His canines and other teeth resemble those of the modern humans of Skhul and Qafzeh, and they lacked the characteristics of the Neandertals,"
explained in Science .
One of the authors of the study, Mina Evron of the University of Haifa, points out that the jaw comes from the same sedimentary layer in which thousands of "museum quality" flint tools have been found and explains that
"The instruments were made with a sophisticated method called Levallois technology, which requires abstract thinking”.
Some researchers are convinced that this method was invented by the H. sapiens and that artifacts of this type would be the sign of the presence of our species and the traces of our first steps out of Africa.
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The findings were dated independently of three different teams using uranium isotope decay and different luminescence methods. This is how the burned flint tools were dated to about 179,000 years ago, which would coincide with the dating of Levallois work tools found in Israel dating back to 140,000. 250,000 years ago. The researchers also dated to 174,000 years ago a sliver of enamel taken from a tooth and say that the crust adhering to the upper jaw is at least 185,000 years old. Experts say that instrument dating seems solid, but in many they have doubts about jaw dating, partly because, as the authors write,
“The jaw was scanned using three times the computed tomography and X-rays could have influenced the amount of radiation trapped in the enamel of the teeth, distorting the dates of the luminescence”.
Alistair Pike, a University of Southampton uranium dating expert, pointed out that a jaw crust "is heavily contaminated with debris" and this contamination could affect radiometric dating to the crust, distorting it even 70,000 years, says the geochronologist Warren Sharp of the Berkeley Geochronology Center. Sharp and others have also pointed out that relying on the tools found near the jaw is problematic, "because it is possible that the bone has been mixed in the tool carrier layer later in time."
But the team of researchers firmly defends its dates, emphasizing that they have made a carefully controlled excavation that "closely connects instruments and fossils in the same sedimentary layer and, therefore, over time".
If their dates are correct,
"It's amazing - said archaeologist Michael Petraglia of the Max-Planck-Institut für Menschheitsgeschichte - The discovery suggests that modern humans migrate repeatedly from Africa, with more groups moving to the Middle Orient".
For the paleoanthropologist Marta Mirazon Lahr of the University of Cambridge, who did not participate in the study, these migrant ancestors
"They may have moved from Africa when the climate was wetter, between 244,000 and 190,000 years ago, but they became extinct again for the arid climate ".
But according to one of the authors of the study, the physical anthropologist Israel Hershkovitz of the University of Tel Aviv,
"The implications go even further, The discovery suggests that our ancestors were born much sooner than we thought. If our species had been in Israel 200,000 years ago, this would mean that our species is very old; it is not only 300,000 years old, but it is older".
And Hershkovitz is convinced, as he told BBC News, that
"We must rewrite the entire history of human evolution, not only for our species but for all other species that lived outside Africa at that time".
Also according to Chris Stringer of the London Natural History Museum, who was not involved in the study,
"The discovery breaks through the 130,000 year-long limit for modern humans outside Africa. The new dating suggests that ancient Homo sapiens from the West Asian region may also exist ".
Until recently, it was thought that the first migrations of Homo sapiens out of Africa were limited to the Middle East, but in recent years the discoveries of modern human fossils made to Daoxian and Zhirendong in China, dated between 80,000 and 120,000 years ago, had suggested that the migratory waves of our ancestors had pushed within Eurasia more than previously thought. Furthermore, genetic studies have revealed signs of crossbreeding between African humans and Neanderthals. A study was published on fossil remains of Neanderthals showing crossings with the H. Sapiens occurred 30,000 years ago. And in 2016, a team of researchers had found signs that pioneering groups of modern men from Africa would cross each other 100,000 years ago with the Neanderthals living in today's Altai region in Siberia.
“We had so many pieces of new evidence and we did not know how to put them together," says Hershkovitz. Now, with the new discovery, all the pieces go to the lotus place: an exodus there probably was already 250,000 years ago, which is the date of the instruments found in the Misliya Cave”.
But the first African migrant Homo sapiens who reached today's Israel probably died out. The results of genetic and archaeological studies tell us that human beings living off Africa are descending only 60,000 years ago. Most DNA studies have failed to find evidence of these older migrations in our genes.
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But the jaw in this Cave speaks to us of something else: of the ancient history of a migratory species from which we descend, of explorers who sought, adapted to new environments and climates, failed and retried, lived, laughed, loved each other and they fought, exchanged genes and cultures with other "races". A "modern" story, so similar to our life and yet so profoundly ancient, that sinks only beneath the surface, when life on Earth was born, an ancestral story, that new discoveries could reveal us older than how much we still think. I personally believe there are still more to come on this.
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