Scientists on Thursday announced the discovery of a fossilized human jawbone in a collapsed cave in Israel that they said is between 177,000 and 194,000 years old.
If confirmed, the find may rewrite the early migration story of our species, pushing back by about 50,000 years the time that Homo sapiens first ventured out of Africa.
Previous discoveries in Israel had convinced some anthropologists that modern humans began leaving Africa between 90,000 and 120,000 years ago. But the recently dated jawbone is unraveling that narrative.
“This would be the earliest modern human anyone has found outside of Africa, ever,” said John Hawks, a paleoanthropologist from the University of Wisconsin, Madison who was not involved in the study.
The upper jawbone — which includes seven intact teeth and one broken incisor, and was described in a paper in the journal Science — provides fossil evidence that lends support to genetic studies that have suggested modern humans moved from Africa far earlier than had been suspected.
“What I was surprised by was how well this new discovery fits into the new picture that’s emerging of the evolution of Homo sapiens,” said Julia Galway-Witham, a research assistant at the Natural History Museum in London who wrote an accompanying perspective article.
Dr. Hawks and other researchers advised caution in interpreting the discovery. Although this ancient person may have shared some anatomical characteristics with present-day people, this “modern human” would have probably looked much different from anyone living in the world today.
“Early modern humans in many respects were not so modern,” said Jean–Jacques Hublin, director of the department of human evolution at the Max Planck Institute for Evolutionary Anthropology in Germany.
Dr. Hublin said that by concluding the jawbone came from a “modern human,” the authors were simply saying that the ancient person was morphologically more closely related to us than to Neanderthals.
That does not mean that this person contributed to the DNA of anyone living today, he added. It is possible that the jawbone belonged to a previously unknown population of Homo sapiens that departed Africa and then died off.
That explanation would need to be tested with DNA samples, which are difficult to collect from fossils found in the arid Levant.
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The upper jawbone, or maxilla, was found by a team led by Israel Hershkovitz, a paleoanthropologist at Tel Aviv University and lead author of the new paper, while excavating the Misliya Cave on the western slopes of Mount Carmel in Israel. The jawbone was discovered in 2002 by a freshman on his first archaeological dig with the group.
The team had long known that ancient people lived in the Misliya Cave, which is a rock shelter with an overhanging ceiling carved into a limestone cliff. By dating burned flint flakes found at the site, archaeologists had determined that it was occupied between 250,000 to 160,000 years ago, during an era known as the Early Middle Paleolithic.
Evidence, including bedding, showed that the people who lived there used it as a base camp. They hunted deer, gazelles and aurochs, and feasted on turtles, hares and ostrich eggs.
Dr. Hershkovitz and Mina Weinstein-Evron, an archaeologist at the University of Haifa, felt that the jawbone looked modern, but they needed to confirm their hunch.
[READ: Skull Fossil Offers New Clues on Human Journey From Africa]
Dr. Hershkovitz has made similar findings in the past. In 2015, he announced finding a 55,000-year-old skull in the Levant. But a 2010 discovery of 400,000-year-old teeth in Israel in which he participated received criticism for how it was reported in the media.
To test their suspicions about the jawbone, the archaeologists sent the specimen on a world tour. “It looked so modern that it took us five years to convince people, because they couldn’t believe their eyes,” said Dr. Weinstein-Evron.
One of the first stops was Austria, home to a virtual paleontology lab run by Gerhard W. Weber, a paleoanthropologist at the University of Vienna. There scientists were able to assess whether the bone belonged to a modern human or a Neanderthal, which are thought also to have occupied the region during that time period.
Using high resolution micro-CT scanning, Dr. Weber created a 3D replica of the upper left maxilla that allowed him to investigate its surface features and, virtually, to remove enamel from the teeth.
He then performed a morphological and metric test that compared the Misliya fossil with about 30 other specimens, including fossils of Neanderthals, Homo erectus, more recent Homo sapiens, and other hominins that lived in the Middle Pleistocene in Asia, Africa Europe and North America.
“The shape of the second molar, the two premolars and the whole maxilla are very modern,” said Dr. Weber.