Humans may have ventured from Africa at least 50,000 years earlier than previously thought based on the age of a jawbone—complete with preserved teeth—found in a cave in Israel, researchers announced Thursday.
The fossil, found on the western slope of Mount Carmel, is thought to be between 177,000 and 194,000 years old, scientist said. That predates the oldest fossils previously found outside of Africa—also in Israel—which were thought to be somewhere between 90,000 to 120,000 years old.
“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.
The discovery, made by an international team led by Israel Hershkovitz from Tel Aviv University, adds to other recent discoveries that have led scientists to rethink humans’ evolutionary tree. Researchers relied on microCT scans and 3-D virtual models to date the jawbone, as well as comparisons to other hominin fossils from Africa, Europe and Asia.
“The dating had to be rock solid,” said Rolf M. Quam, an anthropologist at Binghamton University in New York and an author of the paper. The team dated the tooth dentin and enamel, the sediment stuck to the upper jaw, and tools found near the fossil.
“I don’t know how much more we could do with this little bone,” said Dr. Quam. “I think we’ve squeezed blood from a turnip here.”
Other items found near the fossil also dated back to that time period.
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.
These humans, while sharing anatomical features with present-day people, probably looked quite different in appearance, though.
“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.
Even so, the discovery adds another important piece to the puzzle of how and when humans migrated from the African continent. What ultimately happened to the humans in the Misliya cave, however, is another question. Scientists believe it is unlikely they are the ancestors of anyone alive today.
Prof David Reich, a geneticist at Harvard University and an expert in population genetics and ancient DNA, said: “It’s important to distinguish between the migration out of Africa that’s being discussed here and the “out-of-Africa” migration that is most commonly discussed when referring to genetic data. This [Misliya] lineage contributed little if anything to present-day people.”
“These early exits are sometimes termed ‘unsuccessful’ or ‘failed’,” said Stringer. “Some of these groups could have gone extinct through natural processes, through competition with other humans, including later waves of modern humans, or they could have been genetically swamped by a more extensive 60,000 year old dispersal.”