A fossilized chunk of bone and teeth could rewrite the history of when modern humans left Africa.

The fascinating fossil consists of a partial upper adult jawbone with an intact line of teeth. An international team of researchers dated the fossil to between 175,000 to 200,000 years ago.

"The finding suggests that modern humans left the continent at least 50,000 years earlier than previously thought," notes Binghamton University. The researchers published their findings Thursday in the journal Science.

Enlarge Image Rolf Quam

In mid-2017, scientists announced the discovery of the oldest known Homo sapiens fossils in a cave in Morocco, dating them to 300,000 years ago.

Previously, the oldest modern human fossils found outside Africa dated to between 90,000 and 120,000 years ago. The jawbone expands that history considerably.

"This finding changes our view on modern human dispersal and is consistent with recent genetic studies, which have posited the possibility of an earlier dispersal of Homo sapiens around 220,000 years ago," the researchers say in the paper's abstract.

"It also means that modern humans were potentially meeting and interacting during a longer period of time with other archaic human groups, providing more opportunity for cultural and biological exchanges," says Rolf Quam, anthropology professor at Binghamton University and co-author of the study on the jawbone.

Enlarge Image Misliya Cave Project

Archaeologists discovered the jawbone in 2002 in the Misliya Cave along the western slopes of Mount Carmel in Israel. The cave had collapsed at some point in its history. The challenging excavation revealed a wealth of bones and other artifacts, including the history-making jawbone.

Identifying the fossil as coming from a modern human, rather than a Neanderthal, required a close inspection of the find. The researchers scanned the jawbone and created 3D virtual models to compare with other human and Neanderthal fossils.

According to Science Magazine, three teams independently dated the fossil "using uranium isotope decay and several luminescence methods, which determine how long ago mineral grains were last exposed to light." Flint tools found in the same layer of sediment help to corroborate the jawbone's age.

Jean-Jacques Hublin, a paleoanthropologist with the Max Planck Institute for Evolutionary Anthropology in Germany, told The New York Times the jawbone's owner might not have any genetic ties to today's humans. It could have belonged to an unknown group of Homo sapiens that left Africa and died off.

We can expect scientists to scrutinize the jawbone findings and continue to look for more evidence of early modern humans living outside of Africa.

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