When did humans leave Africa? Once, archaeologists believed that Homo sapiens journeyed from this origin point and outwards to Europe and Asia about 60,000 years ago. But that tidy story no longer holds up. As evidence accumulates that the history of human origins and development was much messier, with H. sapiens overlapping and interbreeding with other hominins, the concept of a single great migration from Africa is also losing ground.
In a new paper, published in Science, an international team of researchers, led by Israel Herskovitz of Tel Aviv University, offers new evidence that H. sapiens left Africa tens of thousands of years earlier than scientists once thought. The researchers identify a jawbone, found in the collapsed Mislaya cave in Israel’s Mount Carmel, as a H. sapiens fossil, exhibiting the characteristics of modern humans. They date this fossil to between 177,000 to 194,000 years, making it the earliest fossil of a modern human found outside of Africa.
The group of prehistoric caves on Mount Carmel was discovered decades ago, and twentieth-century excavations turned up ancient human remains, dated to around 90,000 years ago, in Skhūl cave. The roof of the Mislaya Cave, though, had collapsed in prehistoric times, and excavations that yielded this new discovery did not start until 2001. The jawbone described in the study was uncovered in 2002, but “only later did we appreciate the full importance of the find,” says Herskovitz.
In the paper, Herskovitz and his colleagues present their analysis of the skull fragment, arguing that this long-dead hominin should be grouped with modern humans. Assessing the shape of the jawbone, the teeth, and the parts of the palate and nasal floor that survived, they find that the bones share characteristics with modern humans (although they note that some of these features do appear “occasionally” in other early hominins). In the same issue of Science, Chris Stringer and Julia Galway-Witham of the Natural History Museum London, agree with this assessment. “The size and shape of the specimen fall within the known range of variation of later H. sapiens fossils,” they write.
In some ways, this discovery does not come as a complete surprise. Last year, scientists from the Max Planck Institute for Evolutionary Anthropology published their discovery of fossils in Morocco that dated back roughly 300,000 years and had features that were akin to those of modern humans. Genetic evidence, as well, has indicated that humans may have left Africa even before the time of the Mislaya individual. Increasingly, the idea that there was one migration out of Africa has come into question; instead, it seems possible that groups of H. sapiens left the continent at different times, traveling out in the world and continuing to exchange genetic materials with other hominins.
“The history of our species is longer and probably more complicated than scientists had previously believed,” says Hershkovitz. We’re only just beginning to understand that full story of who we are and how we came to populate this entire planet.