The origin story for modern humans is constantly being revised, but the general gist is that Homo Sapiens first arose several hundred thousand years ago in the area we now call Ethiopia, before migrating out of Africa about 100,000 years ago. Now, a jawbone discovered in a cave in Israel pushes back the date of our African exodus by at least 50,000 years.

The deep history of our species is murky, but a combination of genetic studies and fossil discoveries has let us piece together the basics. It was long thought that Homo Sapiens was about 200,000 years old, and had remained on the African continent until between 90,000 and 120,000 years ago, when we began spreading across the Middle East, Asia and Europe.

But that story has been upset by more recent discoveries. Back in June 2017, archaeologists found fossils and stone tools in Morocco dating back more than 300,000 years, indicating that modern humans were widespread across Africa earlier than previously thought. A more outlandish study even went so far as to claim that humans and chimps split from their last common ancestor in Europe, not Africa, millions of years ago. That study, however, has been widely contested.

The newest revelation is a little more believable, and actually fits in nicely with the Morocco fossils. A team led by researchers from Tel Aviv University and Binghamton University has found bones and tools in Misliya Cave, Israel, and used several different methods to date it to between 177,000 and 194,000 years ago – making it the earliest modern human fossil ever found outside of Africa by at least 50,000 years.

"Misliya is an exciting discovery," says Rolf Quam, co-author of the study. "It provides the clearest evidence yet that our ancestors first migrated out of Africa much earlier than we previously believed. 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."

The fossil is an upper left section of jawbone, including most of the teeth. It was found alongside a range of stone tools, and when these were independently dated, they returned a similar age range.

Extrapolating the exact species from a small section of bone can be tough, so the researchers ran micro-CT scans of the fossil and made 3D models of it to study the internal structures of the teeth. Certain characteristics that are commonly seen in Neanderthals were missing, while other features that are only known to occur in modern humans were present and accounted for.

Although the Misliya fossil is clearly human, it does have some Neanderthal characteristics, but this is to be expected. After all, the Middle East at that time acted as a corridor for migration out of Africa, so several human groups would have met and mingled in the area, cross-breeding in the process.

"All of the anatomical details in the Misliya fossil are fully consistent with modern humans, but some features resemble those found in the remains of Neanderthals and other human groups," says Israel Hershkovitz, lead researcher on the study. "This suggests that, while Africa was the origin of our species, some of our traits must have evolved or been acquired outside of Africa."

The study was published in the journal Science and the team describes the study in the video below.

Sources: Tel Aviv University, Binghamton University, The Conversation

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