What might be the oldest human remains found outside of Africa are an ancient chunk of upper jaw still sporting a handful of teeth. Discovered in a cave in Israel, the fossil places ancient humans in the Middle East more than 177,000 years ago — some 60,000 years earlier than we thought. That is, if the jaw really is human.
Researchers confirmed that the fossil was between 177,000 to 194,00 years old using three different dating methods. And what’s more — the shape of the fossil looked more human than Neanderthal. That means Homo sapiens might have already started migrating out of Africa more than 194,000 years ago, according to the article published today in the journal Science. Other anthropologists have expressed skepticism that the remains are indeed human, though they don’t contest the date.
If it really is a human jaw, it’s a surprising find — because there are two reigning models of human migration from Africa, and this new date doesn’t fit with either of them. One theory is that ancient humans left Africa in a massive migration roughly 40,000 to 80,000 years ago. The other suggests that smaller groups of humans started trickling out of Africa 120,000 to 130,000 years ago. But there are signs of even earlier migrations — including a 120,000-year-old human-looking fossil also discovered in Israel, and genetic hints that humans and Neanderthals might have been boinking in Europe between 470,000 and 220,000 years ago.
This new find adds another important clue towards solving the mystery of this earlier spread of humans out of Africa, write the authors of a commentary published with the study. “I think that’s pretty cool,” agrees John Hawks, an paleoanthropologist at the University of Wisconsin-Madison. “You have a modern-looking upper jaw in Israel that was there much earlier than it was supposed to have been.” He cautions, however, against getting too attached to the label Homo sapiens: with only a small chunk of bone to go on, it’s hard to say for certain. It’s possible that it could be from another, unnamed relative of modern day people, for example.
Archaeologists discovered this unusual upper jaw in 2002, while excavating the Misliya cave along the slopes of Israel’s Mount Carmel. The site had already yielded sophisticated tools and animal bones — but this was the first bone that clearly came from the human family tree, says Mina Weinstein-Evron from the University of Haifa, who led the excavation. “It’s exciting because we have all these details, and it’s good to see face-to-face the hero — the one person, or one of the group, who’s responsible for all these finds,” Weinstein-Evron says.
The team took 3D scans of the jaw and the teeth, and compared the shapes to scans of other, similar fossils from ancient human relatives. The curvature of the palate and the location of the cheekbone and nasal cavity all looked more human-like than Neanderthal. “It has a lot of implications by saying the biological history of our species is much longer than we previously thought,” says Israel Hershkovitz from Tel Aviv University, the biological anthropologist who led the dental exam.
Jeffrey Schwartz, a physical anthropologist a the University of Pittsburgh who wasn’t involved with the study, isn’t as convinced that human-like necessarily means human. The shape of the teeth and the height of the cheekbone looked pretty non-human to him. “What is it? Who knows,” he says. “To me it represents a different kind of human relative. I think the more discoveries that we have, it keeps showing that our evolutionary path was very diverse.”
Hershkovitz welcomes the criticism — but he wants his critics to take a closer look at the fossil, first. “That’s OK, bring your data!” he says. “Bring your evidence, I can argue with evidence. I can’t argue with impressions.” To fuel these arguments, he hopes to make a scan of the fossil available for 3D printing — so anthropologists around the world can study the cast up close, and get back to him. There’s little hope of resolving the question using DNA: the dry, hot conditions in Israel are terrible for preservation, and he doesn’t want to risk the small sample on a fruitless effort.
Despite the dispute over whether the jaw should be called human, the find is another key piece in the puzzle of how human ancestors and their relatives peopled the globe. “That’s where evidence like this is really important,” Hawks says. “The more we find, the more we’ll be able to add to this picture. But I think it’s too soon to say what the whole frame of the picture looks like.”