There’s not much left of this person who lived and died in a cave on the slopes of Israel’s Mt. Carmel between 177,000 and 194,000 years ago. All that remains is the left half of an upper jaw, with some fragments of palate, cheekbone, and the floor of the nasal cavity still attached, along with a complete set of upper left teeth. But those fragments of bone mean that modern humans probably found their way to southwest Asia about 40,000 to 50,000 years earlier than fossil evidence previously suggested.

For early humans, the Levant was the gateway to everything beyond Africa. When the newly discovered fossil human, dubbed Misliya-1, and its companions arrived in the area, they would have found themselves living alongside Neanderthals. Both species were living in spaces once occupied by Homo erectus, an early human ancestor that had reached southern Eurasia by 1.75 million years ago. Understanding which species lived here—and when—is crucial to reconstructing the story of our ancestors’ expansion.

Who, where, and when

And the Misliya-1 fossil is definitely human, not Neanderthal or an early hominin like Homo erectus. The shape of the jaw and the nasal floor look distinctly human, and so do the shape and arrangement of the teeth. Misliya-1’s presence brings the fossil evidence into line with genetic studies, which suggest that modern humans first interbred with Neanderthals around 200,000 years ago somewhere outside of Africa.

“The fact that different lines of evidence (fossils, archaeology, and genetics) do not line up perfectly is in part due to the incompleteness of their respective records,” said anthropologist Julia Galway-Witham of the UK’s Natural History Museum. “However, it is reassuring, as in the case of the Misliya fossil, when new discoveries fit with other recent discoveries to add to our current understanding of the evolution of Homo sapiens.”

Researchers used three different dating methods to arrive at the age. One lab tested the ratio of uranium to thorium in two of Misliya-1’s incisors. Bone contains a small amount of uranium-234, which decays to thorium-230 at a predictable rate, so scientists can use the ratio to tell how old the bone is. Another lab combined that method with electron spin resonance, which measures how many atoms in a sample have unpaired electrons, or free radicals, to measure how long an object has been exposed to the normal background radiation in the environment. And a third lab used thermoluminescence, a method that measures how much radiation an object has absorbed since it was last exposed to heat or sunlight, on some burned flint buried near the fossil. All three methods said the same thing: Misliya-1 is surprisingly old.

Old but crafty

The tools found alongside Misliya-1 use a flint-knapping technique called "Levallois," which is a pretty sophisticated way to make stone tools. Levallois takes planning and forethought, and it produces sharper, more precisely shaped flakes than earlier methods, which mostly involved just chipping flakes off a core chunk of flint. Instead, Levallois involves carefully chipping small pieces off the core around the edges of the flake you actually want to shape. When it’s done correctly, you strike just the right spot, and the carefully shaped flake comes right off.

Archaeologists have found even older Levallois examples in Africa, at sites ranging from Kenya to Morocco, associated with modern human remains. Anthropologist Israel Hershkovitz of Tel Aviv University says the new find suggests that this tool-making method is a human innovation that may have been adopted by Neanderthals, although it’s too soon to say for sure.

Neanderthals were already making stone tools this way well before Misliya-1’s time, as part of what archaeologists call the Mousterian culture. In fact, older Levallois tools, dating to between 190,000 and 260,000 years ago, have been found in caves not far from Misliya. But because they weren’t associated with any skeletal remains, it’s hard to say for sure who made them.

“It is certainly of great interest to understand whether the Levallois was developed once and spread across many regions, or whether it was developed independently in several places,” said Galway-Witham. “But archaeologists do not yet know whether this technique was developed by one species and then inspired the other or whether it was developed independently by both.”

Waves of migration

Before Misliya-1, the oldest definitively human remains outside of Africa were 90,000- to 120,000-year-old sets of remains from two other Israeli caves, Qafzeh and Es-Skhul. A handful of teeth and a partial skull from two other caves in the area have dated to 400,000 years old, but they seem to belong to an earlier human relative.

The researchers suggest that these may actually have been different waves of human occupation in the region, where the climate varied tremendously over the Paleolithic. Between 244,000 and 190,000 years ago, several wetter periods may have made the Levant a hospitable place for migrating humans.

“But there were severe periods of aridity before and after this time, meaning that the region was probably more often a ‘boulevard of broken dreams’ than a stable haven for early humans,” wrote Galway-Witham and anthropologist Christopher Stringer, also of the Natural History Museum, in a paper commenting on Hershkovitz’s findings. That means that Misliya-1’s people were probably not directly related to the people who later lived in the Qafzeh and Es-Skhul caves.

And Galway-Witham suggests that there may have been an even earlier wave of human migration into the region that we just haven’t found evidence of yet. “Certainly, however, now that we have evidence of modern human occupation in the Levant about 180,000 years ago, this makes scenarios of earlier modern human occupation in the region more plausible,” she said.

Science, 2017. DOI: 10.1126/science.aap8369 (About DOIs).