Until now, most researchers have focused on the more complete (but less interesting) of the two skulls. “Apidima 1 has just been ignored,” says Harvati. But its antiquity matters for three reasons. First, it pushes back the known presence of modern humans outside Africa by some 30,000 years. Second, it’s considerably older than all other Homo sapiens fossils from Europe, all of which are 40,000 years old or younger. Third, it’s older than the Neanderthal skull next to it.

Collectively, these traits mess up the standard story of Neanderthal and modern-human evolution. According to that narrative, Neanderthals slowly evolved in Europe, largely isolated from other kinds of hominins. When modern humans expanded out of Africa, their movements into Europe might have been stalled by the presence of the already successful Neanderthals. That explains why Homo sapiens stuck to a more southerly route into Asia, and why they left no European fossils until about 40,000 years ago. “The idea of Europe as ‘fortress Neanderthal’ has been gaining ground,” says Rebecca Wragg Sykes, an archaeologist from the University of Bordeaux, but identifying a 210,000-year-old Homo sapiens skull from Europe “really undermines that.”

“It suggests that early Homo sapiens groups got farther than we may have previously thought, occasionally occupying territories that later became that of Neanderthals,” adds Shara Bailey, an anthropologist at NYU. “Findings like this are very important for informing us on the evolution of our species.”

Read: Scientists have found the oldest known human fossils

The identity of Apidima 1 could also cast doubt on other archaeological finds from Europe, such as stone tools with no accompanying fossils. Researchers had long assumed that within a certain time window, “any archaeology was all the work of Neanderthals,” says Wragg Sykes. But if modern humans also occupied this “safe range,” which species actually created those artifacts?

These interpretations depend on the dating of the Apidima skulls, which has always been difficult. They were found in an odd place—a small niche near the cave ceiling, separated from any sediments that could have been easily dated. They were also entombed in breccia, a composite rock made from fragments that have been cemented together. It seems that, as ice ages came and went and sea levels rose and fell, parts of the cave’s interior were flooded and eroded, and both skulls were dislodged from their original resting places. They fell into a cavity and got stuck.

Harvati’s team estimated their ages by analyzing the minute amounts of uranium within them. They then scanned both skulls, reconstructed what they would have looked like before being broken and distorted, and compared their three-dimensional shapes with those of other hominins. In that comparison, Apidima 2 clearly clustered with Neanderthals, while Apidima 1 grouped with skulls from modern humans.