Archaeologists discover mystery skull dating back 286,000 years 'that's not human'

Scientists might be one step closer to solving one of the longest standing mysteries in human evolution, thanks to the discovery of a mysterious non-human skull.

Initially found in a cave in northern Greece back in 1960, the complete skull baffled archaeologists, who couldn't work out how old it was or who it even belonged to.

However, a new study by the Institut de Paléontologie Humaine in France, might just have the answers researchers have been longing for.

The enigmatic skull was found inside the Petralona Cave, around 22 miles away from Thessaloniki, embedded into the wall but its lower jaw was missing.

As soon as the local who made the discovery reported it, the science community were fascinated, but its origins remained a conundrum.

The skull was found in Petralona cave. (Carlstaffanholmer/CC BY-SA 3.0)

They knew it belonged to the human family, but it was immediately clear it did not appear to be Neanderthals or modern humans. At a guess, researchers placed the skull as being anywhere from 170,000 to 700,000 years old.

However, as part of the new study, published in the Journal of Human Evolution, the team used a dating method called uranium-series (U-series), which works well in caves, by measuring the rate of decay of uranium isotopes into thorium.

The skull has remained a mystery for half a century. (Nadina/CC BY-SA 3.0)

This particular method doesn't work so well on open soil, but in caves, the water seeps through the rock and evaporates, leaving behind calcite deposits containing uranium. Over time, the uranium turns into thorium, and measuring this change tells scientists when the layer formed.

By doing this, the researchers managed to date the skull back to at least 286,000 years old, which was a key step in trying to ascertain the origin of the skull, though the date could vary depending on its positioning in the cave.

“Assigning an age to the Petralona cranium is of outstanding importance because this fossil has a key position in European human evolution," the authors wrote in the study, as per Archaeology Mag.

They used U-series to date the skull. (Falguères et al., Journal of Human Evolution 2025)

The scientists all agreed that the skull appeared for primitive than both modern humans and Neanderthals, however the new timing data suggests that whatever it belonged to, lived around the same time as early Neanderthals in Europe, which was a key period of time for human evolution.

Although they warn it would be impossible to link the skull to any one human ancestor, the findings of this study play a huge step in placing it within our human history.