Archeologists find 400,000-year-old cranium fossil related to Neanderthals

It was the last day of the expedition in the Gruta da Aroeira cave in Portugal. The archeologists were getting ready to close up the site, but one of their final scans of the thick rock revealed something interesting: an outline of a human skull.

What they discovered was the oldest skull everfound in Portugal, dating back 400,000 years, andthe westernmost fossil of a human skull ever found in Europe.

The discovery was made in 2014, but it took 2years to remove the cranium from the sediment. The slow and arduous work paid off, leaving the craniumin "remarkably good condition," according to Rolf Quam, co-author of the study published in Proceedings of the National Academy of Sciences.

Also discovered at the site was a set of Acheulean stone tools, teardrop-shapedhand-axe tools believed to have originated in the Middle East. The tools first appeared in Europe about 500,000 years ago.

The discovery was something of a surprise and illustrates how swiftly the invention of tools spread among early humans.

"This site being at the extreme western end of Europe suggests the spread of this tool technology was relatively rapid," Quam said.

Not a Neanderthal

The researchers were unable to determine whether the cranium belonged to a male or female, though they determined it belonged to an adult.

And while the cranium revealed some clues, what's not yet clear is where this early ancestor of ours belongs in the evolutionary tree.

"There aresome features that are telling us that these guys are ancestors of the Neanderthals they're not fully Neanderthal yet, but they're on the way,"Quamsaid.

One difference is the brain size, which is smaller forthe newly discovered specimenthan aNeanderthal's.

However,some findingssuggest thatalthoughthe skull is not purely Neanderthal, it's pretty close. In Neanderthals, the mastoid process a projection of bone behind the ear opening doesn't project much,nor does it in this cranium. Earlier fossilized craniumsshow a protruding mastoid process.

As well, the shape of the brow ridge resembles that of the Neanderthals, though there is an anatomical difference.

"What species name is it?" Quam asks. "It is broadly similar to otherones from the Middle Pleistocene in Europe, but shows a unique combination of features, and these are all broadly ancestral to the later Neanderthals."

Quamsaid that the specimen will be further studied with the hope it will yieldmore information about the human evolutionary puzzle.