Neanderthals buried their dead, concludes a 13-year study of a former Neanderthal stomping ground in southwestern France.

It’s then possible that our species wasn’t the first on the human family tree to bury our own. At the very least, the discovery adds to the growing evidence that Neanderthals weren’t stupid. They might have been brawny, but they had big brains to match.

“This discovery not only confirms the existence of Neanderthal burials in Western Europe, but also reveals a relatively sophisticated cognitive capacity to produce them,” William Rendu, the study’s lead author and a researcher at the Center for International Research in the Humanities and Social Sciences, said in a press release.

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The findings are published in the latest issue of the Proceedings of the National Academy of Sciences.

Rendu and his team excavated caves at the French site, called La Chapelle-aux Saints. Neanderthal remains, belonging to both adults and children, were found. Bones of bison and reindeer were also unearthed.

In contrast to the reindeer and bison remains at the site, the Neanderthal remains contained few cracks, no weathering-related smoothing, and no signs of disturbance by animals.

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“The relatively pristine nature of these 50,000-year-old remains implies that they were covered soon after death, strongly supporting our conclusion that Neanderthals in this part of Europe took steps to bury their dead,” observed Rendu. “While we cannot know if this practice was part of a ritual or merely pragmatic, the discovery reduces the behavioral distance between them and us.”

Further supporting Rendu and colleagues’ theory, geological analysis of the depression in which the Neanderthal remains were found suggests that it was not a natural feature of the cave floor.

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The study opens up a lot of questions:

Who buried their dead first, Neanderthals or Homo sapiens? (Or maybe even some other ancient human ancestor was the first to bury its dead.)

Why did any human first decide to bury the body of another? There are practical reasons for doing so, but the question still remains unanswered.

Did Neanderthals have spiritual beliefs about death and an afterlife?

What happened to Neanderthal culture? Was it simply absorbed into modern human culture, or did it die out with the species?

Other research has determined that Neanderthals and Homo sapiens interbred, so solving these mysteries will shed light on our own early history in Europe.