Roughly 40,000 years ago, the Neanderthals that lived in the Mediterranean disappeared. Whether they simply up and left, or died off, is anybody’s guess. They were still a common sight in western Europe for another 10,000 years, so outright extinction is off the table.

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In trying to understand what lead to the Neanderthal’s decline, archaeologists favor three ideas, either: climate change did it, humans did it, or a catastrophic volcanic eruption did it. A new study lead by John Lowe and described by the journal Science suggests two of the three are now off the table.

The researchers collected incredibly small particles of volcanic glass, known as cyrptotephra, that were produced by a massive eruption of the Campi Flegrei supervolcano in southern Italy. That event, which took place 40,000 years ago and is known as the Campanian Ignimbrite (CI) eruption, sent volcanic ash far and wide across the region. It also caused the temperature to drop by a couple of degrees, which had been held up as a potential cause for the Neanderthal’s decline.

According to Science, Lowe’s research found that the shift from the Neanderthal’s stone tools to the modern human’s more complex equipment lay underneath the supervolcano’s ash layer at research sites on both sides of the Mediterranean Sea, meaning that “modern humans had replaced Neandertals before the catastrophic events of 40,000 years ago.”

The authors also found that the marks left behind by a sudden global cooling, known as a Heinrich Event, happened at the same time as the supervolcanic eruption—aka, it also occurred after the Neanderthals were already on their way out.

With the eruption and climate change crossed off their list, Lowe and his team put the blame on the only other remaining suspect: humans. Even in the court of law, though, this charge probably wouldn’t hold. Kate Wong for Scientific American, interviewing Clive Finlayson, explains:

The authors claim evidence of competition from modern humans as the cause of the Neanderthal extinction. This is the default argument – we think we didn’t find evidence of climate or volcanic activity on the Neanderthal extinction, therefore it must have been modern people. Why? Show it!

More from Smithsonian.com:

Neanderthals Weren’t Stone Age Rodeo Riders?

Rethinking Neanderthals

Humans and Neanderthals Interbred