Researchers probing the stalagmites of Romania think cold weather may have contributed to the the extinction of our closest human cousins—the Neanderthals.

Evidence suggests that Europe underwent extremely cold and dry intervals that may have put a strain on the archaic humans’ food sources, researchers reported in the journal Proceedings of the Natural Academy of Sciences.

"The Neanderthals were the human species closest to ours and lived in Eurasia for some 350,000 years. However, around 40,000 years ago—during the last Ice Age and shortly after the arrival of anatomically modern humans in Europe—they became extinct,” study author Vasile Ersek of Northumbria University explained in a statement.