An engraving carved into dolomite stone more than 39,000 years old in a seaside Gibraltar cave suggests that Neanderthals were capable of symbolic thinking—once thought unique to modern humans, researchers reported Monday.

Neanderthals, extinct human cousins who left genetic traces in modern people, seem to have vanished from Europe around 40,000 years ago. That was around the time early modern humans arrived. (See: "Neanderthals Died Out About 10,000 Years Earlier Than Thought, With Help From Modern Humans.")

Among the advantages that may have allowed those new arrivals to out-compete the Neanderthals were symbolic thought and language. But the cross-hatched cave carving, reported in Proceedings of the National Academy of Sciences, points to art and symbolic thought among Neanderthals as well.