A series of grooves decorating a cave in Gibraltar are, according to a recent study, proof that Neanderthals were more creative and intelligent than previously expected.

To reach that conclusion, researchers from 11 institutions analyzed 40,000-year-old stone marks.

These were made just before the Neanderthals became extinct and modern man arrived in the territory at the southern end of the Iberian Peninsula, which is currently under the administration of the United Kingdom.

The grooves, which resemble the pattern of the game of tic tac toe, are inscribed on a rock at the bottom of Gorham’s cave.

The scientists who participated in the excavation believe that Neanderthals were capable of abstract thoughts, in the same way as modern humans, and of which art is an elevated expression.