More than 57,000 years have passed since Paleolithic humans stood before the cave wall, with its soft, chalky rock beckoning like a blank canvas. Their thoughts and intentions are forever unknowable. But by dragging their fingers across the rock and pushing them into the cave wall, these creative cave dwellers deliberately produced enduring lines and dots that would lie hidden beneath the French countryside for tens of thousands of years.

Now, scientists have discovered that these arresting patterns are the oldest known example of Neanderthal cave engravings.

Authors of a study published Wednesday in PLOS One analyzed, plotted and 3D modeled these intriguing markings and compared them with other wall markings of all types to confirm that they are the organized, intentional products of human hands. The team also dated deep sediment layers that had buried the cave's opening to reveal that it was sealed up with the engravings inside at least 57,000 and as long as 75,000 years ago—long before Homo sapiens arrived in this part of Europe.

This find, supported by the cave's array of distinctly Neanderthal stone tools, identifies Neanderthals as the cave art creators and adds to growing evidence that our closest relatives were more complex than their dim caveman stereotype might suggest.

"For a long time it was thought that Neanderthals were incapable of thinking other than to ensure their subsistence," notes archaeologist and study co-author Jean-Claude Marquet, of the University of Tours, France. "I think this discovery should lead prehistorians who have doubts about Neanderthal skills to reconsider."

La Roche-Cotard is an ancient cave nestled on a wooded hillside above the Loire River. It was first uncovered in 1846 when quarries were operated in the area during construction of a railroad line. When it was first excavated in 1912, the array of prehistoric stone implements and cut-marked and charred bones of bison, horses and deer within revealed that Paleolithic hunters had frequented the site many thousands of years earlier.