Ancient sketches of Ice Age animals, stenciled hands, and symbols painted on walls inside three Spanish caves were long suspected to have been left by humans. But with enhanced dating techniques, scientists now believe our thick-browed and extinct evolutionary cousins, Neanderthals, were truly responsible for the art.

This would mean that we've been giving our hominid ancestors too little credit for their abilities.

Researchers found these paintings are at least around 65,000 years old, predating the arrival of humans in Europe by some 20,000 years. Assuming the dating is accurate, then these paintings would be the earliest known cave art in the world.

The research, published Thursday in the journal Science, concludes that in the absence of humans, Neanderthals must have created the advanced art, underscoring that these hominids were quite smart — perhaps even matching our own intelligence.

"These papers simply confirm what has been evident in other aspects of the archeological record and their biologies, that there are no evident differences between the Neanderthals and modern humans in terms of basic cognition, symbolic behavior, sociality, or communication," said Erik Trinkaus, a biological anthropologist at Washington University in St. Louis who was not involved in the study.

Red ochre painting on a La Pasiega cave wall in Spain. Image: P. Saura

In another Spanish cave, detailed in a related study also released Thursday, researchers dated marine shells that had been dyed and then stored in larger shell containers. These artifacts were dyed some 70,0000 years before humans ever stepped foot in the region.

Some scientists might disagree that it was Neanderthals who painted such humanistic, advanced art, said Wil Roebroeks, a paleolithic archaeologist at Leiden University who was not involved in the study, in an email. But the evidence in favor of Neanderthal artwork is strong.

A replicated drawing of some of the cave art. It's more difficult to see the symbols, animals, and detail on the calcified cave wall, shown in the image above. Image: Breuil et al.

The cave painting "dates are solid," said Roebroeks. The researchers dated calcite minerals both below the paint and the calcite that had crusted on top to establish a window in time for when the painting likely was done. Roebroeks noted that the sample and dating work was done "carefully" by experienced archeologists.

Neandertals made 'cave art' — deal with it

"Neandertals made 'cave art' — deal with it," he said, using a spelling popular in the scientific literature.

The Neanderthals used a red ochre paint on the cave walls, "an activity hitherto thought to be an exclusive 'modern human' phenomenon," noted Roebroeks. In fact, it seems that by the time humans finally arrived in Europe, "indigenous Neandertals had been producing red ochred motifs on cave walls for at least a thousand generations already," he said.

This cave art might provide compelling evidence for Neanderthals' advanced intellect, but anthropologists already knew that Neanderthals were culturally advanced, even fashioning their own jewelry.

David Frayer, an anthropologist at the University of Kansas, suspects Neanderthals caught eagles and used their sharp talons to make this jewelry. The talons, discovered near a rock shelter in Croatia, had been smoothed out around 130,000 years ago, long before other Neanderthal clans painted the walls of Spanish caves.

Three hand stencil drawings in Maltravieso Cave. The hands can be seen in the top left, center (facing down), and center-right of the image. Image: H. Collado

Even having held and inspected these Eagle talons, Frayer, who had no role in either study, finds the cave art impressive.

"Yet, even me as a Neanderthal appreciator, would not have predicted they could have done these," he said via email.

Of course, once humans arrived in Europe, they too began ornately painting cave walls. Lascaux Cave, in France, is covered in hundreds of detailed animals, including horses, deer, and bulls.

But before Neanderthals went extinct — for unknown reasons — they proved their artistic and cultural prowess was similar to ours, even though their skulls were flatter and shaped differently.

"This does not mean Neandertals were identical to modern humans, just behaviorally and mentally equivalent," said Trinkaus. "And it should put to rest the paleophrenoloigcal arguments about Neandertal abilities derived from their skulls."