A red hand stencil. A series of lines that look like a ladder. A collection of red dots.

These images, painted in ocher on the walls of three separate caves in Spain, are the oldest-known examples of cave art ever found. And new research suggests that all three were created not by humans, but by our ancient cousins the Neanderthals.

In a paper published in Science, an international team of archaeologists shows that each of the three paintings was executed at least 64,000 years ago — more than 20,000 years before the first modern humans arrived in Europe.

"This work confirms that Neanderthals were indeed using cave walls for depicting drawings that had meaning for them," said Marie Soressi, an archaeologist at Leiden University in the Netherlands who was not involved in the study. "It also means that our own group, the one we call anatomically modern humans, is maybe not so special."

For most of the last century, researchers have argued that our Neanderthal cousins were intellectually inferior to their modern human contemporaries — incapable of symbolic thought and possibly devoid of language. This was used to explain why the Neanderthals disappeared from Eurasia about 40,000 years ago, not long after modern humans arrived.

However, archaeological evidence tells a different story. We now know that Neanderthals were sophisticated hunters who knew how to control fire, and that they adorned themselves with jewelry and took care to bury their dead.

In addition, genetic evidence suggests that modern humans and Neanderthals were similar enough that they interbred. Indeed, if you are of European or Asian descent, it is likely that roughly 2 percent of your genome comes from Neanderthal ancestors.

Still, Soressi said the discovery is significant. "The one criteria left that would have distinguished Neanderthals and early modern humans was the interest and need to draw symbols deep in the underground," she said.

But now we now know that Neanderthals and modern humans had that in common as well, she said.

For this work, archaeologists traveled to three different cave sites across Spain: La Pasiega, which is home to the mysterious ladder-shaped painting; Maltravieso in the west, where the hand stencil was found; and Ardales in the south, where red dots were painted on curtain formations inside the cave.

Dirk Hoffmann, the lead archaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said the team targeted symbolic, nonfigurative art, which they guessed would be some of the earliest paintings in each of the caves.

Each of these works took planning to execute — requiring a light source, the preparation of pigments, and a decision about where to place the painting. The hand stencil in particular is a relatively demanding piece to do, Hoffman said. The artist placed his or her hand on the wall and then painted over it. When the hand was removed, its "negative" was left, imprinted on the cave.

Matthew Pope, an archaeologist at the University College of London, said the study "may remove one of the last elements that separate the behavior of Neanderthal populations from modern humans in the archaeological record."

In other words, Neanderthals may have looked different than modern humans, but cognitively it appears they were just like us.

Soressi said the revelations make the demise of the Neanderthals harder to explain. She said, "All of what we know today tells us that it is not because Neanderthals were dummies that they disappeared."