Hominins have lived in Western Spain’s Maltravieso Cave off and on for the last 180,000 years. At some point in those long millennia of habitation, some of them left behind hand stencils, dots and triangles, and animal figures painted in red on the stone walls, often deep in the dark recesses of the cave. The art they left behind offers some of the clearest evidence for a key moment in human evolution: the development of the ability to use symbols, like stick-figure animals on a cave wall or spoken language.

Maltravieso, like La Pasiega in Northern Spain and Ardales Cave in the south, is a living cave, where water still flows, depositing carbonate minerals and shaping new rock formations. In these caves, flowstones and rock curtains have been slowly growing over ancient rock art. By dating those carbonate deposits, scientists can figure out a minimum age for the art without having to take samples from the pigment itself.

Now, two new studies have dated cave art and decorated shell jewelry from sites in Spain to at least 20,000 years before the first Homo sapiens arrived in Europe. That date offers the first clear evidence of Neanderthal art, which means our extinct relatives were also capable of symbolic thought. It’s a surprising discovery, says study coauthor Alistair Pike of the University of Southampton—but not all that surprising.

“There was already evidence that Neanderthals were behaving symbolically, using pigments and beads presumably as body adornment. We didn’t think it would be a huge leap if we found they also painted caves,” he told Ars Technica. “But if you had asked academics if they thought Neanderthals painted caves, most would have said ‘no.’”

Archaeologists have debated for years about whether Neanderthal burial practices or structures like the circles of broken stalagmites at Bruniquel Cave in Southern France counted as clear evidence of ritual behavior or whether they could have a simpler explanation. Others have debated whether body art discovered in Neanderthal burials is really symbolic or if it was just imitation of neighboring Homo sapiens.

“The artists were Neanderthals”

But it’s hard to argue that a drawing of a horse or a deliberate stencil of a hand, placed next to a rock formation in a dark part of a cave—a project that would have required planning and light—isn’t symbolism. All of the cave art dated so far in Europe, however, has either been clearly human in origin, or it has been right around the 40,000-year-old mark, when it could have been the work of either group.

According to Max Planck Institute for Evolutionary Anthropology archaeologist Dirk Hoffmann and his colleagues, however, the art in La Pasiega, Maltravieso, and Ardales Caves is unequivocally Neanderthal. Uranium-thorium dating of rock deposited over paintings in all three caves indicates that the paintings can’t be any younger than 64,000 years. And there were no humans in Europe 64,000 years ago; the first H. sapiens wouldn’t show up until 20,000 years after the rock of the caves began flowing over the art. Neanderthals, on the other hand, lived in the region since at least 243,000 years ago.

J. Zilhão

J. Zilhão

J. Zilhão

J. Zilhão

“The implication, therefore, is that the artists were Neanderthals,” wrote Hoffmann and his colleagues.

And in a sea cave called Cueva de los Aviones, on the southeastern coast of Spain, archaeologists found shells decorated with red and yellow pigment with holes punched in them as for a string. They’re generally assumed to be jewelry, which is another kind of symbol. Jewelry communicates a message, whether it’s “Og is the second-highest-ranking chief” or simply “Og feels pretty today.”

In terms of cognitive evolution, that’s a big step. The ability to use physical objects or images to represent ideas is also an indicator that we could use sounds to do the same thing—language. That’s a hallmark of human cognition as we know it, but the shells in Cueva de los Aviones seem to have been decorated not by humans but by Neanderthals. Here, too, flowing water had deposited a flowstone over the layer of sediment in which these shells were found. And uranium-thorium dating said the flowstone couldn’t be any younger than 114,000 years.

That means the Cueva de los Aviones shells couldn’t have been made by modern humans. In fact, Hoffman and his colleagues say they predate every comparable set of artifacts found so far by at least 20,000 to 40,000 years. And that might mean that the ability to use symbols didn’t originate with modern humans.

J. Zilhão

J. Zilhão

Language and symbolism is older than we thought

The findings, Hoffmann and his colleagues wrote, leave “no doubt that Neanderthals shared symbolic thinking with early modern humans, and that, as far as we can infer from material culture, Neanderthals and early modern humans were cognitively indistinguishable.” The two, they suggest, must have inherited the ability to think in symbolic terms from a shared ancestor.

That capacity probably predates the first appearance of cave art or jewelry, coauthor and University of Barcelona archaeologist João Zilhão suggests. Visual symbols like art and jewelry probably emerged as a product of growing social complexity and population sizes, he argues.

“What we seem to be seeing sometime between 200,000 and 100,000 years ago is the emergence of indicators of increased social complexity,” he told Ars Technica. “Material symbols are not going to appear in the archeological record until such time when individual and social interactions become so complex that people are bound to encounter strangers on a frequent basis, and thus widely shared and understood codes are required.”

Testing that hypothesis will require more data, of course, and Hoffmann and his colleagues say they expect uranium-thorium dating to identify more examples of clearly Neanderthal rock art elsewhere in Europe.