A new discovery that Neanderthals were painting cave walls more than 64,000 years ago has anthropologists rethinking the history of art. Found deep in Spanish caves, the rock art was once thought to be the work of modern humans, but the new dates mean that Neanderthals must have figured out fingerpainting, too.

Using a new and improved radioactive dating technique, researchers discovered that paintings in three different caves were created more than 64,800 years ago. That means the paintings were created 20,000 years before modern humans, or Homo sapiens, arrived in Spain, according to a study published today in the journal Science. The discovery makes these the oldest examples of cave paintings in the world and the first to be attributed to Neanderthals.

“The very last piece of evidence we were lacking.”

Neanderthals are our closest extinct relative, but for a long time, they had a reputation for being pretty backward. Early modern humans, for example, made cave paintings. But even though Neanderthals used pigments and decorated themselves with eagle claws and shells, there was no clear proof that they painted caves. One theory goes that Neanderthals developed their rudimentary culture only after early modern humans arrived in Europe some 40,000 to 50,000 years ago.

Today’s findings show the writing on the wall: Neanderthals were clearly painting splotches and tracing their hands on caves long before modern humans showed up. The discovery adds to a growing body of evidence upending the idea that Neanderthals were less evolved than early modern humans, says Marie Soressi, an archaeology professor at the University of Leiden who was not involved in the research. “It’s impossible to say that one is more clever than the other,” she says. These cave paintings are “the very last piece of evidence we were lacking.”

The reason we didn’t know Neanderthals were cave painters until now is because it’s hard to figure out when cave art was created. The most common dating method can only be used on organic material, like bones, so it usually doesn’t work for cave paintings. Another technique uses the rate of uranium’s radioactive decay as a clock. But it required lots of material to come up with a date, and cave paintings are too rare to risk damaging. Rock art “is unique, it’s precious — there’s a lot of pressure on you not to make a mistake,” says geochronologist Dirk Hoffmann at the Max Planck Institute for Evolutionary Anthropology. So he and his colleagues fiddled with the method until only tiny scrapings of cave walls were needed.

With a new way to date the rock art, researchers carrying lights and scalpels crawled deep underground into caves all over Spain. The plan was to scrape samples off of the mineral-rich crusts that had hardened on top of the cave paintings. By figuring out the age of the crusts, they’d know at least how old the paintings were — without having to disturb them.

They found the oldest dates for three paintings — the outline of a hand, red-painted stalactites, and a ladder-like geometric shape — in three different caves that had been occupied by archaic human species. The most recent painting is at least 64,800 years old, according to this technique, and the oldest is more than 66,000 years old. “When you stand in front of cave paintings, it doesn’t matter who made it,” Hoffmann says. “It’s just the fact that it’s there for over 60,000 years. This is, in a way, breathtaking on its own.”

Other experts agree with the dates and that the timing means the art must have been created by Neanderthals. There’s no fossil evidence of modern humans in Spain that long ago, says John Hawks a paleoanthropologist at the University of Wisconsin-Madison who wasn’t involved in the research. “There’s no secret story,” he says. “The results are just, ‘Hey, Neanderthals were making these things, and you didn’t know it.’”

We don’t know why the Neanderthals painted these images or what they mean, but there’s one thing they show clearly: Neanderthals and their modern human relatives weren’t as different as we thought. “These Neanderthals were human,” Hawks says. “We see them doing human things.”