Whether it’s a depiction of God on the Sistine Chapel or the ineffable feeling of summer dripped across a Jackson Pollock painting, art is a visual proxy for an internal mental state. Specifically, a human internal mental state. The human ability to represent thoughts and events that aren’t actually present is an expression of symbolic thinking, which scientists long believed originated with the first Homo sapiens who created cave art and was never adopted by any other species.

Groundbreaking research published Thursday in Science throws a wrench into all that. In the paper, an international team of scientists, discovering that cave paintings in three sites across Spain are collectively between 64,000 and 66,000 years old, report that there’s no way those cave paintings could have been made by early Homo sapiens. At that time, there was only one species of hominin living in Spain that could have made this art — not humans, who arrived 40,000 years ago, but the Neanderthals.

See also: “Human Language Has Its Origin in Cave Paintings, Linguists Argue”

“We are confident that this art was created by Neanderthals because of the wider archeological evidence for the presence of both Homo sapiens and Neanderthals,” study co-author and University of Southampton archeologist Chris Standish, Ph.D., tells Inverse by email.

“The transition from the Middle Paleolithic, the period when Neanderthals lived in Europe and the archaeological record is dominated by their material culture and the Upper Paleolithic, the period when anatomically modern humans first arrived, is well defined in Iberia … The likelihood that modern humans were present in these caves painting art, or were elsewhere, are therefore minuscule.”

The scalariform (ladder shape) composed of red horizontal and vertical lines dates back to more than 64,000 years. P. Saura

Evidence that Neanderthals created art negates the idea that they were incapable of symbolic thought and belief systems. When the fossilized remains of Neanderthals were first found in the 19th century, German biologist Ernst Haeckel called the species Homo stupidus — the “stupid human.” Over the past decade, however, breakthroughs in genetic technology and archaeological finds have proven that our relatives were not dumb creatures but a thinking, feeling species with a material culture that lives on in our own DNA today. The discovery that they created art, in turn, shows they were not cognitively inferior to Homo sapiens.

“I think we all [the research team] hope that this will help improve the general perception people have of Neanderthals, so that people don’t see them as behaviorally inferior or less cultured compared to us,” says Standish. “We are more similar than previously thought.”

Hand stencils in the Maltravieso Cave, dating back to at least 66,000 years old. H. Collado

Standish and his team used a new technique to analyze the art in three caves in the north, center, and south of Spain: a red linear motif in La Pasiega, a hand stencil in Maltravieso, and red-painted dots and discs in Ardales. Within the rectangular lines of the motif, they made out the heads and bodies of animals — but not well enough to know what type of animals are depicted. Instead of using radiocarbon dating, the technique normally used to date the charcoal used in cave paintings, they used uranium-thorium dating to analyze the carbonate crusts that covered some of the art.

These tiny white crusts are formed when water percolates through the rocks, precipitating a film of the mineral calcite. Because the calcite is on top of the art, it can be assumed that it formed after the paintings were created — and so, dating the crusts reveals the approximate age of the art beneath it.

Researchers from Germany, UK, France, and Spain took carbonate samples from three cave sites. University of Southhampton

The paintings from all three caves were created before anatomically modern humans set foot in what’s now Spain. It’s clear the Neanderthal artists deliberately chose images and selected where to place them, revealing that they too had purposeful behavior, a characteristic we’ve previously only credited to humans. To truly have understood the human story, the authors note, we must continue to study the Neanderthals — and we need to be open to the possibility that, perhaps, we aren’t so special after all. If Neanderthals were capable of symbolic thought, which experts think drove human cognitive developments, who knows what else they were capable of?

“There may be anatomical differences between the two hominin groups, but cognitively they were very similar,” says Standish. “Symbolic behavior is often seen as a key indicator of behavioral modernity, but ever since they were first identified, Neanderthals have been portrayed as uncultured and cognitively inferior. They were much more ‘human’ than we used to think.”