With cut after cut of a stone knife, a Neanderthal painstakingly sliced a sharp talon from the toe bone of an eagle, perhaps crafting a necklace or some other personal ornament. They then tossed aside the bone on a cave floor along with other scraps and broken tools.

More than 39,000 years later, archaeologists found the cut-marked toe bone in what is now Spain. An analysis of the eagle remains, published today in the journal Science Advances, adds a new piece of evidence to our understanding of the behavior of Neanderthals. The find reignites a debate among scientists: Did our extinct cousins engage in symbolic activities, like making art and decorating their bodies, that we've long believed were uniquely human?

The toe bone was unearthed in a narrow cave in Calafell, a village on the Mediterranean coast southwest of Barcelona. Named Cova Foradada, the cave's archaeological significance was discovered by chance in 1997 when hikers found several human bones from the Neolithic period, a time when humans in Europe first started settling in villages and relying on agriculture for sustenance.

Years of subsequent excavations have revealed that Cova Foradada's history extends far beyond the Neolithic. Humans were using the site 38,000 years ago for hunting-related activities. Before that, some of the last Neanderthals in Europe sought shelter there, too.

No Neanderthal bones have been found at Cova Foradada, but the ancient relative of our own species did leave behind telltale tools associated with the Châtelperronian culture. Châtelperronian artifacts, including stone tools and tiny beads, have been linked with Neanderthals in southwestern France and northern Spain. Around 44,000 years ago, this culture coincided with the time period that Neanderthals were in contact with modern humans in Europe before disappearing about 30,000 years ago.

Among the layers of Châtelperronian artifacts at Cova Foradada, archaeologists found a toe bone from an imperial eagle with clear cut marks. In the last decade, archaeologists across southern Europe have started recognizing similar cut-marked raptor bones and talons at Neanderthal sites, such as the 44,000-year-old Fumane cave in Italy and the 130,000-year-old Krapina site in Croatia. Analyses of these artifacts and experiments with raptor carcasses have suggested that the claws at these sites were deliberately removed and worn as personal ornaments. At first these talons seemed like isolated examples. Now they've been documented at about a dozen Neanderthal sites, including Cova Foradada.

"I think it is an important addition to growing body of evidence of personal ornament usage in Neanderthals, now spanning more than 80,000 years," says Davorka Radovčić, a curator at the Croatian Natural History Museum, Zagreb, who studied the talons at Krapina but was not involved in the new study.

Neanderthals lived from Portugal to Eurasia, but their penchant for using raptor claws seems restricted to a specific region of southern Europe, from northern Spain through southern France and northern Italy to Croatia, says the lead author of the new study, Antonio Rodríguez-Hidalgo, a researcher at the Institute of Evolution in Africa (IDEA), which is based in Madrid. Did wearing talon jewelry have special meaning for Neanderthals living in this geographic area?

"We think that the talons are related to the symbolic world of the Neanderthals," Rodríguez says. While it's difficult or even impossible to know what these symbols actually meant to Neanderthals, their use may imply that Neanderthals were practicing a form of communication.

"We're looking at evidence of traditions that have to do with social identification," says John Hawks, an anthropologist at the University of Wisconsin–Madison who wasn't involved in the study. "Why do you wear ornaments? Why do you go through this trouble? Because you notice something interesting, you want to associate yourself with it, [and] you want it to mark yourself for other people to recognize."

The question about wearing talons gets to the heart of a larger debate among paleoanthropologists about Neanderthals. Thirty years ago, scientists only ascribed symbolic behavior to Homo sapiens, and Neanderthals were thought to be totally different from us, Rodríguez says. "Now we have little pieces of evidence that show a different picture."

Those little pieces of evidence include Neanderthal use of pigments, ritualistic burial sites and possible cave art. Still, many of these findings remain extremely controversial. Just last month, the Journal of Human Evolution published a paper signed by more than 40 anthropologists arguing that there is no strong evidence for Neanderthal cave art in Spain. The researchers were responding to findings, reported last year, that suggested a few cave art sites in Spain were at least 65,000 years old, predating the arrival of modern humans in region—meaning they must have been created by Neanderthals. The authors of the response paper contend that we have no reason to believe that Neanderthals made cave art because evidence of their symbolic practices are "exceedingly rare and often ambiguous," paling in comparison to the complex figurative cave art created by modern humans.

Neanderthals are also known to have made birch tar as an adhesive, suggesting they were capable of human-like planning and complex cognition. But a few months ago, another research team published a study claiming that birch tar wasn't actually so hard to make and shouldn't be used as an example of Neanderthals' cleverness.

These cases illustrate how little consensus there is about how to interpret the archaeological evidence at possible Neanderthal sites, Hawks says. "The views that people have are so far apart that it goes all the way from, 'Neanderthals are meat robots that had nothing interesting going on in their head' on one extreme, to 'Neanderthals are fully modern and basically like us and we can't discriminate against them,' on the other end."

While Rodríguez's new study offers a picture of necklace-wearing Neanderthals, he thinks the current body of evidence regarding Neanderthal behavior suggests significant differences between Homo neanderthalensis and the Homo sapiens that displaced them.

"If Neanderthals had a very, very complex world like us, in the record this evidence should be very common," Rodríguez says. With the evidence still fragmentary, he doesn't think scientists can insist yet that Neanderthals were just like modern humans, but perhaps they were more like us than previously believed.