Around 39,000 years ago, a Neanderthal huddled in the back of a seaside cave at Gibraltar, safe from the hyenas, lions and leopards that might have prowled outside. Under the flickering light of a campfire, he or she used a stone tool to carefully etch what looks like a grid or a hashtag onto a natural platform of bedrock.
Archaeologists discovered this enigmatic carving during an excavation of Gorham's Cave two years ago. They had found Neanderthal cut marks on bones and tools before, but they had never seen anything like this. The researchers used Neanderthal tools to test how this geometric design was made — and to rule out the possibility the "artwork" wasn't just the byproduct of butchery. They found that recreating the grid was painstaking work.
"This was intentional — this was not somebody doodling or scratching on the surface," said study researcher Clive Finlayson, director of the Gibraltar Museum. But the discovery poses much more elusive questions: Did this engraving hold any symbolic meaning? Can it be considered art? [Video: First Neanderthal Rock Art Revealed]
Neanderthals roamed Eurasia from around 200,000 to 30,000 years ago, when they mysteriously went extinct. They were the closest known relatives of modern humans, and recent research has suggested that Neanderthals might have behaved more like Homo sapiens than previously thought: They buried their dead, they used pigments and feathers to decorate their bodies, and they may have even organized their caves.
Despite a growing body of evidence suggesting Neanderthals may have been cognitively similar to modern humans, a lack of art seemed to be the "the last bastion" for the argument that Neanderthals were much different from us, Finlayson said.
"Art is something else — it's an indication of abstract thinking," Finlayson told Live Science.
Archaeologists recently pushed back the date of hand stencil paintings found at El Castillo cave in northern Spain to 40,800 years ago, which opens the possibility that Neanderthals created this artwork. But there is no solid archaeological evidence to link Neanderthals to the paintings. [See Photos of the Ancient El Castillo Cave Art]
In Gorham's Cave, Finlayson and colleagues were surprised to find a series of deeply incised parallel and crisscrossing lines when they wiped away the dirt covering a bedrock surface. The rock had been sealed under a layer of soil that was littered with Mousterian stone tools (a style long linked to Neanderthals). Radiocarbon dating indicated that this soil layer was between 38,500 and 30,500 years old, suggesting the rock art buried underneath was created sometime before then. [See Photos of Europe's Oldest Rock Art]
Gibraltar is one of the most famous sites of Neanderthal occupation. At Gorham's Cave and its surrounding caverns, archaeologists have found evidence that Neanderthals butchered seals, roasted pigeons and plucked feathers off birds of prey. In other parts of Europe, Neanderthals lived alongside humans — and may have even interbred with them. But 40,000 years ago, the southern Iberian Peninsula was a Neanderthal stronghold. Modern humans had not spread into the area yet, Finlayson said.
To test whether they were actually looking at an intentional design, the researchers decided to try to recreate the grid on smooth rock surfaces in the cave using actual stone tools left behind in a spoil heap by archaeologists who had excavated the site in the 1950s. More than 50 stone-tool incisions were needed to mimic the deepest line of the grid, and between 188 and 317 total strokes were probably needed to create the entire pattern, the researchers found. Their findings were described yesterday (Sept. 1) in the journal Proceedings of the National Academy of Sciences.