Finlayson and his colleagues also tried to cut pork skin with the stone tools, to test whether the lines were merely the incidental marks left behind after the Neanderthals had butchered meat. But they couldn't replicate the engraving.
"You cannot control the groove if you're cutting through meat, no matter how hard you try," Finlayson said. "The lines go all over the place."
A simple grid is no Venus figurine
The Neanderthals' brand of abstract expressionism might not have impressed Homo sapiens art critics of the day.
"It's very basic. It's very simple," said Jean-Jacques Hublin, director of the Department of Human Evolution at the Max Planck Institute for Evolutionary Anthropology in Germany. "It's not a Venus. It's not a bison. It's not a horse."
By the late Stone Age, modern humans who settled in Europe were already dabbling in representational art. At least a dozen different species of animals — including horses, mammoths and cave lions — are depicted in the Chauvet Cave paintings, which are up to 32,000 years old. The anatomically explicit Venus figurine discovered at Hohle Fels Cave in southwestern Germany dates back to 35,000 years ago. Other busty female statuettes — the Venus of Galgenberg and the Venus of Dolní V?stonice — date back to about 30,000 years ago.
"There is a huge difference between making three lines that any 3-year-old kid would be able to make and sculpting a Venus," Hublin, who was not involved in the study, told Live Science.
Hublin said this discovery doesn't close the question of Neanderthals' cognitive skills. Proof that Neanderthals were capable of making a deliberate rock carving isn't evidence that they were regularly making art, he said.
"My own feeling is that if Neanderthals regularly used symbols, and given their longtime occupation throughout large parts of the Old World, we probably would have found clearer evidence by now," said Harold Dibble, an archaeologist at the University of Pennsylvania, who also was not involved in the study.
Dibble said he was convinced these markings were deliberate, but scientists need "more than a few scratches — deliberate or not — to identify symbolic behavior on the part of Neanderthals."
"Symbols, by definition, have meanings that are shared by a group of people, and because of that, they are often repeated," Dibble wrote in an email. "By itself, this is a unique example and without any intrinsic meaning … the question is not 'Could it be symbolic?' but rather 'Was it symbolic?' And to demonstrate that, it would be very important to have repeated examples."
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