A unique brownish piece of limestone found in a Croatian rock shelter suggests Neanderthals collected unusual rocks, indicating they made decisions based on aesthetics or curiosity about the world around them. The rock was collected a second time more than 100 years ago by scientists who missed its significance.

Two years ago, Dr David Frayer of the University of Kansas discovered that Neanderthals made jewelry from eagle talons. He has added to that discovery with the finding that the same Krapina rock shelter, where the eagle talons were found, also hosted a rock apparently collected for its distinctive appearance. Both items were among those collected at the site between 1899 and 1905 by paleontologist Dragutin Gorjanovi?-Kramberger. 

"If we were walking and picked up this rock, we would have taken it home," Frayer said in a statement. "It is an interesting rock." It seems that more than 100,000 years ago, a Neanderthal thought the same thing. The limestone does not originate in the sandstone shelter, and must have been brought there by one of the inhabitants. Moreover, no obsessively tidy fellow member of the tribe threw it out, suggesting the perception of its value was not unique.

"People have often defined Neanderthals as being devoid of any kind of aesthetic feelings, and yet we know that at this site they collected eagle talons and they collected this rock," Frayer said. "At other sites, researchers have found they collected shells and used pigments on shells."

Frayer has reported the finding in the French journal Comptes Rendu Palevol.

The stone is 12 centimeters (5 inches) long and 10 centimeters (4 inches) wide. A small piece has flaked off, but this is apparently fresh, rather than having been done by the Neanderthals. Nothing similar was found at the site, and it appears to have had no practical use – paperweights being in little demand at the time – making Frayer confident its value was symbolic or aesthetic.

^{The original collector probably found the rock interesting from all angles. David Frayer/ University of Kansas}

Since we now know that humans inherited a portion of our DNA from Neanderthals, it is clear that they were more closely related to us than was once suspected. Nevertheless, the perception of their lack of culture held back research for many years, probably including the failure to notice the artistic significance of the eagle-talon jewelry and the decision to keep a rock simply because it looked interesting.

Both the talons and rock are dated to 130,000 years ago. A Neanderthal construction site found last year is even older. Neanderthals lasted for another 90,000 years or so before becoming extinct, but so far we have not found evidence that their culture developed further over that great span of time. It seems they didn't get the message to "bang the rocks together, guys".