The study, released Monday by the journal Proceedings of the National Academy of Sciences, examined grooves in a rock that had been covered with sediment. Archaeologists had previously found artifacts associated with Neanderthal culture in the overlying layer, suggesting that the engravings must be older, said Clive Finlayson, one of the study's authors. Another recently published study examining the dating of various archaeological sites across Europe raises the possibility that the artifacts may not have been made by Neanderthals but by modern humans. "Any discovery that helps improve the public image of Neanderthals is welcome," said Clive Gamble, an archaeologist at the University of Southampton, England.