Prehistoric dots and crimson hand stencils on Spanish cave walls are now the world's oldest known cave art, according to new dating resultsperhaps the best evidence yet that Neanderthals were Earth's first cave painters. If that's the case, the discovery narrows the cultural distance between us and Neanderthalsand fuels the argument, at least for one scientist, that the heavy-browed humans were not a separate species but only another race. Of the 11 subterranean sites the team studied along northern Spain's Cantabrian Sea coast, the cave called El Castillo had the oldest paintingsthe oldest being a simple red disk. At more than 40,800 years old, "this is currently Europe's oldest dated art by at least 4,000 years," said the study's lead author Alistair Pike, an archaeologist at the University of Bristol in the U.K. If the new dates are correct, they also could make the El Castillo art the oldest known well-dated cave paintings in the worlda title previously held by France's Chauvet cave paintings (pictures), believed to be at least 37,000 years old. Pike's team teased out the new dates using a method that relies on known rates of decay in uraniumspecifically uranium in calcium deposits that had formed over the paint. The mineral-based paint itself couldn't be dated, because it contains neither uranium nor the carbon needed for radiocarbon dating.