Prehistoric dots and crimson hand stencils on Spanish cave walls are now the world's oldest known cave art, according to new dating results—perhaps 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 Neanderthals—and 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 paintings—the 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.