Stone Age artists were painting red disks, handprints, clublike symbols and geometric patterns on European cave walls long before previously thought, in some cases more than 40,000 years ago, scientists reported on Thursday, after completing more reliable dating tests that raised a possibility that Neanderthals were the artists.

A more likely situation, the researchers said, is that the art — 50 samples from 11 caves in northwestern Spain — was created by anatomically modern humans fairly soon after their arrival in Europe.

The findings seem to put an exclamation point to a run of recent discoveries: direct evidence from fossils that Homo sapiens populations were living in England 41,500 to 44,200 years ago and in Italy 43,000 to 45,000 years ago, and that they were making flutes in German caves about 42,000 years ago. Then there is the new genetic evidence of modern human-Neanderthal interbreeding, suggesting a closer relationship than had been generally thought....