About 40,000 years ago in what we now call Italy and the Caucasus Mountains, which straddle Europe and Asia, several volcanoes erupted in quick succession, according to a new study to be published in the October issue of the journal Current Anthropology.

It's likely the eruptions reduced or wiped out local bands of Neanderthals and indirectly affected farther-flung populations, the team concluded after analyzing pollen and ash from the affected area. (See volcano pictures.)

The researchers examined sediments layer from around 40,000 years ago in Russia's Mezmaiskaya Cave and found that the more volcanic ash a layer had, the less plant pollen it contained.

"We tested all the layers for this volcanic ash signature. The most volcanic-ash-rich