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 layer"—likely corresponding to the so-called Campanian Ignimbrite eruption, which occurred near Naples (map)—"had no [tree] pollen and very little pollen from other types of plants," Cleghorn said. "It's just a sterile layer."
The loss of plants would have led to a decline in plant-eating mammals, which in turn would have affected the Neanderthals, who hunted large mammals for food.
Modern humans would have also been affected, but they had "backup populations" in Africa and Asia. Link
(Image credit: Kenneth Garrett, National Geographic)