The ultimate fate of the Neanderthals remains a major mystery. We know they went extinct, but why did they die out when our ancestors thrived? New evidence suggests massive, deadly volcanoes killed off the Neanderthals while completely sparing our ancestors.
The solution to the Neanderthal extinction mystery might be found in the Mezmaiskaya cave, found in Russia's Caucasus Mountains. The site is full of Neanderthal bones and artifacts from tens of thousands of years ago, but it's two deposits of volcanic ash dating back to about 40,000 years ago that caught the attention of researchers. The ashes line up well with a known period of heavy volcanic activity in Eurasia, and the surrounding sediment layers suggest there was sudden, devastating climate change as a result of the volcanoes.
Specifically, the pollen concentrations dropped dramatically around the volcanic layers, suggesting a rapid shift to a cold, dry climate. That would have forced the Neanderthals to radically change how they lived in order to survive, and the evidence from the cave doesn't look good for their chances - all the artifacts are found below the volcanic ash, and there's no indication of any Neanderthal habitation after the second eruption.
The two ash layers were likely caused by the Campanian Ignimbrite super-eruption, a massive volcanic blast in Italy, and a second, smaller eruption within the Caucasus Mountains. The two eruptions would have created a "volcanic winter" that blotted out the sun, possibly for several years. The damage to the climate would have rewritten the makeup of the local ecosystem and likely killed off the Neanderthals.
If this theory is correct, then it means humans weren't really "superior" in any appreciable sense to Neanderthals. Instead, the reason humans survived and Neanderthals didn't was just a simple matter of location, as Eurasia was devastated by volcanoes while Africa was spared most of the carnage. Sure, modern humans' more advanced hunting techniques probably hastened their success, but Neanderthals were likely already on the way out when humans began to expand throughout the rest of the world.