Volcanic Reaction

Anthropologist collaborates on new theory about why Neanderthals became extinct

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Anthropologist Naomi Cleghorn and a team of Russian archaeologists believe they know what drove Neanderthals into extinction, and they’re gaining national recognition for their groundbreaking theory.

Dr. Cleghorn, an assistant professor in the Department of Sociology and Anthropology, worked in a research group led by Liubov Vitaliena Golovanova and Vladimir Borisovich Doronichev of the ANO Laboratory of Prehistory in St. Petersburg, Russia. She co-wrote a paper published in the October 2010 Current Anthropology that suggests climate change following massive volcanic eruptions helped lead to the Neanderthals’ extinction and cleared the way for modern humans to thrive in Europe and Asia. Stories about the research have appeared in The New York Times and on the USA Today and National Geographic News websites.

Evidence comes from the Mezmaiskaya cave in the Caucasus Mountains of southern Russia, a site rich in Neanderthal bones and artifacts. Recent excavations revealed two layers of volcanic ash that coincide with large-scale volcanic events that occurred around 40,000 years ago, the researchers say in their paper.

Geological layers containing the ashes also hold evidence of an abrupt and potentially devastating climate change. Sediment samples from the two layers reveal greatly reduced pollen concentrations compared to surrounding layers. That’s an indication of a dramatic shift to a cooler and drier climate, the researchers explain. Further, the second of the two eruptions seems to mark the end of Neanderthal presence at Mezmaiskaya. Numerous Neanderthal bones and stone tools have been found in the geological layers below the second ash deposit, but none are found above it.

The theory that climate change led to the Neanderthals’ extinction has been around for a while. The problem with it has always been that the Neanderthals had survived several oscillations in environmental conditions before. The research team believes that linking their extinction with a massive volcanic eruption makes more sense than tying it to a gradual climate change.

A volcanic event has a very rapid impact on the landscape,” Cleghorn explains. “The environment literally crashed at that point.”

The ash layers the team studied correspond chronologically to the Campanian Ignimbrite super-eruption of 40,000 years ago in modern-day Italy and a smaller eruption thought to have occurred around the same time in the Caucasus Mountains. The researchers argue in their paper that these eruptions caused a “volcanic winter” as ash clouds obscured the sun, possibly for years. The climatic shift devastated the region’s ecosystems, “possibly resulting in the mass death of hominins and prey animals and the severe alteration of foraging zones.”

Anthropologists have long puzzled over the disappearance of the Neanderthals and the apparently concurrent rise of modern humans. This research suggests that the advantage may have been simple geographic location.

Early moderns initially occupied the more southern parts of western Eurasia and Africa and thus avoided much of the direct impact of the … eruptions,” they write.

While the researchers stress that more data from other areas in Eurasia are needed to fully test the hypothesis, they believe the Mezmaiskaya cave offers “important supporting evidence” for the idea of a volcanic extinction.

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