Wednesday, October 20, 2010

Volcanic fate for Neandertals

Scientists aren’t sure what caused the annihilation of the Neandertals, the ancient species most closely related to modern human beings. It could have been diet, or climate change, or getting outsmarted by modern humans. Or, volcanoes may have helped cleaned them out, say a team of Russian archaeologists.

About 40,000 years ago, new work shows, at least three volcanoes blown up in Europe and western Asia, where most of the Neandertals lived. The Russian researchers, led by Liubov Golovanova, came to this conclusion after studying the Mezmaiskaya Cave in the Caucasus Mountains. These mountains are in southwestern Russia, near the border between Europe and Asia, and Neandertals lived in and around the cave.

The cave contains layers of sediment, which are bits of rock and other materials that settled there over time. Scientists can determine how old each layer is. Then, when the archaeologists find anything within a layer (such as bones), they know how old that is. For this study, Golovanova and his colleagues looked at layers that are 40,000 to 45,000 years old. These layers, the scientists found, contain ash from two separate volcanic eruptions. Golovanova said “For the first time, we have identified evidence that the disappearance of Neandertals in the Caucasus coincides with a volcanic eruption approximately 40,000 years ago”

Modern human beings, Homo sapiens, were secured from the destructive volcanoes because, 40,000 ago, they lived in Africa and in parts of Asia that the eruptions did not affect. However, soon after the eruptions, Homo sapiens moved into the area formerly occupied by the Neandertals, including the cave. Archaeologists have found artifacts there from modern humans dating back 37,000 years.

Golovanova and his colleagues consider that the Neandertals were long gone from the cave before modern humans showed up, but not all scientists agree. Biagio Giaccio, a geologist at the Institute of Environmental Geology and Geoengineering in Rome, says that more work is needed to understand who was where, and when.