Sudden Climate Change Didn't Kill Off Neanderthals

Neanderthals did not die out because of a sudden and extreme change in climate, as some recent theories have proposed, according to research news from Woods Hole Oceanographic Institution.

An international team of researchers has found that neither of the two periods in which Neanderthals might have gone extinct experienced a severely cold climate or drastic climate change. They reached their conclusion after studying ice cores and seafloor sediments from about 28,000 and 32,000 years ago, the two likely dates at which Neanderthals are believed to have died out.

The scientists found a way to establish the likely climate when the Neanderthals went extinct by eliminating the uncertainties that have hampered past studies: the difficulty of matching radiocarbon dates of ancient materials to an actual year in the past, and the difficulty of assigning exact dates to different sections of an ancient climatic record.

Instead, the team correlated their ice core and sediment climate data directly with other geologic and paleontological data from the same period in which the Neanderthals are believed to have gone extinct.
"In this case, we were able to provide a much more accurate picture of the climatic background at the time of the Neanderthal disappearance," said Konrad Hughen, a paleoclimatologist at Woods Hole. "Our approach offers the potential to unravel the role of climate in critical events of the recent fossil record, as it can be applied to any radiocarbon date from any deposit."

By mapping together different kinds of data -- geologic, climatic and paleontological -- from their samples, the researchers were able to determine that neither of the two dates assumed for the Neanderthals' extinction coincided with sudden periods of climate change called "Heinrich Events." Those events occurred when large numbers of icebergs flowed into the North Atlantic, causing a rapid influx of fresh water that altered oceanic and atmospheric circulation patterns that affect climate.

The scientists also found that, if Neanderthals died out more recently than most theorize, the climate was changing but gradually enough to allow them time to adapt. One controversial theory suggests that Neanderthals might have lived until about 24,000 years ago.

Other members of the research team included Chronis Tzedakis of the University of Leeds, Isabel Cacho of the University of Barcelona, and Katerina Harvati of the Max Planck Institute for Evolutionary Anthropology.

Woods Hole Oceanographic Institute, "Extinction of Neanderthals Was Not a Climate Disaster Scenario." URL: (http://www.whoi.edu/page.do?pid=7545&tid=282&cid=32168&ct=162)