Climate change not main cause of Neanderthals' demise, study finds
The mystery of what killed the Neanderthals has come a step closer to being solved, thanks to a new study which rules out one of the leading theories - catastrophic climate change. The study, which was partly funded by the EU, is published in the latest edition of the journal Nature. The Neanderthals inhabited Europe and western Asia for over 100,000 years before becoming extinct around 30,000 years ago. The cause of their demise is a subject that has puzzled scientists since the first Neanderthal bones were discovered in the 19th century. Some argue that they died out as a result of competition from modern humans, who arrived in Europe some 40,000 years ago. Others blame deteriorating climate conditions. 'Until now there have been three limitations to understanding the role of climate in the Neanderthal extinction: uncertainty over the exact timing of their disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record,' explained Professor Chronis Tzedakis of the University of Leeds. One of the Neanderthals' last great strongholds in Europe was the Iberian peninsula, and much research has been carried out at Gorham's Cave, Gibraltar, which scientists think was inhabited by some of the last living Neanderthals. There is strong evidence for occupation of the site at older dates, i.e. around 30-32,000 years ago, and some evidence that the site was occupied 28,000 and even 24,000 years ago, although this latter date is contested. To get a more detailed picture of the climate at these different time periods, the researchers mapped the radiocarbon dates of interest directly onto a well-dated climate archive. They found that 32,000 and 28,000 years ago, Europe's climate was relatively unstable, but the Neanderthals had survived these conditions before. In contrast 24,000 years ago Europe was on the brink of a major episode of climate change, with ice sheets and cooler temperatures spreading across northern Europe. However, thanks to an influx of warm water into the Mediterranean from the subtropical Atlantic, Gibraltar's climate remained relatively unaffected by what was going on further north. 'Our findings suggest that there was no single climatic event that caused the extinction of the Neanderthals,' concludes Katerina Harvati of the Max Planck Institute for Evolutionary Anthropology. 'Only the controversial date of 24,000 radiocarbon years for their disappearance, if proven correct, coincides with a major environmental shift. Even in this case, however, the role of climate would have been indirect, by promoting competition with other human groups.' The scientists believe their approach of mapping radiocarbon dates directly onto climate records could be useful elsewhere. 'Our approach offers the huge 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,' said Konrad Hughen of the Woods Hole Oceanographic Institution. EU funding for the work came from the Marie Curie EVAN initiative (European Virtual Anthropology Network).