"We are increasingly finding evidence of sophisticated behavior among Neanderthals, and now the question is: If they were so smart, why did they become extinct?" said Michael Barton, an anthropologist at Arizona State University in Tempe.
"Our answer is that they became extinct because they were so smart, not in spite of it," he said. "They were doing what everyone else was doing, and how they dealt with worldwide environmental change made their population and probably other endemic populations disappear."
To see how ancient groups of people moved around as the climate changed, Barton and colleagues analyzed stone tools from 167 cave sites that spanned Eurasia from the Near East to Gibraltar. Fossils indicated whether Neanderthals, early humans or both had lived in each cave for some period of time between about 128,000 and 11,500 years ago.
As they scanned the tools, the major clue the researchers looked for was how worn down the stones were. That, in turn, hinted at how much moving around their owners did.