Neandertals arose in Europe and Asia as early as 250,000 years ago, and for most of that time they had Eurasia to themselves—until, that is, modern humans came in and replaced them. Just how long Neandertals hung on after the arrival of Homo sapiens about 45,000 years ago has been a matter of fierce debate among researchers, some of whom argue that they hardly overlapped at all. A new study published online today in Nature, led by dating experts at the University of Oxford in the United Kingdom (two of whom, Thomas Higham and Katerina Douka, are pictured here taking radiocarbon samples at the site of Chagyrskaya in Russia), concludes that Neandertals were entirely extinct by 39,000 years ago. The study, which included 40 sites from Spain to Russia and employed the most recent sample preparation and statistical techniques to increase dating accuracy, found that Neandertals and modern humans did overlap for 2600 to 5400 years, depending on the exact region they inhabited. Although the authors do not speculate on why Neandertals went extinct, their findings would tend to support the hypothesis that they lost out to competition with modern humans, rather than disappeared on their own due to climate change or other factors. The authors also suggest that some late Neandertal innovations, such as sophisticated personal ornaments and stone tools, were actually the result of “acculturation”; that is, these behaviors were either copied from, or inspired by, their modern human cousins.