Paleontologists know plenty about our nearest human cousins, the Neanderthals. They know that this highly successful species walked the Earth for some 300,000 years (we've been around for less than 200,000). They know the Neanderthals kept their caves surprisingly tidy; that they ate things other than raw meat; that they practiced recycling, wore jewelry and were generally much more sophisticated than their popular reputation would suggest.
Yet it didn't take long after our own species invaded their last known outpost in Europe that the Neanderthals went utterly extinct. Now a new paper in Nature suggests it happened over a period of between 2,600 and 5,400 years or so—which is twice as fast as anyone had thought. The two groups did, evidently, coexist: "They lived in Europe at the same time," says lead author Tom Higham, of Oxford, "although they were spatially separated. It was like a mosaic." Agrees William Davies, of the University of Southampton, who wrote a commentary on the new research, also in Nature, "It's not a neat story. It's quite complex."
The key to the new analysis was an unusually large sample of human and Neanderthal remains from 40 different sites across Europe, along with improved methods for filtering out contaminants from the samples before attempting to date them. In many cases, the remains weren't bones but rather stone tools thought to characteristic of one species or the other—so-called Mousterian and Châtelperronian tools for the Neanderthals and Uluzzian tools for our own ancestors.
That raises, if not a red flag, then at least a sort of pinkish one, according to Davies. "In the old days, we had very few assemblages of tools, so it was quite easy to say that Mousterian tools represented Neanderthals, while tools with longer blades reflect anatomically modern humans." But with more and more tools in their collections, paleontologists have become less sure. "The whole thing has become more blurred and less certain."
The new analysis doesn't depend entirely on who made what tools, however, and, says Davies, "the areas they've chosen to analyze are places where we can be more confident than most." What makes the work so potentially important, he says, is that it gives a much finer-grained picture than ever before of where Neanderthals and modern humans lived and when, and how those patterns changed as Neanderthal numbers dwindled, then vanished.
That in turn will help anthropologists figure out how the Neanderthals vanished—what force or forces drove them extinct by about 40,000 years ago. "We think the Neanderthals had very low population numbers when modern humans arrived," says Higham, perhaps in part because Europe was in the throes of an Ice Age at the time, so they were struggling against harsh conditions that couldn't support large numbers of individuals. Modern humans, Higham observes, had been living in Africa, which was much more benign. "Modern humans also seemed to have more modern technology," he says, "which wouldn't have been a huge advantage, but over the long duration might have given them an edge."
Scientists also know that Neanderthals and modern humans interbred at some level, which is why about 2% of our genes, on average, are Neanderthal in origin. The details of those interactions are still completely unknown—for now, anyway. "For me," says Davies, "the big achievement here is that we now have a way of getting much more information out of both skeletal and archaeological remains. We can look at the molecular level on genetic inheritance, movement patterns, even what they were eating."
The mystery of when and where the Neanderthals made their last stand may be just about wrapped up. And the answer to why they disappeared might not be a mystery for much longer.