Neanderthals, the closest extinct human relatives, lived throughout Europe and Asia some 200,000 years ago. Scientists have long debated the question of when Neanderthals became extinct, and what kind of contact they might have had with modern humans, who began migrating from Africa around 60,000 years ago. Now, an analysis of remains from more than 40 archaeological sites throughout Europe provides the most definitive answer yet.

Previous attempts to date Neanderthal remains, in the hopes of building a chronology of their interaction with humans and their eventual extinction, have yielded uncertain results. According to some of these findings, modern humans and Neanderthals coexisted for as little as 500 years, spurring theories that humans may have either slaughtered their predecessors or passed on deadly diseases that Neanderthals were unable to resist.

In the new study, an international team of researchers analyzed remains found at more than 40 archaeological sites from Spain to Russia. Working at Oxford University, they used cutting-edge advances in radiocarbon dating technology to date around 200 samples of bone, charcoal and shell materials. As a result, they were able to come up with the most accurate chronology yet for the Neanderthal extinction, and provide a more complete picture of how Neanderthals might have coexisted alongside modern humans before they died out.

According to the researchers’ findings, published this week in the journal Nature, humans started to appear in small clusters distributed across Europe about 45,000 years ago, several thousand years earlier than was previously believed. Neanderthals then disappeared from Europe between 41,000 and 39,000 years ago, meaning that the two species coexisted for some 5,000 years, or 10 times longer than earlier estimates.

What the study suggests is that over those 5,000 years, humans gradually began to proliferate while Neanderthals became less common and more widely dispersed (as humans had been before). Archaeological and genetic evidence shows that Neanderthals were already in decline by the time humans arrived; they were low in numbers and becoming increasingly inbred. The new data adds to this picture, suggesting that the arrival of humans compounded Neanderthals’ problems, as they were now forced to compete for resources.

The new study also supports the theories of some archaeologists that early humans provided the inspiration for advances made in late Neanderthal stone tools, as well as their use of jewelry. As lead author Tom Higham, a radiocarbon scientist at the University of Oxford in England, told the BBC, “I think we can set aside the idea of a rapid extinction of Neanderthals caused solely by the arrival of modern humans. Instead we can see a more complex process in which there is a much longer overlap between the two populations where there could have been exchanges of ideas and culture.”

It’s not news that humans and Neanderthals interacted, and possibly interbred, at least in Asia. Other recent findings have suggested that the DNA of non-African people living today is anywhere from 1.5 to 2.1 percent Neanderthal in origin, resulting from interbreeding that occurred some 50,000 to 60,000 years ago in western Asia. But until the new study’s findings, scientists had little idea that humans and Neanderthals overlapped for such a significant time period in some areas of Europe.

On the other hand, while some scientists have suggested that a Neanderthal population existed in Iberia until just 30,000 years ago, the new study found no evidence of this. The date range they linked to the Neanderthal extinction (nearly 10,000 years earlier) coincides with the beginning of an extremely cold period in Europe, and they speculate that this deep chill might have been the factor that pushed the declining Neanderthal population into extinction.