It turns out humans and Neanderthals did not meet at Vindija Cave, modern day Croatia, which was previously one of the top candidates for the site of interaction between the two species.
The history of our species and the Neanderthals is closely intertwined. The two species interbred about 50,000 years ago. The Neanderthals gave us their genes, giving us a predisposition to traits like nicotine addiction.
Exactly where the intimate encounters happened is not known. It was previously thought that Vindija Cave was a likely option, due to the presence of both Neanderthal and human bones. Initial studies estimating the age of the bones suggested that there was a period when both humans and Neanderthals lived and died in the cave.
But a study published in the journal PNAS has found that the Neanderthal bones are in fact much older than previously thought. Earlier studies had put them as young as 28,000 years old, at a time when there was human activity in the area.
The findings were controversial, as Neanderthals were thought to have disappeared from Europe around 40,000 years ago. The new study puts the Vindija Cave Neanderthals as among some of the last in Europe, at 40,000 years old.
"Our previous research has shown that Neanderthals in Europe did not survive after 40,000 years ago, so the Vindija Neanderthals were not a refugial group, rather they were present just before modern humans began to penetrate Europe for the first time," Tom Higham of the PalaeoChron group at Oxford, also an author of the study, said in a statement.
The team used a new method to refine the bones' age estimate. They focused the radiocarbon dating on the amino acid hydroxyproline in collagen tissue. This helps to avoid contamination with modern tissues, which can make the bones seem younger than they really are.
"We think that all human bones from the Palaeolithic period ought to be dated using this technology due to impact of even small amounts of contamination from modern times," said Thibaut Devièse, also of the University of Oxford and a study author.