One to four percent of non-African human genomes are comprised of Neandertal sequence, an international research team has found.

The researchers found evidence suggesting modern humans interbred with Neandertals an estimated 50,000 to 80,000 years ago, with Neandertal DNA apparently entering the human population after modern humans left sub-Saharan Africa.

Evidence of Neandertals has been detected in Europe and parts of Asia from about 400,000 years ago up until around 30,000 years ago. But although Neandertals appear to be one of the closest evolutionary relatives to humans, past mitochondrial DNA studies argued against intermixing between Neandertals and humans.