Humans and Neanderthals mated in Europe and Asia thousands of years ago to give rise to a legacy of Neanderthal DNA in modern humans, a study published on Wednesday confirmed.

Previous theory on the link between the species had claimed that modern Europeans and Asians are related to Neanderthals because they originated from a similar sub-population in Africa.

However, scientists at Edinburgh University and Wageningen University have shown that, the genetic similarity between Neanderthals and modern human populations outside of Africa must have arisen after they began interbreeding in Europe and Asia.

In their new study published in the journal Genetics, they developed a new method to compare the competing theories on the relationship between humans and Neanderthals. They divided the genetic code of each species into a series of short blocks, which allowed them to calculate the statistical likelihood of each scenario.

They have confirmed the origins of the biological ties that exist between humans and the ancient species, which are believed to have died out around 30,000 years ago.

Earlier studies have shown that the two groups emerged at different times, and that Neanderthals left the African continent 200,000 years before humans did.

"Although there has been mounting evidence for genetic exchange between modern humans and Neanderthals in Eurasia from a number of recent genetic studies, it has been difficult to rule out ancestral structure in Africa," Dr. Konrad Lohse of the University of Edinburgh's School of Biological Sciences said. "We hope our study settles this issue."