Neanderthals, who disappeared nearly 40,000 years ago, may have interbred with humans much earlier than we thought, a new study has suggested.

A multidisciplinary team, which included participants from the Spanish National Research Council (CSIC), has discovered that Homo neanderthalensis and Homo sapiens crossbred over 100,000 years ago, putting back the previously first-known case of a hybrid produced by the two species by 50,000 years.

This earlier genetic exchange, which may have taken place in the Near East, has not been detected in European Neanderthals.

Researcher Antonio Rosas explained that the work poses a brand new scenario, saying that over 100,000 years ago, anatomically modern humans ventured out of Africa for the first time. These modern humans met and interbred with a group of Neanderthals, which later may have moved to the south of modern day Siberia, carrying the genes of H. sapiens.

This history-making new research has discovered, therefore, that modern humans also passed their genes to the Neanderthal population. H. sapiens and Neanderthals cross-bred on at least two separate occasions, 100,000 years ago and 50,000 years ago.

According to the researchers, following the results of this latest study, the meaning behind -and the geographical reach of- the first H. sapiens to leave Africa has yet to be analysed, as does the extent to which this exodus contributed to today's genetic diversity.

The work appears in 'Nature' magazine.