Long ago, Neanderthals and humans interbred. But among Neanderthals, their human blood came mostly from their female ancestors, and a new genetic study finds this was likely due to their mating preferences.

Learn how sex-biased interbreeding between Neanderthals and modern humans explains why Neanderthal DNA is largely missing from the X chromosome.

Geneticists have a better understanding of how prehistoric pairings unfolded, with new research suggesting they were mostly between male Neanderthals and female humans.

WASHINGTON, Feb 26 (Reuters) - When Homo sapiens trekked out of Africa, our species encountered Neanderthal populations already inhabiting the vast expanses of Europe, Asia and the Middle East. As the presence of Neanderthal DNA in most present-day people shows,

Neanderthal males had a tendency to mate with human females, new research suggests.

When ancient humans interbred, new research shows that the pairings were predominantly male Neanderthals and female Homo sapiens.