New research reveals that ancient interbreeding between humans and Neanderthals shaped our modern human DNA - especially on the X chromosome.

Researchers have identified inherited genetic variants that may predict the loss of one copy of a woman's two X chromosomes as she ages, a phenomenon known as mosaic loss of chromosome X, or mLOX.

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