Sex-biased interbreeding left a lasting Neanderthal DNA pattern in modern humans

A genetic analysis comparing Neanderthal genomes with African references shows Neanderthals carried far more modern human DNA on their X chromosome than on other chromosomes, while modern humans have very little Neanderthal DNA on their X. The researchers argue that this pattern results from sex-biased interbreeding—likely Neanderthal males with modern human females—rather than widespread genetic incompatibility. Computer simulations using a mating bias reproduce the observed distribution, suggesting social/partner-choice factors shaped inheritance. The team plans to investigate population structure to determine which sex moved between groups and how cultural practices influenced mating in ancient encounters.