Recent research from DNA analysis has revealed that unions between Neanderthal men and modern human women were more common compared to the reverse relationships. This suggests a gender asymmetry in prehistoric relationships that went beyond mere casual encounters. The study, which points to a significant imbalance in these prehistoric unions, indicates that modern human women often paired with Neanderthal males during a period when both species interacted, approximately 60,000 to 40,000 years ago.

During this era, the two species coexisted for a significant duration as modern humans expanded their range northward. Genetic research has uncovered this dynamic, revealing that the offspring were predominantly sired by Neanderthal males with modern women. Moreover, the study contributes to understanding the genetics of modern humans; notably, the limited Neanderthal DNA found in modern human X chromosomes is partially explained by the mating pattern identified in the research.

The ancestors of Neanderthals and modern humans diverged around 600,000 years ago, creating two separate lineages. Sarah Tishkoff, a professor at the University of Pennsylvania who led the study, emphasizes the implications of these findings for understanding human evolution and social dynamics during this period of human prehistory.