Research suggests mating direction bias between Neanderthals and humans

"We found a pattern indicating a sex bias: gene flow occurred predominantly between Neanderthal males and anatomically modern human females. This ancient mating pattern explains why Neanderthal DNA is largely missing from the human X chromosome, creating regions known as Neanderthal deserts where Neanderthal genetic material is notably absent from modern human genomes."

"The ancestors of modern humans and Neanderthals diverged about 600,000 years ago. Our ancestors evolved in Africa, while Neanderthal ancestors evolved in and adapted to life in Eurasia. Over hundreds of millennia, human populations migrated into Neanderthal territories and back again, and when these groups met, they mated, swapping segments of DNA."

"Today, individuals of non-African heritage typically have a few per cent Neanderthal DNA, while those of African heritage typically have a lower proportion. It's hard to say how many times these interbreeding events occurred, but evidence suggests this was happening more frequently than originally speculated by researchers."

Modern humans and Neanderthals diverged approximately 600,000 years ago, with humans evolving in Africa and Neanderthals adapting to Eurasia. When human populations migrated into Neanderthal territories over hundreds of millennia, the two species interbred and exchanged DNA segments. Today, non-African individuals typically carry a few percent Neanderthal DNA, while African populations have lower proportions. Genetic analysis reveals a significant sex bias in this interbreeding: mating occurred predominantly between Neanderthal males and anatomically modern human females. This pattern explains the notable absence of Neanderthal DNA on the human X chromosome, creating regions called Neanderthal deserts where Neanderthal genetic material is largely missing.

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