Overview
- The Science paper from University of Pennsylvania scientists analyzes three high-quality female Neanderthal genomes and compares them with present-day African genomes with minimal Neanderthal ancestry.
- The team finds Neanderthal X chromosomes carry about 62% more modern-human DNA than their autosomes, mirroring the scarcity of Neanderthal DNA on the human X chromosome.
- These reciprocal X-chromosome patterns are best explained by repeated interbreeding that more often paired male Neanderthals with female Homo sapiens than the reverse.
- Statistical modeling suggests this directional bias could have persisted across multiple admixture episodes potentially separated by up to roughly 200,000 years.
- The authors caution the inference is not definitive given sparse ancient-genome sampling and note that alternatives such as sex-biased migration or selection could also produce similar signals.