Chromosome

For years, geneticists have wrestled with a curious absence: many modern people carry Neanderthal DNA, yet large stretches of the human X chromosome are almost empty of it. A new study argues that this pattern may not be a story of “bad” genes being purged, but a social one - ancient mate choice that was strongly sex-biased. The research, published in Science, suggests that interbreeding happened more often between male Neanderthals and female Homo sapiens than the other way around. If that sounds like tabloid material, the consequences are anything but: those ancient pairings still shape where Neanderthal ancestry sits, or doesn’t sit, in our genomes today writes Penn Today . Princeton Study Maps 200,000 years of Human–Neanderthal Interbreeding Modern