Simulation Study Links Archaic Ancestry on X Chromosome to Sex Biased Introgression

Brown University researchers reporting in PLOS Genetics consider potential sex-biased contributions to the archaic introgression patterns present on the X chromosome. By digging into archaic ancestry profiles on autosomal chromosomes and the X chromosomes of modern-day humans, the team saw far more archaic ancestry on the autosomes relative to the X chromosome, particularly in samples from European individuals. That ratio was somewhat lower in other populations, including individuals from South Asia, prompting the authors to take a closer look at sex-biased archaic introgression and its effects. "Using simulation studies, we find that when the archaics were mostly male, modern humans end up with less archaic DNA on chromosome X than their autosomes, compared to when there is a female-bias or no sex-bias," they report, adding that "male sex-bias could be contributing to the difference in the amount of archaic DNA on chromosome X versus the autosomes," though there are "plenty of other factors to be explored about how demography and selection have shaped our DNA."