Contextualizing Population Genetic Models of Sex‐Biased Migration and Admixture

Models of sex-biased migration or admixture in human history often use sex itself as the factor that controls the probability that an individual migrates. This modeling strategy unites work across a large range of times and populations, from Neanderthal archaic introgression to the consequences of colonialism. However, inferring the degree of sex bias in a migration event from a general model relies on the assumption that two equally sex-biased events should leave equivalent signals, on average, in the genome. We apply a contextualist view of sex to highlight the possible effects of intrasexual variation on the inference of sex-biased migration when individuals within a sex category are not exchangeable. Using simulations, we demonstrate that demographically identical migration events can leave distinguishable patterns of ancestry in the genome and argue that modeling intrasexual variation can be an important step in capturing the signals of sex-biased migration.