A test of the hypothesis that variable mutation rates create signals that have previously been interpreted as evidence of archaic introgression into humans.

摘要: Abstract It is widely accepted that non-African humans carry 1-2% Neanderthal DNA due to historical inter-breeding. However, inferences about introgression rely on a critical assumption mutation rate constant and back-mutations are too rare be important. Both these assumptions have been challenged, recent evidence points towards an alternative model where signals interpreted as driven mainly by higher rates in Africa. In this model, non-Africans appear closer archaics not because they harbour introgressed fragments but Africans diverged more. Here I test idea using the density of rare, human-specific variants (RHSVs) proxy for rate. find sites contribute most signal tend occur tightly defined regions spanning only few hundred bases which differs greatly between two human populations being compared. Mutation invariably population into inferred. confirmed RHSV reflects conducting parallel analysis looking at RHSVs around with three alleles, independent class site also requires recurrent mutations form. Near-identical peaks found, suggesting common cause. Similarly, coalescent simulations confirm that, rate, do preferentially high variants. Together, observations difficult reconcile excess base-sharing archaic legacies instead provide support inside Africa driving increased divergence from ancestral state.