Longer time scale for human evolution

Abstract

During the past few years, the best estimates of the human single nucleotide mutation rate have been cut in half. Until recently, estimates of mutation rate have relied on counting substitutions between primate species and assuming that fossil relatives of living species can accurately pin dates onto phylogenetic branches. This procedure allows very precise estimates, but introduces systematic bias toward higher substitution rates and longer branch lengths because a new lineage can leave a fossil record only after its origin, never beforehand (1). Now, widespread resequencing, initially of de novo Mendelian genetic disorders (2, 3) and later of whole genomes in parent–offspring trios (4), has allowed direct comparisons of parent and offspring genomes. The most commonly used, but now outdated, estimate of the mutation rate was 2.4 × 10−8 changes per nucleotide per generation (5). Current estimates of the same value based on resequencing data are much lower, approximately 1.1 to 1.28 × 10−8 (3, 4).