Methods for estimating the timing of species divergences are widely used but require a large amount of computational time for even a modest number of genomes. Current methods also rely on calibrations of the molecular clock, including modelling differences in the rate of the molecular clock across lineages, which has many uncertainties. To overcome these difficulties, Tamura et al. present a method called RelTime, which estimates relative divergence times for each branch point on a phylogenetic tree, thus overcoming the need for calibrations. It is much faster than existing Bayesian methods.