Rate of ERV integration in the sequenced catarrhines. Branch thickness shows the number of loci estimated to have integrated at different times, with each increment corresponding to a period of two million years. Integration dates are estimated by LTR divergence (except in the poorly assembled baboon, where they are estimated using a nearest neighbor analysis). Numbers of loci have been normalized using the human genome as a reference to allow for variation in quality of genome assembly as follows: branch thickness leading to human is calculated from the human genome; other branch thicknesses are adjusted proportional to a comparison between (i) the number of loci that integrated into the human genome and (ii) the number that integrated into the second species’ genome during the time period when the genome was shared. The baboon was similarly normalized using the macaque instead of the human genome. Data for each species are shown as frequency histograms in Additional file 1: Figure S1.