Dating the pseudogenization events. (a) Timing of the disruptive mutations that gave rise to human unitary pseudogenes by analyzing shared mutations. Only pseudogenes with annotations from orthologous mouse genes are shown. Ones without close paralogs are underlined. (b) Timing of several pseudogenization events that occurred in the human lineage after the human-chimp divergence. See Table S3 in Additional file 1 for the estimates and their standard errors. LCA, last common ancestor.