Fig. 1.

Phylogenetic timeline of primate evolution. The major branches represent Strepsirrhini, Platyrrhini, and five genera of Catarrhini (Macaca, Pongo, Gorilla, Pan, and Homo), with branch points denoting the hypothesized most recent common ancestor (million years ago). Drawings underneath each branch represent the increased brain volume and cortical folding for each genus. The waves of retrotransposition that have been predicted to occur within the past 63 million years in primates are shown for two major families of retrotransposons; Alu (blue) and L1 (green). For each wave of retrotransposition the names of common active subfamilies are noted. New additions to the genome driven by each wave of retrotransposition are noted in red and coinciding changes in brain structure are noted in black