Fig. 7: Estimated sequence of local cortical expansion from the last common ancestor of rodents and primates to Homo.

a Consecutive expansion maps between the cortical surfaces are obtained from ancestral state reconstruction of all ancestors of Homo until the LCA with Glires. b Decoding these expansion maps as correlations with statistical maps of human cortical function⁵⁴ and retaining the 1% most highest correlated maps at each time-point allows to perform (c) hierarchical clustering of the sequential correlation of expansion patterns in the deep ancestral human lineage (Supplementary Data 7a). d This reveals a decomposition of evolutionary cortical surface expansion that can be approximated as a sequence of steps (Supplementary Data 7b), starting with the expansion of primary visual, auditory and motor regions in the Cretaceous up until the Oligocene, followed by the expansion of higher order association areas in the Miocene, Pliocene and Pleistocene. The common x-axis of all subplots (a–c) denotes million years ago (Mya). The colormap on the cortical surfaces (a) indicates relative area expansion between estimated speciation points. Markers for correlations in subplot (b) are jittered in horizontal direction to reduce overlap. Correlations are summarised for each cluster using violin plots in subplot (d) and joined at their median values through time. Statistical significance for differences between distributions was assessed using repeated measurements ANOVA. Statistical information as well as sample numbers for each cluster and time-point are omitted for space reasons and can be found in Supplementary Data 7c, license information for artwork used in Supplementary Data 7d. Abbreviations: P.I. Ptilocercus iowii. N.t. Notharctus tenebrosus. A.a Archicebus achilles, C. Cercopithecoidea, O.b. Oreopithecus bambolii, S.t. Sahelanthropus tchadensis, A.r. Ardipithecus ramidus, H.s. Homo sapiens.