Fig. 1: Schematic illustration of evolutionary analysis to infer subtle regulatory shifts underlying human-specific single-cell transcriptomic divergence.

a, We used the single-nucleus transcriptomic atlases of the MTG of five primates to create a consensus classification of MTG cell types. The bar plot shows the percentage of within-species cell-type clusters associated with each consensus cell type, coloured by species. b, We quantified the similarity of gene expression profiles across primates to select genes with conserved expression signatures across non-human primates but diverged in humans (left). We then tested for signatures of differential regulation driving human-specific cell-type expression profiles by measuring changes in co-expression network connectivity between humans and 18 animals sampled broadly across metazoan phylogeny (right). The figure indicates that the gene retains its top ten co-expression partners in all animals except humans, suggesting that differential co-expression connectivity could underlie human-specific expression divergence. Silhouettes for all five primates are from www.phylopic.org (public domain). ExN, excitatory neuron; InN, inhibitory neuron; NonN, non-neuron.