Human-specific gene ARHGAP11B promotes basal progenitor amplification and neocortex expansion

Build the builders before the brain Humans are much smarter than mice—key to this is the relative thickness of the human brain's neocortex. Florio et al. combed through genes expressed in the progenitor cells that build the neocortex and zeroed in on one gene found in humans but not in mice. The gene, which seems to differentiate humans from chimpanzees, drives proliferation of the key progenitor cells. Mice expressing this human gene during development built more elaborate brains. Science , this issue p. 1465