LAUSR

Description A genetic change could explain increased cortical neurogenesis in modern humans The neocortex, the outer region of the cerebral cortex, is an evolutionarily advanced brain structure that is responsible for cognitive abilities. It has expanded in size and function across the mammalian clade (1). The extraordinary cognitive abilities of humans are thought to rely on brain size (and thus the number of neurons) and the intricate cytoarchitecture of the neocortex. The expansion and folding of the neocortex have been partly attributed to the existence of basal radial glial cells (bRGs). These progenitors generate most cortical neurons, and their number increases in gyrencephalic mammals (which have neocortical folds), such as primates and ferrets. On page 1170 of this issue, Pinson et al. (2) report that expression of a variant of human transketolase-like protein 1 (TKTL1) increases the number of bRGs in modern humans and thereby the output of upper layer projection neurons. This genetic change could contribute to differences in cognition with extinct archaic humans.