Gene Expression in Neurons Solves a Brain Evolution Puzzle

The neocortex stands out as a stunning achievement of biological evolution. All mammals have this swath of tissue covering their brain, and the six layers of densely packed neurons within it handle the sophisticated computations and associations that produce cognitive prowess. Since no animals other than mammals have a neocortex, scientists have wondered how such a complex brain region evolved. Original story reprinted with permission from Quanta Magazine, an editorially independent publication of the Simons Foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences. The brains of reptiles seemed to offer a clue.