Design principles of the human brain

The evolution of the brain in mammals has been accompanied by a reorganization of the brain as a result of differential growth of certain brain regions. Consequently, the geometry of the brain, and especially the size and shape of the cerebral cortex, has changed notably during evolution. Comparative studies of the cerebral cortex suggest that there are general architectural principles governing its growth and evolutionary development and that the primate neocortex is uniformly organized and composed of neural processing units. We are beginning to understand the geometric, biophysical, and energy constraints that have governed the evolution of these neuronal networks. In this review, some of the design principles and operational modes will be explored that underlie the information processing capacity of the cerebral cortex in primates, and it will be argued that with the evolution of the human brain we have nearly reached the limits of biological intelligence.