Brain Ontogeny in Human and Primate Evolution

Steven R. Leigh, Department of Anthropology, University of Illinois at Urbana-Champaign

Abstract:  An understanding of human brain evolution at the phenotypic level is critical for new "genome-up" views of human brain evolution. Unfortunately, several factors compromise our understanding of the evolution of this phenotype. This analysis addresses the problem of human brain phenotypic evolution from the perspective of comparative growth and development (ontogeny). Comparisons of fossils and nonhuman primates suggest complexity in the evolution of human brain ontogeny with respect to the timing of brain growth periods. Distinct changes during the time periods over which the brain grows have important implications for many aspects of human evolution. An ontogenetic viewpoint substantially improves our understanding of the human brain as an evolving phenotype.