Extended parental provisioning and variation in vertebrate brain sizes

Abstract

Large brains provide adaptive cognitive benefits but require unusually high, near-constant energy inputs and become fully functional well after their growth is completed. Consequently, young of most larger-brained endotherms should not be able to independently support the growth and development of their own brains. This paradox is solved if the evolution of extended parental provisioning facilitated brain size evolution. Comparative studies indeed show that extended parental provisioning coevolved with brain size and that it may improve immature survival. The major role of extended parental provisioning supports the idea that the ability to sustain the costs of brains limited brain size evolution. How do large-brained species account for the high energy requirements of their growing brains when they cannot yet produce the cognitive benefits needed to provide the energy? In this Essay, the authors suggest that extended parental provisioning could solve this energy dilemma.