Role of Brain Maturation and Reproductive History in the Evolution of the Primate Brain

摘要

All primates conform to a 12% ratio of brain weight to body weight throughout fetal life. This pattern evolved at the beginning of primate evolution, initially as an adaptation to the low energy density of the insect food resource in a strictly arboreal habitat. However, when a wider range of food resources became available, the higher primates retained the 12% trajectory and made it the basis for rapid evolution toward large brain size, which would not have been possible within the restrictions imposed by the 6% brain growth trajectory. The 12% trajectory originally evolved to reduce maternal investment in an energy-poor environment, but became a preadaptation to brain expansion once the energy limitation was overcome by the development of herbivory and frugivory by the higher primates. (ERA citation 06:017500)