Human Brain Evolution
Much of the allure of the neurosciences stems fromthe common conviction that there is something unusualabout the human brain and its behavioral capacities.Nevertheless, modern neuroscientists have paidrather little attention to the study of brain evolution,and so our understanding of how the human braindiffers from that of other animals is very rudimentary.In part, this neglect is due to a widely held belief thatmammalian brains are all essentially similar in theirinternal structure and that species differ mainly in thesize of the brain. In this chapter, we review the modern evidence concerningbrain evolution, and see that brain structure,far from being uniform across species, exhibits someremarkable variations. The subject is vast, so the discussionwill necessarily be selective. After a brief reviewof evolutionary principles, we discuss the evolutionaryhistory of three groups of vertebrates that areof special interest to people: mammals, primates, andhumans themselves. Also, we focus primarily on theevolution of the cerebral cortex, because this structurehas been studied in a wide variety of mammalian speciesand because the cortex is critically involved inpsychological phenomena that we think of as beingdistinctively human.