What makes the human brain different?

Despite decades of research that has revolutionized the neurosciences, efforts to explain the major features of human brain evolution are still mostly based on superficial gross neuroanatomical features (e.g. size, sulcal patterns) and on theories of selection for high-level functions that lack precise neurobiological predictions (e.g. general intelligence, innate grammar). Beyond its large size we still lack an account of what makes a human brain different. However, advances in comparative neuroanatomy, developmental biology, and genetics have radically changed our understanding of brain development. These data challenge classic ideas about brain size, intelligence, and the addition of new functions, such as language, and they provide tools with which we can test hypotheses about how human brains diverge from other primate brains.