From a review of a new book by Nabokov scholar Brian Boyd called On the Origin of Stories: Evolution, Cognition, and Fiction:
Boyd considers storytelling a human adaptation, in the Darwinian sense. It derives from play, which itself is an adaptation observed among intelligent animals, from gorillas to dolphins. More important, storytelling carries with it crucial advantages for human survival. It sharpens our skills in human interaction ("social cognition" is the term Boyd uses). It encourages cooperation. It fosters creativity. Had humanity been consciously looking for an intellectual device to encourage it on the way to evolutionary success, we couldn't have done better than invent that endlessly prolific form we call narrative.