AbstractThis paper reviews arguments against the evolutionary plausibility of a traditional genetically specified universal grammar. We argue that no such universal grammar could have evolved, either by a process of natural selection or by other evolutionary mechanisms. Instead, we propose that the close fit between languages and language learners, which make language acquisition possible, arises not because humans possess a specialized biological adaptation for language, but because language has been shaped to fit the brain, a process of cultural evolution. On this account, many aspects of the structure of human languages may be explained as cultural adaptations to the human brain. Copyright © 2010 John Wiley & Sons, Ltd.This article is categorized under:Cognitive Biology > Evolutionary Roots of CognitionLinguistics > Evolution of LanguagePsychology > Language