In this article, the authors argue that evolutionary social science theorists have fundamentally confused mechanisms and metaphors. While social science theorists have searched to explain human cognition, motivation and behaviour by identifying underlying psychological “mechanisms”, what they have done in fact has been to identify metaphors. The authors, who are researchers in psychology, point out that while metaphors serve a useful function in science and scientific thinking, they do not stand in for an actual mechanism in any scientific explanation. Metaphors account for culture, social behaviour and psychological life, and as such, they are far removed from material referents and mechanistic analogs that are necessary in order to explain mechanism or function.