ADAPTATIONS, EXAPTATIONS, AND SPANDRELS

Adaptation and natural selection are central concepts in the emerging science of evolutionary psychology: Natural selection is the only blow n causal process capable of producing complex functional organic mecha nisms. These adaptations, along with their incidental by-products and a residue of noise, comprise all forms of life. Recently, S. J. Gould (1991) proposed that exaptations and spandrels may be more important t han adaptations for evolutionary psychology. These refer to features t hat did not originally arise for their current use but rather were co- opted for new purposes. He suggested that many important phenomena-suc h as art, language, commerce, and war-although evolutionary in origin, are incidental spandrels of the large human brain. The authors outlin e the conceptual and evidentiary standards that apply to adaptations, exaptations, and spandrels and discuss the relative utility of these c oncepts for psychological science.