Adaptations, exaptations, and spandrels

Adaptation and natural selection are central concepts in the emerging science of evolutionary psychology. Natural selection is the only known causal process capable of producing complex functional organic mechanisms. These adaptations, along with their incidental by-prod-ucts and a residue of noise, comprise all forms of life. Recently, S. J. Gould (1991) proposed that exaptations and spandrels may be more important than adaptations for evolutionary psychology. These refer to features that did not originally arise for their current use but rather were co-opted for new purposes. He suggested that many important phenomena--such as art, language, com-merce, and war--although evolutionary in origin, are incidental spandrels of the large human brain. The au-thors outline the conceptual and evidentiary standards that apply to adaptations, exaptations, and spandrels and discuss the relative utility of these concepts for psycho-logical science. Oi ver the past decade, evolutionary psychology rhas emerged as a prominent new theoretical per- spective within the field of psychology. Evolu-tionary psychology seeks to synthesize the guiding prin-ciples of modem evolutionary theory with current formu