Abstract: Following Charles Darwin (1871), evolutionary psychology has analyzed the origins and functions of complex psychological adaptations. Following Egon Brunswik (1956) and J. J. Gibson (1979), ecological psychology has analyzed the adaptive fit between organisms and environments with regard to perception, judgment, and action. Despite their common bio-functional orientation, these fields have developed in almost total isolation from each other. This paper tries to integrate their conceptual and empirical strengths by introducing the notion of ‘fitness affordances’ – objects and situations in the environment that carry potential fitness costs and benefits (negative or positive implications for survival or reproduction), and that can be avoided or exploited behaviorally by animals of a particular species. The fitness affordance idea grounds perceptual theory firmly in evolutionary biology, solves many traditional problems in epistemology, integrates diverse empirical work in evolutionary and ecological psychology, and offers new directions forward for 21st century research on sensation, perception, cognition, emotion, and decision-making

Key words: ecological psychology, functionalism, social affordances, specification