Evolutionary psychology holds great promise as one of the possible pillars on which information systems theorizing can take place. Arguably, evolutionary psychology can provide the key to many counterintuitive predictions of behavior toward technology, because many of the evolved instincts that influence our behavior are below our level of conscious awareness; often those instincts lead to behavioral responses that are not self-evident. This paper provides a discussion of information systems theorizing based on evolutionary psychology, centered on key human evolution and evolutionary genetics concepts and notions. It is argued here that there is often a need to integrate evolutionary and non-evolutionary theories, and four important preconditions for the successful integration of evolutionary and non-evolutionary theories are discussed. An example of integration of evolutionary and non-evolutionary theories is provided. The example focuses on one evolutionary information systems theory—media naturalness theory—previously developed as an alternative to media richness theory, and one non-evolutionary information systems theory, channel expansion theory.