It has long been recognized (e.g., Galen, Paley) that organisms consist of functional mechanisms—hearts, lungs, livers, bones, prostates, uteruses, etc.—but before 1859 their origin was unknown. Darwin and Wallace proposed that these mechanisms—termed adaptations—evolved by natural selection and, thus, necessarily were designed to promote reproduction. Psychologists have demonstrated that cognitive processes, like the body's other mechanisms, have functional structure. Evolutionary psychologists propose that this structure evolved by natural selection to serve reproduction. Given that the brain mechanisms underpinning vision, hearing, motor control, pain, memory, etc., have obvious reproductive utility, this proposition is compelling. Further, these examples suggest that the brain is made up of many functionally specialized parts.
Evolutionary psychology draws on well-accepted evolutionary principles identical to those used by scientists researching the evolved behavior and cognition of non-human animals. Nonetheless, EP is controversial, especially regarding its hypotheses concerning innate psychological sex differences.
Scores of researchers have published in this field, and the applications of evolutionary psychology include economics, aggression, law, psychiatry, politics, literature, sex, etc. In fact, scholars in just about every field of the social sciences and humanities have employed EP in their research. In addition to Cosmides and Tooby, some of the best known authors are: Donald Symons, David Buss, Margo Wilson, Martin Daly, Steven Pinker, Robert Wright, David C. Geary, Geoffrey Miller, Sarah Blaffer Hrdy, Robin Dunbar.