Evolved psychological mechanism

An evolved psychological mechanism (EPM), is a form of psychological adaptation and is evolved human or animal behavior resulting from evolutionary pressures. It could serve a specific purpose, have served a purpose in the past (see vestigiality), or be a side-effect of another EPM (see spandrel (biology)). Evolutionary psychology proposes that the human psychology mostly comprises psychological adaptations, in opposition to tabula rasa or blank slate model of human psychology such as the standard social science model, popular throughout most of the twentieth century. Instead, EPM's are ongoing processes in their emotions and intellect, that help individuals with their well being whether its through their mental state of mind or in culture.

The least controversial EPMs are those commonly known as instincts, including interpreting stereoscopic vision and suckling a mother's breast.

Evolutionary Psychology as Adaptation
Evolutionary psychologists are scarce because they try and determine not the interaction between environment behavior but why a behavior is created in a specific environment. In a Darwinian outlook, evolutionary psychology is seen as a succession of psychological adaptations occurring at individual times. Not every trait of humans or animals are adaptations, but the ones that are tend to reflect the trend of the current population. Evolutionary psychologists tend to study adaptations to give meaning to specific behaviors found in humans today.

Evolutionary psychologist, David Buss David Buss, lays out six properties of evolved psychological mechanisms (EPM's):
 * 1) An EPM exists in the form that it does because it solved a specific problem of survival or reproduction recurrently over evolutionary history.
 * 2) An EPM is designed to take in only a narrow slice of information
 * 3) The input of an EPM tells an organism the particular adaptive problem it is facing
 * 4) The input of an EPM is transformed through decision rules into output
 * 5) The output of an EPM can be physiological activity, information to other psychological mechanisms, or manifest behaviors
 * 6) The output of an EPM is directed toward the solution to a specific adaptive problem

Natural Selection as Adaptation
Charles Darwin's theory of Natural Selection is one of the more common psychological adaptations to be studied in history. His ideas began the understanding of adaptation due to survival. The idea of Zietgeist also has a way of explaining psychological adaptation. The idea is of the nature of the times in which a specific event takes place. Whether its cultural influences, environmental influences, or political influences, the zietgiest should have an impact on the ways in which adapting occurred.

EPM's tend to aid in solving specific adaptive problems. In biology, the idea that a plant or animal becomes fitted to its environment is the result of natural selection adapting to its inherited variation. However, in Psychological adaptation, the part of the environment causing the adaptation is society and culture of the times, while the adapting is taking place in the individual rather than the plant or animal. This helps contribute to ideas in human nature such as food selection, mate selection and intrasexual competition.

Further important properties include the following:
 * EPM's provide nonarbitrary criteria, (i.e. adaptive function) for "carving the mind at its joints," (i.e. evolved structure).
 * EPM's are believed to be numerous, which contributes to human behavioral flexibility. An analogy would be like a carpenter who, instead of having one tool that does everything, has many tools, each with a specific function for a specific task, (e.g. a hammer for pounding nails, a saw for cutting wood, etc.)
 * Some EPM's are domain-specific, (i.e. evolved to solve specific, recurrent adaptive problems), while others are domain-general, (i.e. evolved to aid the individual in dealing with novelty in the environment).