What Is Evolutionary Psychology?

Evolutionary psychology is a theoretical approach in the social and natural sciences that examines psychological structure from a modern evolutionary perspective. It seeks to identify which human psychological traits are evolved adaptations – that is, the functional products of natural selection or sexual selection in human evolution.

Adaptationist thinking about physiological mechanisms, such as the heart, lungs, and immune system, is common in evolutionary biology. Some evolutionary psychologists apply the same thinking to psychology, arguing that the modularity of mind is similar to that of the body and with different modular adaptations serving different functions.

Evolutionary psychologists argue that much of human behavior is the output of psychological adaptations that evolved to solve recurrent problems in human ancestral environments.

Adaptations

Evolutionary psychology is not simply a subdiscipline of psychology but its evolutionary theory can provide a foundational, meta-theoretical framework that integrates the entire field of psychology in the same way evolutionary biology has for biology.

Evolutionary psychologists hold that behaviors or traits that occur universally in all cultures are good candidates for evolutionary adaptations, including the abilities to infer others’ emotions, discern kin from non-kin, identify and prefer healthier mates, and cooperate with others.

There have been studies of human social behaviour related to infanticide, intelligence, marriage patterns, promiscuity, perception of beauty, bride price, and parental investment, with impressive findings. The theories and findings of evolutionary psychology have applications in many fields, including economics, environment, health, law, management, psychiatry, politics, and literature.[1]

Criticism of evolutionary psychology involves questions of testability, cognitive and evolutionary assumptions (such as modular functioning of the brain, and large uncertainty about the ancestral environment), importance of non-genetic and non-adaptive explanations, as well as political and ethical issues due to interpretations of research results.[2]

Theoretical Foundations Of Evolutionary Psychology

Evolutionary psychologists say that natural selection has provided humans with many psychological adaptations, in much the same way that it generated humans’ anatomical and physiological adaptations. As with adaptations in general, psychological adaptations are said to be specialized for the environment in which an organism evolved, the environment of evolutionary adaptedness, or EEA.

Sexual selection provides organisms with adaptations related to mating. For male mammals, which have a relatively fast reproduction rate, sexual selection leads to adaptations that help them compete for females. For female mammals, with a relatively slow reproduction rate, sexual selection leads to choosiness, which helps females select higher quality mates.

Charles Darwin described both natural selection and sexual selection, but he relied on group selection to explain the evolution of self-sacrificing behavior. Group selection is a weak explanation because in any group the less self-sacrificing animals will be more likely to survive and the group will become less self-sacrificing.

Inclusive Fitness Theory

In 1964, William D. Hamilton proposed inclusive fitness theory, emphasizing a “gene’s-eye” view of evolution. Hamilton noted that individuals can increase the replication of their genes into the next generation by helping close relatives with whom they share genes survive and reproduce.

According to “Hamilton’s rule“, a self-sacrificing behavior can evolve if it helps close relatives so much that it more than compensates for the individual animal’s sacrifice. Inclusive fitness theory resolved the issue of how “altruism” evolved. Other theories also help explain the evolution of altruistic behavior, including evolutionary game theory, tit-for-tat reciprocity, and generalized reciprocity.

These theories not only help explain the development of altruistic behavior but also account for hostility toward cheaters (individuals that take advantage of others’ altruism).[3]

Generalized Reciprocity

Herbert Gintis, behavioral scientist and educator contributed the idea that one can play nice with non-kin strangers even in single interactions if social rules against cheating are maintained by neutral third parties (e.g., other individuals, governments, institutions, etc.), a majority group members cooperate by generally adhering to social rules, and social interactions create a positive sum game (i.e., a bigger overall “pie” results from group cooperation).

Generalized reciprocity may be a set of adaptations that were designed for small in-group cohesion during times of high intertribal warfare with out-groups.

Today the capacity to be altruistic to in-group strangers may result from a serendipitous generalization (or “mismatch”) between ancestral tribal living in small groups and today’s large societies that entail many single interactions with strangers. (The dark side of generalized reciprocity may be that these adaptations may also underlie aggression toward out-groups.)

Sexual Selection

Sexual selection favors traits that provide mating advantages, such as the peacock’s tail, even if these same traits are usually hindrances. Evolutionary psychologists point out that, unlike natural selection, sexual selection typically leads to the evolution of sex differences.

Sex differences typically make reproduction faster for one sex and slower for the other, in which case mates are relatively scarce for the faster sex. Sexual selection favors traits that increase the number of mates for the fast sex and the quality of mates for the slow sex.

For mammals, the female has the slower reproduction rate. Males typically evolve either traits to help them fight other males or traits to impress females. Females typically evolve greater abilities to discern the qualities of males, such as choosiness in mating.

[1] Buss, D.M. (2019). Evolutionary Psychology: The New Science of the Mind. Routledge, 6th edition

[2] Rose, Hilary (2000). Alas, Poor Darwin : Arguments Against Evolutionary Psychology. Harmony; 1 Amer ed edition (10 October 2000). ISBN 978-0-609-60513-4