Evolutionary psychology is a branch of psychology that explores the evolutionary adaptability of human psychological mechanisms and explains the nature and origins of human psychological traits from an evolutionary perspective. Originated in the 1980s, it was deeply influenced by evolutionism, ethology, cognitive revolution, and sociobiology. The main representative figures in this field include Robert Ludlow Trivers, Richard Alexander, Donald Symons, Leda Cosmides, John Tooby, Martin Daly, Margo Wilson, David Michael Buss, Steven Pinke, Mark Ridley, and Geoffrey Miller. Among them, Tooby and Cosmides were credited with coining the term “evolutionary psychology.”

Psychological Perspective

Evolutionary psychology holds that the human mind is a set of information-processing devices, formed through natural selection to address adaptability challenges encountered by our ancestors during the process of evolution. According to evolutionary psychology, psychological traits of human beings, like the heart, lungs, eyes, and other organs, are evolutionary products of adaptation for survival and reproductive needs. Therefore, evolutionary psychology advocates exploring the adaptiveness of human psychological mechanisms. The first step in understanding psychology is to clarify the functions of these psychological mechanisms.

Representative Studies

British evolutionary biologist William Donald Hamilton proved that when the worker bees nurture their sisters instead of reproducing themselves, they can actually pass on more copies of their genes through studying the way worker bees reproduce. Hamilton extended this argument beyond bees to other organisms, and suggested that the need for an organism to pass on its genes can either be directly met by reproducing offspring or indirectly by helping other relatives to reproduce. The closer the genetic relationship between two individuals and the higher the proportion of shared genes, the more likely they are to have altruistic behaviors toward each other. This mechanism is known as kin selection. Kin selection explains why individuals exhibit altruistic behavior toward other relatives besides their own offspring.

Robert Trivers pointed out that in mating activities, those who invest more in reproducing offspring are eligible to become selectors, while those who invest less have to compete for sexual resources. For most animals, this means males have to compete with each other for females, as females invest more in mating and reproducing from the beginning than males (e.g., in mammals, females are responsible for pregnancy, giving birth, breastfeeding, and raising offspring). Following this logic, it can be understandable why females are selective in choosing mates. As the higher-investing party, females (including human females) will suffer even more if they make poor choices in mate selection. Trivers referred to the total cost invested in raising offspring as parental investment. Differences in parental investment between the two sexes will ultimately lead to differences in their physiological and behavioral traits.

Alexander proposed that moral principles stem from social systems, and these social systems are also the product of Darwinian selection. To cope with various ecological pressures, such as acquiring food, warding off predators, and defending against other human groups, our ancestors formed increasingly larger communities. As they chose to live in large communities, their minds had to adapt to the needs of a large-scale collective lifestyle. This adaptation led to a set of new challenges, such as how to distribute resources, how to elect leaders, and how to make group decisions. Just as physiological structures that adapt to the natural environment are selected in animal evolution, psychological mechanisms that adapt to social life are selected in human psychological evolution. As a result, most of the social rules and moral values followed by human society have emerged as adaptations to gregarious living during the evolutionary process. For example, fairness and justice can reduce conflicts within the community, reciprocal cooperation can maximize the group’s access to resources, and loyalty and obedience to authority can ensure the optimal allocation of resources.

Research Methods

In terms of methodology, evolutionary psychology often employs reverse engineering, which involves studying the design purposes of a particular trait to infer why the trait has occurred in the evolutionary process. The specific procedures for this method include: (1) Analyzing the goals and tasks that can be achieved by a certain psychological mechanism to reveal its functions. (2) Tracing back the evolutionary history, selection history, and selection pressures that led to the formation of this psychological mechanism based on its function. (3) Explaining psychological phenomena or social behaviors based on evolutionary causes. During specific studies, evolutionary psychology often integrates findings from research in a variety of disciplines, including biology, archaeology, anthropology, comparative zoology, genetics, and social psychology. Therefore, it is a branch of psychology that synthesizes knowledge from multiple disciplines.

Evaluation

Evolutionary psychology is a thriving discipline, and its research scope has extended to cover various aspects of human activities, including partner selection, altruistic behavior, aggression, warfare, cooperation, social class, group relationships, aesthetic preferences, language, friendship, and food preferences, among others. However, some critics have questioned the explanatory framework of evolutionary psychology, arguing that its conclusions often lack sufficient credible empirical evidence.