In this blog post, I will summarize how we can interpret the human mind and behavior through the lens of evolution—using the core ideas of evolutionary psychology and various everyday examples presented in ‘The Old Toolbox’—and examine the critiques of this approach.

Darwin and the Framework of Evolutionary Psychology

In the 150 years since the publication of Darwin’s ‘On the Origin of Species’, evolutionary theory has had a profound impact on various academic disciplines, including psychology. Evolutionary psychology is an attempt to explain the human mind and behavior from the perspective of universal “nature”—the product of human evolution—and seeks to connect various fields of psychology under a single theoretical framework. The book ‘The Old Toolbox’ introduces evolutionary psychology through familiar examples, likening the human mind to a toolbox containing specialized tools designed to solve specific adaptive problems. It argues that even topics such as literature, consumption, and romance—which at first glance seem unrelated to evolution—can yield new insights when viewed from an evolutionary perspective.

Storytelling and Culture: Why We Enjoy Fiction

The reason people become deeply engrossed in fictional stories seems, at first glance, difficult to connect intuitively to evolution. Evolutionary psychology offers two hypotheses to explain this phenomenon. One hypothesis is that the ability to gather and transmit information was selected because knowing more rumors faster and in greater quantity provided an advantage for survival and reproduction; the other is that the tendency to enjoy stories is itself a sophisticated adaptation. From the latter perspective, novels and stories function as simulations that provide models for life. In other words, it is argued that gaining social and ecological information, honing skills, and testing strategies through stories would have been advantageous before entering the actual battlefield.
This perspective also applies to literary creation and criticism. It can also be argued that we empathize with and enjoy works from different eras and cultures because we share a common emotional foundation and a set of assumptions. Therefore, viewing literature from an evolutionary perspective can provide new insights into the functions stories have served for humans and the psychological mechanisms they stimulate.

Conspicuous Consumption and Romance: The Costly Signaling Theory

The “costly signaling theory”—which posits that costly traits evolved as signals honestly indicating “superior genes”—explains why seemingly inefficient, conspicuous consumption, such as a peacock’s tail, emerged. This theory views conspicuous consumption not as mere waste but as a sexual and social signal that serves to communicate one’s quality to a potential partner.
Experimental results also support this view. Research showing that men in love tend to engage in more conspicuous and inefficient consumption suggests that such spending may be part of a courtship strategy rather than a mere personal preference. The author predicts that while existing consumer studies have primarily focused on “how people consume,” evolutionary psychology can expand consumer research by adding the question of “why people consume that way.”

Evolutionary Explanations for Incest Avoidance and Sexual Selection

It is a well-known fact that incest is perceived as dangerous, both morally and biologically. In this regard, evolutionary psychology proposes the hypothesis that “incest avoidance” is the result of a psychological mechanism formed through natural selection due to biological risks. In other words, the explanation is that psychological mechanisms were selected to reduce sexual attraction toward relatives and to instill aversion to sexual relations with them.
This hypothesis is compared to explanations such as the Westermark effect, which posits that growing up with relatives leads to a loss of sexual interest in them. While the Westermark effect also explains many observations, some view the evolutionary psychological perspective as having greater scientific persuasiveness because it directly identifies the biological risks of incest and the resulting avoidance mechanisms as the cause.
Meanwhile, the phenomenon of women frequently rejecting men’s sexual advances can also be explained from an evolutionary perspective. The logic is that, since a woman’s reproductive success from a single pregnancy depends not only on the number of children she has but also on how well she raises them, it was advantageous for her to select a partner with good genes. Indiscriminate sexual relations increase the risk of losing a partner who would provide resources and protection; since, historically, unmarried fathers or divorced men with children were rare in social reality, it is suggested that women’s selective behavior may have been evolutionarily advantageous.

Criticism and Counterarguments: The Adaptationist Debate and Concerns About Social Justification

Evolutionary psychology offers many compelling explanations, but it remains highly controversial. The most prominent criticism concerns adaptationism. Some critics have pointed out that evolutionary psychology reduces all traits to the result of natural selection without sufficiently considering other possible hypotheses. This criticism cautions against “Parnassian”-style, overly optimistic adaptive explanations.
In response, evolutionary psychologists have revised their research methods. They now adopt “methodological adaptationism,” which involves first formulating predictions based on the assumption that natural selection is a key causal factor, comparing those predictions with actual traits, and then examining other factors (e.g., genetic drift, developmental constraints, cultural influences) to explain any observed discrepancies. This approach has largely mitigated the adaptationist critique.
Another criticism is the concern that evolutionary psychology is a cynical discipline that justifies the status quo. However, evolutionary psychologists merely point out that innate psychological mechanisms may not have changed significantly over thousands of years, while also emphasizing that how those mechanisms manifest can vary greatly depending on the environment. In other words, just because psychological mechanisms are constant does not mean behavior is constant.

Conclusion: The Status and Prospects of Evolutionary Psychology

Although evolutionary psychology has not yet reached the stage of presenting definitive laws like physics, it has continued to develop its theories and methods in the face of various criticisms. Efforts to elucidate the interaction between genes and the environment have the potential to contribute to the integration of not only psychological phenomena but also diverse fields such as the humanities, social sciences, and consumer studies. From this perspective, ‘The Old Toolbox’ demonstrates, through various examples, that evolutionary psychology is a useful tool for understanding both our daily lives and academic frameworks.
Personally, I believe that many everyday phenomena and academic problems can be explained from an evolutionary psychological perspective. However, we must remember that these explanations are hypotheses that must be continuously verified and refined, rather than definitive truths. As its name suggests, evolutionary psychology is constantly evolving through the work of researchers.