In this blog post, we will examine the claim that rape is a trait adapted through natural selection, along with various counterarguments to this claim, and explore why it is difficult to view rape as an evolutionary adaptation.
The Debate Surrounding the Evolutionary Adaptation of Rape
The debate over whether rape is an adaptation has sparked significant social controversy since Randy Thornhill published ‘A Natural History of Rape’. This issue has been actively discussed across various fields, including evolutionary biology, psychology, and the social sciences, with numerous scholars presenting differing viewpoints. Furthermore, this claim has been criticized by many social scientists and feminists, and opinions have been sharply divided even among evolutionary biologists.
Professor Cosmedes took a relatively favorable stance toward the claim that rape is an adaptation. He suggested that male rape behavior might not simply be a culturally learned behavior, but rather an adaptation selected by natural selection in the process of increasing men’s reproductive success. He also argued that even if rape were not a direct adaptation, it could be a byproduct of intense sexual desire and is fundamentally closer to sexual behavior than to simple acts of violence.
In contrast, Professor Coin criticized Randy Sonhill’s research for failing to provide sufficient evidence to support his claim and opposed the view that rape is an adaptation. While Sonhill cited the fact that a significant proportion of rape victims are women of childbearing age as evidence, Coin pointed out that a considerable percentage of non-childbearing women are also victims, and that cases of child sexual abuse account for a significant portion of the total, arguing that this claim lacks sufficient explanatory power.
Professor Pinker emphasized that even if rape were assumed to be an adaptation, that would not ethically justify it. He explained that whether a behavior is an evolutionary adaptation and its moral evaluation are entirely separate issues and should not be conflated. He also believed that studying rape from an evolutionary biological perspective is not intended to justify crime but can help deepen our understanding for the purpose of crime prevention.
As such, even among world-renowned scholars, there are diverse views on whether rape is an adaptation. Those who argue that rape is an adaptation explain it as a behavior selected by natural selection to increase men’s reproductive success, while those who oppose this view raise concerns about the lack of evidence and the very scope of the concept of adaptation. However, I believe it is difficult to view rape as an adaptive behavior shaped by natural selection. This is because the explanation that rape was selected by natural selection to ensure the reproductive success of men with limited mating ability does not sufficiently align with the various cases observed in reality.
Can rape be viewed as an adaptation for reproductive success?
The claim that rape is an adaptation selected by natural selection to increase reproductive success also does not fully align with actual crime statistics. Even in past statistics on sexual violence released by the South Korean National Police Agency, cases involving child victims accounted for a significant proportion. Since children are a non-reproductive group incapable of procreation, these cases demonstrate that rape is not necessarily a behavior linked to reproductive success.
This fact can be observed not only in crimes against non-reproductive-age women but also in cases of same-sex sexual violence and incest. Furthermore, in reality, there are numerous instances where perpetrators kill or imprison their victims after the rape. If rape were a behavior intended to increase reproductive success, it would actually serve that purpose better if the victim survived and gave birth. Therefore, I believe it is more reasonable to interpret this behavior not as an adaptation for reproductive success, but as criminal behavior resulting from a combination of various factors, such as sexual impulses, the exercise of power, and violence.
Of course, those who argue that rape is an adaptation often claim that same-sex and incestuous sexual violence are rare exceptions, and they cite research findings suggesting that the likelihood of pregnancy increases during rape or that changes in semen composition occur.
However, incestuous and same-sex sexual violence have been consistently documented throughout history. If such behaviors were unrelated to reproduction—and thus traits that should have been immediately eliminated through natural selection—it would be difficult to explain why they have been repeatedly documented across diverse cultures over such a long period. Furthermore, research indicates that physiological changes observed during rape may also be influenced by psychological factors; therefore, we must exercise caution in interpreting these findings as direct evidence of an evolutionary adaptation.
Taking these points into consideration, I believe it is more likely that rape is a byproduct of a combination of complex factors—such as human sexual impulses and aggression—rather than an adaptation selected by natural selection to increase reproductive success.
Can it be explained by the concept of adaptation?
Adaptation refers to the process by which traits that allow for better response to the environment are passed down to subsequent generations as a result of natural selection. If rape is indeed an adaptation, then such a tendency should be stably transmitted across generations and repeatedly manifest itself.
However, there is no evidence that the ancestors of rapists consistently engaged in the same behavior. Furthermore, there is no conclusive evidence that a tendency toward rape is stably transmitted as a specific genetic trait. Therefore, these points also make it difficult to view rape as an adaptation shaped by natural selection.
In response, proponents of the view that rape is an adaptation sometimes suggest the possibility that this tendency was suppressed by self-control and thus did not manifest in behavior. However, if it is an adaptation, it must provide a benefit through natural selection by increasing reproductive success via actual behavior. Since a trait that is rarely expressed in behavior is unlikely to be maintained through natural selection, I believe this explanation also lacks sufficient persuasiveness.
Are animal and war examples appropriate evidence?
To support the claim that rape is an adaptation, some cite examples of forced mating-like behaviors or specialized reproductive organs found in certain insects or arthropods.
However, rape as defined in human society refers to the forced performance of sexual acts against the will of the other party. In contrast, these animals cannot be said to possess the same level of consciousness or ability to express intent as humans, and it is difficult to apply human legal and ethical concepts directly to them. Furthermore, since the relevant organs may simply be standard reproductive organs necessary for the species’ reproduction, there are limitations to viewing them as equivalent to human rape.
Another piece of evidence cited is the fact that rape occurs more frequently in wartime than in peacetime. Some explain this as behavior adapted to the environmental changes brought about by war.
However, the “adaptation” referred to here is adaptation in the general sense of becoming accustomed to environmental changes, which is conceptually different from biological adaptation formed through natural selection. Therefore, it is inappropriate to conclude that rape during war is a biological adaptation simply because the same term “adaptation” is used.
As such, various counterarguments can be raised against the claim that rape is an adaptation shaped by natural selection. A significant number of rape victims are unable to reproduce, and crimes against same-sex partners or relatives also occur. Furthermore, the perpetrator’s behavior following the rape is often interpreted as an attempt to conceal the crime rather than as an action intended to increase reproductive success.
Furthermore, even if the concept of adaptation is applied, there is insufficient evidence to suggest that a propensity for rape is stably inherited and maintained across generations. Taking these points into consideration, it is difficult to conclusively assert that rape is an adaptation shaped by natural selection.
Rather than simply explaining the cause of rape as an adaptation formed during the evolutionary process, I believe it is more important to comprehensively analyze various psychological, social, and environmental factors, identify the root causes, and develop effective prevention strategies.
