This blog post examines why rape has not been completely eradicated from human society, exploring in a balanced manner the respective impacts of evolutionary factors and cultural environments.
The provocative and radical question, ‘Is rape an adaptation?’ is the core theme of the evolutionary debate raised in the book “Darwin’s Table.” The question of whether rape is an adaptation elicits an immediate rejection response from most people. Many display unconditional opposition, as if showing even a moment’s thoughtful consideration of this question would brand them as holding unsound ideas. But is that truly the case? If the answer were so obvious that the question wasn’t worth discussing, and the conclusion that rape is not an adaptation were self-evident, then renowned scholars like Gould, Dawkins, Cosmides, and Coan would have had no reason to engage in such fierce debate over this issue. Therefore, it is necessary to examine how evolutionary experts view this problem.
Before reviewing various scholars’ views, we must first clarify the concepts of adaptation and natural selection. Adaptation is a product of evolution, specifically natural selection. Natural selection is based on the principle that individuals possessing traits better suited to a specific environment gain an advantage in survival and reproduction over those without such traits. Consequently, individuals surviving through natural selection are those ‘adapted’ to that environment. Thus, the perspective that ‘the fittest survive’ is less accurate than ‘those who survive are the adapted ones’. Most scholars agree on this point. However, opinions diverge significantly on how powerfully natural selection has shaped the human mind and behavior. The core of this debate is whether human psychology and behavior were formed according to the logic of natural selection and adaptation.
Cosmides supports Randy Thornhill’s “The Natural History of Rape,” arguing that male rape behavior is a result shaped by natural selection over a long evolutionary process. According to her argument, rape is a survival strategy available to males with limited mating opportunities to increase their reproductive success, thereby enabling males to spread their genes more widely. Pinker also criticizes the humanities and social sciences for interpreting human sexual behavior solely through ideological lenses, pointing out that many confuse the ‘fact’ that rape is a product of natural selection with ethical issues.
In contrast, Stephen Jay Gould and Coen oppose this argument. They contend that “The Natural History of Rape” fails to provide sufficient evidence for why rape is adaptive and that there are flaws in Sohill’s analysis itself. They specifically note that the high proportion of child victims among all rape victims, who are unlikely to become pregnant, suggests rape is more likely a behavior arising from social learning rather than an adaptation. They also note that male-male rape, incestuous rape, and child rape are not linked to genetic reproduction, contradicting the claim that rape is adaptive. However, these counterarguments can be refuted from the perspective of Richard Dawkins’ ‘selfish gene’ theory.
Dawkins explains that genes programmed within organisms operate to spread their copies as widely as possible, defining this as ‘selfishness’. Accordingly, organisms evolve to increase their reproductive success, and in humans, this genetic drive manifests as the ‘reproductive urge’. Males with mates express this through copulation, but males without mates may choose rape. Even males with mates may engage in the same behavior if they judge the benefits gained through rape outweigh the losses. Up to this stage, it can be understood as the action of genes surrounding survival and reproduction.
However, not all individuals behave in the same way. Some individuals may have weakened sexual desire regulation genes or issues with genes responsible for sexual partner selection, leading to sexual desire being expressed in directions unrelated to reproduction. In such cases, this can potentially lead to behaviors that do not aid reproduction, such as same-sex rape, incestuous rape, or child rape. Humans are no exception. The phenomenon of sexual desire, which was a potential reproductive urge, manifesting in non-reproductive directions is difficult to explain independently of these genetic factors.
Opponents will likely argue that this explanation is overly simplistic and that reducing some cases solely to ‘genetic problems’ is problematic. However, evidence supporting rape as an adaptation exists beyond this. According to Professor Sonhill’s research, rape was observed in a significant number of animal species when examining 3 million out of approximately 25 million species. Some species, like male scorpion flies, possess biological structures suited for rape. This indicates that rape has functioned as an adaptation for a long time even in animal societies lacking intellectual thought. Conversely, in human societies capable of forming cognitive abilities and ethics/morals, rape has been ‘reevaluated’. With the development of human rights concepts and strengthened legal sanctions, rape rates have generally decreased. However, the forms and contexts of rape have changed, but it has not completely disappeared.
As human civilization has advanced, humans are no longer in situations where survival is threatened in the wild, and it has become difficult to say that reproduction is the top priority for survival. Animals evolved sexual desire for reproduction, and at that time, the need for reproduction and sexual desire were relatively aligned. However, in human society, the reduced need for reproduction fails to fully satisfy the entire sexual desire, leaving some sexual desire unfulfilled. It is argued that this residual sexual desire can lead to rape unrelated to reproduction. Furthermore, sexual curiosity can also be used to explain attempted rape targeting non-reproductive women or children.
Some also refute the claim that rape is an adaptation from a linguistic perspective. They ask: if rape is a product of natural selection, it should be far more prevalent. Why are there more individuals who do not rape? However, this is a misunderstanding of natural selection. There is an essential difference between a trait being subject to natural selection and a trait becoming dominant within a population. Even if a specific trait only occupies a certain proportion within a population, that trait can be considered to have undergone natural selection. In “The Selfish Gene,” Dawkins explains that all populations employ multiple strategies for survival, and these strategies, through competition, form one or more ‘evolutionarily stable strategies’ (ESS). Assuming strategies A, B, C, and D exist, in a stable state, each strategy will be present at a certain proportion. This ratio may fluctuate depending on circumstances, but it is highly likely that multiple strategies coexist. Therefore, even if rape exists at a rate of 5% or 10%, if that strategy survives, it can be interpreted as having undergone natural selection. This is because traits that do not undergo natural selection eventually disappear from the population. Thus, the very existence of the behavior of rape serves as evidence of adaptation.
Opponents raise two further questions. First, if natural selection is independent of frequency, are birth defects or genetic diseases also subject to natural selection? However, this is an error of comparing rape and mutation on the same level. The incidence of rape is significantly higher than that of common mutations, and rape is a strategy with the potential to increase reproductive success. In contrast, mutations are mostly detrimental to survival and reproduction. No one views hemophilia as a survival strategy. In other words, rape is a strategy that can persist and manifest within a population even at low rates, whereas mutations are inherently incapable of being strategies.
Second, it is argued that if rape were to completely disappear in the future, it could not be considered an adaptation. However, rape has persisted throughout human history, implying it served an adaptive function at least in the past. Looking to the future, there is no reason for rape to suddenly vanish from animal societies. In human societies, rape rates may decrease due to heightened awareness of human rights and strengthened legal sanctions. However, sexual desire and the urge to reproduce are powerful biological impulses humans have long possessed, making them difficult to eradicate completely. Just as accidents do not disappear entirely in countries where gun ownership is legal despite stricter regulations, it is plausible to argue that rape may decrease but will not vanish.
The above discussion has covered various theories and counterarguments regarding whether rape is adaptive. Perspectives ranging from Dawkins’ theory of the selfish gene, the meaning of natural selection, to the issue of rape’s sustainability have been presented. In conclusion, rape can be interpreted as one survival strategy for reproduction. Evidence that a trait has undergone natural selection lies in its actual expression within a population. Therefore, as long as the behavior of rape persists and does not completely disappear in human and animal societies, it must be regarded as an adaptation.
