In this blog post, we will examine the debate over whether “rape is a result of natural selection” based on the concept of adaptation in evolutionary biology, and critically evaluate the claim that rape is an adaptation.

Evolution, Adaptation, and the Meaning of Natural Selection

Since Charles Darwin presented the theory of evolution in ‘On the Origin of Species’, evolutionary theory has firmly established itself as a scientific theory and has had a profound impact on various fields—not only biology but also chemistry, astronomy, linguistics, anthropology, and even social philosophy and ethics. Darwin proposed the following four conditions necessary for evolution to occur.

All living organisms exhibit slight variations.
These variations are generally passed on to the next generation.
Since the environment can only support a limited number of individuals, fierce competition for survival exists.
Individuals with traits that allow them to adapt better to a given environment survive in greater numbers and produce more offspring.

To put this simply, all living organisms undergo slight variations, but most of these variations are so minor that they go unnoticed. However, the situation changes if a variation affects survival. Individuals with variations that give them an advantage in the competition for survival in a specific environment are more likely to survive than those without such variations, and they are also more likely to pass those traits on to future generations. This is the core concept of natural selection.
Furthermore, the process of surviving in a specific environment and producing more offspring is called adaptation. Adapted individuals then give rise to new variations, and as these variations also undergo natural selection, they lead to the evolution of the entire species in the long term.
Therefore, adaptation is a very important concept in evolutionary biology. However, discussions regarding the scope of the concept of adaptation are still ongoing. Some scholars interpret the scope of adaptation broadly, explaining that not only human biological traits but also cognitive and behavioral traits are products of adaptation. Scholars who hold this view are called adaptationists.
In contrast, anti-adaptationists argue that a significant number of the cognitive and behavioral traits humans have acquired during the evolutionary process are byproducts of evolution rather than the result of natural selection. In particular, Stephen Jay Gould and Richard Lewontin, in ‘The Spandrels of San Marco’, criticized the tendency to indiscriminately interpret even traits that cannot be explained by natural selection as adaptations. In other words, they pointed out that there are many instances where even characteristics arising from processes other than natural selection are explained as adaptations.
These differing viewpoints have sparked debates surrounding various topics, including human language, art, politics, and crime. In particular, the question of whether “rape is an adaptation” has caused a major stir not only within the field of evolutionary biology but also in the humanities and social sciences, as well as among the general public. This is because simply labeling rape as an adaptation could inadvertently create the false impression that rape is an evolutionarily natural behavior. Therefore, before discussing whether “rape is an adaptation,” it is necessary to accurately understand the concept of adaptation.

How Are Adaptations and Byproducts of Evolution Distinguished?

One common misconception regarding adaptations and byproducts of evolution is the belief that anything beneficial to an organism is an adaptation. For example, flying fish leap out of the water, glide through the air, and travel long distances. They then fall back into the water under the influence of gravity. Returning to the water is clearly beneficial to the flying fish’s survival. However, this is not the result of an adaptation. It is merely a phenomenon caused by the physical law of gravity; natural selection did not cause the flying fish to return to the water.
An important lesson from this example is that adaptations must be formed through natural selection.
Applying this to the question “Is rape an adaptation?” leads to the following inquiry:
Is rape truly a trait selected by natural selection because it conferred an advantage for survival and reproduction?
In ‘Darwin’s Table’, the author sets up a hypothetical scenario—a televised debate—to explain the question “Is rape an adaptation?” and presents the views of various evolutionary biologists. The key figures leading the discussion in this debate are four scholars: Leda Cosmides, an evolutionary psychologist at the University of California, Santa Barbara; Jerry Coyne, an evolutionary biologist at the University of Chicago; Steven Pinker, a cognitive scientist at MIT; and Stephen Jay Gould, a paleontologist at Harvard University. Among them, Kosmidis and Pinker participate in the discussion from the adaptationist perspective, while Coine and Gould do so from the anti-adaptationist perspective.
The arguments of the two positions are as follows.
First, adaptationists argue that rape was subject to direct natural selection throughout evolutionary history because it contributed to increased reproductive success. They also argue that describing rape as an adaptation does not automatically confer ethical justification; rather, an evolutionary biological approach could help prevent rape.
On the other hand, anti-adaptationists criticize this view, arguing that rape is merely sexual violence stemming from excessive sexual desire, and that the argument of “reproductive potential” put forward by adaptationists is insufficient to fully explain the purpose of rape. They also argue that this explanation alone makes it difficult to devise effective preventive measures.

Is Rape an Adaptation That Aids Reproduction?

Even when viewed separately from social and ethical perspectives, it is difficult to agree with the claim that rape is an adaptation. First of all, the argument that rape aids reproduction lacks persuasiveness.
The most effective way for a male to pass on his traits to future generations is to father many offspring. It is true that the more sexual encounters a male has, the higher the likelihood of passing on his traits to future generations. However, in the case of humans, sexual intercourse and reproduction are not the same concept.
Human reproduction does not end with sexual intercourse alone. It is a process that includes pregnancy, childbirth, and long-term child-rearing. In this process, the stable survival of the woman and her children is essential, and this requires ongoing protection and a steady food supply from the community, including the male parent.
However, rape often involves physical violence to force sexual intercourse, which fails to guarantee a woman’s safety. Furthermore, once the perpetrator has satisfied his temporary sexual desire, he often shows no interest in the subsequent reproductive processes, such as pregnancy, childbirth, and child-rearing.
Moreover, in the event of an unwanted pregnancy, rape victims often face the choice of terminating the pregnancy, or, even if they give birth, find themselves in situations where normal child-rearing is difficult. Furthermore, the targets of rape are not limited to women of childbearing age but also include children and men; in cases of gang rape, where sperm from multiple men compete, it is difficult to view the act as highly efficient for reproduction.
Taking these points into consideration, it is more reasonable to understand rape as a violent act intended to satisfy sexual desire rather than as behavior aimed at reproduction. Therefore, rape can be viewed as a behavior with little direct relevance to reproduction, rather than an adaptation that aids in reproduction.

A Review of the Argument for “Conditional Adaptation”

In response, adaptationists might counter as follows.
For individuals with low competitiveness who find it difficult to secure a mate through conventional means, rape may be chosen as a last resort to pass on their genes. The logic is that in such situations, only those with low competitiveness who resort to rape will pass on their genes, and as a result, the tendency toward rape may be transmitted to future generations.
Therefore, the argument is that rape is a conditional adaptation that occurs only in cases of low competitive ability.
Furthermore, it is argued that in early human environments, rape may have been more advantageous in terms of time and effort than raising a single child, and that it may have been subject to natural selection because it allowed for the dissemination of more genes than the normal courtship process.
However, there are several problems with these arguments.
First, it is difficult to conclude that a significant number of rapists are individuals with low competitiveness. In fact, a review of cases involving serial sexual offenders reveals that a considerable number are ordinary adults who have established families and lead normal social lives. Furthermore, there are cases—such as that of Kang Ho-soon, a serial killer and sexual offender—where perpetrators committed their crimes by exploiting their physical appearance or social skills. In other words, the premise that only individuals with low competitiveness commit rape does not align with reality.
Even if some rapists are individuals with low social competitiveness, that alone does not justify viewing rape as an adaptation. If rape were a conditional adaptation specific to individuals with low social competitiveness, genetic traits common to rapists should have been identified as a result of natural selection.
However, research to date has not identified any specific genetic traits common exclusively to rapists. Instead, psychological and social characteristics—such as experiences of sexual abuse during childhood, social isolation, a lack of empathy, and distorted perceptions of sexuality—have been repeatedly reported.
Furthermore, if rape were an adaptation formed through natural selection, the corresponding trait would gradually increase across generations and become relatively widespread within the population. However, rape cannot be considered a universal behavior in human society even today. While sexual violence is certainly a serious social problem, it is difficult to view it as a common behavioral pattern established across the entire human population.
This point also casts doubt on the claim that rape is an adaptation formed through natural selection.

Was rape a advantageous strategy even in early human environments?

Adaptationists sometimes argue that in early human history, rape may have been a more advantageous reproductive strategy than mating through normal courtship. They explain that if males could forcibly pass on their genes and then leave childbirth and child-rearing to females, they would have been able to pass on more genes with less time and effort, and thus would have been subject to natural selection.
However, this argument fails to fully account for the unique characteristics of the human species.
For this argument to hold, it requires the premise that females could give birth to and raise children on their own. Yet, unlike many other animals, humans are a species that requires a long period of postnatal care. As we have seen, human reproduction is not a process that ends with simple fertilization; it encompasses pregnancy, childbirth, and long-term parenting.
In particular, during prehistoric times, securing food and ensuring safety were far more difficult than they are today, so it would have been even harder for a woman to raise children stably on her own. Therefore, it is difficult to view forced sexual intercourse alone as a guarantee of reproductive success in the human species. From this perspective, the claim that rape held an advantage over normal courtship as a reproductive strategy lacks validity.
Furthermore, just because a certain behavior benefits a specific individual does not automatically mean it is an adaptation. As in the example of the flying fish discussed earlier, even if a result that aids survival occurs, it cannot be considered an adaptation unless it was formed through natural selection. An adaptation must be a trait formed through natural selection.

Is Rape Not Perceived as an Adaptation Due to Social Repression?

Adaptationists may present another counterargument: that rape is, in fact, an adaptation but does not appear to be one due to external social conditions.
In other words, the reason rape is not universally prevalent today is not because it is not an adaptation, but because laws and social institutions strongly suppress it.
They argue that since rape is merely being suppressed by strengthened crime prevention efforts, investigations, and punishments, one cannot conclude that it is not an adaptation simply because its incidence is low.
Furthermore, they explain that cases where the victims of rape are children or men rather than women of childbearing age are byproducts of psychological disorders or external environmental influences. For example, they interpret this as the original adaptation manifesting in a different form during the process of selecting victims who are easier to assault or less likely to report the crime.
However, it is difficult to view this argument as sufficiently explanatory either.
If rape has not increased due to external social environments, it ultimately implies that humans are adapting to and living within such social environments. In other words, if rape were a behavior advantageous for reproduction, it should have been maintained or spread through natural selection even within such environments. However, this is not the case in reality. This suggests that rape was not advantageous for reproduction and therefore did not become subject to natural selection.
Furthermore, if we explain that the targets of rape changed as the objects of sexual desire shifted due to external factors, we ultimately arrive at the conclusion that rape is not a behavior for reproduction but rather a behavior in which sexual desire is expressed in a different way.
In other words, while sexual desire itself can be explained as an adaptation for passing on one’s genes, rape is merely one behavior in which such desire manifests under specific environmental and psychological conditions; it is difficult to view it as a direct product of natural selection. To put it another way, it is more reasonable to understand rape as a byproduct stemming from the adaptation known as sexual desire.

Conclusion

We have examined the question, “Is rape an adaptation?”
This article has argued that sexual intercourse and reproduction must be distinguished. Human reproduction does not simply mean sexual intercourse; it is a process that includes pregnancy, childbirth, and long-term child-rearing. Therefore, in any era—including prehistoric times—while rape may increase the frequency of sexual intercourse, it is largely disadvantageous as a reproductive strategy when child-rearing is taken into account.
Furthermore, through various case studies, we have seen that while rape is closely related to sexual desire, it is difficult to view it as a behavior directly linked to reproduction.
For a trait to be considered an adaptation, it must have been shaped by natural selection, contribute substantially to survival and reproduction, and be capable of being maintained across generations. In light of these criteria, it is difficult to view rape as fulfilling the conditions for an adaptation.
Therefore, it is more reasonable to understand rape not as an adaptation formed as a result of natural selection, but rather as a behavior arising from the complex interplay of sexual desire and various psychological and social factors.