In this blog post, I will summarize and critically examine the pro- and con arguments regarding whether rape should be viewed as an adaptation—as discussed in “Darwin’s Table”—and present my own position.
The Concepts of Natural Selection and Adaptation
The mechanism of “natural selection,” as explained by Darwin in ‘On the Origin of Species’, addresses “the question of how organisms have adapted to their environment and thereby altered the distribution of their genetic traits.” If a specific genetic trait is more advantageous for survival in nature, individuals possessing that trait are more likely to reproduce successfully; consequently, over the long term, the distribution of traits within a population’s gene pool may change. Individuals altered in this way by natural selection are said to be “adapted.”
So, among the various human behaviors currently identified, to what extent are they adaptations, and to what extent are they byproducts of adaptation? On this topic, ‘Darwin’s Table’ presents a debate between adaptationists—who argue that “since natural selection can act quite powerfully on species, even human psychological mechanisms can be viewed as products of adaptation”—and anti-adaptationists who oppose this view.
Summary of Arguments For and Against in the Book
In this book, Professors Cosmides and Pinker appear as proponents of the claim that rape is an adaptation. They agree with the views of Professor Thornhill, author of ‘The Natural History of Rape’, and argue that rape is an adaptive behavior that helps males who struggle to mate achieve greater reproductive success. Furthermore, citing the fact that male primates possess specific anatomical structures that facilitate rape, they add further evidence to the argument that rape in humans is also an adaptation. Above all, they argue that Thornhill’s approach is significant in that it scientifically elucidates the evolutionary and psychological mechanisms underlying rape in humans.
However, Professors Coin and Gould strongly disagree with this view. First, Professor Coin questions the reliability of the evidence in Professor Thornhill’s research. Thornhill used statistical data to argue that rape is an adaptation based on the fact that most rape victims are young women of childbearing age, but Coin contends that this is not a correct interpretation of the data. Professor Coin’s position is that analyzing the trauma and extent of harm caused by rape based solely on victims’ testimonies cannot accurately reveal its true impact. Professor Gould argues that rape cannot be explained by adaptation theory, citing various forms of rape such as male-on-male rape, incest, and child rape.
The Author’s Criticism and Rationale
I do not believe that rape is a behavior driven by adaptation. To be clear, I agree that many behaviors of biological organisms—and even psychological mechanisms—can be interpreted as the result of adaptation through natural selection. However, for the conclusion that “rape”—the result of a man’s psychological judgment—is an adaptation resulting from natural selection to hold, it is essential to assume that the probability of successful reproduction for individuals who choose to commit rape is significantly higher than that of a control group, thereby altering the gene pool. However, I oppose the claim that rape is a type of adaptation selected by natural selection because I believe that the act of rape itself does not increase an individual’s probability of reproduction, nor does it increase the survival rate of the individual’s genes.
In ‘The Selfish Gene’, Richard Dawkins argues that humans act based on unconscious judgments driven by the selection of genes, and that genes “selfishly” program humans to act solely in the interest of the reproduction and prosperity of their own species. If so, how, then, can we interpret altruistic behavior in humans? Dawkins argues that altruistic behavior, too, is fundamentally rooted in the selfish behavior of genes. He introduces the mechanism of kin selection, explaining that even behavior that appears altruistic is, in reality, “selfish” behavior calculated based on kinship, and thus the fundamental behavioral principle of genes remains unchanged.
Given that the behavior of a species under natural selection is fundamentally an effort to pass on genes identical to one’s own—that is, genes with a high degree of kinship—into the gene pool, I believe rape cannot be considered an adaptation.
First, rape is an act that violates the general principles of society. The biological species “human” acts in groups called “societies.” The term “society” used here refers to “group behavior” in the broadest sense—a practice that has existed since the time when humans evolved from primates in prehistoric times. To ensure survival, humans have lived in groups since prehistoric times to facilitate cooperation among individuals. Therefore, the disintegration of such a group directly threatened the survival of all its members. Consequently, in these group-based societies, various methods have been used to sanction behaviors that could harm others and, in the long run, damage the group’s interests, in order to maintain order within the group.
For example, all acts that we commonly refer to as crimes today—such as theft, robbery, and murder—have been discouraged by the public since ancient times, even if the methods of enforcement have varied. Many people choose not to commit such acts even though they could gain significant benefits by killing someone and taking their possessions right now. The reason may be that such acts violate social norms and result in punishment, or it may be because they know that even if they could avoid punishment, they themselves would suffer harm if such acts became widespread throughout society.
In other words, if the group disintegrates, all members—including oneself (and, in many cases, numerous individuals with whom one shares close blood ties)—would suffer a blow severe enough to threaten their survival. To prevent this, choosing to accept a small loss or engage in behavior that yields no short-term gain can be interpreted as “selfish” behavior calculated for the long term.
Let’s consider the case of a man raping a woman. To make the argument more universal, let’s assume a typical rape scenario in which a man rapes a woman in a confined space. Adaptationists argue that if the woman in front of him is of reproductive age, his genes will lead him to choose the option: “Let’s rape this woman to increase my reproductive success.”
But can this really increase reproductive success? Even for a woman of childbearing age, the probability of passing on her genes to future generations through a single sexual encounter is not very high. On the other hand, if the rape attempt fails, the risks to this man are quite significant. First, he will be punished according to the rules of his society, and that “punishment” does not end with the punishment itself but can also cause members of society to shun him. Consequently, a single act of rape eliminates countless potential opportunities for reproduction that might have followed.
Furthermore, since he must also consider the possibility of retaliation from close relatives or other family members with a high degree of kinship to the woman, raping a woman whose status is uncertain at that moment can by no means be considered a rational choice from a genetic perspective. Even if a male were to be fortunate enough to pass on his genes through rape, the more individuals like himself who engage in rape increase in the gene pool, the lower the likelihood that his own genes will be safely transmitted to future generations. Therefore, from a long-term perspective, rape cannot be interpreted as an appropriate behavior for passing on genes.
In the above discussion, we examined general cases of rape. However, according to data submitted by the National Police Agency in 2007 in response to a National Assembly audit request, rape of children who are not yet of childbearing age accounts for as much as 30% of all rape victims; that rape also occurs between partners of the same sex, and that there are numerous cases where the victim is killed after the rape. These facts reaffirm that rape cannot be interpreted simply as an adaptive behavior aimed at propagating genes.
Some adaptationists attempt to use statistical data on the shock and severity of harm caused by rape to argue that women of childbearing age suffer greater harm than those who are not of childbearing age. However, as Professor Coine points out in his book, this is not a correct interpretation; moreover, since the man’s decision was made at the very moment the rape occurred, it is questionable whether analyzing the severity of the harm caused by rape can serve as evidence for the claim that rape was committed for the purpose of gene propagation.
Second, they cite the fact that a certain insect, the “bottom,” possesses an organ that facilitates rape. However, it cannot be guaranteed that natural selection observed in one species will necessarily occur in another. If this argument were correct, all species sharing the same habitat would have to possess identical psychological mechanisms and physical structures. This is because the argument implies that genetic traits optimized for specific situations are selected through natural selection to ensure survival, and that this applies equally to the gene pools of different species.
Third, a counterargument has emerged stating that civilized societies developed enough to enact “punishment” have only emerged recently, and their history is too short to discuss adaptation through natural selection. However, the “punishment” for rape discussed in this article is used in a broad sense; it does not necessarily refer solely to statutory punishment under a legal system.
In a society that lives in groups, the greatest form of punishment would be exclusion by other members—that is, the refusal to recognize an individual as a member of the group. In fact, it is easy to foresee that in a primitive society, if an individual were to be separated from the group, their chances of survival as an independent individual would converge to nearly zero. The term “punishment” used in this argument refers to the harm and threats an individual will face from society as a result of rape, regardless of how it is carried out. Since such behavior dates back to primitive times when hierarchical orders were established within groups, the proponents’ argument that human history is too short to discuss adaptation is not applicable here.
Conversely, considering that rape is not beneficial in the long term even as a reproductive act, and that many instances of rape occur with no connection to reproduction—with their characteristics resembling basic sexual desire rather than reproduction—I believe rape cannot be viewed as an adaptation.
Rather, it would be more accurate to view rape as occurring when a vigorous sexual desire stemming from the species’ reproductive instinct cannot be properly restrained due to a failure in regulatory mechanisms.
