Sociobiological theories of rape

Sociobiological theories of rape are theories that explore what role, if any, evolutionary-psychological adaptations play in causing the act of rape in animals and humans. Such theories are highly controversial, as traditional theories typically do not consider rape to be a behavioral adaptation. Some object to such theories on ethical, religious, feminist, or political as well as scientific grounds.

Rape as an adaptation among animals
It has long been observed that some animals appear to show behavior resembling rape in humans, such as combining sexual intercourse with violent assault, often observed in ducks and geese. Sometimes an animal is sexually approached and penetrated while it is clear that it does not want it -- e.g. it tries to run away. These observations of forced sex among animals are not controversial. What is controversial is the interpretation of these observations, and the extension of theories based on them to human beings.

It is because rape occasionally results in reproduction that some sociobiologists theorize that rape may be genetically advantageous for rapists, and thus prosper as a psychological adaptation.

It has also been recorded that certain species of mole will 'rape' new borns of their own species, the advantage to this is that when those moles mature and become fertile, they will become pregnant with the sperm of the mole that had mated with them at a very young age.

See: Non-human animal sexuality

A Natural History of Rape
The idea that rape evolved as a genetically advantageous behavioral adaptation was popularised by biologist Randy Thornhill and anthropologist Craig T. Palmer in their book A Natural History of Rape: Biological Bases of Sexual Coercion.

Thornhill and Palmer's argument begins with the statement that all human behaviors are, no matter how indirectly, the result of some evolutionary adaptation. They note that since the human brain itself, and thus all capacities for any kind of action whatsoever, evolved from natural selection, the only point of dispute is whether rape is only a by-product of some other unrelated adaptation (such as a desire for aggression, domination, etc.) or if rape itself is an adaptation favored because it increases the number of descendants of rapists. They argue that the latter case is true.

Thornhill and Palmer argue that the underlying motivations of rapists evolved because they were at one time conducive to reproduction. In the book, they note that the overwhelming majority of rape victims are of childbearing age, suggesting that childbearing ability is involved in a rapist's choice of victims.

Women, they argue, have evolutionary-psychological adaptations that protect their genes from would-be rapists. "We feel that the woman's perspective on rape can be best understood by considering the negative influences of rape on female reproductive success," they write. For example, the book cites a study claiming that victims of childbearing age suffer more emotional trauma from rape than older women. They present this as evidence consistent with their theory, as women in the ancestral environment beyond their reproductive years had less to lose, in terms of genetic progeny, by being raped.

Although they present rape as an evolutionary inclination, they stress that they are doing so primarily to reveal better ways to combat rape, not to excuse modern rapists. Rape can only be eliminated, they argue, once a society is fully aware of its evolutionary origins. A large section of the book is spent discussing rape-prevention methods. They investigate the effectiveness of chemical castration and other punishments common today, and advocate harsher sentences for rapists than are currently employed, and, more controversially, educational programs explaining the evolutionary causes of rape to young men so that they can better suppress these instincts.

Harvard Professor of Psychology and popular science writer Steven Pinker has spoken out in support of Thornhill and Palmer's work. He writes, "This is a courageous, intelligent, and eye-opening book with a noble goal - to understand and eliminate a loathsome crime. Armed with logic and copious data, A Natural History of Rape will force many intellectuals to decide which they value more: established dogma and ideology, or the welfare of real women in the real world."

Other sociobiological theories of rape
Other proponents of various sociobiological theories of rape have expressed the views described here, which may or may not represent Thornhill and Palmer's.

Viviparous females, and human females in particular, whose offspring remain dependent upon their parents for many years, must invest significant time and bodily resources in pregnancy in order to reproduce and raise their offspring, whereas males can biologically father considerably more offspring with much less of a bodily investment. Many sociobiologists argue that this causes females to be more likely to scrutinize their mates, whereas males are more likely to be motivated simply to have many mates. (This theory is contested by many biologists who claim that humans are a pair-bonding species, and that other situations are deviations.) These strategies are known as K-selection and r-selection, respectively. Proponents of the view that rape is genetically adaptive see rape as a male attempt to violently remove the female's decision making power regarding reproduction. Occasionally there is a deliberate attempt to impregnate the female victim; this is thought to have often been the case when hundreds or thousands of Darfur women were raped during the last eruption of the Sudanese Civil War in 2003-2004.

Proponents of this theory have also stated that during the most fertile part of the female menstrual cycle, women are more likely to pursue potential mates while simultaneously avoiding situations conducive to the possibility of rape. Reports appear to show a higher incidence of rape occurring during the less fertile points in the menstrual cycle of the victim with one exception: those on birth control medication (such as "the pill") do not report rape with any bias towards a specific period of their cycles--birth control inhibits ovulation on some level.

According to these theories, males who attempt rape are considered more desperate to mate, and one result of this desperation could be endemic misinterpretation of a female's signals. This could illustrate why many rapists justify their actions with "she said no but meant yes". Variations of this theme are common. For example, there is no clear, objective delineation between sexual touch and non-sexual touch. Holding hands may be considered by one side to be a sexual touch whereas the other considers it completely platonic. Human sexual behavior and Date Rape describe these issues further.

Human behaviour regarding rape
Some supporters of these theories argue that many common attitudes and practices regarding sexuality and rape have origins as rape-preventative measures.

Females tend to be more cautious about rape in young adulthood. They are also more likely to resist rape, or resist more forcefully, during young adulthood, although this is explicable somewhat in that younger women may be quantitatively stronger and more able to resist forcefully than older women.

Proponents of these theories have also claimed that fathers' protectiveness of their daughters is caused by an instinct, not only to protect their genes in the form of their offspring, but to ensure the genetic "quality" of future grandchildren by protecting the daughter from rape.

Public showers, public restrooms, locker rooms, and fitting rooms often have separate male and female sections in many countries. This gender segregation, according to some sociobiologists, reduces the likelihood that a woman will find herself alone with a man (to wit, a potential rapist) in an environment that is sexually suggestive and/or in which she is especially vulnerable, such as being unclothed and in a small room (note also the typical warmth and humidity of such places; such conditions in the weather lead to increased reports of rape). Dormitory arrangements are often gender segregated as well. In some countries, more privacy tends to be afforded for females than for males in gender-segregated areas such as showers and fitting rooms. There may be more curtains, visibility screens, etc. in the women's sections.

Also, in some countries, women are forbidden to leave the house with any amount of skin showing. Some sociobiologists see this as a way to reduce the female's likelihood of attracting attention and (by extension) rape. However, since it is usually the woman's husband who does not allow her to leave without being completely covered, it is more likely that the custom's function is simply to prevent her from attracting sexual attention from other men.

Criticisms from within evolutionary psychology
The distinguished proponent of evolutionary psychology Edward H. Hagen states in his Evolutionary Psychology FAQ that he believes there is no clear evidence for the hypothesis that rape is adaptive. He believes the adaptivity of rape is possible, but claims there is not enough evidence to be certain one way or the other. However, he encourages such evidence to be obtained: "Whether human males possess psychological adaptations for rape will only be answered by careful studies seeking evidence for such cognitive specializations. To not seek such evidence is like failing to search a suspect for a concealed weapon." 

Criticisms from other fields
Many biologists are strongly opposed to these theories, and often to evolutionary psychology itself. The book Evolution, Gender, and Rape brings together the views of twenty-eight prominent biologists in opposition to these theories.

Some critics argue that it is difficult to determine to what extent the idea of rape can be extended to intercourse in other animal species, as the defining attribute of rape in humans is the lack of informed consent, which is difficult to determine in other animals. They believe these theories are founded on anthropomorphic interpretations of animal behavior.

Others claim that forced sex in animals is ineffective as a means of reproduction; males will attack other males, or groups of males will attack lone females, killing them in the process.

Some critics do not deny the generally observed attempts to control female sexuality and reproduction, but see these as being culturally conditioned, rather than as a product of evolution.