Thornhill and Palmer write that "In short, a man can have many children, with little inconvenience to himself; a woman can have only a few, and with great effort." Females thus tend toward selectivity with sexual partners.They point to several other factors indicating that rape may be a reproductive strategy. Most rapes occur during prime childbearing years. Rapists usually use no more force than necessary to subdue, argued to be since physically injuring victims would harm reproduction. Moreover, "In many cultures rape is treated as a crime against the victim's husband." McKibbin et al. (2008) argue that there may be several different types of rapists or rape strategies. One is rape by disadvantaged men who cannot get sex otherwise. Another is "specialized rapists" who are more sexually aroused from rape than from consensual sex. A third type is opportunistic rapists who switch between forced and consensual sex depending on circumstances. A fourth type is
psychopathic rapists. A fifth type is partner rape due to
sperm competition when the male suspects or knows that the female has had sex with another male. There are varying degrees of empirical support for the existence of each of these types. More generally they mention research finding that at least one-third of males "admit they would rape under specific conditions" and that other surveys find that many men state having coercive sexual fantasies. They, as have others, "propose that rape is a conditional strategy that may potentially be deployed by any man." Studies have also found that sensitivity for potential coercive behaviors in males as well as handgrip strength (but only in a simulated coercive situation) increase during the fertile phase of the menstrual cycle.
Naturalistic fallacy Thornhill and Palmer write that "Rape is viewed as a natural, biological phenomenon that is a product of the human evolutionary heritage". They further state that by categorizing a behavior as "natural" and "biological" they do not in any way mean to imply that the behavior is justified or even inevitable. "Biological" means "of or pertaining to life," so the word applies to every human feature and behavior. But to infer from that, as many critics assert that Thornhill and Palmer do, that what is biological is somehow right or good, would be to fall into the so-called
appeal to nature. They make a comparison to "natural disasters as epidemics, floods and tornadoes". This shows that what can be found in nature is not always good and that measures should be and are taken against natural phenomena. They further argue that a good knowledge of the causes of rape, including evolutionary ones, are necessary in order to develop effective preventive measures. Evolutionary psychologists McKibbin et al. argue that the claim that evolutionary theories are justifying rape is a fallacy in the same way that it would be a fallacy to accuse scientists doing research on the causes of
cancer that they are justifying cancer. Instead, they say that understanding the causes of rape may help create preventive measures. Wilson et al. (2003) argue that evolutionary psychologists like Thornhill and Palmer use the
naturalistic fallacy inappropriately to forestall legitimate discussion about the ethical implications of their theory. According to Thornhill and Palmer, a naturalistic fallacy is to infer ethical conclusions (e.g., rape is good) from (true or false) statements of fact (e.g., rape is natural). Wilson et al. point out that combining a factual statement with an ethical statement to derive an ethical conclusion is standard ethical reasoning, not a naturalistic fallacy, because the moral judgment is not deduced
exclusively from the factual statement. They further argue that if one combines Thornhill and Palmer's factual premise that rape increases the fitness of a woman's offspring with the ethical premise that it is right to increase fitness of offspring, the resulting deductively valid conclusion is that rape has also positive effects and that its ethical status is ambiguous. Wilson et al. state that Thornhill and Palmer dismiss all ethical objections with the phrase 'naturalistic fallacy' although "it is Thornhill and Palmer who are thinking fallaciously by using the naturalistic fallacy in this way".
Preventing rape Thornhill and Palmer (2000) suggest a number of possible strategies for preventing rape. One example is explaining to males that they may have predispositions to misread the female invitation of sex. They believe that viewing rape as being due to a desire for domination, and not related to sexual desire, is generally harmful. One example given is the claim that the way women dress will not affect the risk of rape. They argue that the much greater societal freedom of dating without supervision, and removal of many barriers between males and females, have created an environment that has also removed many earlier societal controls against rape. It is recommended that "men and women interact only in public places during the early stages of their relationships".
Victim counseling Counseling of rape victims may also be improved by evolutionary considerations, according to Thornhill and Palmer, and they argue that the view that rape is due to a domination desire, cannot explain to the victim why the rapist seemed to be sexually motivated. Evolutionary considerations can also help explain the emotional pain felt, as well as the form it takes. They may also help the rape victim understand why the rape victim's partner may see the rape as a form of
infidelity. They also argued that the victim's partner may be helped by such understanding, and be more able to change his or her reaction.
Edge cases In sociobiological theory, rape is always and only an act of vaginal penetration with ejaculation. By posing rape as a reproductive strategy of low-status males, critics pose that sociobiology fails to explain a range of cases such as rape. Those include rape by wealthy, high-status and married males, rapes of women too young or old to reproduce, murder-rapes, homosexual rape, oral and anal rape and rape with contraception. == Criticism ==