Sociobiological theories of rape

Sociobiological theories of rape are theories that explore to what degree, if any, evolutionary adaptations influence the psychology of rapists. 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, 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 approached and sexually penetrated while it appears to not want it -- e.g. it struggles or tries to escape. 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 humans. This is the most controversial of all the theories. “Thornhill introduces this theory by describing the sexual behavior of scorpion flies. In which the male may gain sex from the female either by presenting a gift of food during courtship or without a nuptial offering, in which case force is necessary to restrain her.” It is believed that men have uncontrollable sexual urges that are as innate as those found in the animal world. When male animals have sexual urges they take a female. They do not ask; they simply satisfy themselves whether or not the female has consented. This type of interaction can be and very often is extremely forceful. “Human rape appears not as an aberration but as an alternative gene-promotion strategy that is most likely to be adopted by the 'losers' in the competitive, harem-building struggle. If the means of access to legitimate, consenting sex is not available, then a male may be faced with the choice between force or genetic extinction.” > This theory asserts that men are predisposed to rape due to biology and in most cases is used as a reproductive strategy. “Rape is viewed as a natural, biological phenomenon that is a product of the human evolutionary heritage”

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.

Criticism
Evolutionary psychology proponent 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." 

The book Evolution, Gender, and Rape compiles the views of twenty-eight prominent biologists in opposition to sociobiological theories of rape.