Expected paternal investment[ edit ] Elizabeth Cashdan  proposed that mate strategies among both genders differ depending on how much parental investment is expected of the male, and provided research support for her hypotheses.
When men expect to have to provide a high level of parental investment, they will attempt to attract women by emphasising their ability to invest. In addition, men who expect to invest will be more likely to highlight their chastity and fidelity than men who expect not to invest. Men with the expectation of low parental investment will flaunt their sexuality to women. The author argues the fact the research supports the idea that men expecting to invest emphasise their chastity and fidelity, which is a high cost strategy because it lowers reproductive opportunities , suggests that that type of behaviour must be beneficial, or the behaviour would not have been selected.
Research suggests that father absence can lead to an increase in rape behaviour. Research conducted by Malamuth  found that men raised in the absence of their father or where resources were scarce reported more use of sexual coercion in the past, and were more likely to indicate being more willing to rape, in the event that there was no chance of them getting caught. Research has also found that parental divorce and rape correlate positively. Males with a restricted sociosexual orientation will be less willing to have sex outside of their committed relationship, and adjust their strategies according to their desire for commitment and emotional closeness with their partner.
A comparison of a desirable waist-to-hip ratio 0. It has been found that such males are less likely to approach attractive females who have greater waist-to-hip ratios 0. Consequently, males will adjust their sexual strategies by showing less willingness to approach such females. Age of first sexual intercourse[ edit ] One study has several factors that influence the age of first sexual intercourse among both genders. Those from families with both parents present, from high socioeconomic backgrounds, who performed better at school, were more religious, who had higher parental expectations, and felt like their parents care, showed lower levels of sexual activity across all age groups in the study age In contrast, those with higher levels of body pride, showed higher levels of sexual activity.
This includes sexual coercion. Sexual coercion functions to increase the chance of a female mating with a male, and decrease the chance that the female will mate with another male. These are harassment , intimidation , and forced copulation rape. The first, that rape is a by-product of an adaptation other than rape. The second, that rape as an adaptation the rape specific adaptation hypothesis , which suggests that rape evolved because it was an adaptive, beneficial behaviour in the environment of evolutionary adaptation.
Thornhill and Palmer argue that these two theories are the strongest of the ten for several reasons. For example, both hypothesis argue rape exists because it functions to increase matings, thus improving reproductive success. Because rape can be a costly behaviour for the male - he risks injury inflicted by the victim, or punishment by her social allies, it must have strong reproductive benefits for the behaviour to survive and be demonstrated today.
Thornhill and Palmer also use several facts to support the idea that the two evolutionary based hypotheses are the most reasonable.
They argue that the fact that most rape victims are of childbearing age, that married women and women of childbearing age suffer more psychological distress after rape than single or post-menopausal women, and that rape takes place in a variety of other species, all point towards an evolutionary heritage for the rape behaviour.
In this case, the benefit would be a higher chance of reproductive success through increasing mate number. The hypothesis suggests that rape behaviour is the result of psychological mechanisms designed specifically to influence males to rape, unlike in the by-product hypothesis.
This theory suggests that rape by a man which offers no chance of reproductive success, i. This idea is supported by the fact that rape is disproportionately committed by men with a lower socioeconomic status. This subsequently results in less alternative reproductive options. Therefore, while there is indeed a relationship between a lack of alternative reproductive options and rape behaviour, there are likely to be a number of co-morbid factors affecting this correlation, leading Thornhill and Palmer to conclude that the idea of a specific psychological adaptation that motivated men with a lack of sexual access to females is unlikely, and that further research need be conducted.
Rejected hypotheses[ edit ] One of Thornhill and Palmer 's rejected hypotheses for why men rape implicates violent pornography. Subscribers to the social science theory of rape   purport that one of the main reasons why the human male learns to rape is via learning imitative behaviour when watching violent pornography.
However, this fails to explain why if males are likely to imitate behaviour witnessed in violent pornography they would not also imitate the actions of human males in other videos.
Furthermore, no explanation is offered into why this behaviour is inspired in some men and not others. It is also limited in its ability to predict valuable variables surrounding why rape occurs such as who, when or where. For this reason, Thornhill and Palmer argued that "although the removal of violent pornography may be desirable in its own right, it is very unlikely to solve the problem of rape".
This hypothesis suggests that men would be most likely to rape reproductive-age females. Research shows that the age of US rape victims correlates slightly better with age of peak fertility than age of peak reproductive potential. Development of sexual coercion[ edit ] Though it is a widely held view that sexually coercive behaviour occurs as a result of sexual selection, Smuts and Smuts proposed that sexual coercion is best described as a third type of sexual selection, rather than attempting to fit it into either of the other two forms: Male sexual entitlement[ edit ] Coercive behaviour of men towards the opposite sex can be argued to be a result of male sexual entitlement.
Gender stereotypes view men and boys as being the more typically aggressive sex. This is known as male sexual entitlement — the belief that women and girls owe men sex due to society viewing their sexual gratification as more important. This can result in men being more likely than women to view pressuring a woman or girl into sex as acceptable behavior. Compromising sexual strategies[ edit ] Sexual strategies are essential to males when pursuing a mate in order to maximize reproductive potential, in order for their genes to be passed on to future generations.
Women have higher levels of parental investment because they carry the developing child, and higher confidence in their maternity since they witness giving birth to the child. Hence women have reason to accept greater responsibility for raising their children.
By comparison, males have no objective way of being certain that the child they are raising is biologically theirs. Because of this difference, males have to adapt their own sexual strategies to accommodate the strategies of the females around them. Such a strategy is seen in males, and maternity is never doubted by the female, and so a chaste male is not highly valued by a women.
However, for men, female chastity confirms paternity, causing the male to compromising his sexual strategies in order to select a chaste mate. Male homoeroticism[ edit ] Homoerotic behaviour differs from homosexuality see below in that it is purely same-sex sexual behaviour that occurs for pleasure, whereas homosexuality is the sexual orientation or enduring sexual preference for the same-sex.
There is evidence of the long-standing existence of homoeroticism, dating back to early human history. From cave paintings of men engaging in sexual acts  to modern history, homoerotic behaviour is still prevalent today. Evidence suggests that male-male sexual relations in early human periods often occurred between younger adolescent boys and older males.
Sexual acts have been viewed as a psychological factor in societies used for bonding. These direct effects on survival also led to indirect effects of reproductive success. The advantages the young males would obtain from their sexual relations with older men made them a more desired mating choice amongst females.
The age and status difference between the men involved, suggests that a dominance-submission dynamic was an important factor in these relations. Therefore, same-sex behaviour allowed younger men to have reinforced alliances with other older males, which later gained them access to resources and females which were both scarce at the time.
The older male receives sexual gratification from the relationship whilst the younger male has to bear the cost of engaging in non-reproductve sex. However, the younger male is able to later receive the social benefits discussed, through this same-sex alliance. This relationship can be viewed as a resource exchange. Examples of this in modern history include Roman Emperors; such as Augustus Caesar , who supposedly acquired the throne in part due to their sexual relations with their predecessors.
It was very common for adult males and adolescent males in ancient Greece, to engage in sexual relations. Similarly to relationships found in early humans who displayed homoeroticism, the relationship dynamic between males involved in pederasty in the ancient Greek period was unequal.
These young males also received benefits such as increased social networks and educational development. Homoerotic behaviour has been thought to be maintained by indirect selection, since it does not encourage reproduction.
Relatively newer studies suggest that similar to how heterosexual bonds provide non-conceptive benefits, including the maintenance of long-term bonds, homoerotic behaviour aid in same-sex alliances that help in resource competition or defense. Before that period of their life, same-sex alliances are important in aiding survival, and among the Q'eqchi' of Belize , significantly more children survive past six months for men with same-sex alliance due to the increase in productivity of agricultural labour.
Same-sex alliances do not need to be sexual in nature, although when competition for partners is especially severe the sexualisation of same-sex alliances occur more often. This effect is most pronounced with men with high progesterone , a hormone that is associated with affiliative motivation in humans. In spite of the opportunity costs homoerotic behaviour and motivation were thought to incur, the results provide data constituting evidence that homoerotic motivation, and subsequently homoerotic behaviour, holds the adaptive function of encouraging alliance formation and bonding.