Sexual Selection (8+16) marks

Sexual Selection and Human Reproductive Behaviour

Intrasexual Selection:
- members of one sex compete with each other for access to members of the other sex.
- the victors are able to mate and so pass on their genes, whereas the losers do not.
- Whatever trait leads to success in these same-sex contests will be passed on to the next generation
Intersexual selection:
- involves the preferences of one sex for members of the oppsite sex who posses certain qualities- eg. if females prefer tall males, overtime their will be an increase in the number of tall males in the population.
- the preferences of one sex, therefore determine the areas in which the other sex must compete. This may be in terms of plumage, or economic resources.
- These indicators reveal traits that could be passed on to offspring, as well as info about the chances of the mate being able to give protection and support to offspring.

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human beings are perceptually pre-programmed to attend to displays of these important indicators, which in turn increases their willingness to mate with the individual who possess them

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men appear to lower their standards in the context of short-term mating opportunities and then show a marked decrease in attarction following sex- and evolved adaption to bring about a hasty departure which prevents them spending too long with one women, (Buss and Schmitt 1993)

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Penton-Voak et al (1999) suggests that far from being constant, female mate choice varies widely across the menstrual cycle
- women choose a slightly feminised male face as most attractive for a long term relationship
- for short term sexual relationships, during the high conception risk phase of the cycle, they preferred a more masculinised face.
- sexual selection may well have favoured females who pursure a mixed strategy under certain conditions

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Buss's study concluded that males have a distinct preference for younger women, a finding consistent with the thoery of sexual selection, however critics have tried to explain this in terms of social power. younger women are easier to control and therefore, prefered as mates
Kenrick et al (1996) rejected this hypothesis.
- he found that teenage males preffered females who are five years older than them, despite the fact such women so no interest in them and are not more easily controlled by adolescent males.

If sexual selection, human reproductive behaviour and the relationships it involves are driven by purely evolutionary considerations, then they would be highly predictable. In fact human reproductive behaviour has changed dramatically over the last century, with nonheterosexual relationships, widespread use of contraception, and couples choosing not to have children. This implies that we have more control (free will) over our behaviour than is implied by the evolutionary approach.

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Gender Bias:
- men could never have evolved their sesire for casual sex without a willing female.
- when a man has sex with a new partner, the women is also.
- Greiling and Buss (2000) suggest the women could profit in a number of ways, including using short term mating as a way of leaving a poor-quality relationship or as a way of producing more genetically diverse offspring

Buss's survey of mate choice has problems with the ecological validity of it. However many real-life studies support these mate-choice hypotheses.
Buss (1989) studied marriages in 29 cultures and confirmed that men do choose younger women.
Men who divorce and remarry tend to marry women who are increasingly younger than them.

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