Bassaleg Psychology - Megan

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A01 - Sexual selection
Inter- and intra-sexual selection

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An important feature of most sexually reproducing species is that males are more brightly coloured than their female counterparts; the classic example of this it the peacock's tail. One would expect such disadvantageous traits not to be naturally selected - unless they enhance reproductive success in some way. To explain this, Darwin (1874) came up with his theory of sexual selection, describing two processes through which it took place.

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A01 - Sexual selection
Inter- and intra-sexual selection

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Intrasexual selection (mate competition) - Members of one sex compete with each other for members of the opposite sex. The victors are able to mate and so pass on their genes, whereas the losers do not. Whatever traits lead to success in these same-sex contests will be passed on to the next generation.
Intersexual selection (mate choice) - Involves the preferences of one sex for members of the opposite sex who possess certain qualities, e.g. if females prefer tall males, over time there would be an increase in the number of tall mates 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 information about the chances of being able to give good protection and support to offspring.

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A01 - Sexual selection
Short-term mating preferences

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According to parental investment theory, men evolved a greater desire for casual sex, and would ideally seek sex earlier in a relationship. Female behaviour would not be subjected to the same evolutionary processes. Over the period of one year, a male who managed to impregnate a large number of females would have passed on more copies of his genes than a less successful male. On the other hand, a female who had sex with the same number of men in the same time period would only produce one child. The less time a man allows to elapse before he has sexual intercourse with a woman, the larger the number of women he can impregnate in a given time (Buss 2007). Men appear to lower their stndards in the contect of short term mating opportunties and then show a marked decrease in attraction following sex.

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A01 - Sexual selection
Long-term mating preferences

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In long-term mating, both sexes typically invest heavily in any offspring. As a consequence of this, sexual selection should favour high levels of choosiness in both sexes. Poor long-term mate choice could be disastrous, because they would have wasted valuable resources. As women have an obligatory biological investment in their children, they are predicted to be very particular about their choice of mate. This means being attracted to males who (i) are able to invest resources in her and her children, (ii) are able to physically protect her and her children, (iii) show promise as a good parent, and (iv) are sufficiently compatible to ensure minimal costs to her and her children. However, people do not give away their resources indiscriminately; therefore, males would be more attracted to females who display signals of fertility, an indication of their reproductive value.

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A02 - Sexual selection
Gender bias in short term mating (IDA)

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Although research consistently reports that men more than women have a desire for a variety of sexual partners and a greater willingness for casual sex, men could never have evolved this desire in the absence of willing females. Every time a man has sex with a willing new partner, the woman is also having sex with a new partner. Despite the fact that short-term mating carries a considerable potential cost to the woman, there must also be some benefits.

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A02 - Sexual selection
Validity

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Studies such as Buss's survery of mate choice might suffer from a lack of validity. However, many real life studies also support these mat-choice hypotheses. For example, a study of actual marriages in 29 cultures confirmed that men do choose younger women. In fact, men who divorce and remarry tend to marry women who are increasingly younger than they are.

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A02 - Sexual selection
Nature V Nurture

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Buss' study sugggests that the concept of human reproductive behaviour are the result of biological origin rather than socialisation as the same behaviour was seen across various cultures. Furthermore, as a representational sample was used it suggests the universality of this evolution explination has credibility. However, it is possible that participants gave the socially desirable answer in terms of what they were looking for in an ideal partner. This therefore questions the validity of the results of the study.

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A02 - Sexual selection
Methodological issues

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Although these studies support the factors of this explination, there are some methodological issues. Waynforth and Dunbar involved analysing lonely hearts columns. Although this method excludes the influence of investigator effects, the study took place in the USA which results in a non-representative ethnocentric sample.

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A02 - Sexual selection
Ethical issues (IDA)

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Clark and Hutfield's study raised some ethical issues as participants were decieved and there was a lack of consent in behalf of the participants and therefore raises ethical concerns.

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A02 - Sexual selection
Deterministic (IDA)

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A disadvantage with evolutionary theory can be considered extremely deterministic as it claims human reproductive behaviour is influenced by genes rather than cognition. This produces a problem as this theory claims it would be considered acceptable for males to impregnate women as they are only carrying actions that they were pre-programmed to participate in. However, biologist Richard Dawkins believes we can override biology with free will. For example, evolutionary theory predicted that men who cannot attract a mate would resort to rape. While this does happen, the majority of single men would not resolve to this vile action as they know that it is morally unacceptable.