Discuss the relationships between sexual selection and human reproductive behaviour (8 marks & 16 marks)


The relationship between sexual selection and human reproductive behaviour (AO1)

Darwin’s theory of sexual selection is based on the assumption that characteristics are selected because they increase reproductive potential, for example, make the individual more attractive to the opposite sex or more able to compete for mates and so increase the individual’s chance of reproduction.

 Anisogamy is an important factor that affects sexual selection. Anisogamy refers to the difference in the size of the sexual gametes, the female egg has greater biological cost than the male sperm because the egg is larger, limited in number and takes longer to produce than the ‘cheap’ male sperm and so the male has a much lower parental investment than the female.

There are two types of sexual selection. The sex that invests least (males) must compete for the sex that invests the most (females) and so this means Intrasexual selection(within sex mate competition) is the male strategy and refers to competition for reproductive success between members of the same sex- for example men competing with other men for sex with women (reproductive) opportunities. In humans, males compete for the position of alpha male and so have greater access to females. The winner is able to mate and pass on their genes, whereas losers cannot. This means that whatever traits lead to success in these same sex contests will be passed on to the next generation.

Intersexual selection is mate choice between the genders and this is the female choice due to her greater parental investment. This involves the preference of females for men who possess certain qualities. For example, if females prefer tall males, over a period of time there would be an increase in the number of tall males in the population. This preference of women therefore, determines the areas in which men must compete and women are attracted to the features of men that have survival value e.g. economic resources.

Female intersexual selection is explained by two strategies: According to the “good sense” desirable qualities such as symmetry, height, wealth, etc. are taken by females to indicate traits that could be passed on to offspring (so selection for good denes) or they can give information about the chances of the man being able to give protection and support for the offspring so selection as a good parent. This is also known as the handicap hypothesis because if the male can survive despite the extra evolutionary effort needed to maintain the characteristic, for example, in human’s high testosterone challenges the immune system so females would be attracted to highly masculine men because they survive despite the handicap. Similarly, a woman may select a man not because he drives an expensive car such as a Ferrari, but because he has the handicap of running an expensive car such as a Ferrari (e.g. initial cost, insurance, cost of petrol etc.). Therefore, he must have good survival genes.

The second stratergy is known as the “good taste” or “**** sons” hypothesis and this


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