Discuss the relationship between sexual selection and human reproductive behaviour. (8 marks + 16 marks)

Here you should largely look at sexual selection and the origins of mate choice.


Intrasexual selection is the evolutionary process by which members of one sex (usually males) compete with each other for members of the opposite sex. The victors are able to pass on their genes while the losers are not. The factor that made the male successful is then passed on to the offspring, helping to ensure their survival and the passing on of their genes.

Intersexual selection refers to the fact that members of each sex have innate preferences for mates with certain characteristics. The preferences of one sex determine the areas in which the other sex must compete (e.g. physical attractiveness for women). These indicators reveal traits which could be passed on to offspring (e.g. height) or which could give protection & support to the offspring (e.g. economic resources).

Men have a greater desire for casual sex & tend to seek sex earlier in the relationship. This is because men can produce several children within a year, while women cannot: men have an evolutionary desire to impregnate a woman as soon as they can before moving on. Men experience a decrease in sexual attraction following sex to prevent them from spending too much time with any one woman.

For long-term mating, both sexes must invest heavily in any offspring. Choosiness is therefore high in both sexes, as they wouldn't want to waste valuable resources if their mate is providing poor genes or little child-rearing support. Women are particularly choosy, as have to make an obligatory bio investment in the child. Females thus look for good resources, physical strength, etc.

Buss explored what males & females look in a marriage partner for 10,000+ folks from 37 cultures. The results supported predictions of evolutionary explanations of sexual selection. For example, women want good financial prospects: men with financial resources to provide for children. Men want physical attractiveness, which research has consistently confirmed to be linked av fertility & health. Men also wanted younger women: an indication of fertility.

Studies such as Buss' may suffer from a validity problem, as although they provide information about expressed mate choices, this may be different to info about actual mate choice (in which compromises are made). However, another study by Buss of actual married couples from 29 cultures supported the original results. For example, men do marry younger women.

Although Buss' study supports the idea that men prefer younger women, this may not be because of fertility. Some critics have tried to explain this in terms of social power: younger women are easier to control and are therefore preferable as mates. Kenrick et al. rejected this hypothesis by finding that teenage males are most attracted to women 5 years older than them: these women are not easily controlled.

Evolutionary explanations of sexual selection have faced some scepticism as being choosy about sexual partners can be costly, as it requires time and energy, and would result in the creation of less children than if we were to mate with any available partner. These disadvantages of being choosy are real, but they do not outweigh the advantages of being choosy: choosiness allows the production of high-quality offspring whose genes are much more likely to be passed on.

The claim that males are more likely than females to seek short-term mating opportunities is supported by research. Clarke & Hatfield found that 75% of males were willing to have sex with an attractive stranger, but no females were. This suggests that males have evolved such mechanisms to increase reproductive success.

Research suggests that female mate choice varies across the menstrual cycle. Penton-Voak et al. found that females preferred more masculine faces during more fertile phases & more feminine faces during less fertile phases. This suggests that females may choose a partner whose feminine features suggest kindness & cooperation in child-rearing, but mate with a male who possesses desirable qualities in offspring.

Visual & chemical indicators can tell men when women are at their most fertile stage in the menstrual cycle. According to evolutionary explanations, men would find women most attractive at these times. Miller et al. analysed tips earned by lap dancers. They earned almost twice as much money in these phases, showing that men are most attracted to women when in the most fertile phase of the menstrual cycle.

There may be a gender bias in research on short-term mating. Although short-term mating can be costly to females, they could also profit from it. They may use short-term  mating as a way of ending a relationship with a poor-quality male or as a way of producing more genetically diverse offspring.