Discuss the relationship between sexual selection and human reproductive behaviour (24 marks)
In this essay I will be discussing the two theories of sexual selection within humans and their reproductive behaviour. The evolutionary explanation of relationships says humans have an innate drive to reproduce and pass on our genes. Sexual selection is a process within natural selection where characteristics are selected because they’re attractive to the opposite sex, and so this increases reproductive success and passes on these traits to their offspring. Sex differences in sexual selection comes from our evolutionary past and so males and females have different reproductive behaviour; these differences are shown from their mate choice (inter sexual selection), mate competition (intra sexual selection) and differences within their short term and long term mating strategies.
Males and females differ in mate selection as the different sexes have different needs which are stemmed from our genetic code which has evolved over millions of years. According to the inter sexual selection theory males and females look for different characteristics in a mate and behave differently to attract these mates. It is important to men that women prioritise physical attractiveness and so men are responsive to those who are young and attractive as it connotes that these women are more likely to be fertile and so the man can reproduce and pass on his genes. Therefore, men are attractive to women who are healthy, take care of their bodies, wear makeup so they look youthful, curvaceous (to show child bearing hips) and are also faithful. Whereas men find physical appearance important women look for indicators of socioeconomic status that are cues from a males that he has, or could potentially get, resources which are necessary for her survival and her offspring. So women are more attracted to men who are dressed well; in a suit for example, have a nice car, ambitious, hardworking and have a strong figure to show protection. The inter sexual selection theory clearly shows difference between sexual selection in different sexes. Another factor which we should also consider is that males and females have also evolved different strategies for long and short term mating. Due to the lack of male involvement in offspring this means that males must seek as may short term mating opportunities as possible so they ca pass on their gees, whereas women have massive repercussions if they choose the wrong man to mate with and so must be more choosy; so they seek a long term mate who will successfully help her raise her offspring. This shows that males and females have different reproductive behaviour and also have different sexual selection strategies.
A study which supports the inter sexual selection theory is by Buss. In an extensive study of 37 cultures (in 33 countries) Buss analysed results of more than 10,000 questionnaires which asked participants to rate factors such as intelligence, age and sociability for their importance in a sexual partner. The results showed that men valued physical attractiveness more than women, whilst women were more likely than men to value a good earning potential and high occupational status, which was a signal of resources that could be inherited in their offspring. This study supports inter sexual selection as it shows that men and women value different characteristics in a partner and these valued characteristics are the same across 37 culture; which suggests this behaviour is innate. This portrays human reproductive behaviour and sexual selection in men and woman and what they value in a partner so that they can reproduce and pass on their genes.
A strength of the inter sexual selection theory is that Buss’ supporting study has a very high population validity. The study used a large sample of 10,000 participants from 37 cultures in 33 countries. This is a strength as the findings are representative of a large number of people from different places. Therefore this provides strong evidence to support the inter sexual selection theory as the same behaviours were found across all cultures which suggests that mate selection is innate rather than culturally determined and shows us the differences in sexual selection within men and women.
A further strength of the inter sexual selection theory is that it has high face validity. The fact that there are ‘trophy wives’, ‘sugar daddies’ and ‘gold diggers’ show real world evidence to support the validity of gender differences in mate choice and what they find attractive, predicted by the evolutionary theory. This suggests that the inter sexual selection theory can explain sexual selection in gender. However, this does not mean that all relationships can be used to explain this theory.
An issue of the inter sexual selection theory is that it is based on Darwin’s evolutionary theory which was done on animals. Although we can generalise this to humans we should do with caution as we cannot be certain that animals and humans have the same behaviour and cultural transmission plays a big role in humans and their sexual selection. Humans are much more complex than animals and animals don’t have a cognitive component to their behaviour and we can’t be sure we have the same behaviour towards choosing a mate and whether humans have evolved to choose the right person to mate with like animals have. This is a limitation because we would struggle to generalise the evolutionary theory based on animals to humans and therefore this does not support the inter sexual selection theory.
Another theory is the intra sexual selection theory. The Intra sexual selection theory is the competition for mates, so the competition for reproductive success between members of the same sex. This usually takes the form of male to male combat to drive other males away or kill rivals off for access to fertile females. Evidence for this comes from the physical fact that, on average, human males are around 12 to 15% larger than human females and this sexual dimorphism has evolved due to intra sexual selection; males have evolved to be naturally bigger and stronger than females and are more aggressive. Aggression in males is an adaptive behaviour that has evolved because of intra sexual selection as they will fight for the most fertile female and will also get aggressive if their partner shows to be unfaithful.
Research which supports the intra sexual selection theory is again, by Buss. He found that men are significantly more likely than women to make threats of violence towards other men who had made sexual advances towards their mate. In contrast to this women are more likely to use verbal aggression towards potential rivals and target the attractiveness or sexual conduct of their competitors to reduce their physical attractiveness to the male. This study supports the intra sexual selection theory of human reproductive behaviour as the findings suggest that men use physical aggression to scare off any competition and so the male can be confident that any child his mate is carrying is definitely his. Females use verbal aggression over physical aggression as they don’t want the confrontation to affect their looks as their mate may no longer find them attractive and abandon them. This therefore shows the difference between male and female’s sexual selection and how they fight for the right mate to reproduce with.
Another study which supports intra sexual selection is by Daly and Wilson and they found that 90% of all same sex murders involve men at an age, 20 to 40 years old, where mate competition is most intense and that a large proportion of this violence is connected to sexual rivalry and fighting off potential competition. This also supports the intra sexual selection theory as it shows that men use physical violence to fight of competition from their mates and portrays their human reproductive behaviour and how they compete for their sexual selection.
An issue of the intra sexual and inter selection theories is that it shows determinist behaviour. Both theories suggest that genes control behaviour and so, ignore the free will of humans and ignore the ability that they can control their own behaviour; for example most men choose to be monogamous even though they sometimes have the opportunity not to be. These evolutionary theories ignore or underestimate social and cultural influences. If it was the case that human reproductive behaviour was completely driven by evolutionary considerations then they would be predictable. However, this isn’t the case as human reproductive behaviour has changed massively over the last century such as the use of contraception, couples choosing not to have children and men having a relationship with a woman who has a child and knowing full well that the child isn’t theirs (stepdads). This shows the people have freewill over their actions and so, the inter and intra sexual selection theories as explanations for human reproductive behaviour is limited.
Another issue of the intra and inter sexual selection theories is that it suggests human reproductive behaviour is reductionist. They reduce the complex human reproductive behaviour down to only one factor, which is a gene. We should also consider emotional, social and development factors which are also important to human reproductive behaviour. Therefore, these theories can only be seen as oversimplified accounts at best, which is elaborated by the fact that relationships are not always about reproducing. For example these evolutionary theories can’t explain why women who do not want children still look for a partner; they also can’t explain homosexual relationships and emotions such as love are ignored. Therefore, the inter and intra sexual selection theories to explain human reproductive behaviour is limited.
In conclusion, there is evidence to support that men and women do look for different characteristics in a partner and that men are willing to compete for their perfect partner to reproduce with. However, neither the inter or intra sexual selection theory explain outside factors which contributes to human reproductive behaviour and focuses too much on the nature of the human being and doesn’t consider that humans can make their own choices and that they have control of their own behaviour. These evolutionary theories were largely based around animals which aren’t as complex as humans as people simply seek partners for happiness and comfort and not just to reproduce. So overall, we shouldn’t rely on inter and intra sexual selection theories as a whole to explain human reproductive behaviour.