Discuss the relationship between sexual selection and human reproductive behaviour Essay
AO1 Psychologists suggest that there is a relationship between human sexual selection and reproductive success. Explaining this relationship there is intra-sexual selection and inter-sexual selection. Intra-sexual selection suggests that members of the same sex compete with each other in order to get a member of the opposite sex and ensure reproductive success. The winner mates and then passes on their genes. Whichever traits led to their success i.e. health because there genes are stronger, will be passed onto the next generation (the offspring) through their genes. This is known as male competition as they fight for women with certain traits i.e. an hourglass figure because they are more fertile/ young age because of their reproductive ability.
Inter-sexual selection suggests that members of one sex will be attracted to the opposite sex if they possess certain qualities i.e. power because they can offer more resources to ensure survival for offspring. This is known as female choice as the females choose the male on offer most powerful the opportunity to mate, as she feels this will increase the rate of reproductive success.
AO2/AO3 (P) There is supporting empirical evidence by Singh (1993) into the relationship between human sexual selection and reproductive success.(E) Singh found that although breast size, weight and physique varied over the years of beauty winners, a consistent feature was a small waist set against full hips. This suggests that the waist to hip ratio may symbolise fertility as this is a quality men find attractive and look for in women when choosing their partner.(C) This supports the theory of that there is a relationship between human sexual selection and reproductive success as it supports the intra-sexual selection explanation of that men look for certain traits in order to ensure reproductive success. By supporting the theory, this increased its internal validity.
(P) There is a second piece of supporting empirical evidence by Swami & Furnham (2006),(E) that found that the optimum waist to hip ratio of 0:7:1 closely corresponds to supermodels.(C) Just like Singh, it was found that the waist to hip ratio was an attractive quality in women for men. This improves the internal reliability of the theory that there is a relationship between human sexual selection and reproductive success as the same results were found by Singh and Swami & Furnham.
(P) However both pieces of supporting empirical evidence by Singh and Swami & Furnham contain a methodological flaw.(E) Both studies measure mate preference as opposed to actual choice as it takes into account our desires only which we will not all gain.(C) Therefore the findings of the study do not set out to measure what we had actually hoped to (the relationship between human sexual selection and reproductive success) and thus decreased the internal validity of both studies. This furthermore reduces the internal validity of the theory as both pieces of its supporting empirical evidences have been weakened by methodological flaws.
(P) Yet the theory of that there is a relationship between human sexual selection and reproductive success is supported by another piece of empirical evidence from Davies (1990).(E) Davies concluded that there is sexual strategies in human selection after finding that males and females attempted to improve their perceived fertility and ability to raise offspring.(C) As findings show that both sexes changed their sexual selection in order to ensure reproductive success, it supports that there is a clear relationship between the two, increasing the theorys internal validity.
(P) Davies study has also been criticised for containing a methodological flaw.(E) Davies focused on chimpanzees during his study and so the research is based on animal studies.(C) Findings consequently cannot be generalised to the sexual selection of humans and the reproductive success of humans. This therefore reduces the population validity of the study and furthermore the internal validity of the theory as its supporting empirical evidence has just been weakened.
(P) The theory of that there is a relationship between human sexual selection and reproductive success has been criticised for being deterministic.(E) Within the intra-sexual selection explanation it is suggested that men look
for certain traits in women that are found to be fertile such as young age. Yet this fails to consider the role of free will and individual differences in what individuals perceive to be as an attractive trait.(C) The theory therefore cannot explain a relationship between human sexual selection and reproductive success in all romantic relationships and fails to deliver as a good explanation, thus reducing the theorys external reliability.
(P) The theory has also been criticised for failing to explain the nature of homosexual partner selection,(E) as it only takes into account the evolutionary perspective of human sexual selection and reproductive success between the opposite sexes.(C) This therefore means that the theory of a relationship between human sexual selection and reproductive success cannot explain all romantic relationships, specifically homosexual relationships, thus reducing the theorys external reliability.