Sexual Selection And Human Reproductive Behaviour – Psya3 Relationships (AQA A A2 Psychology A* Essay)
Sexual Selection Theory (AO1)
Sexual Selection theory by Darwin proposes that species do not just evolve through Natural selection but also “Sexual Selection”– This is the view that competition for mates between individuals of the same sex affects the evolution of certain traits.
Any physical trait that enhances reproductive success will gradually be passed down and enhanced over evolutionary time.
Darwin proposed that animals possess features that make them attractive to members of the opposite sex and allow them to compete better with members of the same sex.
An example of this in humans is the relative hairlessness of human beings compared with other great apes; Such a feature allowed our ancestors to not only keep cool but to advertise to others good hygiene (Pagel et al).
This trait therefore becomes desirable in a mate and is the result of sexual selection. The greater loss of body hair in women would have been through greater pressures on women from sexual selection in comparison to men.
The Handicap Hypothesis – Sexual Selection Theory
The strange case of the peacocks tail seems to go against this however as it offers no advantage; it is heavier, more noticeable by predators and does not help the peacock fly any better.
Different sexual selection pressure occurs between the genders due to differences in gametes (Eggs & Sperms).
Males have millions of sperms however can never be certain of paternity and suffer little cost to reproduction therefore natural selection favours them maximising their mating opportunities.
Females however have a limited number of eggs with each representing a huge investment during and after pregnancy but are certain of paternity. Due to this they must be more choosy in finding strong, healthy and committed males with resources.
There are then two types of sexual selection that take place in relation to human reproductive behaviour:
Intra-sexual selection in males and Intersexual selection in females.
Intra-sexual selection occurs in males who compete with each other for access to females. As a consequence of this men for example have evolved indicators such as strong jaw lines, high cheekbones triangular backs and wide shoulders as these are signs of strength and testosterone which women will seek. High levels of testosterone can damage immune systems how- ever and they would only be able to be displayed in strong males (Handicap principle). Thornhill et al also found that women tended to prefer men with such traits suggesting these are indicators within sexual selection theory for humans. Men on the other hand look for signs of fertility through youth and physical attraction as this maximises reproductive success for them.
Intersexual selection occurs between women who then go on to select men who show the best indicators of providing good genes for offspring, the ability to protect her and her child, provide status and resources.
Psychologists propose it is this evolutionary behaviour that then shapes mate selection in males and females. Males should in theory look for females showing signs of fertility, youth and physical attraction and females should seek males showing signs of genetic strength, masculine features and the ability to provide and protect.
To get the full A* essay with AO2/AO3 evaluation too For Psya3 A2 Psychology, check out my model essay answers book for Psya3 Relationships which provides proven A* essay answers written by myself and used in the exam to score an A* grade (100ums). Every possible essay question is addressed with A* model essay answers for Psya3 Relationships for June 2015.
To cite this article: