Discuss the relationship between sexual selection and human reproductive behaviour.
Charles Darwin’s theory of natural selection proposed that at any time in which the natural environment exerts selective pressure on an individual. The pressure separates those who do fit into the environment from those who do. Fitness is the extent to which the individual’s characteristics are adapted to its environmental niche. However natural selection can’t explain why many animals develop exaggerated characteristics that appear to threaten rather than enhance the chances of survival.
Darwin solved this problem with the sexual selection concept. Sexual selection is the selection of characteristics that are concerned solely with success of reproduction. In general the females of any given species tend to be the choosers whereas the males are the ones who compete to be selected. However this is different in humans where it is both the males and the females competing for selection. The ‘sexy sons’ hypothesis (fisher), indicates that the females choose a trait in males that eventually becomes dominant in future generations by the ‘runaway’ genetic process. One of the main traits that females in most species especially humans look for is symmetry. This is because symmetry is a sign of good health and well being. The other main hypothesis to show sexual selection is the Handicap Principle by Zahavi, This is where high genetic quality is advertised by males by carrying a biological burden e.g. the long tail of the widow bird. There was also a study done to show that the biological burden of a large tails on male peacocks was preferred by female peacocks and so the males with large tails with more spots on them where constantly selected more often. This created a runaway process meaning this trait was continued in the genes of the new peacock offspring.
