While I’m feeling interested in the evolutionary benefit and genetics of sexual behaviour, another report worth mentioning has turned up, this time from the University of Newcastle, which explains why there is such an unexpected diversity of individual appearance in the population. Evolutionary theory would suggest that there would be strong positive selection for attractiveness, leading to far less diversity (and everyone boringly attractive?), and this fact is often used as evidence by creationists that Darwin’s theories of evolution are flawed.
The new theory is that some individuals will create greater genetic diversity because some spontaneous mutations will damage their DNA repair functions. This in turn will mean that in these individuals any other spontaneous mutations will not be repaired. When these mutations happen in the disease resisting parts of the gene, it gives the individual much greater resistance to infections. A computer model has shown that this extra diversity giving disease resistance (as well as diversity in appearance) would be of greater benefit than the reduction in diversity caused by sexual selection leading to more attractive people.
So next time you decide someone is unattractive, just think, they could be much more healthy than you are.