The evolution of sexual selection is an adaptive process whereby organisms change directionally over time. The basic premise of evolutionary theory, with regard to mate selection, is that human organisms will select mates that maximize their chance of reproductive success. Reproductive success will be influenced by multiple factors such as investment, reproductive characteristics, and environmental concerns. The success of an organism is not only measured by the number of offspring left behind, but by the reproductive fitness of the offspring.
The sexual selection theory proposed by Charles Darwin states that the frequency of traits can increase or decrease depending on the attractiveness of the individual. He also hypothesized that sexual selection could be what caused differentiation among human races, as he did not believe that natural selection provided a satisfactory answer. Drawing on some of Darwin’s largely neglected ideas about human behavior, Geoffrey Miller a social biologist has hypothesized that human culture arose through a process of sexual selection. He argues that cultural traits such as art, music, dance, verbal creativity and humor are of no survival value. Miller is critical of theories that imply that human culture arose as accidents or byproducts of human evolution. He believes that human culture arose through sexual selection for creative traits. In that view, many human characteristics could be considered subject to sexual selection as part of the extended phenotype, for instance clothing that enhances sexually selected traits.
Mate selection inherently involves consideration of the reproductive characteristics of the potential mate. An ideal mate would possess desirable genes to increase the likelihood that offspring will develop into healthy, reproducing adults. Analyses of mate selection processes find mechanisms or strategies that organisms use to identify the potential health of a mate. Such mechanisms increase the attraction or desire of organisms to mate with one another.
Sexual attractiveness in non-human animals depends on a wide variety of factors. Often, there is some element of the animal’s body which exists for sexual attraction, like the bright plumage and crests of some species of birds. In many species, there are behaviors which appear to be sexual display. Some of these attributes seem to exist solely to demonstrate fitness and health, by demonstrating the ability to sustain a biologically expensive. Conversely, the receiving sex may be predisposed to perceive these features as sexual attraction. It is possible that these features by the giving or the receiving ends cause major survival problems, especially where a direct competitive element is involved.