structural:scholar_edition, linguistic:paraphrasing
Shifts in research

The function or functions of the human female orgasm have been debated among researchers. Researchers have several hypotheses about the role if any, of the female orgasm in the reproductive and therefore evolutionary process. The literature started with the argument that female orgasm is a byproduct of shared early male ontogeny, where male orgasm is an adaptation. Research has shifted to investigate and also support the sire-choice hypothesis, which proposes that female orgasm has been shaped by natural selection to function in the selection of high-quality sires (male parents) for offspring. Therefore, orgasm increases the chances of conceiving with males of high genetic quality. Research by Randy Thornhill et al. (1995) suggested that female orgasm is more frequent during intercourse with a male partner with low fluctuating asymmetry.