The theory predicts that preferred mate choices have evolved to focus on reproductive potential and reproductive investment of members of the opposite sex.[1] This theory predicts both intrasexual selection and intersexual choice due to differences in parental investment; typically there is competition among members of the lower investing sex (generally males) over the parental investment of the higher investing sex (generally females) who will be more selective in their mate choice. However, human males tend to have more parental investment compared to mammal males (although females still tend to have more parental investment).[37] Thus, both sexes will have to compete and be selective in mate choices. These two theories explain why natural and sexual selection acts slightly differently on the two sexes so that they display different preferences.