Final answer:
The main conclusion of the Simpson and Gangestad study is not given, but it likely relates to the differences in sexual behaviors between 'restricted' and 'unrestricted' singles. The context suggests it would involve discussion on the sexual double standard and varying frequencies of sexual activity.
Step-by-step explanation:
The main conclusion from the study by Simpson and Gangestad that is cited by Van Epp is not explicitly provided in the provided reference texts. However, the context of the question, which mentions 'unrestricted' and 'restricted' singles and their dating and sexual practices, points towards the discussion of sexual attitudes and practices. Such studies often explore the differing sexual behaviors and inclinations between groups of people who have varying levels of sexual permissiveness, such as the number of sexual partners or attitudes towards casual sex. While the details of Simpson and Gangestad's study are not given, studies like those by Pedersen et al. and Reiss indicate that there are evolved sex differences in the number of partners desired and a prevailing sexual double standard that impacts sexual behavior.
It is also noted that sexual practices can greatly vary among different groups, with married couples in their 30s reportedly having sex more frequently than singles. Furthermore, discussions on sexual standards reveal that historically, a double standard has existed that permitted men to have multiple sexual partners while expecting women to engage in sex only within committed relationships. There may also be implications from this study on how societal norms and attitudes towards sex may influence the sexual practices of different groups, particularly when it comes to the number of sexual partners and the concept of 'restricted' versus 'unrestricted' sexual behaviors.