Scientific research on human sexuality does not aim to define the personal meaning of sex in our own lives. We could know every available fact about sex—that the initial spasms of male and female orgasm come at 0.8-second intervals, that systolic blood pressure rises some 60 points and respiration rate reaches 40 breaths per minute, that female nipples expand 10 millimeters at the peak of sexual arousal—but fail to understand the human significance of sexual intimacy.

Intimacy expresses our social nature. One study of 2035 married people found that couples who reported being in a deeply committed relationship before having sex also reported greater relationship satisfaction and stability—and better sex than those who had sex very early in their relationship (Busby et al., 2010; Galinsky & Sonenstein, 2013). For both men and women, but especially for women, sex is more satisfying (more orgasms, less regret) for those in a committed relationship, rather than a sexual hook-up (Armstrong et al., 2012; Garcia et al., 2012, 2013). Partners who share regular meals are more likely than one-time dinner companions to understand what seasoning touches suit each other’s food tastes. So, too, with the touches of loyal partners who share a bed.

Sex is a socially significant act. Men and women can achieve orgasm alone. Yet most people find greater satisfaction after intercourse and orgasm with their loved one (Brody &Tillmann, 2006). Sex at its human best is life uniting and love renewing.