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As we all know, sex and love are not necessarily connected. People often have sex outside the context of romantic relationships, without feeling anything for their sexual partners, as in the case of one-night stands. Still, sexual desire plays a key role not only in attracting potential partners to each other, but also in fostering the development of an attachment between them.
To be sure, impregnation is not sufficient for the survival of human offspring. Infants depend on our caring during an exceptionally long period, such that throughout our history, kids' survival chances increased enormously if both parents raised them together. We therefore had to develop mechanisms that encouraged us to stay with a sexual partner, at least until the kids could survive without our caring.
An in-depth look at the set of qualities that distinguish human sexuality from that of other mammals suggests that the sexual system is one such mechanism1. Humans, for example, prefer the “missionary” sexual position, which enables face-to face, belly-to-belly contact during intercourse. Humans also tend to have sex in private and to sleep together afterward. Such behavioral tendencies may instill a sense of closeness that helps build emotional connection between partners.
In addition, experiences of sexual desire and romantic love are characterized by similar patterns of brain region activation (e.g., caudate, insula, putamen)2. This pattern of activation hints at the existence of a pathway through which sexual arousal enhances affectional bonding to a partner. Supporting this possibility, the neuropeptide oxytocin, which facilitates emotional bonding3, is secreted during foreplay, sexual intercourse, and the moments preceding orgasm. We, as humans, experience an extended exposure to oxytocin because our sexual interactions are not limited to the days that precede ovulation. Rather, we engage in sex throughout the menstrual cycle, further reinforcing attachment to a partner.
Of course, instead of relying on indirect evidence for the role that sex plays in relationship initiation, one can ask people directly about the meaning of sex in their life. Think about your reasons for engaging in sex. Why do you have sex? Your gut reaction might be: "I want to have sex because I'm horny." And yet, when asked such a question, people actually mention many other reasons, such as "I have sex to relieve stress" or "I have sex to feel good about myself." When we analyze the meanings of sex and the reasons for having it, we find that among the most prevalent meanings are those that reflect the belief that sexual activity promotes intimacy between partners and intensifies a relationship.
Beyond associating sex with relationship promotion, people also act accordingly, behaving in a way that allows them to get closer to potential partners. In a series of studies, we exposed participants to either sexual or neutral stimuli. Participants, for example, were seated in front of a computer screen and we flashed pictures on the screen so quickly the participants weren’t aware of them. Half the participants were exposed to erotic photos, while half were shown neutral pictures. Following this exposure, participants encountered a potential partner and rated this partner’s attractiveness and romantic interest in them. Participants’ interest in the partner was self-reported or evaluated by raters.
We found that merely having sexual thoughts, even without being aware of them, may arouse romantic interest in a prospective partner and thereby encourage the adoption of an optimistic outlook on one’s courting prospects with this partner.4 (Read more here.) In this way, a sexually tinged mindset helps people overcome their initial rejection concerns, motivating them to strive to become closer to a desirable new acquaintance.
Sexual activation not only biases interpersonal perceptions in a way that may help perceivers allay rejection fears, but also motivates people to actually engage in strategies that foster closeness between previously unacquainted people. By doing so, sex helps set the stage for deepening emotional connections with prospective partners.
People, for example, tend to reveal more personal information5 (read more here) and provide more help to a prospective partner when sexually aroused.6 (Read more here.) Being in a sexy mood has also been found to motivate people to conform to a potential partner's preferences in order to make a favorable impression.7 (Read more here.) Activation of the sexual system apparently encourages human beings to connect. It does so by inspiring interest in potential partners and motivating men and women to impress those partners and become more intimate with them.
See my TEDx talk on why humans make sex so complicated here.
Facebook image: Milan Ilic Photographer/Shutterstock
References
1. Birnbaum, G. E., & Finkel, E. J. (2015). The magnetism that holds us together: Sexuality and relationship maintenance across relationship development. Current Opinion in Psychology, 1, 29-33. Research Gate
2. Diamond, L. M., & Dickenson, J. (2012). The neuroimaging of love and desire: Review and future directions. Clinical Neuropsychiatry, 9, 39-46.
3. Carter, C. S. (2014). Oxytocin pathways and the evolution of human behavior. Annual Review of Psychology, 65, 17-39.
4. Birnbaum, G. E., Iluz, M., Plotkin, E., Tibi, L., Hematian, Mizrahi, M., & Reis, H. T. (in press). Seeing what you want to see: Sexual activation makes potential partners seem more appealing and romantically interested. Journal of Social and Personal Relationships. Research Gate
5. Birnbaum, G. E., Mizrahi, M., Kaplan, A., Kadosh, D., Kariv, D., Tabib, D., Ziv, D., Sadeh, L., & Burban, D. (2017). Sex unleashes your tongue: Sexual priming motivates self-disclosure to a new acquaintance and interest in future interactions. Personality and Social Psychology Bulletin, 43, 706-715. Research Gate
6. Birnbaum, G. E., Mizrahi, M., & Reis, H. T. (2019). Fueled by desire: Sexual activation facilitates the enactment of relationship-initiating behaviors. Journal of Social and Personal Relationships, 36(10), 3057-3074. Research Gate
7. Birnbaum, G. E., Iluz, M., & Reis, H. T. (2020). Making the right first impression: Sexual priming encourages attitude change and self-presentation lies during encounters with potential partners. Journal of Experimental Social Psychology, 86, 103904. Research Gate
