| Romantic relationships are critically important for social species as they provide enhanced stress coping, social support, and overall health for both partners. Social attraction is a component of romantic relationships, bringing individuals together during initial relationship formation and keeping partners engaged in affiliative behavior as relationships progress. Oxytocin (OT) is a neuropeptide that modulates the formation and maintenance of social relationships. Specifically, OT activity promotes affiliative behavior towards partners in romantic relationships. While significant interest has been given to how OT contributes to the formation and maintenance of romantic relationships, it remains unclear how OT augments affiliation within the context of social attraction. Specifically, whether OT augments the expression of affiliation which makes a partner appear more attractive, or whether OT enhances attractiveness innately, making partners more willing to express affiliation. We examined the role of OT in social attractiveness, as a component of both received and initiated social behavior, where received behavior was behavior directed towards OT-treated marmosets from an untreated, opposite-sex strangers and initiated behavior was behavioral outputs exhibited by OT-treated marmosets. OT treatment did not impact received behavior, but did influence initiated behavior. When male marmosets received OT they exhibited higher rates of genital investigation of non-partner female marmosets, as well as displayed higher average penile erection durations. Both male and female marmosets that received OT decreased the number of times they gazed at opposite-sex non-partners, but there was no change to overall duration of gazes. Males and females displayed differential rates of behavior regardless of OT treatment; male marmosets displayed higher rates of open mouth displays overall, as well as gazed at, approached, and reached towards female marmosets more often than female marmosets. However, female marmosets exhibited a higher total duration of gaze than males. These results suggest that while OT may not impact innate social attraction within early stages of romantic relationships between potential partners, OT agonist treatment does increase initiated behavior through social interest, as well as sexual interest in males. |
