Why Female Bonobos Use Sex to Power Up Their Status

Bonobos are famous for having liberal sexual behaviors, but new field research reveals why female bonobos particularly favor sex with each other. In a wild bonobo community observed for a year, researchers found that adult females engaged in same-sex genital rubbing far more often than males did medicalnewstoday.com. When competing or needing allies, females consistently chose other females as sexual partners medicalnewstoday.com. These female-female encounters released higher levels of oxytocin (the bonding hormone) than male-female mating medicalnewstoday.com. The result: women who had same-sex sex ended up with stronger social bonds and coalitions than those who mated only with males.

Key observations: Bonobo researchers noted that virtually all adult females participated in female-female sex, whereas males did it rarely medicalnewstoday.com. During conflicts, females would rub genitals with allies. Urine tests showed a spike in oxytocin after female-female sex, but not after sex with males medicalnewstoday.com. In other words, same-sex sex appeared more rewarding and unifying for females. Co-author Liza Moscovice says this behavior may help women establish equality with males: by bonding together, females maintain shared dominance over male coalitions medicalnewstoday.com.

Why it matters: This study (published in Hormones and Behavior) suggests sex in bonobos is not just for reproduction, but a tool for social cooperation. It provides a physiological basis (oxytocin release) for why female bonobos are so egalitarian and cohesive. Similar ideas may apply to human social bonding, though obviously cultural factors differ. The authors caution against direct analogy: human homosexuality has its own contexts, but the evolutionary point is that same-sex behaviors can reinforce alliances medicalnewstoday.com.

Summary: Female bonobos engage in copious sex with other females partly because it makes them team up. Higher oxytocin means each encounter strengthens friendship and trust. The females who rub together stay close and support each other. This deep cooperation likely helps them share power over the group, keeping bonobo society unusually female-friendly.