Willingness to protect from violence, independent of strength, guides partner choice

Ancestrally, physical violence from conspecifics was a recurrent adaptive problem. Did selection favor preferences for partners who are both strong (highly able) and willing to protect us from violence? Strength and willingness are interrelated, so dissociating their effects is necessary. Here we assessed both inferences and preferences. In 7 experiments (N = 4,508 U.S. adults recruited via MTurk), we systematically varied the willingness of a date or friend to physically protect you from an attack, compared to scenarios where you do not have this information. We also varied that person's strength. Discovering that a person is willing to protect greatly increased their attractiveness as a romantic partner or friend, regardless of their strength. This held for both women and men raters, and when evaluating both opposite- and same-sex dates and friends. In fact, partners who were willing to protect were attractive even if they tried to do so but failed, and even if you were harmed because of their failure. Discovering that a partner is unwilling to protect decreased their attractiveness, and was a deal-breaker for women evaluating a male date. Unwillingness decreased attractiveness more when the rater was a woman, when the target was a man, and when the target was being evaluated as a date versus friend. Women placed some importance on a male date's strength, but this was mostly due to inferences about his willingness to protect them. Surprisingly, we found only weak evidence that differences in strength, independent of willingness, increased the attractiveness of a partner.