Born to be kind: The evolutionary significance of prosocial behaviors in humans

Humans prefer kind romantic partners. Worldwide surveys have identified kindness as the defining feature of an ideal long-term partner, often explained as a signal for evolutionary fitness, demonstrating the ability to provide resources and ensure survival. Instead, we propose an alternative explanation: human preference for prosociality stems from an innate desire to be treated well. To test this, we asked participants whether they preferred kindness directed towards them or kindness exhibited more generally. Results indicate that participants were significantly more attracted to people who were kind to them personally than to people who were broadly kind to others. Interestingly, participants were equally repelled by people who demonstrated unkindness towards themselves and others. These findings suggest that people’s attraction to kindness is driven primarily by self-interest rather than evolutionary signals alone. Our research further supports that the human capacity for prosociality may have developed through sexual selection for kind behaviors, highlighting the deep-rooted nature of kindness in human interactions. Future research could explore the interplay of evolutionary and cultural factors in shaping human kindness using longitudinal models, providing deeper insights into the motivations that drive prosocial behavior.