The role of altruistic costs in human mate choice

There is a large body of research exploring the role of altruism in mate choice, showing altruism is a mating signal. However, it is still unclear whether these traits signal good genetic quality, due to their costly nature, or good partner/parenting qualities. We report the findings of three experiments that aimed to address this, by comparing the desirability of individuals who displayed either moderate or high levels of altruistic behaviour, and non-altruistic behaviour in dictator games and hypothetical social scenarios. These experiments adopted a variety of experimental designs to test our hypotheses. We consistently found that individuals displaying moderate levels of altruism were rated as more desirable than those displaying higher levels (and both more so than non-altruistic individuals). Our findings offer strong evidence for the underlying characteristics displayed by altruistic behaviour, rather than their absolute costs, being more important in mate choice. To our knowledge, this is the first paper to report a suite of experiments providing strong support that the cost of an altruistic act is more important than the act itself in a mate choice context. These findings go beyond and extend previous literature on altruism and mating by unpacking the role of prosociality in mate choice.