The emotional foundations of human prosociality.

Humans are fundamentally cooperative beings whose survival and success depend on prosocial behavior, including with non-kin and strangers. Even young children engage in prosocial behaviors such as helping, sharing, and comforting that are often intrinsically motivated. While evolutionary accounts explain why prosociality emerged, they leave open the proximate question of what motivates individuals, including young children, to engage in costly actions that benefit others. This chapter argues that evolution has equipped humans with affective mechanisms that motivate us to initiate, sustain, and repair prosocial interactions from early in development. Sympathy motivates us to initiate prosocial responses by creating concern for those in need. Warm glow (positive affect from acting prosocially) and gratitude sustain cycles of prosociality within and between individuals by making cooperation emotionally rewarding and motivating reciprocity. Guilt and forgiveness help repair damaged relationships, with guilt prompting transgressors to make amends and forgiveness enabling victims to restore trust and cooperative bonds. Drawing on behavioral, physiological, and cross-cultural research, we show that these mechanisms emerge within the first years of life and become increasingly flexible and context-sensitive with development. We conclude by outlining a developmental proposal for the emergence of prosocial emotions, discussing methodological and cultural challenges, and highlighting directions for future research. Together, the evidence suggests that early-emerging affective processes work in concert to enable even young children to navigate the cooperative landscape that defines human social life.