When communal sharing relationships (CSRs) suddenly intensify, people experience an emotion that English speakers may label, depending on context, “moved,” “touched,” “heart-warming,” “nostalgia,” “patriotism,” or “rapture” (although sometimes people use each of these terms for other emotions). We call the emotion kama muta (Sanskrit, “moved by love”). Kama muta evokes adaptive motives to devote and commit to the CSRs that are fundamental to social life. It occurs in diverse contexts and appears to be pervasive across cultures and throughout history, while people experience it with reference to its cultural and contextual meanings. Cultures have evolved diverse practices, institutions, roles, narratives, arts, and artifacts whose core function is to evoke kama muta. Kama muta mediates much of human sociality.