This article argues for the value of interdisciplinarity by attempting to integrate an evolutionary theory of human ontogeny with psychodynamic perspectives to explain the origins of an American cultural schema of marriage. Specifically, I draw on the work of evolutionary psychologist Michael Tomasello to propose that key features of the American “cultural” schema for marriage—commitment to it and the expectations it be shared, mutually beneficial, and lasting—are understandings that arise largely out of young human children's capabilities for emotional alignment or attunement and, thereafter, for fully developed joint intentionality. This focus of the American marital relationship on joint intentionality, and on even earlier beginnings of shared intentionality, I interpret as evidence—drawing on psychodynamic theory—that marriage as an American institution is largely a defense, a regression, that allows a return or “retreat” to feelings of dependency never fully resolved in adulthood because of the extreme emphasis on independence and self‐reliance in American child‐rearing. cultural schemas, defense mechanisms, evolutionary psychology, marriage