Evolved mechanisms in depression: the role and interaction of attachment and social rank in depression.

Evolved mechanisms underpinning attachment and social rank behavior may be the basis for some forms of major depression, especially those associated with chronic stress. We note the heterogeneity of depression, but suggest that some of its core symptoms, such as behavioral withdrawal, low self-esteem and anhedonia, may have evolved in order to regulate behavior and mood and convey sensitivity to threats and safety. Focusing on the evolved mental mechanisms for attachment and social rank helps to make sense of (1) depression's common early vulnerability factors (e.g., attachment disruptions, neglect and abuse), (2) the triggering events (e.g., loss of close relationships, being defeated and/or trapped in low socially rewarding or hostile environments), and (3) the psychological preoccupations of depressed people (e.g., sense of unlovableness, self as inferior and a failure). This focus offers clues as to how these two systems interact and on how to intervene.