Is depression an adaptation?

Many functions have been suggested for low mood or depression, including co mmunicating a need for help, signaling yielding in a hierarchy conflict, fo stering disengagement from commitments to unreachable goals, and regulating patterns of investment. A more comprehensive evolutionary explanation may emerge from attempts to identify how the characteristics of low mood increa se an organism's ability to cope with the adaptive challenges characteristi c of unpropitious situations in which effort to pursue a major goal will li kely result in danger, loss, bodily damage, or wasted effort. Tn such situa tions, pessimism and lack of motivation may give a fitness advantage by inh ibiting certain actions, especially futile or dangerous challenges to domin ant figures, actions in the absence of a crucial resource or a viable plan, efforts that would damage the body, and actions that would disrupt a curre ntly unsatisfactory major life enterprise when it might recover or the alte rnative is likely to be even worse. These hypotheses are consistent with co nsiderable evidence and suggest specific tests.