The Bargaining Model of Depression

Minor depression — low mood often accompanied by a loss of motivation — is almost certainly an adaptation to circumstances that, in ancestral environments, imposed a fitness cost. It is, in other words, the psychic equivalent of physical pain. Major depression is characterized by additional symptoms — such as loss of interest in virtually all activities and suicidality — that have no obvious utility. The frequent association of these severe and disabling symptoms with apparently functional symptoms, like sadness and low mood, challenges both dysfunctional and functional accounts of depression. Given that the principal cause of major unipolar depression is a significant negative life event, and that its characteristic symptom is a loss of interest in virtually all activities, it is possible that this syndrome functions somewhat like a labor strike. When powerful others are benefiting from an individual’s efforts, but the individual herself is not benefiting, she can, by reducing her productivity, put her value to them at risk to compel their consent and assistance in renegotiating the social contract so that it will yield net fitness benefits for her. In partial support of this hypothesis, depression is associated with the receipt of considerable social benefits despite the negative reaction it causes in others. DEPRESSION IS STILL A MYSTERY After more than a century of inquiry, unipolar depression remains a profound scientific mystery. Like people working on a large and difficult jigsaw puzzle, researchers in genetics, biochemistry, cognitive psychology, social psychology, and psychodynamics have pieced together detailed accounts of depression from their various theoretical vantage points, but these disparate views have yet to be integrated into a single, coherent whole. Just as an unfinished puzzle often reveals itself in parts that give little clue of the final picture, depression is well understood in aspects, yet no one can answer the question: What, ultimately, is depression? Recent personal problems are clearly implicated in its onset, and Chapter from: Genetic and Cultural Evolution of Cooperation Edited by P. Hammerstein, 2003 ISBN 0-262-08326-4 © The MIT Press