Depression and other mental health issues in evolutionary perspective

Mental illness currently accounts for 11.5% of global disease burden, more than all cancers combined. Depression alone is now the fourth-leading cause of the global disease burden and the leading cause of disability worldwide. Suicide accounts for about the same number of deaths as all wars and homicides combined.

My research explores, in evolutionary-ecological perspective, mental health problems including depression, suicidality, deliberate self-harm, and addiction. Minor depression—low mood often accompanied by a loss of motivation—is almost certainly the psychic equivalent of physical pain. Major depression, however, is characterized by additional symptoms—such as loss of interest in virtually all activities and suicidality—that have no obvious utility. Given that the principle 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 has two related functions.

First, it could be a costly and therefore honest signal of need to social partners with whom one has severe conflicts. Second, it could function 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 in order 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 these hypotheses, depression is associated with the receipt of considerable social benefits despite the negative reaction it causes in others. This framework also works well for suicidality and deliberate self-harm.

Field sites ▾

Field sites

Associated personnel

Related publications

LNK Gaffney M, Adams K, Syme KL, Hagen EH 2022. Depression and suicidality as evolved credible signals of need in social conflicts. Evolution and Human Behavior.
LNK Smith CB, Rosenström T, and Hagen EH 2022. Strength is negatively associated with depression and accounts for some of the sex difference: a replication & extension. Evolution, Medicine and Public Health.
PDF Hagen EH and Syme KL 2021. Credible sadness, coercive sadness: Depression as a functional response to adversity and strife. Oxford Handbook of Evolution and the Emotions.
LNK Syme KL and Hagen EH 2021. Parent-Offspring Conflict and Bargaining Behaviors in Adolescence and Young Adulthood among Chon Chuuk (Chuukese) Micronesians. Under review.
PDF Syme KL and Hagen EH 2020. Mental health is biological health: Why tackling “diseases of the mind” is an imperative for biological anthropology in the 21st century. Yearbook of Physical Anthropology.
PDF Syme KL and Hagen EH 2018. When Saying “Sorry” Isn’t Enough: Is Some Suicidal Behavior a Costly Signal of Apology? Human Nature.
PDF Hagen EH and Thornhill R 2017. Testing the psychological pain hypothesis for postnatal depression: Reproductive success versus evidence of design. Evolution, Medicine, and Public Health, 1, 17-23.
LNK Rosenström T, Fawcett TW, Higginson AD, Metsä-Simola N, Hagen EH, Houston AI, Martikainen P 2017. Adaptive and non-adaptive models of depression: A comparison using register data on antidepressant medication during divorce.
PDF Hagen EH and Rosenström T 2016. Explaining the sex difference in depression with a unified bargaining model of anger and depression. Evolution, Medicine, and Public Health.
PDF Syme KL, Garfield ZH, Hagen EH 2015. Testing the bargaining vs. inclusive fitness models of suicidal behavior against the ethnographic record. Evolution and Human Behavior.
PDF Hagen EH 2011. Evolutionary Theories of Depression: A Critical Review. Canadian Journal of Psychiatry, 56, 716–726.
PDF Hagen EH 2008. Non-bizarre delusions as strategic deception. In: Medicine and Evolution: Current Applications, Future prospects, Sarah Elton and Paul O'Higgins (eds.). Taylor and Francis.
PDF Hagen EH, Watson PJ and Hammerstein P 2008. Gestures of Despair and Hope: A View on deliberate self-harm from economics and evolutionary biology. Biological Theory, 3, 123-138.
PDF Hagen EH and Barrett HC 2007. Perinatal sadness among Shuar women: support for an evolutionary theory of psychic pain. Medical Anthropology Quarterly, 21, 22-40.
PDF Hagen EH 2003. The Bargaining Model of Depression, In: Genetic and Cultural Evolution of Cooperation, P. Hammerstein (ed.). MIT Press, 95-123.
PDF Hagen EH 2002. Depression as bargaining: The case postpartum. Evolution and Human Behavior, 23, 323-336.
PDF Hagen EH 1999. The Functions of Postpartum Depression. Evolution and Human Behavior, 20, 325-359.