Hypothesized Adaptive Evolutionary Theories of Depression

The incidence of depression is highest among those of reproductive age (25-45) which is common of very few chronic conditions. This leads many to believe that there may be an evolutionary purpose to the manifestation of mild depressive symptoms; that is in fact adaptive as opposed to the common held believe that depression is maladaptive.³

Psychology Pain Hypothesis- Psychological pain many have informed our ancestors that certain circumstances in the social environment (such as that which caused the loss of a family member) could have detrimental physical consequences to them and the others in the community.¹

Honest Signaling Theory- Maintains that the exhibited symptoms of depression, such as crying and loss of appetite or activity engagement, signaled to others in the community that the sufferer needed support.²

Social Navigation Hypothesis- Hypothesizes that depressed individuals will consider a wider range of (including costlier and riskier) possible solutions to a problem than their less-desperate non-depressed fellow community members.¹⁶ Additionally, the loss of pleasure in normal activities may have also served to force the sufferer to focus on fixing the problem by preventing cognitive distractions.³

Bargaining Theory- Depressive signals compel reluctant community members to respond to the sufferer's need in order to ensure their ability to contribute to the community, thus ensuring the sustainability of the community writ large (e.g. if a sufferer no longer does their piece of the communal work, community members would work to alleviate the person's pain in order to make sure they can to the work that will benefit everyone).³

Prevention of Infection- When the symptoms of depression manifest in fatigue and sleep, it is hypothesized that this was a forced-induced rest period necessary for the conservation of energy and re-allocation of that to certain parts of the body (i.e. the immune system).⁴

Analytical Rumination Hypothesis- Depression causes the affected individual to excessively ruminate on solving the problem at hand.⁵ Also, as stated in the social navigation hypothesis, the loss of pleasure in normal activities forces the individual to focus on fixing the problem at hand by preventing cognitive distractions.³

References

1. Neese, R. M (2005). Is Depression and Adaptation? Archives of General Psychology (American Medical Association). 57(1) 14-20. doi: 10.1001/archpsych.57.1.14
2. Hagen, E.H. (2003). The Bargaining Model of Depression. Genetic and Cultural Evolution of Cooperation.
3. Watson, P.J., Andrews, P.W. (2002). Journal of Affective Disorders 72, 1-14.
4. Kinney, D.K. & Tanaka, M. (2009). An evolutionary hypothesis of depression and its symptoms, adaptive values and risk factors. Journal of Nervous and Mental Disease 197, 561-7.
5. Andrews, P.W. & Thompson, J.A. (2009). The Bright Side of Being Blue: Depression as an Adaptation for Analyzing Complex Problems. Psychological Review 116, 620-54.