Evolutionary Value of Depression

Depression is awful.  It takes all the meaning and joy out of life, it reduces our capacity to care for, or even defend ourselves, and it can lead to an endless downward spiral leading to years of anhedonia and even suicide.  So why would anyone want to talk about any value of depression?

Scholars who take an evolutionary approach to diseases like depression look for adaptations that might have made our ancestors’ lives easier – adaptations that have become a part of all of our lives and brain patterns.  From this perspective, depression may have its roots in something useful, an insight that has profound consequences for how depression is treated.

Feelings of sadness or “low mood” may be a part of our repertoire for a number of reasons.  All these are hypotheses that lack real proof, but all of them show some hopeful results that could lead to a complete re-evaluation of depression and its treatment.

Paul Andrews and Anderson Thompson at the University of Virginia have developed a theory that extreme rumination which is triggered by a tragic or traumatic event may be an adaptive mechanism for dealing with reversals, even if the rumination leads to clinical depression.  Patients can use the period of rumination to ponder how they will move forward in life while the depression actually insulates them from distractions.

This “analytical rumination hypothesis” can, of course, be criticized on a number of grounds.  Mostly, it only accounts for a small subset of depression, and leaves out of consideration depressions that have no clear starting point, or that fail to lift for a lifetime.  Andrews and Thompson acknowledge this argument, but they say in response that the point is that sadness or negative feelings may not have to always be seen as pathological.  Culturally, perhaps we are too anxious for everyone to be happy and therefore see sadness as something that automatically needs treatment, when we could take into consideration the possibility of “healthy sadness” or “healthy low moods”.

How to draw the line between “healthy” and “unhealthy” sadness is, it should be obvious, a question that will invite years of debate.  Still, it’s an interesting question, and just asking it shows that we are beginning to move beyond the equation of mental health with happiness.

There are several other theories about the adaptive functions of sadness and low mood.  Some consider that people who are under “social adversity” may become depressed in order to lower the likelihood that they will risk reaching out, under adverse circumstances, and therefore lose even more face or social capital than they had at the outset.  A variant of this theory looks at the prevalence of depression particularly in women of childbearing age, and considers the need for extended care of human infants, compared with other animals.  An adaptive type of low mood, therefore, would keep new mothers near home to insure care for their most vulnerable offspring.

Another theory considers sadness as a kind of surrender to a person or group of greater power or hierarchical status.  Thus, showing sadness tells the more dominant person that you accept the hierarchy and are willing to play a subordinate role in it.  A variant of this view looks at different types of sadness used in different circumstances, for example, crying is more common, and more adaptive, in response to bereavement, while pessimism and fatigue, which would conserve resources and decrease initiative, would be more prominent in response to failure, stress, and wintertime.

These academic debates, and others, are of importance to our growing understanding of major depressive disfunction, but any real-world effects of the work may be a long way off.  However, the suggestion that major depression should be understood as a dysfunction of healthy sadness does have immediate clinical implications.  Maybe clinicians should be focusing on restoring healthy sadness rather than on eliminating sadness from our lives altogether.

Nancy

References:

Hagen, E.H. Evolutionary Theories of Depression: A Critical Review.   Can J Psychiatry. 2011;56(12):716–726. doi/pdf/10.1177/070674371105601203

Andrews, P. W., & Thomson, J. A., Jr. (2009). The bright side of being blue: Depression as an adaptation for analyzing complex problems. Psychological Review, 116(3), 620–654. https://doi.org/10.1037/a0016242