Taking people as they are: Evolutionary psychopathology, uncomplicated depression, and the distinction between normal and disordered sadness

In this chapter, we review the results of a research program aimed at testing a controversial hypothesis that was generated by an evolutionary approach to psychopathology. The evolutionary approach is in conflict with the standard symptom-based approach to diagnosis utilized by the American Psychiatric Association’s official Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5; American Psychiatric Association (APA), 2013). The conflict arises because many biologically designed features that are part of normal human functioning may be undesirably “symptomatic” or undesirable from our present value perspective. Such problematic normal conditions range from the pain of childbirth and the discomfort of teething to the intensity of grief, anxious vigilance regarding potential threats, and taste for fat and sugar. Evolutionarily shaped features such as these were presumably useful or neutral when they evolved but may be undesirable in our present quite different context. Such features, although often deserving treatment or some other social response (Cosmides & Tooby, 1999), are not necessarily medical disorders simply because they entail suffering or socially disvalued behavior. Distress and perceived need for help also occur in normal conditions in which nothing is going wrong in the organism because evolution has favored fitness over comfort and pleasure. This perspective has implications for the classification, research, and treatment of mental disorders as well as for DSM-5’s nosological distinction between disorders and what DSM-5 lists as “Z Codes,” that is, non-disorders about which clinicians may nonetheless be consulted.