Evolutionary medicine attempts to solve a problem with which traditional medicine has struggled historically; how do we distinguish between diseased states and “healthy” responses to disease states?

Fever and diarrhea represent classic examples of evolved adaptations that increase the likelihood of survival in response to the presence of pathogens in the body. Whereas, the severe mental disorders like psychotic mania or the schizophrenias may involve true “disease” states best treated pharmacologically, most non-psychotic “disorders” that revolve around negative affects like depression or anxiety are likely adaptations that evolved to serve a function that increased inclusive fitness in our ancestral past.

What this likely means is that the proximal mechanisms underlying the non-psychotic “disorders” are “species typical” and neither diseases nor disorders. Rather, they are coordinated “whole body” responses that prepare the individual to respond in a maximally functional fashion to the variety of different challenges that our ancestors faced.

A case can be made that depression evolved to facilitate a deliberate cognitive style (rumination) in response to complex (often social) problems. What this further suggests is that those interventions that best facilitate the functions that those adaptations evolved to serve (such as rumination) are likely to be preferred over those like medications that simply anesthetize the distress.

We consider the mechanisms that evolved to generate depression and the processes used in cognitive behavior therapy to facilitate those functions from an adaptationist evolutionary perspective.

Introduction
Why Do People Have Painful Feelings?

It Is All About the Squids and the Sea Bass
What Is the Evidence that Melancholia Is an Adaptation?
What Is the Content of Rumination and What Is Its Function?
What Is the Relationship Between Rumination and Spontaneous Remission?
Why Do Depressed People Often Have Recurrences?
Does CBT Disrupt Rumination or Make It More Efficient?
Stigmatize Vs. Validate?
Is It Better to Treat Depression With [antidepressant medications] ADM or CBT?
Why Do Depressed People Often Have Inaccurate Beliefs?
Summary And Conclusions