Depression and Survival of The Species

Excerpted from Depression Not Adaptation.

Every so often I see the argument that psychological depression is common because it evolved for a purpose. Usually the idea is that depressive symptoms bring social benefits to the sufferer, as "honest signals" of mental hardship. Less commonly, I see other hypotheses, such as the idea that depression gives people a "breather" to work out their problems. I don't think any of these are convincing, because they don't demonstrate the fitness advantages of the behavior.

Why do deer freeze in your headlights? I think human depression represents the same sort of frozen decision making, future shock, if you will, sensory overload, if you prefer. That humans have a high degree of awareness of their circumstances lends overload to become a form of incapacity, a depression.

And, to answer the question presented in the article.....

The evolutionary calculus for depression—as for any psychological “adaptation”—demands an answer to this question: how does that condition affect your expected number of offspring?

...well, that question has as many answers as there are grains of sand; or least as many answers as there, have and will be people.