Is There an Evolutionary Reason for Depression?

In a recent article from the Health section of the New York Times, author Jonah Lehrer explores the evolutionary connection between natural selection and depression. According to Charles Darwin's--who also suffered from severe depression--Theory of Natural Selection, we all know, that a species evolves over time to possess the traits, both physical and mental, that are strongest. Thus weeding out the weaker members of the species. Lehrer asks in his article why then is something like half the population being treated for depression? Especially when all other mood disorders are exhibited only in a very small portion of society. This causes one to wonder, is there an evolutionary reason for being depressed? Or is it just a huge glitch in the evolution of the human species? Or maybe just misdiagnosis and overmedicating?

Evolutionary Psychology is the school of study which looks at psychology from an evolutionary perspective--in terms of Darwin's theory. Doctors try to explain why the human species is so prone to sadness if it impedes reproduction and the furthering of the species. Clinical depression causes a decrease in sex drive and unfortunately and very frequently, the desire/need/fixation, etc. with taking one's own life. Why would an illness that is so counterintuitive to the well-accepted, well-proven theory of Evolution be so prevalent? I don't think there can be a clear answer. These are not questions that can be easily answered. My inclination is that it's really just our society, our culture and it's inability to deal with emotion. We have become extremely sensitive, especially our generation. Perhaps it is just misdiagnosis. Psychologists, therapists, and psychiatrists are all so eager to put a label on things, that they might jump the gun.

Or maybe, who knows, there really is a reason. It's been said for a long time that in order to know happiness, one must know sadness. Perhaps this is why. Without sadness there would be no love, no art, no beauty in the world. Or maybe the process of Rumination, which Lehrer explains in the article is named after the way in which cows chew and rechew their food. Rumination is the process--one that every person with depression knows of--of constantly milling over negative thoughts in one's head. But maybe they're not actually negative. Perhaps the constant thinking causes the person to adapt. To pick apart what they have done and prevent it from happening again. That is if you can survive the emotional toll of the process.