Evolutionary purpose of depression

Evolution can explain why do we do certain things not others, why do we behave in a certain way or even why do we like the things we like, but when we put the evolutionary lens on depression, things get confusing real quick; because why would natural selection keep a behavior that can reduce fertility and increase chances of suicide? This goes against everything that we learned in the biology class. Listen to the entire audio to understand what might have been the evolutionary benefit of depression and how it actually saves our life. This is 3 of 3 podcast from the new series on depression. Podcasts in this series: 1. What is depression: Symptoms, causes & treatment 2. Depression diet: Metabolic typing, studies & grocery list 3. The evolutionary purpose of depression