I guess that explains why I'm so adaptable.

It’s a good article.

It’s easy to see how some of the “mental illnesses” might have survival benefits, if not for the individual, then for the village. Those having bipolar e.g. have startling bursts of insight, energy and creativity, beneficial to the group at large, even with the subsequent period of depression. Some prominent leaders are said to have had bipolar disorder, such as Winston Churchill. Obviously you wouldn’t want everyone in the village to be that way.

In “Rethinking Madness” it is posited that schizophrenia is a desperate survival attempt, and that those afflicted usually emerge as deeply aware in a spiritual sense, potentially becoming leaders or teachers.

If a blizzard is going on there is survival value in lying lowly—hiding out in a depressed state until it’s over. This has been pointed out often. Another reason for depression might be that subconsciously a person might know that contemplation and mental analysis is needed to resolve some inner conflict. Thus they awaken in the night, or they devote a lot of time to solitary brooding.