Darwin Meets Bipolar Disorder

Several years ago I attended a conference on the Bipolar Spectrum of Illnesses. Among the speakers and presentations was a delving into the origins of manic depression. Looking at a genetic predisposition raised the question of why it occurred. Was this mood disorder, back in the dawn of time, somehow adaptive behavior? Several theories were put forth. Here is one I found particularly fascinating:

Back in the Time of Prehistoric Man
Back in the dawn of time, as the seasons changed, so did man’s moods. In the autumn, man became more sluggish and moody. Perhaps in the colder climates of past ages, we were hibernating creatures. Becoming more sluggish led to increased grazing, such that weight was gained and a layer of fat was developed; while at the same time, reducing activity, dozing more and more. Much like a depressive of the current era, depression was characterized by increased sleeping, eating comfort foods, and reduced activity.

After a winter of deep sleep and reduced metabolism, archetypal man used the extra fat he’d gained for the long winter’s sleep and became more alert in the spring. Food gathering became particularly more important and necessary to regain strength and vitality. Man, a hunter, developed a strategy of following and then slaying animals, some of which were much bigger, stronger, and aggressive than he. Requiring a mindset to go along with this hunting activity, man had to be hyper-alert. In some ways, grandiosity was necessary to pit oneself against other animals that could easily maim or kill man quite easily. As well, hunting required tracking an animal over a large area for extended times, so that lack of sleep for days at a time was not only not unusual, but appropriate to survival.

A Theoretic Conclusion
Mania, like depression, may have had an adaptive purpose, and bipolar disorder may have fit into human survival habits before our modern history and technology made it redundant and unnecessary. While depression is a more isolative activity, mania is more social, conducive to group life and motivation, important for hunting in a pack. Excitement is infectious.