An Upside to Depression? A Darwinian Perspective

John McManamy Health Guide
  • Perhaps some of you have figured out this riddle: If depression is heritable, what are its selective advantages? How could such a disadvantageous condition be passed on from generation to generation?


    As I see it, there are two possible answers to this question, and both have to do with a branch of evolutionary biology called evolutionary psychology. The first answer is that depression is actually a positive adaptive trait, or at least one whose advantages outweigh its disadvantages. Thus, without depression, our species never would have made it past the Stone Age. 


    The second is that depression is the price of a highly complex brain capable of doing extraordinary things. Both answers are related.

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    According to evolutionary biologist Randolph Nesse of the University of Michigan, we will never understand mental illness if we simply think of it as abnormal. In 2005, I heard Dr Nesse speak on the topic at the American Psychiatric Association annual meeting. Using anxiety as an example, he asked us to imagine a distant ancestor at an ancient watering hole. He hears a sound behind him. A lion? A mouse?


    We are wired to panic first and think about it later. That way we live long enough to get an opportunity to pass down our genes - anxious ones and all - to the next generation.


    According to Dr Nesse, if we think of our limbic system as a smoke detector, we are programmed for a thousand false alarms. Better to be safe than sorry. One can make a case that our stone age brains are ill-equipped to face modern world challenges. Yet, healthy anxiety is how we get through the day. It’s perfectly all right to be anxious in traffic or during a meeting.


    But then we can be too anxious for our own good. Nevertheless, anxiety in and of itself is not bad.  


    So what about depression? What could possibly be good about depression? We are entering the realm of speculation, but here are some possibilities:


    Depression is when the rose-colored glasses come off. We think as realists. We don’t take unnecessary risks. We don’t go off on wild goose chases. That way, we may just survive long enough to make a contribution to our genetic future.


    I like to think of depression as part of our healing, a sort of forced time-out. It is the psychic pain that tells us that we need to stop whatever crazy things we are doing so we can allow our brains to rest. Time is the healer. Unfortunately, our modern world doesn’t appreciate this. Tied into this is the idea that depression is part and parcel of the ancient hibernation reflex. We need to occasionally shut down, we need to conserve our energy.


    So can there be a such things as a healthy depression? Most definitely. A slowed-down brain is not always a bad thing. Indeed, life can be a lot more manageable in this state.


    But then, we can be too depressed for our own good. We all know what that is like. But again, depression in and of itself is not necessarily a bad thing. What evolutionary psychology teaches us is that we need to be listening to our depressions. If we are in a bad relationship or a toxic work environment our depression may be telling us we need to make some serious changes. Now, before it’s too late. Before our brains (or our hearts or something else) completely collapse under the strain. 


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    The other way of looking at depression is that it is the price we pay for a highly complex brain. Evolutionary biologists refer to this as a trade-off. For instance, vulnerability to sickle-cell anemia may be the price for protection against malaria (the same variation in a particular gene regulates both). To gain insight into this, we need to understand the mechanics of evolution:


    Unlike say aeronautics, we simply can’t scrap the old bi-wing propeller plane and substitute a new jet aircraft. Evolution is all about adding stuff to our 1903 Wright Brothers flying machine. Thus, we basically have three brains - reptile, mammalian, and neo-cortex. It’s pretty amazing, when we think of it, but no one would exactly design a brain like this from scratch. Depression happens.


    To reconcile the two possibilities: Despite the obvious negatives, there are positives to depression. Our recovery and healing depends in large part upon listening to our depressions. Likewise, brains as complex as ours are capable of breaking down, especially ones that carry certain genetic vulnerabilities (say to stress). Thus the need for good brain maintenance. Again, we listen to our depressions.


    In short, if we accept depression as something we learn to live with rather than as a scourge that must be eliminated at any cost we may be in a better position to deal with it. Certainly, we can begin with the proposition that indeed our depressions are valid and work from there.


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Published On: April 30, 2013