One of my friends came across a fascinating little article on depression: Can depression, anxiety, and somatization be understood as appeasement displays? (Journal of Affective Disorders, 2003, Volume 1). Basically, the authors argue that depressive and anxious mood states, fatigue syndrome, and somatoform disorders resemble the kinds of appeasement displays that animals show when they want to signal their submission (and, therefore, avoid conflict). If these appeasement displays were adaptive for these animals (and, by extension, to our human ancestors), then perhaps this mode of dealing with conflict remains with us on some primitive level. It is interesting, for example, that the symptoms of depression in humans often include feelings of powerlessness, of being defeated, or of just wanting to give up.

The authors suggest that two ancient parts of the human brain (the "reptilian brain" including the limbic system and basal ganglia) controlled the trigger of appeasement displays as modes of coping. Today, however, we also have a newly developed cerebral cortex which is capable of dealing with situations in a more rational matter (e.g., using verbal dialogue to resolve a conflict, or even to signal defeat without using depression/anxiety as an appeasement display). However, since this part of the brain is so recent, it has still not developed to such an extent that it is activated as frequently, or more frequently, than the more ancient, reptilian part of the brain.

The authors suggest that many theories of depression are related to such issues as separation and loss. Because separation reactions are present in mammals (i.e., those with more than simply a reptilian brain), then mood is controlled by higher brain centers. However, they cite evidence that electrical stimulation of the basal ganglia (part of the reptilian brain) can also induce depression. Here we have the suggestion that depression may be an appeasement display because it can be induced by a part of the brain that can respond specifically to threat. The problem I have with this is that the authors contend that only one part of the brain is primarily responsible for inducing depression. Does this mean that depression can't be induced by other parts of the brain, for reasons other than appeasement display, and via other mechanisms? While I don't want to discount the appeasement display idea, I also don't want to be wed to the idea that there is one major, overarching cause of depression/anxiety/etc. While elegance in explanation may be attractive, sometimes overarching evolutionary explanations can be too exclusive.

The authors suggest that interpersonal therapy can help depressed/anxious people by teaching how to more effectively draw on the cognitive resources of the relatively newer, rational part of the brain. I find this idea to be quite fascinating. However, for the most part, I don't really see why the cause of depression/anxiety is important. In the Rogerian, non-directive mode, positive results are achieved for a whole array of troubling emotions, moods, and behaviours, with little attention paid to the actual causes. If unconditional positive regard, empathy, and therapist congruence and genuineness can by themselves help people draw on their own internal resources in order to achieve maximal growth and self actualisation (and, hence, shed the need for depression/anxiety), digging for the specific causes of conflict and thwarted development becomes little more than a topic of academic or philosophical interest (at least for the person experiencing the thwarted development).

However, if I had to, I would argue that even the concept an evolutionarily-based depressive/anxious appeasement display fits within the framework of humanistic therapy: "I can't express my true feelings, and, hence, be who I truly am, so I'll just revert to a depressive/anxious submissive stance as a defensive maneuver".

(See also my 25 March 2003 entry on the 'causes' of depression).