Evolutionary Approach Highly Informative but Should Not Be Overstated

Abstract

Dear Editor: I thank The CJP for its thought-provoking issue examining evolutionary explanations for mental illness and, in particular, Dr Edward H Hagen's fascinating article on depression.1 My patients often find it helpful when their symptoms are presented within an evolutionary context as adaptive mechanisms that are malfunctioning in some way. However, one issue I would like to call attention to is that significant evolutionary change in humans occurs on large time scales (that is, many generations or millennia).2 Therefore, it is plausible that current behaviours appearing to be maladaptive were adaptive for our ancestors tens of thousands of years ago but may no longer be useful for modern life. A trivial example would be children's fear of the dark, which may have protected them from nocturnal predators in ages past but currently serves only to make bedtime more difficult. Let us examine the 2 behaviours that Dr Hagen highlights as possibly adaptive - excessive rumination and suicidality in response to a Stressor. Ruminating about a problem until a solution presents may have been a relatively straightforward process in our ancestors whose cognitive sophistication and options for addressing problems were much more limited than our own. In contrast, presentday patients with depression can end up in complicated, often futile ruminative cycles that are actively counterproductive. Regarding suicidality, one might imagine that an aggressive response to a Stressor could have been adaptive for earlier humans fighting for social status or resources. Suicidality may represent this kind of aggression maladaptively turned inwards. Excessive rumination and suicidality are serious, debilitating symptoms with the latter potentially fatal. It seems at least as likely that they reflect a mismatch between the needs of modern humans and those of our recent ancestors than behaviours that should be considered healthy or adaptive at present. On a separate note, Dr Hagen is absolutely correct that depression may represent a cry for help and that we need to do a better job of addressing its precipitants. But even if it has adaptive underpinnings, depression is clearly a source of true suffering and its theoretically adaptive value is an insufficient argument for withholding antidepressants or other treatments that may provide relief. Even if it has adaptive origins, we are not going to stop treating suicidality. We need to be careful to use evolutionary theory for its capacity to explain human behaviour rather than as a source of normative ethics. As scientists, we can certainly work toward understanding the use of some depressive symptoms, but as healers, when patients come to us for help, we must also seek to alleviate their suffering, adaptive or not.