Could mental illnesses be caused by the mismatch between our present environment and the one for which we are adapted?
Evolutionary psychologists argue that to understand the brain properly, we must understand the environment in which the brain evolved and was shaped. They believe memory, perception, and language all are the products of natural selection.
Psychiatrists who subscribe to this view also have developed the field of evolutionary psychopathology — a new take on abnormal psychology from the perspective of evolution.
J. Anderson Thomson Jr., M.D., of the University of Virginia has found this approach helpful in treating depression. He believes that, though it appears to be all cost and no benefit, major depressive disorder might be “a psychological adaptation engineered by natural selection to help individuals resolve complex, socially-imposed stresses that could affect long-term fitness.” It does so by “signaling need and compelling help from reluctant others,” he said. Drug monotherapy may not be enough. Instead, Thomson recommends that physicians ask about the patient’s social conflicts and “become tenacious advocates for their resolution.”
Professor Randolph M. Nesse of the University of Michigan agrees. A pioneer of the movement, he currently is investigating how and when mood disorders provide an advantage. In his opinion, some cases of depression are an extreme version of a system that adapted to “disengage motivation when an organism is engaging in efforts that will not pay off.”
Such situations may well be much more common for humans nowadays than they were in ancestral times, because many of us pursue large goals with uncertain payoffs. For Professor Nesse, therapy would include going over the patient’s life goals in order to find out if an unreachable goal is the root of his or her depression.
Edward H. Hagen of Humboldt University in Berlin also is a proponent of evolutionary psychology, although he concedes that it is not without major problems. For example, researchers cannot directly study complex neural circuits, so it is hard to “unveil the workings of the brain.” A clear idea of the environment which evolutionary psychologists believe we are adapted for does not exist. And such adaptations would have to be shown in humans around the globe to be confirmed.
Nevertheless, Hagen argues that the theory may explain depression, suicide attempts and deliberate self-harm as rational bargaining tactics to gain assistance from others.
The evolutionary psychology theory has come in for criticism from many directions. It contains widely divergent theories and a broad range of treatment recommendations based upon them. Some experts have asked why natural selection seems unable to eliminate predispositions to mental disorders, such as schizophrenia or bipolar disorder.
Matthew C. Keller, a postdoctoral fellow at the Virginia Commonwealth University, looked for a plausible answer. He explored three potential ideas about such predispositions: that they were not harmful for our ancestors; that they sometimes may have boosted survival; and that they are inevitable given the complexity of genes influencing our behavior.
Only the third explanation “seems consistent with the data on mental disorders,” Keller said, pointing to the relatively small prevalence of serious mental disorders, the “costs” they carry for survival, and the fact they can be triggered by events such as brain damage.
Another major area of disagreement in evolutionary psychology is the ‘nature/nurture’ question. Can many cases of depression, anxiety, and addiction be explained solely by a patient’s present social environment?
Daniel Nettle Ph.D of the University of Newcastle, UK believes so. He highlights the importance of the modern environment, offering situations in which we pay the psychological price for behaving in line with our underlying nature, adapted to a very different world.
He gives the example of channeling previously beneficial risk-taking behavior into modern-day gambling, and the negative financial and emotional consequences this can bring.
For therapists who see a value in evolutionary psychology, many avenues of treatment can be explored. Evolution-based therapies to date include a focus on how our current lifestyle differs from that of our ancestors, and tackles inactivity, social isolation, sleep deprivation, overwork, and bad diet. To remedy this, we need more aerobic exercise, nutritious food, natural light, social interaction, and sleep — with which psychologists of all persuasions would agree.
Other treatment tackles the consequences of previous trauma and stressful circumstances. Avoiding self-criticism and learning compassion and the evolutionary basis of negative mood are central to this approach. One such practitioner, Shani Robins of the Institute for Wisdom Therapy in San Diego, says that understanding the evolutionary origin of problems can help patients put them in perspective.
“Anger, for instance, serves the adaptive functions of focusing our attention on interpersonal antagonisms, social conflict, cheating and injustice,” he writes. “Fear, anxiety and stress, on the other hand, focus our attention towards risks and the necessity of precaution.”
Looked at from this standpoint, the patient judges him- or herself less harshly and symptoms often reduce.
Hagen E.H., Watson P.J., and Thomson J.A. Love’s labour’s lost: Depression as an evolutionary adaptation to obtain help from those with whom one is in conflict. As yet unpublished.
Keller M. C. and Miller G. Resolving the paradox of common, harmful, heritable mental disorders: Which evolutionary genetic models work best? Behavioral and Brain Sciences, Vol. 29, August 2006, pp. 385-404.