In “Good Reasons for Bad Feelings,” Dr. Nesse—a psychiatrist who has made himself an informed devotee of evolutionary biology—brings his expertise to one of the key questions in biology and medicine: Why are we so vulnerable to mental illness? “Why do mental disorders exist at all?” he asks. “Why are there so many? Why are they so common? Natural selection could have eliminated anxiety, depression, addiction, anorexia and the genes that cause autism, schizophrenia and manic-depressive illness. But it didn’t. Why not?” Photo: WSJ Good Reasons for Bad Feelings
By Randolph M. Nesse
(Dutton, 365 pages, $28)
One possibility is that these conditions only seem to be disorders, and actually serve some evolutionary purpose. Dr. Nesse doesn’t fall into this fallacy: “Hammers are for pounding,” he writes. “Eyes are for seeing. So it seems natural to ask what schizophrenia is for and how anorexia nervosa is useful. But disorders don’t have functions.” Instead they often derive from the misfiring of otherwise functional traits.
The stated goal of Dr. Nesse’s book is to emphasize how natural selection has made the human species susceptible to such misfires and malfunctions. He acknowledges that he does not, as yet, have a tool kit of treatments. But he hopes to help professionals and lay people to better understand mental illness, and along the way provides an illuminating catalog of the evolutionary reasons that explain why we are so vulnerable to disease, physical as well as mental.
First, there’s what he calls “mismatch”—in particular, the human body’s unpreparedness to cope with modern environments. When it comes to physical health, this leads to dietary-related scourges such as coronary artery disease and obesity-related illnesses like diabetes: High levels of fats and sugars were available rarely, if at all, in humanity’s ancestral environments. The same, of course, is largely true for distilled alcohol and a wide array of psychically active chemicals; that’s why Dr. Nesse believes “mismatch” explains much substance abuse.
Then there’s infection. Bacteria, viruses and other pathogens are small, with rapid reproductive rates compared to those of human beings. Their attack strategies thus evolve more rapidly than our defenses do. To cite just one example, the severe psychiatric condition known as Pandas has symptoms that can include obsessive-compulsive tics: The name stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. If only our immune systems evolved as rapidly as streptococci bacteria, this disease probably wouldn’t exist.
Finally, mental disorders can be influenced by factors directly related to the exigencies of evolution. Complicated things like brains tend to be delicate and easily disrupted, whether by trauma, nutritional inadequacy or other “insults” to the system. And every part of the body has advantages and disadvantages: The immune system is crucial but can be too reactive, leading to autoimmune diseases such as lupus or rheumatoid arthritis. Likewise, responding to threats is a highly adaptive behavior useful to humans, but an overfunctioning threat-detection system can manifest as paranoia.
As Dr. Nesse helpfully analogizes, “Most of the responses that cause human suffering are unnecessary in the individual instance but still perfectly normal because they have low costs but protect against huge possible losses. They are like false alarms from smoke detectors. The occasional wail when you burn the toast is worth it to ensure that you are warned early about every real fire.” Similarly, anxiety syndromes, including panic attacks, can be understood as cases in which the Smoke Detector Principle leads to troublesome outcomes. “In a city where car theft is common,” Dr. Nesse explains, “a sensitive car alarm system is worthwhile despite the false alarms, but in a safer locale it would be just a nuisance.“
Normalcy, in short, involves a kind of Goldilocks principle, in which mental states alternate between too much and too little—a balancing act as demanding as it is crucial. This insight leads the author, in turn, to a thoughtful consideration of what moods are “for.” The question at first seems unnecessary, but once pondered, leads to intriguing realizations. We could in theory pursue our days in a steady state, but there seem to be some benefits ascribable to excessively low and high moods (i.e., depression and mania).
Dr. Nesse’s book is not just about evolution; it’s also about psychiatry—a discipline the author believes to be in a sorry state. “Like the six blind men each touching a different part of an elephant,” he writes, “each different approach to mental disorders emphasizes one kind of cause and a corresponding kind of treatment. Doctors who look for hereditary factors and brain disorders recommend drugs. Therapists who blame early experience and mental conflicts recommend psychotherapy. Clinicians who focus on learning suggest behavior therapy. Those who focus on distorted thinking recommend cognitive therapy . . .” And so on. Dr. Nesse has found that, when sufferers can recognize the origin of their conditions not in their own past but in the happenstance of natural selection, it often helps them grapple with their problems.
All psychiatrists and patients who find themselves having occasional “bad feelings” about our current understanding of mental illness will have many “good reasons” to consult this book. I do fully expect that someday nearly all psychiatry will be identified as evolutionary psychiatry. If so, Randolph Nesse’s book should be seen as the field’s founding document.
Mr. Barash is professor of psychology emeritus at the University of Washington. His most recent book is “Through a Glass Brightly: Using Science to See Our Species as We Really Are.”
Click here to view original web page at ‘Good Reasons for Bad Feelings’ Review: Suffering’s Silver Lining