It’s often puzzled me (and, I daresay, many other skeptics and boosters of science- and evidence-based medicine) why various forms of quackery and woo that have either about as close to zero prior probability as you can get and/or have failed to show evidence greater than placebo in clinical trials manage to retain so much traction among the public. Think homeopathy. Think reiki. The former is nothing more than sympathetic magic prettied up with science-y sounding terms, while the latter is nothing more than faith healing given a slant based on Eastern mysticism and religion instead of Christianity. Indeed, reiki was even inspired by stories of Jesus’ healing powers, complete with a trip into the wilderness for fasting and prayer, resulting in revelation. Or consider acupuncture, a modality that is seemingly more popular than ever, even invading the very sanctum sanctorum of the ivory towers of academic medicine, yet every study of which that is done under rigorous conditions with proper placebo controls shows it to be no more efficacious than a placebo. It’s easy enough to shake one’s head and chalk it up to irrationality, ignorance of science, or even religious faith, but I’ve always been dissatisfied with such glib explanations, even though admittedly I have myself used them on occasion.
That’s why a study released last week in PLoS One by Mark M. Tanaka, Jeremy R. Kendal, Kevin N. Laland out of the Evolution & Ecology Research Centre, School of Biotechnology & Biomolecular Sciences, University of New South Wales, the Department of Anthropology, University of Durham, and the School of Biology, University of St Andrews, Fife, respectively, entitled From Traditional Medicine to Witchcraft: Why Medical Treatments Are Not Always Efficacious. Besides loving the title, I also like the methodology, which in essence adapts the tools of modeling evolution and the spread of traits throughout a population and asks the question: Why do ineffective or even harmful (or, as the authors characterize them, “maladaptive”) treatments for various illnesses persist in populations? The results are surprising and counterintuitive, yet ring true. In essence, the authors conclude that the most efficacious self-treatments are not always the ones that spread and that even harmful treatments can spread. Both of these observations are entirely plausible based on the prevalence of usage of common woo and quackery, and what the authors have done, in essence, is to model mathematically why quackery persists.
Indeed, the authors set the stage: