From traditional medicine to witchcraft : why medical treatments are not always efficacious
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Complementary medicines, traditional remedies and home cures for medical ailments are used extensively world-wide, representing more than US$60 billion sales in the global market. With serious doubts about the efficacy and safety of many treatments, the industry remains steeped in controversy. Little is known about factors affecting the prevalence of efficacious and non-efficacious self-medicative treatments. Here we develop mathematical models which reveal that the most efficacious treatments are not necessarily those most likely to spread. Indeed, purely superstitious remedies, or even maladaptive practices, spread more readily than efficacious treatments under specified circumstances. Low-efficacy practices sometimes spread because their very ineffectiveness results in longer, more salient demonstration and a larger number of converts, which more than compensates for greater rates of abandonment. These models also illuminate a broader range of phenomena, including the spread of innovations, medical treatment of animals, foraging behaviour, and self-medication in non-human primates.
Tanaka , M M , Kendal , J R & Laland , K N 2009 , ' From traditional medicine to witchcraft : why medical treatments are not always efficacious ' PLoS One , vol 4 , no. 3 , e5192 . DOI: 10.1371/journal.pone.0005192
© 2009 Tanaka et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The work was supported by the Research Councils UK, Biotechnology and Biological Sciences Research Council UK and the European Union. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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