Limits...
From traditional medicine to witchcraft: why medical treatments are not always efficacious.

Tanaka MM, Kendal JR, Laland KN - PLoS ONE (2009)

Bottom Line: With serious doubts about the efficacy and safety of many treatments, the industry remains steeped in controversy.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.

View Article: PubMed Central - PubMed

Affiliation: Evolution & Ecology Research Centre, School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia. m.tanaka@unsw.edu.au

ABSTRACT
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.

Show MeSH
The effect of abandonment and conversion rates on the probability of spread.A density plot showing the treatment with the highest probability of spreading  as a function of  and the relative rate of conversion during healthy and sick periods (), colour boundary range {−5,17.5;±2.5} (low values, dark). Unless otherwise stated , , , , , , ,  and  (see Methods for interpretation of parameter values).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2664922&req=5

pone-0005192-g006: The effect of abandonment and conversion rates on the probability of spread.A density plot showing the treatment with the highest probability of spreading as a function of and the relative rate of conversion during healthy and sick periods (), colour boundary range {−5,17.5;±2.5} (low values, dark). Unless otherwise stated , , , , , , , and (see Methods for interpretation of parameter values).

Mentions: Generally, highly efficacious treatments have higher cultural fitness than superstitious/maladaptive traits in multiple-episode cases, but nonetheless superstitious treatments ( close to 0) can spread. Superstitious and maladaptive practices are most likely to spread where treatments are primarily demonstrated in sickness (i.e. a low ratio of ) and low abandonment (), particularly where relapse is unlikely ( small). Figure 6 illustrates this principle through a density plot of the with highest probability of spread as a function of and the relative rate of conversion during healthy and sick periods ().


From traditional medicine to witchcraft: why medical treatments are not always efficacious.

Tanaka MM, Kendal JR, Laland KN - PLoS ONE (2009)

The effect of abandonment and conversion rates on the probability of spread.A density plot showing the treatment with the highest probability of spreading  as a function of  and the relative rate of conversion during healthy and sick periods (), colour boundary range {−5,17.5;±2.5} (low values, dark). Unless otherwise stated , , , , , , ,  and  (see Methods for interpretation of parameter values).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2664922&req=5

pone-0005192-g006: The effect of abandonment and conversion rates on the probability of spread.A density plot showing the treatment with the highest probability of spreading as a function of and the relative rate of conversion during healthy and sick periods (), colour boundary range {−5,17.5;±2.5} (low values, dark). Unless otherwise stated , , , , , , , and (see Methods for interpretation of parameter values).
Mentions: Generally, highly efficacious treatments have higher cultural fitness than superstitious/maladaptive traits in multiple-episode cases, but nonetheless superstitious treatments ( close to 0) can spread. Superstitious and maladaptive practices are most likely to spread where treatments are primarily demonstrated in sickness (i.e. a low ratio of ) and low abandonment (), particularly where relapse is unlikely ( small). Figure 6 illustrates this principle through a density plot of the with highest probability of spread as a function of and the relative rate of conversion during healthy and sick periods ().

Bottom Line: With serious doubts about the efficacy and safety of many treatments, the industry remains steeped in controversy.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.

View Article: PubMed Central - PubMed

Affiliation: Evolution & Ecology Research Centre, School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia. m.tanaka@unsw.edu.au

ABSTRACT
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.

Show MeSH