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Aversive medical treatments signal a need for support: a mathematical model

  • Mícheál de Barra (a1), Daniel Cownden (a2) and Fredrik Jansson (a3) (a4)


Ineffective, aversive and harmful medical treatments are common cross-culturally, historically and today. Using evolutionary game theory, we develop the following model to explain their persistence. Humans are often incapacitated by illness and injury, and are unusually dependent on care from others during convalescence. However, such caregiving is vulnerable to exploitation via illness deception, whereby people feign or exaggerate illness in order to gain access to care. Our model demonstrates that aversive treatments can counter-intuitively increase the range of conditions where caregiving is evolutionarily viable, because only individuals who stand to gain substantially from care will accept the treatment. Thus, contemporary and historical “ineffective” treatments may be solutions to the problem of allocating care to people whose true need is difficult to discern.

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This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (, which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.

Corresponding author

*All authors contributed equally.
Corresponding author. Centre for Culture and Evolution, Room 110, Marie Jahoda Building, Brunel University London, Uxbridge UB8 3PH, UK. Email:


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Aversive medical treatments signal a need for support: a mathematical model

  • Mícheál de Barra (a1), Daniel Cownden (a2) and Fredrik Jansson (a3) (a4)


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