Most globally popular drugs are plant neurotoxins or their close chemical analogs. These compounds evolved to deter, not reward or reinforce, consumption. Moreover, they reliably activate virtually all toxin defense mechanisms, and are thus correctly identified by human neurophysiology as toxins. Acute drug toxicity must therefore play a more central role in drug use theory. We accordingly challenge the popular idea that the rewarding and reinforcing properties of drugs “hijack” the brain, and propose instead that the brain evolved to carefully regulate neurotoxin consumption to minimize fitness costs and maximize fitness benefits. This perspective provides a compelling explanation for the dramatic changes in substance use that occur during the transition from childhood to adulthood, and for pervasive sex differences in substance use: because nicotine and many other plant neurotoxins are teratogenic, children, and to a lesser extent women of childbearing age, evolved to avoid ingesting them. However, during the course of human evolution many adolescents and adults reaped net benefits from regulated intake of plant neurotoxins.
Keywords: pharmacophagy, zoopharmacognosy, drug reward, evolution, self-medication, evolutionary medicine
Citation: Hagen EH, Roulette CJ and Sullivan RJ (2013) Explaining human recreational use of ‘pesticides’: the neurotoxin regulation model of substance use vs. the hijack model and implications for age and sex differences in drug consumption. Front. Psychiatry 4:142. doi: 10.3389/fpsyt.2013.00142
Received: 28 June 2013; Accepted: 12 October 2013;
Published online: 05 November 2013.
Edited by:Hanna Pickard, University of Oxford, UK
Reviewed by:Serge H. Ahmed, Centre national de la recherche scientifique, France
Copyright: © 2013 Hagen, Roulette and Sullivan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Edward H. Hagen, Department of Anthropology, Washington State University, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686-9600, USA e-mail: firstname.lastname@example.org