An evolutionary perspective on substance abuse

This article describes how recent advances in understanding the evolutionary functions of emotions can help to reconcile diverse approaches to substance abuse. Emotions can be understood as specialized states that prepare individuals to cope with opportunities and threats. Drugs that artificially induce pleasure or block normal suffering disrupt these evolved mechanisms, and thus should tend to interfere with adaptive behavior, even if the drugs are medically safe. Nonetheless, we routinely use drugs quite safely to block defenses like pain, cough, and anxiety. This apparent contradiction is explained by the relatively small costs of defenses compared to the potentially huge costs of not expressing a defensive response when it is needed. An evolutionary perspective has implications for substance abuse research, treatment, and social policy. This perspective suggests that the search for etiology needs to address the human tendency to abuse drugs separately from individual differences in these tendencies, that clinical treatments that take account of the broad range of patients' emotional life are well justified, and that social policies need to address substance use and abuse not as diseases to be cured but as human tendencies that need to be managed. To prepare for future drugs that will likely alter emotions safely, we urgently need a better understanding of the adaptive function of the emotions.