The adaptive significance of self-medication

Not all pharmacists are human; other species also use medicinal substances to combat pathogens and other parasites. Self-medicating behaviour is a topic of rapidly growing interest to behaviourists, parasitologists, ethnobotanists, chemical ecologists, conservationists and physicians. Although most of the pertinent literature is anecdotal, several studies have now attempted to test the adaptive function of particular self-medicating behaviours. We discuss the results of these studies in relation to simple hypotheses that can provide a framework for future tests of self-medication.