Self-medication behaviour is the use of natural materials or chemical substances to manipulate behaviour or alter the body’s response to parasites or pathogens. Self-medication can be preventive, performed before an individual becomes infected or diseased, and/or therapeutic, performed after an individual becomes infected or diseased. We summarized all available reports of self-medication in mammals and reconstructed its evolution. We found that reports of self-medication were restricted to eutherian mammals and evolved at least four times independently. Self-medication was most commonly reported (...) in primates. Detailed analyses of primates suggest that self-medication is a life-history trait associated with body size, absolute brain size and longevity, but we found no support for the hypothesis that self-medication evolved to reduce the costs of social living. Large, longer-lived species might thus benefit uniquely from self-medication. (shrink)

Effective altruism is a growing humanitarian movement with a track record of success in evaluating the effectiveness of charitable spending across a wide range of projects. We suggest ways in which the foundations of this movement can be applied to the complex world of conservation.

We agree with N. Sekar and D. Shillers (“Engage with animal welfare in conservation,” Policy Forum, 7 August, p. 629) that welfare considerations are an important part of the myriad values in conservation. However, more humane conservation tactics are often costlier. The money and resources spent on humane conservation practices detract from the resources available for other conservation projects. This hidden ethical cost of humane conservation must be considered when proposing new approaches to conservation management.