What can evolutionary theory do for public health?

Evolution is perhaps the most basic scientific theory. Some would say it is the most powerful. And yet its application to health and medicine is vastly underutilised. Evolutionary theory insists we understand the body not as a product of design but of natural selection. As Nesse and Stearns have previously argued, “bodies are vulnerable to disease—and remarkably resilient—precisely because they are not machines built from a plan. They are, instead, bundles of compromises shaped by natural selection in small increments to maximize reproduction, not health.”

Today The Lancet publishes a three-part Series on evolutionary public health. 

It aims to widen appreciation of the value of evolutionary theory for designing public health interventions and for understanding why they often fail. As Jonathan Wells, the Series lead, and colleagues lay out in the  rst paper, evolutionary theory o ers a holistic framework for public health that takes account of individuals’ physiological and behavioural decisions in the context of their life-course trajectories and responses to environmental exposures. The two other papers consider the evolutionary perspective of human reproduction, and how human behaviour and microbes interact to shape our physiology and metabolism.

The Series reminds us that bodies exist to achieve maximal reproductive and genetic  tness, not to be maximally healthy or live long. This natural selection imperative means that caloric expenditure and time must be conserved, which can conflict with health goals. In fact, reproductive success can diminish health outcomes. For example, an initiative in rural Ethiopia working to reduce the energy burden on women carrying large loads of water was expected to improve women’s nutritional status and hence their children’s. Instead, the reduced stress improved women’s fertility, which led to increased malnutrition among their o spring.

The Series may be challenging to public health practitioners vested in action. For those working to advance broader social and political change to enhance public health and reduce disparities, the use of evolutionary theory may feel too reductionistic. We welcome readers’ engagement with and response to this fascinating and thought-provoking Series.  The Lancet