Human Health as a Judicious Conservation Opportunity

In Southeast Asia, smoke from fires used to clear lowland forest drifts downwind to Singapore and other population centers, measurably increasing cardiopulmonary disease (Johnston et al. 2012). Around the world, dams, irrigation projects, and deforestation are associated with significant human exposures to vector-borne diseases such as malaria, dengue, filariasis, onchocerciasis, and Japanese encephalitis (Jobin 1999). These examples highlight a growing appreciation of the links between ecosystem alteration and human health. Until fairly recently, the health community viewed the natural world mostly as a source of disease and disability. This view has changed as the world has begun to recognize the importance of natural systems in the provision of a range of services needed to support human health. Such a position was lent significant weight by the Millennium Ecosystem Assessment (MEA) that mapped out the nature and extent of human reliance on ecosystem services and the ways in which altering natural ecosystems could negatively impact humans. Human health is a global priority and a major source of spending—at a scale that dwarfs conservation spending. For example, in 2006 spending on global health efforts was $45 billion (Garrett 2009), whereas annual global spending on conservation at that time was estimated at $3 billion (Waldron et al. 2013). This level of global investment and the idea that natural systems supply ecosystem services has led some in the conservation community to claim in brochures or on Web sites that biodiversity is a foundation for human health. Despite attempts to link conservation and health, human health and its relationship to natural ecosystems has unfortunately not been the subject of much scientific attention by the conservation community (but see Myers & Patz 2009; Sala et al. 2009; McMichael 2012). As the pendulum swings toward an increasingly human-modified Earth, conservationists are struggling to base their arguments for biodiversity conservation on the significance of relatively intact ecosystems. Facing tenuous support for saving biodiversity, conservation professionals must find new partners who can help make the case for conservation. Such new partnerships should be forged with the human health community, but they need to be based not on convenience or conviction but on sound science and compelling evidence. The cornerstone research question for building this partnership is the relationship between human health and ecosystem intactness. In other words, when, where, and how do the interests of the conservation community and the public health community coincide? Science can help us figure that out. For example, despite the realization that intact ecosystems provide vital goods and services to humans, there are many cases where substantial alterations to ecosystems have resulted in dramatically improved human health. In many cases, the motivation to significantly alter ecosystems for dams, agriculture, and built infrastructure has been to provide cornerstones of health such as clean energy, food security, and better housing. Clearly destruction of ecosystems can be good for human health. We do drain swamps to eliminate malaria. Despite the relative lack of mainstream conservation attention, the relationship between ecosystems and health (human and animal) has drawn considerable attention from the veterinary and public health communities, with new interdisciplinary groups (e.g., One Health, EcoHealth) holding conferences, establishing new journals and initiatives, developing government programs, and creating new funding streams. Important publications have laid out general frameworks on health-ecosystem and environment linkages (e.g., Chivian & Bernstein 2008). The conservation community has been largely left out of these advances. Even our current fascination with ecosystem services has largely omitted careful examination of human health. A recent review paper (Myers et al. 2013) made the case for a new field that focuses on the impacts on human health of anthropogenic alterations to the structure and function of Earth’s natural systems. This field would build on, but be different from, the dose-response epidemiological model that makes up the current environmental health focus on threats such as indoor air pollution and exposure to asbestos or lead paint. It would study what happens as humans replace natural ecosystems that have provided mixes of ecosystem services, including food, safe drinking water, fuel, fiber, and protection from infectious disease, with agricultural lands engineered to maximize food production or engineered infrastructure to manage water supplies. Myers et al. (2013) argue that