Sustaining Life: How Human Health Depends on Biodiversity

Editors: Eric Chivian and Aaron Bernstein

Reviewed By: John F. Pearson

If you wonder: "Humans are so small, isn't it arrogant to assume we could be affecting something so large as the entire planet?" then the first section of Sustaining Life, with its treatment of subjects as broad as ozone depletion, invasive species, and war, will serve as a resounding answer that yes, human actions are impacting the world around us. What distinguishes Sustaining Life from many of the ecologically-focused narratives of the environmental community is that it demonstrates the inseparable nature of human and environmental health through the use of well-documented research, a myriad of controlled experiments, and countless intriguing anecdotes.

In the popular imagination, the link between biodiversity and human health is often seen as the potential loss of new therapeutics from destruction of tropical rainforests. Sustaining Life provides an in-depth account of the science and medicine behind this common conception, but also shows that our environmental dependence is not limited to extracting cures from diversity-rich areas. Perhaps less appreciated from a health perspective are the numerous free services, "Ecosystem Services," that humanity derives from nature such as clean air, clean water, flood mitigation and more.

While these services are vital to our continued presence on this planet and well-detailed through citations of numerous peer-reviewed studies, Sustaining Life hits its stride when it begins to contrast global benefits from ecosystems with the unexpected drawbacks of ecosystem degradation, such as outbreaks of infectious diseases. There are many examples, from how malaria tends to spread more at forest edges, to how habitat degradation plays a key role in the spread of Lyme disease in the United States. One underlying theme appears to be that reductions in biodiversity, whether of hosts or the ecosystem itself, favor the generalist vectors that utilize many species, including humans, to facilitate the spread of disease. Understanding this process is crucial for future physicians: International and domestic health projects cannot rely on medication and healthcare access alone to eliminate infectious diseases. The vital role of healthy ecosystems and land use patterns must be taken into account.

Later, Sustaining Life brings the global and wide-ranging impacts of humanity back to the dinner plate through a detailed discussion of the impact of food supplies on biodiversity and health. Cases such as the prophylactic use of antibiotics in chickens resulting in drug-resistant Campylobacter jejuni diarrhea outbreaks in humans give new meaning to the "free range" and "antibiotic free" labels in the supermarket. In the discussion of the direct health effects of consuming conventionally farmed foods (with pesticides and herbicides), the authors point out in "Precautionary Principle" style, that the long term effects are largely unknown, and virtually no studies examined the combination of various chemicals present in much of the conventional food supply. This ability to elucidate the current limits of our research and understand what to do next is one of the strengths of the book.

The final chapter provides some antidotes to the crushing awareness of the first two by providing tools for individuals to live more sustainability in nearly every aspect of their lives: from food choices, to transportation, to energy use and ways we can support organizations that conserve wildlife. The plethora of resources here should provide any conscientious individual with the the first steps to living a more sustainable and engaged life. While these actions are important, and future physicians and health professionals should seek to live a moral, sustainable life by example, the text itself integrates myriad case studies and success stories while discussing the dangers of conventional practices.

Sustaining Life is a handbook for physicians, public health officials, health practitioners, and students worldwide to understand how their patients health truly is part of the planet, both locally and globally. And such a handbook is desperately needed as current models of medical education tend to exclude this information altogether. While there are a variety of reasons for this, ranging from NIH funding to general lack of available expertise, the need to understand and tackle such problems is made dramatically clear by the over 300 expert authors of Sustaining Life. Students, as inheritors of the planet and our global healthcare system, clearly have a vital role to play in ensuring that our medical education takes the necessary steps to lead our species into a sustainable future.