"There's such a fundamental misunderstanding that most people have about the environment—that it exists outside of us," said Harvard Medical School's Eric Chivian at the January 14, 2009, launch of Sustaining Life: How Human Health Depends on Biodiversity, which he co-edited. This disconnect "is really at the heart of the global environmental crisis, and it's the reason we wrote this book." Chivian was joined by the Natural Capital Project's Michael Wright and the Heinz Center's Thomas Lovejoy, who called Sustaining Life "a remarkable achievement," for a discussion of the myriad ways in which biodiversity benefits human health—and how its loss endangers us.
Proof Positive: Biodiversity Supports Health
The most exotic—and unlikely—species can yield valuable discoveries, Lovejoy explained. For example, slime molds on the banks of the Zambezi River repel their enemies with chemicals that can treat cancers resistant to Taxol, one of the main chemotherapy drugs—which is itself derived from the needles and bark of the Pacific yew tree. Chivian offered another remarkable example: The best new pain medication, which is 1,000 times more powerful than morphine, is derived from the toxins of marine cone snails.
Of Polar Bears and Parasites
Polar bears—which new research suggests are likely to be extinct in the wild by 2100 due to the melting of the Arctic ice sheet—may help cure several devastating diseases. Polar bears "den," or near-hibernate, for five to nine months of each year, yet substances in their blood prevent them from losing bone mass during that time. "Osteoporosis is an enormous public health problem; it kills some 70,000 people in the United States every year, costs the U.S. economy $18 billion dollars a year," explained Chivian.
When they den, polar bears go for months without eating, drinking, defecating, or urinating. Studying this phenomenon may provide humans with alternatives to dialysis or kidney transplants. Finally, while polar bears are extremely obese, they do not develop Type II diabetes. In contrast, 16 million Americans—6 percent of the population—have obesity-related Type II diabetes, costing the United States $91 billion a year. "Again, polar bears may hold the secret for treating this very difficult and lethal disease," said Chivian.
Not only can certain species help us treat human diseases, but the loss of biodiversity can increase the prevalence of others. For instance, Lyme disease is more common in degraded environments with low vertebrate diversity. In these environments, the disease spreads more quickly because the white-footed mouse—the best vector for Lyme disease—has fewer predators and competitors for food.
Better Safe Than Sorry
By providing dozens of concrete examples of how we depend on and benefit from the environment, Sustaining Life is "a wonderful rebuttal to people who call conservationists treehuggers," said Wright. Yet he reminded the audience that the path from species to valuable product is serendipitous and unpredictable. Therefore, he argued, we should endeavor to protect all species in order to save those that may most benefit human health.
Chivian, who shared a Nobel Peace Prize for his work on the medical dimensions of nuclear war, argued that it is difficult for the public to grasp the threats posed by climate change: "The level of complexity and abstraction is really an order of magnitude—or many times more than that—greater than it is about nuclear weapons…and therefore, it's even more essential for physicians and public health professionals to describe and discuss these global environmental changes in human-health terms."
Drafted by Rachel Weisshaar and edited by Meaghan Parker.