Evolution has solved a number of challenges humans face, for instance, flight. (Credit: Museum of Science)
– by Julia Darcey
Harvard undergraduates who take Noel Michele Holbrook’s course on biodiversity often do not end up becoming scientists. The future lawyers and businesspeople listen thoughtfully to her lectures on preserving the variety of Earth’s species, but lacking the passion of a biologist, there is one critical point that they have difficulty understanding. One student finally approached Professor Holbrook about it. The student explained that she understood that species were going extinct, and that habitats were disappearing, but she still had one fundamental question: “Why does this matter?”
Biologists like Holbrook now have a solid and penetrating argument that preserving biodiversity matters because of its benefits for human health. In a new book, world-renowned scientist Eric Chivian compiles hundreds of studies on how evolution has allowed snails, bears, frogs and trees to solve major medical problems facing humans. He presented the book, titled Sustaining Life: How Human Health Depends on Biodiversity during a public conversation with Holbrook last night at the Boston Museum of Science.
Despite the clear benefits of biodiversity, species are disappearing at an unprecedented rate due to a combination of pollution, development and climate change. Extinction can have a big impact on humanity, Chivian said, because the keys to solving many human health problems already exist in the natural world-we just have to figure out how to use them.
One example is the medical possibilities in 40,000 distinct toxins made by the 700 species of aquatic cone snails. The shelled slugs bombard their prey with sharp, poison-coated harpoons, the most potent of which hijack the victim’s nervous system. The study of cone snail toxins has already produced the painkiller Prialt, which is 100 times more effective than morphine and does not lead to tolerance.
The trick to preventing disease associated with obesity may also exist in the belly fat of the polar bear. The polar bear, Chivian said, becomes massively obese before entering its den to sleep for the winter, and yet never develops Type II Diabetes or other obesity diseases. “If we lose the polar bear,” said Chivian, “we will perhaps lose the secret to a disease that kills 1.5 million people a year.”
A drug for peptic ulcer disease, which affects 25 million Americans, may have once dwelt in the rainforests of Australia, inside the stomachs of gastric-brooding frogs. Females of these species ate their eggs, which would slowly incubate inside the mother’s stomach. The eggs survived by secreting chemicals that stopped the production of digestive enzymes. However, all research on these frogs came to halt in the 80s, when the only two species of gastric-brooding frog went extinct.
“Those compounds-which may have evolved over millions of years-are gone forever,” Chivian said. To him, this is an idea that everyone can understand. Numbers of species lost have not been effective in communicating the urgency of biodiversity loss, partly because it happens far from day to day life, often in rainforests or at the microscopic level. When educating the public about biodiversity, Chivian said, “the most basic fundamental focus should be on what the impacts on us would be.”
“We hope that the book will make the connection that humans are not separate from biodiversity,” he said. Written in plain language, it is designed to be used by scientists, the lay public, and even as a textbook. This is the first text that explains in great detail why biodiversity matters, and Professor Holbrook, for one, now includes it on her syllabus.