The secrets of crabs, polar bears, and snails

By Bina Venkataraman, Globe Correspondent

What do horseshoe crabs, the polar bear, and coral reef-dwelling cone snails have in common?

According to Dr. Eric Chivian and Dr. Aaron Bernstein, editors of the recent book "Sustaining Life: How Human Health Depends on Biodiversity," they are all fauna that will unlock secrets for improving people's health.

"We don't have a choice about whether we protect the natural world," said Chivian, director of the Center for Health and the Global Environment at Harvard Medical School. "We have to protect the natural world because our health and our lives depend on it."

The book is part textbook; part summary of scientific literature on the role of biodiversity in human health; and part call to action to prevent further species extinctions. While the idea of plants and animals contributing valuable medicines is not new, the book is a detailed account of how invaluable medical breakthroughs continue to rely on the natural world, despite the emergence of genomics and computer programs that screen for new pharmaceuticals.

Studies of the Brazilian pit viper's venom, for example, directly led to the development of ACE-inhibitors for blood pressure regulation, one of the most commonly prescribed set of drugs in the US. Research on polar bears and other bears that retreat to their dens for months on end without eating, drinking, or excreting waste could help scientists unearth treatments for osteoporosis and renal failure. An estimated 700 species of underwater cone snails each produce more than a hundred poisons that they use to paralyze their prey. Just one of those toxins directly led to the development of ziconotide (commonly known as Prialt), which Dr. Bernstein calls the "single most important painkiller since morphine." Thousands of these poisons have yet to be studied.

But the editors, both Boston physicians affiliated with Harvard Medical School, warn that the nexus between human health and biodiversity extends beyond finding cures: Human diseases also emerge from the ways we change the environment and the destruction of species, they say.