Medicine Quest: In Search of Nature’s Healing Secrets. Mark J. Plotkin. Viking, 2000, hardcover, 240 pp. ISBN 0-670-86937-6. $22. Sale Price $13.95 ABC Catalog #B481.

Ethnobotany is a romantic science. Its practitioners such as Mark Plotkin vanish for long periods into remote jungles to make contact with tribes as arcane as the Tirios, Akuriyos, or Yanomani. They emerge clutching strange plants and uttering tales of powerful cures, species on the brink of extinction and vanishing cultures. It all seems a long way from our commonplace urban existences. Yet in ways we cannot fully understand, our weather, atmospheric composition, the plants we eat and drink, the diseases we suffer from, and the drugs with which we treat them are all connected to geographically remote ecosystems.

In describing his activities in the Amazon jungle, Plotkin occasionally reports cures, such as in the opening story about diabetes, which remind one of the Italian proverb, si non è vero, è ben trovato (loosely translatable as ""if it isn’t true, it should be""). However, the potential rewards of ethnobotanical research, and the threat to ethnobotanic knowledge and the ecosystems from which it derives, are both so great that exaggeration is excusable.

Species tend to come to human attention because of their toxicity. However, in Shakespeare’s phrase, in poison there is physic (i.e., medicine). Profoundly toxic substances can be tamed to become powerful pharmacological agents. The deadly curare poisons of South America gave rise to the muscle relaxants used in surgical procedures. The toxins from cone shells, a group of slow-moving marine snails, are so potent that they almost instantaneously immobilize fish. A whole host of drugs are being developed from these toxins, with application to neurodegenerative and cardiovascular diseases. ACE inhibitors such as captopril (Capoten), standard treatment for high blood pressure, were derived from venom components of deadly pit vipers. A small frog from the rain forests of Ecuador yields the toxin, epibatidine, a pain killer 200 times more potent than morphine. As Plotkin says in this book, the forest where the frog was found has now been cleared for banana plantations. Other specimins were located elsewhere, but only enough to collect less than one milligram of the poison. Further, when bred in laboratories, these frogs contain no epibatidine.

When people think about threatened ecosystems, however, it is typically the large, most obvious species they think of: the whales, grizzly bears and sequoia trees. It is not in these species that new pharmacological agents are to be found. Such agents are elaborated for purposes of defense or offense. Large species, with their teeth, thorns and talons, are not reliant on chemical weapons. Plotkin’s book celebrates the small, the slow, the soft and the unconsidered. He points out that drugs such as cyclosporin (used to prevent tissue rejection in transplant operations), mevacor (cholesterol-lowering drug), and the antibiotics vancomycin and chloramphenicol were discovered in fungi, microorganisms residing in soil. Such discoveries are of incomparably greater economic value than the banana plantations, two-by-fours, and beef for hamburgers for which so many unexamined species are heedlessly bulldozed to oblivion. Here, the undiscovered vanishes forever into the undiscoverable.

Mark Plotkin studied under the late Richard Evans Schultes at Harvard, and has spent 25 years researching the ethnobotany of the Amazon. Medicine Quest describes some of his experiences, mixed with general discussion of issues surrounding ethnobotany. The book is an easy read, and a significant contribution to public education. A pathologist stopped me in the corridor of my medical center to say that he had not been able to put the book down until he had finished it. What better recommendation can a book have?

—Ryan J. Huxtable, Ph.D.