The Importance of Preserving Biodiversity

Ecologists Anne and Paul Ehrlich argue that preserving biodiversity is necessary for all the undiscovered benefits humanity may still derive from flora and fauna that haven't been studied in-depth.

| May/June 1981

Whenever populations die out and species become extinct, the most serious consequence is the loss of the ecosystem services the creatures formerly helped provide ... but that's far from being the only serious repercussion of extinction. Few people, for instance, are aware of the enormous direct economic (and other) benefits Homo sapiens derives from its living companions on this global spaceship, and even fewer realize that the potential benefits are greater still! This range of direct and indirect, known and unknown benefits underline the importance of preserving biodiversity.

Medicinal Plants

Many examples of the direct "pluses" that Earth's flora and fauna provide us with can be found in the field of medicine. In 1955, Paul's father died after a grim, 13-year battle with Hodgkin's disease, a leukemia-like disorder. Just after his death, Canadian scientists discovered that an extract of the leaves of a periwinkle plant from Madagascar caused a decrease in the white blood cell count of rats. When chemists at Eli Lilly & Co. analyzed the periwinkle's leaves, they discovered a large number of alkaloids—poisonous compounds evolved by the plant to fend off predators and parasites.

Two of the alkaloids, vincristine and vinblastine, have since proved effective in the treatment of Hodgkin's disease. Indeed, with radiation combined with these and other drugs, it's now usually possible to control—or even cure—this kind of cancer. Thus a chemical that was later found in a plant species could have greatly prolonged Bill Ehrlich's life ... and it's now available to aid the 5,000 to 6,000 people, in the U.S. alone, who contract this disease each year.

As one measure of the economic value of the discovery, the world sales of vincristine, in 1979, totaled $35 million. (The drug is also used to fight a variety of other cancers, including several that afflict children and one form of leukemia.) Had the periwinkle become extinct before the 1950's, of course, humankind would have suffered a great loss ... although no one would even have realized it.

Furthermore, vincristine is just one example of the contributions made by plants to human health. There is evidence that Neanderthal people made medicinal use of plants, and many "folk" or "herbal" remedies derived from them are based not on superstition, but on the truly efficacious chemicals that plants contain.

This fact will come as no surprise, however, to folks who remember that the Peruvian Indians long cured malaria with an extract of the bark of Cinchona trees, which are members of the coffee family. The substance's active ingredient, quinine, became the main drug used against the disease—worldwide—for a century. And even the antimalarial drugs now in use have molecules whose design was inspired by the chemical structure of quinine.

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