The Quiet Apocalypse

By Jamie Murphy

The history of life on earth has been punctuated by mass extinctions, the sudden disappearance of a large variety of plants and animals, possibly as the result of impacts by giant meteors or comets. In one of the most dramatic die- offs, 65 million years ago, more than half of all species on earth, including the dinosaurs, vanished. While experts debate the cause of these catastrophes and the probability and timing of the next one, scientists at the recent National Forum on BioDiversity warned that another sort of mass extinction is now taking place.

The current problem has been brought on not by celestial visitors but, as biologists agreed during the four-day meeting in Washington, by man. They attribute the developing ecological disaster to the systematic destruction of the world's tropical rain forests, particularly those in Latin America and Southeast Asia. Deforestation at the hands of loggers, farmers, ranchers and mining concerns, says Norman Myers, an environmental consultant based in Oxford, England, may result in the eradication of 1 million species by the end of the century. Harvard Professor of Science Edward O. Wilson concurs. "The extinctions ongoing worldwide," he says, "promise to be at least as great as the mass extinction that occurred at the end of the age of dinosaurs."

Perhaps most troubling to the scientists is the fact that plants and animals are disappearing faster than they can be found and described. Naturalists have cataloged 1.6 million species, a small fraction of the estimated 4 million to 30 million that remain undiscovered. While most of these unknown species are insects, even a creature as garrulous and brightly colored as a parakeet of the genus Pyrrhura (its species name has not yet been assigned) eluded researchers until it was first sighted in Ecuador in 1980. "No one knows the diversity in the world, not even to the nearest order of magnitude," says Wilson. "We don't know for sure how many species there are, where they can be found or how fast they're disappearing. It's like having astronomy without knowing where the stars are."

Tropical rain forests blanket about 7% of the planet and support nearly 50% of earth's known species. A single hectare (2.5 acres) of this lush arboreal growth may include more than 100 species of tree, each with its own interdependent colonies of plants and animals. But in the past several hundred years, the area of the globe covered by rain forest has decreased by some 44%. According to one U.N. study, 23,000 sq. mi. of rain forests are cut down every year -- an area about the size of West Virginia. One World Resources Institute staffer calculated that developers leveled 350 sq. mi. of rain forest while the biodiversity conference met.

These threatened ecosystems have already proved a valuable source of medicines, foods and new seed stock for crops. Nine years ago, for example, a strain of perennial, disease-resistant wild maize named Zea diploperennis was found in a Mexican mountain forest, growing in three small plots. Crossing domestic corn varieties with this maize produces hardy hybrids that should ultimately be worth billions of dollars to farmers. A great many of the prescription drugs sold in the U.S. are based on unique chemical compounds found in tropical plants. For example, vincristine, originally isolated from the Madagascan periwinkle, is used to treat some human cancers. Scientists are convinced that still undiscovered forest plants could be the source of countless new natural drugs.

In search of such medical bounty, Mark Plotkin, director of the World Wildlife Fund's plant program, has spent months at a time living with the Tirio tribe on the Suriname-Brazil border, studying the little-known plants the shamans use to treat patients. "Each time one of the medicine men dies," he says, "it's as if a library has burned down."

Plotkin and his colleagues are also assessing the economic potential of such tropical plants as "killer" potatoes, which trap insects on their sticky surface hairs; the Amazonian buriti palm, rich in vitamins A and C; the pupunha palm, whose proportions of carbohydrates, proteins, oil, minerals and vitamins make it an ideal staple; and Fevillea, a vine with seeds rich in an oil that may one day be used as an industrial lubricant.

Even plants and animals with no immediate use are worth saving. Each contains a unique repository of genes that might someday have important applications in bioengineering. "Natural species are the library from which genetic engineers can work," says World Wildlife Fund Executive Vice President Thomas Lovejoy. "Genetic engineers don't make new genes, they rearrange existing ones."

Alarmed by the rate of tropical deforestation, scientists are no longer shy about criticizing commercial and public development schemes that eat away vast tracts of rain forest. "In the past, many biologists thought it was almost unscientific to get involved in conservation politics," says Lovejoy. "But no more. The rate of species loss is suddenly dawning on people." The warning has been heeded in government circles as well. The House of Representatives two weeks ago passed legislation sponsored by Gus Yatron, Democrat of Pennsylvania, mandating that the U.S. Agency for International Development set aside $10 million to preserve biodiversity.

While scientists applaud the intent of the bill, they know the amount is too little and fear the gesture may be too late. Says Wilson: "The time has come to link ecology to economic and human development. When you have seen one ant, one bird, one tree, you have not seen them all. What is happening to the rain forests of Madagascar and Brazil will affect us all."

With reporting by Andrea Dorfman/Washington