Biodiversity - Page 4 - By Mara Hurwitt


Biological and Economic Resources
Diverse ecosystems supply the biological resources for man's basic necessities in life and promote continued economic productivity. Modern agriculture depends on the infusion of genetic variety from traditional and wild plant life for resistance to disease and increased crop yields. A large number of modern drugs are derived from naturally occurring compounds, some of which cannot be synthetically duplicated in pharmaceutical laboratories. Diverse species also provide man with natural, non-toxic forms of pest control, as well as a variety of industrial products.

The economics of these human activities, which depend on the conservation of biodiversity, are immense. Modern agriculture generates $3 trillion in global revenues annually. In 1988, sales of the top 20 medicinal drugs in the United States, all developed from naturally occurring life forms, reached $6 billion worldwide. This figure is likely to grow, with each wild plant used to produce a new drug compound expected to generate an additional $290 million or more in sales each year. In recent years, biodiversity itself has become an income-producing attraction, with protected national parks and natural habitats forming the basis of an entire ecotourism industry.

Food. Man has used 5000 species of plant life for food, but less than 20 species now provide nearly 90% of the world's food supply. The vast majority of the world's population rely on just three or four carbohydrate crops as their dietary staples. The world's major food crops, such as soybeans, wheat, and corn, all require the introduction of new genetic material from wild plants to maintain their health and productivity. The diverse gene pool of wild vegetation provides resistance to disease, greater environmental tolerances, and increased crop yields. Teosinte, a wild corn discovered in Mexico, is resistant to half of the major diseases that attacked U.S. corn in the 1970s. The introduction of this genetic variation was key to restoring the health of American corn crops. Conservation of genetic diversity among plant species may also be critical to adapting food crops to future global climate changes.

Wood products. Wood remains a basic commodity for shelter and fuel throughout the world. It is also used to build furniture, produce paper, and manufacture a range of consumer products. The timber industry generates significant revenues for various national economies. However, the loss of old growth forests and the wholesale destruction of forest habitats severely threaten biodiversity.

Medicine. Biological resources have provided mankind with a rich supply of medicines. In the developing world, 80% of the population relies on traditional medicine, including wild and cultivated medicinal plants, as the primary source of health care. In the United States, traditional and alternative medicine are gaining mainstream acceptance; America now imports over $20 million in medicinal plants from the world's rainforests annually.

Of the 150 best-selling prescription drugs in the U.S., 79% originated in nature. Worldwide, 119 different chemicals extracted from 90 species of higher plant life are used in the manufacturing of pharmaceuticals. For example, a drug to combat ovarian cancer has recently been developed from components of the Pacific yew tree. Still, only 2% of the quarter million scientifically described species of vascular plants have yet been screened for chemical compounds as a potential source of new medical treatments.

A number of synthetic drugs, such as aspirin, were first found in nature. However, many other important drugs cannot be synthetically reproduced. These include digitoxin, the most widely prescribed cardiac stimulant in western medicine, which is extracted directly from the Digitalis plant, commonly known as foxglove.

The rosy periwinkle (Catharanthus roseus), a flowering plant found in Madagascar, is the source of the alkaloid chemicals vinblastine and vincristine that are used to treat Hodgkin's disease and acute lymphocytic leukemia, two otherwise highly fatal cancers. The survival rate for lymphocytic leukemia, the most common form of childhood leukemia, was only 4% prior to the discovery of the rosy periwinkle's medicinal qualities. Today 73% percent of those diagnosed survive. Although pharmaceutical companies have attempted to replicate the periwinkle's anti-cancer alkaloid compounds, synthetic vincristine has been found to be only 20% as effective as that made with the natural ingredients derived from periwinkles.

Anti-cancer agents of some potency have so far been identified in one of every ten plant species globally. A much larger portion are used to manufacture drugs and other nature-based health products or provide a source of important scientific information. The anti-cancer drugs developed from the rosy periwinkle alone have saved countless lives and are the basis of $100 million a year industry. Yet Madagascar's other five species of periwinkles have never been adequately screened for their potential medical applications, and one of them is threatened with extinction due to habitat destruction.

Plants are not the only source of natural substances for human health care. The European medicinal leech secretes hirudin, a powerful anticoagulant. Today doctors use hirudin to treat medical conditions where blood clotting could be dangerous or painful, such as contusions and thrombosis, preventing thousands of deaths each year. Surgeons have also adapted hyaluronidase, an enzyme produced by leeches, to circulate injectable drugs and anesthetics; other substances found in leeches show promise as a cure for migraine headaches. Medicinal leeches, once regarded as a tool of medieval medicine, are now a $4 million annual business!

Minute organisms and processes. Man is also learning to harness the potential uses of biodiversity at the microscopic level. The fields of diagnostic and forensic medicine have been greatly advanced by the polymerase chain reaction, produced by a bacterial enzyme found in samples of boiling mud from Yellowstone National Park. "Oil-munching microbes" have become the latest weapon in cleaning up oil spills and reducing their sometimes devastating effects on oceans, beaches, and marine life.

Future resources. Man has barely scratched the surface of the potential benefits to be reaped from Earth's biological resources. Future nature-based products may include sunscreens from corals, lightweight high-tensile fibers from spider silk, and instant adhesives from barnacles or velvet worms. There is a wealth of informal knowledge about biological diversity among the traditional cultures of local communities and indigenous peoples around the globe. Their understanding of the natural world can provide us with many valuable new products, while supporting the sustainable use of resources and preservation of local ecosystems.

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