【正文】 species that he could locate and actually could point to two confusingly similar species and tell him they were different. Nowadays, ethnobotany and ethnozoology are important areas of research not least for what they reveal of the utility of plant and animal species already wellknown to indigenous people. Local expertise about native plants and animals has other implications, as well. When we pare lists of plants and animals drawn up by local peoples with those of professional biologists, it confirms our notion that species are real entities in the natural world, not just figments of Westernworld classificatory imaginations. Local expertise can also dovetail conservation efforts with the economic needs of indigenous peoples: for example, by paying locals to act as guides in conservation reserves, or to serve as parataxonomists helping in the sorting and identification of species the elemental particles of biodiversity in biologically poorly known regions. The world holds far more than the 40,000 or so species currently being utilized on a daily basis. That is why the exploratory research efforts of the chemical and pharmaceutical industries must go beyond simply cataloguing the experiences of local peoples. Although we have no precise idea of how many plant, animal, fungal, and microbial species populate the pla, there are at least 10 million of them. The living world is a vast cauldron of geic variation: Most of it remains entirely unknown to us, yet much is undoubtedly of great potential use. For good reason, much of the exploratory research has been focused on the tropical rain forests. Most of the terrestrial species of our pla reside in the Tropics, and tropical forests are disappearing at a frightening clip. Estimates vary, but 30 hectares per minute now seems, if anything, to be an underestimate. More recently, however, some attention has been shifted to the sea, the last great earthly frontier. We are, of course, ourselves a terrestrial species, having abandoned the sea to take up life on land some 350 million years ago. Until recently, our direct utilization of sea life has been restricted to fishing and to hunting marine mammals. This last great vestige of a huntinggathering mode of existence until recently threatened to extirpate many whale and seal species and, as we have already seen, now threatens to collapse the most productive fisheries in the world. Corals and sponges are but two of the major groups of marine invertebrate animals that live firmly rooted to the sea floor. They don39。t escape when a predatory fish or crab es by and tries to bite off a piece. These sessile creatures have evolved a stunning array of chemical defenses against such attacks defenses that have recently begun to attract a lot of attention from the chemical and pharmaceutical industries. The case for the great diversity of living species as a storehouse of vital geic variation is crystal clear. We have relied upon that variation increasingly since we developed agriculture, even as it has indeed seemed that we were abandoning nature. That reliance on the natural geic storehouse will only increase as time goes on, a pelling reason why we must arrest the destruction of ecosystems and species that right now is systematically dismantling and destroying this vital resource. Specific utilitarian uses are only part of the story. Ultimately what might prove even more crucial is the simple overall health of the global system: the purity of the air, the balance among carbon dioxide, oxygen, nitrogen, and other gases of the atmosphere。 the vital cycles of carbon, nitrogen, phosphorous, and other atomic constituents of our bodies. In short, in fouling our nests, in destroying ecosystems, and driving many species to extinction, we are beginning to approach a limit on how much of the global living system and we ourselves can actually survive. In the long run, the most valuable aspect of diversity may well be the ability of our species to continue to live on the pla. EARTH39。t we continue our 10,000year course of habitat conversion and ecosystem destruction now that most of us no longer look to local renewable resources in our daily lives? Can we not live in a world wholly of our own cultural devising without all but a few of the world39。t see, appreciate, or fully understand without which, life on Earth for all species, including ourselves, would be pletely impossible. Take the air we breathe. The atmosphere close to Earth39。s fresh supplies of oxygen are produced by singlecelled, microscopic plantlike anisms floating near the surface of the oceans, supplemented, of course, by the photosynthesizing activities of terrestrial plants. The mighty oceans are the last great frontier of relatively undespoiled natural habitat, but landbased human activity is beginning to sicken even them. Pollutants reaching the sea through streams and via the atmosphere (as gases are dissolved in water droplets), direct oceanic dumping, and the degradation of natural marine ecosystems through overfishing and mining operations are beginning to have their cumulative effects. Consider what else green plants do for us. I was struck by a recent report detailing the salutary effects of a single, mature shade tree alongside a house in Chicago. Shade in the summer, insulation in the winter, and, amazingly, measurable purification of the air immediately surrounding the house. Once, while visiting the botanical gardens in Naples, Italy, a botanist told me that the air where we were standing was some six times purer than the air on the trafficcongested street only some 200 meters away from us! Green plants have the happy facility of filtering out noxious gases, utilizing carbon dioxide in the very act of photosynthesis, but also absorbing other noxious effluents a