nutrients bind with aluminum and iron or wash away in thentorrential rains. The land becomes a “wet desert,” unable tonsustain agriculture or husbandry at a profitable level fornmore than several years.nWhat are the rural poor to do if they cannot clear thenland? The answer lies partly in zoning on a broadnscale, while improving agriculture on the arable landsnalready under cultivation. It also lies in developing newnmarkets for products from wild species. The plants andnanimals of the forests and other natural habitats are amongnthe most important resources available to mankind, and sonfar they are the least utilized. In the course of history, fornexample, people have relied heavily on about twenty cropnspecies, including wheat, rye, millet, and rice. These arenmostly the plants that Neolithic man encountered haphazardlynat the dawn of agriculture in Mesoamerica, the Fertilencrescent, and tropical Asia. Yet there are at least fiftynthousand plant species in the worfd with edible parts, andnsome of them are demonstrably superior to prevailing cropnspecies. The winged bean {Psophocarpus tetragonolobus) ofnNew Guinea, for example, is a veritable supermarket. Thenentire plant, including roots, seeds, leaves, stems, andnflowers, is palatable, and a coffee-like beverage can be madenfrom its juice. It grows very rapidly, reaching a height ofnthree meters in a few weeks, and has a nutritional valuenequal to that of soybeans.nIntelligent economic developmentncan save the natural environment, andnthe natural environment can be usednto accelerate economic development.nThe key lies in the preservation and use ofnwild species and genetic strains, innother words biological diversity.nThe animal equivalent of the winged bean is the giantnriver turtle Podocnemis expanse of the Amazon River. It cannbe reared at low cost on rough vegetation in natural andnartificial ponds on the river banks. It yields tasty, low-fatnmeat at 440 times the rate of cattle grown in equivalentnareas.nWild species are a potential cornucopia of new fibers,npetroleum substitutes, and pharmaceuticals. The Amazoniannbabassti palm, Orbignya phalerata, is one of the mostnproductive sources of vegetable oil in the world, a stand ofnfive hundred trees producing about one hundred andntwenty-five barrels a year. One in ten plant species containsnanticancer substances of at least some degree of potency. Anstriking success story is the rosy periwinkle, Catharanthusnroseus, a native of Madagascar. This inconspicuous littlenplant yields two alkaloids, vinblastine and vincristine, thatneffectively cure two of the deadliest forms of cancer,nHodgkin’s disease and acute lymphocyctic leukemia. ThenU.S. National Cancer Institute is currently screening somenten thousand substances a year from wild plants for activityn18/CHRONICLESnnnagainst other forms of cancer and the AIDS virus.nNot only can species be drawn from natural habitats andncultivated for their products, but the habitats can benconverted into extractive reserves from which the productsnare harvested at minimal expense. A study recently conductednin the Amazonian rain forest near Iquitos, Peru, demonstratednthat a greater profit can be made from treating thenforest as an extractive reserve, in other words as a source ofnoil, latex, fruits, and other products, than by cutting it forntimber and using the cleared land for ranching or conventionalnagriculture. And such is the case even though mostnpotentially profitable species in the forest have not yet beennidentified or studied with a market in mind. Many of thenplants and animals do not even bear a scientific name. It isnclear that with proper research and capital investment, thenfauna and flora of the world can enhance the quality ofnhuman life to a hitherto undreamed-of degree.nIn conclusion, environmentalism means a great dealnmore than cleaning air and water, the obvious goals that stillndominate public debate. It extends to the fuller use ofnorganisms for the improvement of human existence. Thennew environmentalism also requires us to address thenpopulation problem frontally, without deference to anynideology or religion. The planet cannot sustain the continuedngrowth of a species that already co-opts 40 percent ofnthe sun’s energy available to life. The time has come tonbegin the discussion of optimal population size, the numbernof people at equilibrium or near equilibrium that is best forneach country in turn. National birth control policies willneventually have to be designed to attain these safer levels,nhowever distasteful this constraint on reproductive freedomnmay seem. I suspect that the optimum sizes for mostncountries will prove to be far below those already reached.nYet — how can anyone be certain either way in our presentnstate of ignorance and timidity? Population policy, no lessnthan economic policy, must come to occupy center stage innthe years ahead.nPopulation and environmental policies more rational thannthose now in existence are crucial to the saving of thisnplanet, which is our home forever. Both pivot on ethics,nwhich turn on our self-image as a species. In an earliernarticle for Chronicles (April 1990), I suggested the need forn”deep history,” which traces not just cultural history of thenpast ten thousand years, but the far older genetic history thatncreated the brain and sensory apparatus from which culturenis built. Humanity is a product of biocultural evolution, anprocess extending over hundreds of thousands of years.nCulture is deeply affected by the results of genetic evolution,nwhile genetically prescribed neurosensory evolution occursnwithin the arena of culturally transmitted social behavior.nBiocultural evolution — deep history — was played outnmostly in a natural environment, where technologicallynprimitive people lived amidst a rich fauna and flora,nexploring them, using them, and drawing from them thenmetaphors of art and the totems that mystically reaffirm ournkinship to other forms of life. Our roots in the naturalnenvironment may be deeper than even dedicated environmentalistsnhave argued. If we cut those roots free in responsento a misguided Promethean ethic, it will be at the peril of thenhuman spirit. <®>n