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A self-destructive war
***The heady race for economic growth coupled with hurried urbanisation has contributed to an alarming depletion of the world's biological diversity. On land and in the sea, the story is much the same. Spurred by poverty, population growth, ill-advised policies and simple greed, humans, it seems, are at war with plants and animals they share the planet with, writes Md. Asadullah Khan.***
MERE greed has turned a part or East Asia into a disaster area that has hardly any parallel. Every year fire from manmade forests in Indonesia envelopes the far away region of Malaysia and Singapore in a cloud of gas and ash other than Indonesia itself. With the burning of forests from Brazil to Madagascar to Indonesia vital life forms are getting extinct. Besides, extensive damage by industrial pollution and car exhausts have added to the miasma that has persisted in the urban areas. The potent mix of sulphur dioxide, nitrogen dioxide and ash has rendered the air not only opaque in most of the Asian countries but has been causing extinction of plant species. This is just an example, as to how biodiversity is being destroyed by humans simply out of greed. The director of the Missouri Botanical Garden predicts that if things are allowed to go on like this, during the next three decades humans will drive an average or 100 species to extinction every day.
Extinction, believably, is part of evolution. But the present rate is at least 1000 times the pace that has prevailed since pre-history. Experts, like Harvard Biologist E. O. Wilson believe that even the mass extinction 65 million years ago that killed off the dinosaurs and countless other species did not significantly affect flowering plants. But these plant species are disappearing now through greed and population pressure and people not comets or volcanoes are the 'angels' of destruction.
Unfortunately, the earth is suffering the decline of entire ecosystems the nurseries of life forms. Reports have it that in Bambey, a place 100km from Dakar (Senegal), the landscape runs on endlessly, broken by nothing more than a few stunted trees buried under the dust. The soil has lost its protective cover and lies exposed to the relentless forces of wind and the sun. The last best hope to preserve biodiversity remains in the tropics. Tropical forests cover only seven per cent of the earth's surface but they house between 50 per cent and 80 per cent of the species.
Even developed countries can't afford to dismiss the growing concern about this planet earth's future or so to say their own country's environmental woes. With the alarm bells ringing, governments in many countries have turned their attention to high profile animals like tigers, elephants and rhinos while most people hardly see the point of worrying about insects or plants. These are on the verge of extinction. And extinction is a sort of environmental calamity that is irreversible. As these low species become extinct, they take away with them survival mechanism of other species.
Records so far catalogued reveal that only about 1.7 million of the estimated five million to 30 million different life forms have been specified. The world has neither the scientists nor money nor time to identify the yet unexplored and uncounted. "It is as though the nations of the world decided to burn their libraries without bothering to see what is in them", said University of Pennsylvania biologist Daniel Janzen. Harvard's Wilson called this profligacy the "folly" that future generations are not likely to forgive.
Humanity has already benefited greatly from the little known species. Some 25 per cent of the pharmaceuticals in use in the US today contain ingredients originally derived from wild plants. Hidden anonymously in clumps of vegetation, ready to be bulldozed or burned might be plants with cures for still unconquered diseases like AIDS and cancer. So said Janzen, "I know of three plants with the potential to treat AIDS". One grows in an Australian rain forest, one in Panama and one in Costa Rica".
Diversity is the raw material of earth's wealth, but nature's true creativity lies in the relationship that links various creatures. The coral in a reef or the orchid in a rainforest is a part of the ecosystem that supports as well as offer check and balance integrating life forms into functioning communities. Given the complex workings of the ecosystem, it is never clear which species, if any, are expendable.
Biologists have identified numerous "hot spots" where ecosystems are under attack or assault and surely a large number of unique species face an immediate threat of extinction. These troubled areas include Madagascar where 90 per cent of the original vegetation has disappeared, the monsoon forests of Himalayan foothills that include Nepal, India and Bangladesh that are being denuded by villagers in search of firewood, building materials and arable land, as well as forests of East Africa, Peninsular Malaysia, Indonesia along with the Atlantic coast of Brazil and Mexico.
There are also practical obstacles that must be understood. Social scientists hasten to add: "How can countries worry about biodiversity when their people have so much concern about feeding themselves"? Solutions to such nagging problems are quite close at hand and that must be addressed by rich nations reducing the debt burden of the poor. But equally important is a concerted campaign to convince people of developing countries that is in their own longterm interest to preserve their environment. Wiping out forests may make the developing nations momentarily richer, but it is bound to produce a poorer future.
Experience has turned our apparent concern into what we may
call now a disaster. Destruction of forests can have disastrous consequences on our economy and society. Forests are vital watersheds that absorb excess moisture and anchor topsoil. Deforestation contributed to the recent droughts in many parts of the world, including Africa, Asia, Europe and North America and a vast region of Bangladesh in the recent past. Halting the assault on biodiversity will not be easy but we must initiate some actions. The first step we can take is to educate people through radio and TV programmes about the irreversible consequences of a loss of genetic diversity.
Few people realise how often exotic plants and animals yield unexpected benefits. Some examples:
(1) Squibb, a pharmaceutical company used the venom of the Brazilian pit viper to develop "Capoten", a drug for high blood pressure.
(2) By transplanting genes from tropical tomatoes, the NPI biotech firm increased the density of the US tomatoes by two per cent promising manufacturers extra profits.
(3) Scientists believe that arcelin, a natural protein in wild Mexican beans that repels insects, might protect some US crops without poisoning soil and water.
(4) Future newspapers may be printed on paper from kenaf, an African plant that can produce five times as much pulp an acre than the trees normally cut for newsprint.
It was so exciting for Michael Tyler, a renowned biologist in the University of Adelaide in Australia to spot a frog unlike any he'd encountered in a boulder strewn, fast flowing creek in an Australian rain forest. While its appearance brown back and cream coloured underside was nothing special, its reproductive behaviour proved to be downright bizarre. The female swallowed her own eggs, incubated them in her stomach and gave birth through her mouth. A single mother coughed up 21 offspring in the same litter.
It was a thrilling experience for Tyler to see the Australian-gastric-brooding frog carry eggs, (and then the tadpoles) inside her stomach without having the offspring digested by stomach acid. To his amazement, Tyler found that the mother frog had the ability to turn off her stomach acids while carrying her precious cargo. It could be interesting for a pharmaceutical company to figure out the potential
here. Excess stomach acid causes great misery in millions of human beings. Perhaps the frog secreted a compound that could help chemists develop a new drug to relieve some human stomach ailments. Maybe so, but we'll never know, The Australian gastric-brooding frog went extinct in 1980, long before a drug company could uncover its secret.
At the dawn of the 21st century, with technology evolving at an everincreasing rate, many people mistakenly believe the natural world has nothing left to offer us in the way of new medicines. This could not be further from the truth. Mother Nature has been creating weird and wonderful chemicals for more than 3 billion years, and we're only beginning to sift through these hidden treasures. New technologies enable us to find, analyse and manipulate molecules as never before. While today's laboratory scientists can synthesise new molecules from scratch at a pace unimaginable just a few decades back, promising compounds produced by nature's most creative creatures increasingly provide the optimum starting points.
Time and again, we find that
plants and animals make strange molecules that chemists would never devise in their wildest dreams. For example, researchers could not have invented the anticancer compound taxol, taken from the Pacific yew tree. It is too fiendishly complex a chemical structure, says natural-products chemist Gordon Cragg of the U.S. National Cancer Institute.
Some of the most promising natural wonder drugs come from compounds not usually associated with healing: poisons. Merck is marketing a blood thinner based on the venom of the deadly "saw-scaled viper". A protein from another Asian pit viper is being studied because it appears to inhibit the spread of melanoma cells, and a compound called SNX482 from the venom of the Cameroon red tarantula may lead to new treatments for neurological disorders.
Every species everywhere has the potential to teach us something new. How tragic then that just as innovative technologies give us the ability to take advantage of natural compounds as never before, we continue to threaten the world's species and the habitats on which
they depend. The European leech, source of a new blood thinner, was almost wiped out by overzealous collectors. The same is true for poison dart frogs, producers of many intriguing chemicals. Tropical cone snails and sponges, known to harbor analgesic and anticancer compounds, respectively, live on coral reefs, one of the planet's most endangered marine ecosystems.
Biologists estimate that more than half the species occur in the tropical rain forests. From these natural greenhouses, many world records of biodiversity have been reported425 kinds of trees in 2.5 acres (1 hectare) of Brazil's Atlantic forest and 1,300 butterfly species from a corner of Peru's Manu National Park, both more than 10 times the number from comparable site in Europe and North America. At the other extreme, the McMurdo Dry Valleys of Antarctica, with the poorest and coldest soils in the world, still harbor sparse communities of bacteria, fungi and microscopic invertebrate animals.
Researchers of biodiversity agree that we are in the midst of the seventh mass extinction. Even if the current rate of habitat destruction were to continue in forests and coral reefs alone, half the species of plants and animals would be gone by the end of the 21st century. Our descendants would inherit a biologically impoverished and homogenised world. Not only would there be many fewer life forms, but also faunas and floras would look much the same over large parts of the world, with disaster species such as fire ants and house mice widely spread. Humanity would then have to wait millions of years for natural evolution to replace what was lost in a single century.
In the long term, the quenching of life's exuberance will be more consequential to humanity than all of present-day global warming, ozone depletion and pollution combined. Why? For practical reasons, if nothing else. Humanity's food supply comes from a dangerously narrow sliver of biodiversity. Throughout history, people have cultivated or gathered 7,000 plant species for food. Today only 20 species provide 90 per cent of the world's food and three -maize, wheat and rice -- supply more than half. Tens of thousands of species of the world's still surviving flora can be bred or provide genes to increase production in deserts, saline flats and other marginal
habitats.
Natural pharmaceuticals offered by biodiversity are also underutilised. Only a few hundred wild species have served to stock our antibiotics, anticancer agents, pain killers and blood thinners. The biochemistry of the vast majority -millions -- of other species is an unfathomed reservoir of new and potentially more effective substances. The reason is to be found in the principles of evolutionary biology. Caught in an endless arms race, these species have devised myriad ways to combat microbes and cancer-causing runaway cells. We have scarcely begun to consult them for the experience stored in their genes. If the future enhancement of agriculture and medicine is not thought enough to merit conservation, then consider survival. The biosphere gives us renewed soils, energy, clean water and the very air we breathe, all free of charge. The more species that compose wild communities, the more stable and resilient becomes the planet as a whole. One of the primary goals of the century should be to settle humanity down before we wreck the planet. To that end, it is important to accept the responsibility of global conservation and to do so right now, before it is too late.
Md. Asadullah Khan is controller of examinations, BUET.