Temps de lecture :3 minutes
Biodiversity is essential for the functioning of ecosystems – from forests and fresh waters to coral reefs, soils, and even the atmosphere – that sustain all life on Earth. The ongoing and escalating disappearance of that diversity will harm society in myriad ways. One way that is often overlooked is the damaging impact on medical science.
For millennia, medical practitioners have harnessed substances from nature for treatments and cures: aspirin from the willow and, more recently, TaxolÔ– the groundbreaking anti-cancer drug – from the bark of the Pacific yew. Some of the biggest breakthroughs may be yet to come. But this can happen only if nature’s cornucopia is conserved, so that current and future generations of researchers can make new discoveries that benefit patients everywhere.
Consider the polar bear, threatened with extinction in the wild by climate change. These mammals spend up to seven months of the year hibernating, during which time they are essentially immobile. A human would lose a third or more of bone mass when immobile for this period of time.
Astonishingly, hibernating bears lay down new bone, by producing a substance that inhibits cells that break down bone and promotes those that produce bone and cartilage. Studying hibernating bears in the wild may lead to new ways of preventing the millions of hip fractures that result from osteoporosis – a disease that costs $18 billion and kills 70,000 people each year in the United States alone.
While hibernating bears can also survive for seven months or more without excreting their urinary wastes, humans would die from the buildup of these toxic substances after only a few days. Unraveling how the bears accomplish this miraculous feat may offer hope to the estimated 1.5 million people worldwide receiving treatment for kidney failure.
Polar bears, which pile on fat to survive hibernation and yet do not become diabetic, may also hold clues for treating Type II diabetes, a disease associated with obesity that afflicts more than 190 million people worldwide, reaching epidemic proportions in many countries.
But hibernating bears are just the beginning of the story. The wood frog can survive long periods of freezing temperatures without suffering cell damage. Might it hold the key to a way to better preserve scarce organs needed for transplants?
Pumiliotoxins, like those manufactured by the Panamanian poison frog, may lead to medicines that strengthen heart contractions – important in treating cardiac disease. And the 700 species of coral reef-dwelling cone snails may produce up to 140,000 different toxins, large numbers of which may have value as medicinal compounds. Yet only about a hundred have been investigated.
One of these toxins, now available as the drug PrialtÔ, has been shown to be 1,000 times more potent than morphine, without causing addiction or tolerance, as opiates do. Clinical trials indicate significant pain relief for advanced cancer and AIDS patients.
The loss of biodiversity has already closed promising new avenues of medical research. Australia’s gastric brooding frog, Rheobatrachus, begins life in the female’s stomach, where it would, in all other vertebrates, be digested by enzymes and acid. This could have led to new insights into preventing and treating peptic ulcers, but studies could not be continued: both species of Rheobatrachus are now extinct.
In 2010, the United Nations International Year of Biodiversity, governments are supposed to reduce substantially the rate of loss of the world’s rich array of animals, plants, and other organisms. This has not happened. Indeed, the pace of biodiversity loss has accelerated, and we are rapidly entering what scientists are calling “the sixth wave of extinctions.”
The next opportunity for governments to commit to reversing these losses comes at the 65th UN General Assembly in New York this September, followed by the meeting of the Convention on Biological Diversity (CBD) in Nagoya, Japan.
This needs to be the year when a cure for environmental degradation is found and a far more intelligent management of a natural world starts taking shape: this will be a key breakthrough for the wealth but also increasingly the health of humanity in the 21st century.
by Eric Chivian, Aaron Bernstein and Achim Steiner
Eric Chivian and Aaron Bernstein are physicians and researchers at the Center for Health and the Global Environment, Harvard Medical School, and the lead authors of Sustaining Life: How Human Health Depends on Biodiversity. Achim Steiner is a United Nations Under-Secretary General and Executive Director of the UN Environment Program.
Copyright: Project Syndicate, 2010.