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At 5:30 in the morning we are deep in a dark forest on an island in the middle of the Panama Canal. We' ve been out walking for only 15 minutes, but I' m already soaked in sweat.
As a colleague and I plod along, my head lamp picks out the occasional trail marker, but mainly the light seems to operate as a major local landmark for insects. Several mosquitoes have already discovered the delights of the soft parts of my ears, while others are slowly working their way between my socks and legs to be discovered later after much scratching. Suddenly a deranged roaring and barking starts 25m above my head and builds chaotically and intensity before slowly quieting after several minutes. Similar mad choruses respond from other areas of the forest. Hearing the dawn cacophony of howler monkeys always given me a deep sense of pleasure -- the joy of being back in the tropics. It may be a hot, humid place where insects, plants and fungi rule, but the phone and fax won’t find me here. I' m free to watch monkeys, collect data and try to tease out a tiny piece of the great puzzle of life’s diversity.
That diversity faces disaster, and every biologist has a horror story to tell. Each year many of us return to the field after a cold winter’s teaching to discover that our research sites have been destroyed and our experiments and study organisms have disappeared. We can see with our own eyes the mass extermination of the world’s animal and plant life as forests, savannas and wetlands give way to farmland, housing developments and shopping malls. If current rates of habitat destruction continue, it is likely that we will condemn from a quarter to half the world’s currently living species to extinction within the next 100 years.
Nowhere is life more diverse than in tropical rain forests, and nowhere is the assault on life more tragic. Scientists are only beginning to understand the complex webs of interdependencies among various species. Increasingly, ecological re- search in the tropics in revealing how dependent humans are on forests for a wide variety of important services, particularly regulation of the earth’s atmosphere and climate. We may owe as much to the residents of the rain forests as we do our cat- tie, corn and wheat.
Much of our understanding of tropical-forest biology comes from research on Barro Colorado Island, a 1,600-hectare dot in the middle of the Panama Canal. B. C. I. , as the island is affectionately known to the biologists who work there, is covered with dense tropical forest, which was declared a nature reserve in 1923. The Smithsonian Tropical Research' Institute facility on B. C. I. , established in 1946, is a Mecca for tropical biologists, who work to uncover the complex links between the large variety of species that live in forests and to demonstrate the importance of these woodlands as sources for medicines and other products of incalculable value to humans.
The atmosphere at the research station is probably similar to that at Los Alamos, New Mexico, in the 1940s when a group of the world’s top physicists were cloistered together trying to design the atom bomb. The justified the creation of a nuclear weapon by assuming it would provide the ultimate deterrent that could be used to reinforce peace in a democratic world. Similarly, the longer-term future of human civilization on earth is dependent on the earth’s forests, which act as its lungs, livers and kidneys. That is why scientists on B. C.I. are struggling to unravel the mysteries of the forests before they disappear.
At first the forest in Panama just looks tike a wall of green. Then you start to notice differences between plant species, and the sheer diversity seems suddenly overwhelming. Variations between plants are often subtle and only apparent for the short period of time that a species bears flowers or fruit. Slowly you begin to identify specific types and family groups such as the palms, helico
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During the time he stayed in Houston, Pedro
听力原文： American researchers have made a discovery that might help them better understand the mysterious sense of smell. VOA’s Jessica Bermon reports. There are about a thousand protein receptors in the nose that tell the brain what it’s smelling. Each receptor can detect one or more odors but scientists have never before linked a specific odor molecule to a particular receptor. Writing in the journal Science, researchers at New York’s Columbia University report doing just that with a meat odor and a receptor in the noses of rats. Steward Fairstine led the team of investigators. He says humans are capable of deceming something like ten thousand different odors. Mr. Fairstine says the research might also tell scientists more a bout brain chemicals and hormones which are part of the same family as odor receptors. Jessica Bermon, VOA news Washington.
The discovery by American researchers might help them understand ______.
The author "took the chair" for all the following reasons EXCEPT that
SANTEE, CALIF -- When news broke about the mayhem and killing at Santana High School, Charles Williams frantically dashed to the school to make sure his 1S-year-old son wasn't hurt. As he searched the chaotic tableau of sobbing teens and panicked parents, Williams called a girl: "Do you know where Andy is？" Her quiet reply: "With the cops."
Until that moment, Williams apparently had no idea what his son, Charles Andrew, had planned to that morning when he left their small apartment in this town northeast of San Digeo. But, sadly, others had a clue. The teen had bragged to several friends and at least one adult, 29-year-old Chris Reynolds, about his scheme to shoot his classmates. Some of his friends thought it was simply bluster from a kid. Yet two of them were so concerned that they patted Williams down that morning. They didn’t go far enough to find his father’s 22-caliber, long-barrel revolver in Williams’s yellow backpack.
Bombs and hit lists. Even before last week’s shooting, the collective culture had been changing. Last month, potential disasters were foiled in schools from New York to California because students reported their concerns. Just days after the Santana High shooting, students tipped off police who arrested a handful of kids at several other California schools for allegedly making threats that included plotting to put a bomb on a teacher’s desk and drawing up a hit list of 16 students. "The climate is changing where young people are more willing to report threats, but that change is happening slowly." says Ron Stephens, executive director of the National School Safety Center. "Santee is certainly a lesson in that. We must continually work with young people about why it is in their interest to come forward."
That’s tough task, considering children are taught almost from kindergarten, not to tattle. No one wants to be an in former, but as Tom Hall, San Diego schools security chief, says: "We' ve got to get kids to understand that there is a proper time to tell. "A recent Secret Service study found that in more than three quarters of school shootings, the attacker told someone, almost always a peer, about his plan beforehand. Only twice out of 37 cases did that kid tell an adult. "We as lay people, kids and adults, don't need to make the decision about whether someone is joking," says Marceta Reilly, superintendent of the Kansas school district where a student last mouth turned in three teens for an alleged plot to blow up the school. "It is important to turn it over to someone who can investigate it properly."
Overall, school violence is down, despite the outpouring of high-profile shootings that often produce imitators including many after Santee. No one wanted to take any chances in Elmira, N.Y. , where the entire town has worked to prevent an other Columbina. Last month, students noticed an 18-year-old student acting oddly on the bus. After students told school authorities, an officer found 18 pipe bombs and a sawed-off shotgun in a green bag and a 22-semiautomatic pistol folded in his trousers. "We've tried to foster a new attitude: This is not snitching", says Chemung County District Attorney John Trice. "These are kids who have decided, ' I don’t want anyone to get hurt. '"
Bullies. Some classmates described Andy Williams as a friendly, quiet kid. But others said he was deeply troubled, disturbed by the separation from his mother, who had been divorced from his father for about 10 years. The youngster was also a frequent target of bullies. Experts believe the Santee shooting will fuel a redoubling of anti-bullying efforts that began after Columbina. Colorado is working on a bill that would require all schools to develop bully-prevention plans. A new law requires New Hampshire school beards to adopt anti-bullying policies. Oregon is considering a bill that would ban bullying.
Some parents and civil libertarians may worry that the Santee shooting
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