VOA慢速英語:'The Map of Life'; Ancient Dogs; Golden Gate at 75

00:00

00:00

MP3下載 文本下載

https://online2.tingclass.net/lesson/shi0529/0008/8384/20120626b.mp3

https://image.tingclass.net/statics/js/2012

CHRISTOPHER CRUISE: This is SCIENCE IN THE NEWS, in VOA Special English. I'm Christopher Cruise.

BARBARA KLEIN: And I'm Barbara Klein. Today, we tell about a project called "The Map of Life." We also tell about a study of modern dogs and their ancestors. And we tell about a major anniversary for the world famous Golden Gate Bridge.

(MUSIC)

CHRISTOPHER CRUISE: Suppose you would like to catch a muskellunge. Where in the world would you go to find that fish species? Where can you take a picture of the rare Giant Petrel bird? Or where would you find fields of calaloo?

If you have an Internet connection, you may get the answers to such questions with a new map. It shows the natural habitat, or living spaces, of about twenty-five thousand species. They include all land animals with backbones, animals that live on land and water, and most of the fresh water fish in North America.

You can test a version of this new technology tool at Mappinglife.org. Information is being continually added. And, perhaps best of all, the information is free. You do not pay to use the service.

BARBARA KLEIN: The new map was described recently in the journal Trends in Ecology and Environment. Its creators say the map will provide the first interactive, two-way path to information about biodiversity – the many living creatures found on Earth. Users will be able over time to add or change information about species.

Walter Jetz is a conservation biologist at Yale University in Connecticut. He was lead writer of the report. He says information used in the map comes from several sources. They include workers with the United States National Park Service, field guides, and observations from individual scientists. The Global Biodiversity Information Facility in Denmark also supplied information. The center made available more than three hundred million records of plant and animal locations.

The information is in different colors and shapes so it is easy to recognize what areas you want to research.

Mr. Jetz says, "The map is the where and the when of a species. The hope is for this to include hundreds of thousands of animals and plants and show how much or how little we know of their whereabouts."

CHRISTOPHER CRUISE: Robert Guralnick of the University of Colorado is another member of the mapping team. He says the online map will help governments and scientists decide how to use land and plan conservation efforts. And, it may also provide information about climate change and about diseases passed between animals and people.

The researchers say the success of the project will depend on the help of other scientists, environmental groups and people with knowledge of the subject.

Mr. Guralnick says the next step is to provide ways for anyone, anywhere to find animal and plant distributions with mobile or wireless technology. He says it is even possible that people could learn their chances of making contact with a wildlife species. He adds that the "Map of Life" project is following the examples of other banks of knowledge.

(MUSIC)

BARBARA KLEIN: Modern dogs may look like the animals painted on the walls of ancient Egyptian buildings. But a new report says many centuries of cross-breeding make it hard to learn about the ancestry of man's best friend. The report appears in the scientific journal Proceedings of the National Academy of Sciences USA.

Scientists say it is wrong to call some modern dog breeds "ancient." That includes what are said to be ancient breeds, like the Shar-Pei, the Akita and the Afghan hound. The new report says those animals are not closer to the first domesticated dogs than any other modern breed. Earlier research suggested that their genetic structure was similar to ancient breeds.

CHRISTOPHER CRUISE: Dogs were the first animals to become domesticated. Experts say dogs stopped being wild about fifteen thousand years ago. Domestication involved changes in the make-up, or structure, of genes. Over time, dogs became work animals. For example, some breeds were very good at protecting and guiding farm animals. But others were not house-trained and were not kept as pets until about two thousand years ago.

The international team of scientific researchers based their results on a study of ancient and modern dogs. They worked with one thousand three-hundred seventy-five animals. The animals represented thirty-five dog breeds.

BARBARA KLEIN: The researchers examined the genetic structure of one hundred twenty-one breeds. Then they compared that information with a worldwide archeological study of the remains of the earliest dogs. They also studied the genes of nineteen wolves. Earlier research suggested that modern dogs may have developed first from the grey wolf.

The researchers say human movement is another reason for the genetic difference between ancient and modern dog breeds. Historic events like the two world wars also affected the dog population.

CHRISTOPHER CRUISE: Greger Larson of Durham University in England was lead writer of the report. Professor Larson says dogs have followed humans everywhere. And he notes, "We really love our dogs, and they have accompanied us across every continent."

The researchers say some of the findings about what are considered "ancient" breeds seem opposite of what you might think. For example, none of the oldest breeds came from areas where the oldest archeological remains have been found.

Keith Dobney from the University of Aberdeen in Scotland also worked on the research team. He said, "We still have some way to go to understand how, where and when the dog became man's best friend."

(MUSIC)

BARBARA KLEIN: Finally, the Golden Gate Bridge is celebrating its seventy-fifth anniversary. The bridge opened to vehicle traffic on May twenty-eighth, nineteen thirty-seven. Since then, more than two billion vehicles have crossed the world famous structure between San Francisco and Marin County, California. As many as one hundred twelve thousand cars make the trip each day.

The Golden Gate Bridge had the longest suspension span in the world, at the time it was built. The suspended roadway stretches one thousand two hundred eighty meters between the bridge's two tall towers. Today it still rates among the top ten longest bridge spans in existence.

CHRISTOPHER CRUISE: Mary Currie works for the Golden Gate Bridge, Highway and Transportation District. She says the bridge is one of the most extraordinary engineering projects of all time.

MARY CURRIE: "The Golden Gate Bridge is an engineering marvel certainly, and it gets award after award after award for what it means in civil engineering and structural engineering. It's also a place where things happen first. For example, we were the first suspension bridge to have to change the roadway deck."

The Golden Gate Bridge is named after the Golden Gate Strait. That narrow passage of water connects the San Francisco Bay to the Pacific Ocean. Joseph Strauss was the chief engineer of the Golden Gate Bridge project. Work began in nineteen thirty-three. The project took four years to complete.

BARBARA KLEIN: The bridge is two thousand seven hundred eighty-eight meters long from one end to the other. It is twenty-seven meters wide. Two large cables pass over the top of the bridge's towers. These structures stand two hundred twenty-seven meters above water and one hundred fifty-two meters above the road. Each cable holds more than twenty-seven thousand five hundred strands of wire.

Two hundred fifty pairs of vertical suspender ropes connect the support cables to the suspension bridge. This is part of what enables the bridge to move up and down by nearly five meters.

CHRISTOPHER CRUISE: The Golden Gate Bridge weighed eight hundred eleven million five hundred thousand kilograms when it was completed in nineteen thirty-seven. The San Francisco Chronicle newspaper called the finished project, "a thirty-five million dollar steel harp!"

Architect Irving Morrow gets credit for the bridge's bright orange color. The Navy wanted the bridge painted in yellow and black. The Air Force had suggested red and white.

MARY CURRIE: "But we were fortunate that Irving Morrow knew that that color would blend with the environment, it would contrast with the ocean and the air above, and it would also allow the art deco styling to really stand out."

(MUSIC)

BARBARA KLEIN: This SCIENCE IN THE NEWS was written by Jerilyn Watson and June Simms, who was also the producer. I'm Barbara Klein.

CHRISTOPHER CRUISE: And I'm Christopher Cruise. You can find transcripts, MP3s and podcasts of our programs at voa.com. And you can find us on Twitter and YouTube at VOA Learning English. Join us again next week for more news about science in Special English on the Voice of America.