VOA慢速英语20060606b

SCIENCE IN THE NEWS - AIDS at 25: Scientists Confirm That H.I.V. Came From ChimpsBy Caty Weaver³ and Lawan Davis

Broadcast: Tuesday, June 06, 2006

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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Steve Ember.

VOICE TWO:

And I'm Faith Lapidus. On our program this week, twenty-five years into the AIDS crisis, new findings about its history ...

VOICE ONE:

Also, a new theory about the history of humans and chimps² ...

VOICE TWO:

And a report on the dangers of indoor air pollution from solid cooking fuels.

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VOICE ONE:

On June fifth, nineteen eighty-one, a medical report described an unusual infection in five young men in Los Angeles. The Centers for Disease Control reported that all five were homosexuals, and two had died. Soon doctors identified more and more cases. In time, the infection became known as Acquired Immunodeficiency Syndrome⁴.


Seven-year-old AIDS patient in Bangkok, Thailand

A United Nations report last week said the spread of AIDS worldwide appears to be slowing. But rates of new infections continue to increase in some areas of the world. The newest estimate is that around forty million people are currently infected with the virus that causes AIDS.

The report says about three million people died of AIDS in two thousand five. Four million others became infected.

VOICE TWO:

After twenty-five years, scientists continue to work on a vaccine⁵ to protect against H.I.V., the virus that causes AIDS. There is no cure for AIDS. But antiretroviral medicines can add years to survival.

Scientists say H.I.V., human immunodeficiency virus, is related most closely to an animal virus. This virus is known as S.I.V., simian⁶ immunodeficiency virus. Simians include apes and monkeys.

Scientists have known for years that S.I.V. has been found in chimpanzees living in captivity⁷. But they were not sure if the virus existed in chimps in the wild. Now experts say they have direct evidence to confirm that the human virus came from chimps.

In west-central Africa, they have found what they call an important missing link in the history of H.I.V. An international team gathered chimpanzee waste from the forest floor in areas of southern Cameroon.

VOICE ONE:

Beatrice Hahn of the University of Alabama at Birmingham led the study. Doctor Hahn says tests on the droppings showed antibodies to S.I.V. Antibodies are white blood cells that fight invading organisms.

The scientists also did genetic⁸ tests on the waste to identify individual chimps as well as communities of chimps. Doctor Hahn says these tests showed which ones had the kind of S.I.V. that led to what is now the most common form of the human virus.

The researchers found infection rates as high as thirty-five percent in some chimp¹ communities in southern Cameroon.

VOICE TWO:

The scientists believe that the virus spread from chimps to humans most likely through bushmeat hunters.

Developing the tests to do this study without further endangering chimp populations took seven years. Science magazine published the findings. But there are questions that remain, such as how the virus developed in chimps before it jumped to humans.

VOICE ONE:

The first known case of H.I.V. was found in a man from what is now the Democratic Republic of Congo. His name is not known. He had given blood in nineteen fifty-nine for research on genetic resistance to malaria⁹.

Researchers at the University of Washington in Seattle stored the blood for future study. In nineteen eighty-six, five years after the first report of AIDS, the blood tested positive for H.I.V.

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VOICE TWO:

You are listening to SCIENCE IN THE NEWS in VOA Special English.


Adult chimpanzee and baby

Genetic experts say humans and chimps are ninety-eight percent related. A new study suggests that the development of humans from chimps may have been more recent than scientists have thought. And more complex.

The scientists who did the study say they found evidence of a period when humans reproduced with chimps. The result when different species are combined is a hybrid¹⁰.

Scientists traditionally believe that hybrid populations die out. But the new theory suggests that this one continued to evolve into the humans of today.

VOICE ONE:

The theory comes from scientists at the Broad [pronounced brode] Institute. This is a joint¹¹ program of the Massachusetts Institute of Technology and Harvard University. The findings appeared in the publication Nature.

David Reich led the team that did the research. In his words: The study gave unexpected results about how we separated from our closest relatives.

VOICE TWO:

The scientists studied the genetic history of humans and of chimps and other apes. They believe that more than one million years after the ancestors of humans and chimps split, the two species produced hybrids¹². The theory is that modern humans developed from these hybrids, not from the earlier forms of humans.

The scientists say human females might have mated with chimps because males of hybrid species often cannot reproduce. They say the final split between humans and chimps took place perhaps less than five million four hundred thousand years ago.

VOICE ONE:

This estimate differs from findings by other researchers.

In two thousand two, scientists reported the discovery in Chad of a skull¹³ from a creature known as Toumai. Tests suggested that this nearly complete head bone was between six million and seven million years old.

The scientists who found Toumai described it as a new kind of hominid, a member of the family that includes modern humans. It apparently¹⁴ had human-like teeth and walked on two legs.

The researchers who did the new study say the dating of Toumai could be wrong. But if the fossil is that old, they say, then it may have come from before the final split into humans and chimps. Possible evidence for their theory that the separation took longer and was not as clean a break as people might think.

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VOICE TWO:

The World Health Organization says half of the world's population burns wood, coal, animal waste or other solid fuels. More than three thousand million people use solid fuels to cook and to heat and light their homes.

But people who burn these fuels often breathe in large amounts of smoke. This can lead to pneumonia¹⁵ and other diseases.

The W.H.O. recently published a report about the dangers of solid fuels. The report says these fuels are the cause of one and one-half million deaths each year, mostly in Southeast Asia and southern Africa. Most victims of indoor air pollution are children and women.

VOICE ONE:

The World Health Organization says there has been little progress since nineteen ninety in supplying more people with modern cooking fuels. The report discusses what it would take to cut the use of solid fuels in half by two thousand fifteen.

To do that, almost five hundred thousand people every day would need to gain modern energy services. But experts say gains in health and productivity would more than pay for the costs required.

VOICE TWO:

The W.H.O. estimates a yearly cost of thirteen thousand million dollars to supply liquefied petroleum¹⁶ gas to half the people now using solid fuels. It says that investment would result in yearly economic gains of ninety-one thousand million dollars. Other kinds of fuel would cost more.

The report says there are simple solutions that could help people in the short term. These include cleaner-burning stoves and better systems to clear the air in homes. Longer-term solutions include a change to cleaner cooking fuels such as liquefied petroleum gas, biogas, ethanol or plant oils.

VOICE ONE:

The report is called Fuel for Life: Household Energy and Health. It can be found on the World Health Organization Web site at w-h-o dot i-n-t (who.int). Enter the words Fuel for Life in the search box at the top.

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VOICE TWO:

SCIENCE IN THE NEWS was written by Caty Weaver and Lawan Davis. Brianna Blake was our producer. I'm Faith Lapidus.

VOICE ONE:

And I'm Steve Ember. Read and listen to our programs at www.unsv.com. To send us e-mail, write to [email protected]. And join us again next week for more news about science in Special English on the Voice of America.

1 chimp   

n.黑猩猩

参考例句：

• In fact,the color of gorilla and chimp are light-color.其实大猩猩和黑猩猩的肤色是较为浅的。
• The chimp is the champ.猩猩是冠军。

2 chimps   

（非洲）黑猩猩( chimp的名词复数 )

参考例句：

• Chimps are too scarce, and too nearly human, to be routinely slaughtered for spare parts. 黑猩猩又太少，也太接近于人类，不可以作为人器官备用件说杀就杀。 来自英汉非文学 - 生命科学 - 医学的第四次革命
• And as nonprimates, they provoke fewer ethical and safety-related concerns than chimps or baboons. 而且作为非灵长类，就不会产生像用黑猩猩或狒狒那样的伦理和安全方面的顾虑。 来自英汉非文学 - 生命科学 - 医学的第四次革命

3 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

4 syndrome   

n.综合病症；并存特性

参考例句：

• The Institute says that an unidentified virus is to blame for the syndrome. 该研究所表示,引起这种综合症的是一种尚未确认的病毒。
• Results indicated that 11 fetuses had Down syndrome. 结果表明有11个胎儿患有唐氏综合征。

5 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

6 simian   

adj.似猿猴的；n.类人猿，猴

参考例句：

• Ada had a wrinkled,simian face.埃达有一张布满皱纹、长得像猿猴的脸。
• Curiosity is the taproot of an intellectual life,the most valuable of our simian traits.好奇是高智生命的根源，也是我们类人猿特征中最有价值的部分。

7 captivity   

n.囚禁；被俘；束缚

参考例句：

• A zoo is a place where live animals are kept in captivity for the public to see.动物园是圈养动物以供公众观看的场所。
• He was held in captivity for three years.他被囚禁叁年。

8 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

9 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

10 hybrid   

n.(动，植）杂种，混合物

参考例句：

• That is a hybrid perpetual rose.那是一株杂交的四季开花的蔷薇。
• The hybrid was tall,handsome,and intelligent.那混血儿高大、英俊、又聪明。

11 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

12 hybrids   

n.杂交生成的生物体( hybrid的名词复数 )；杂交植物（或动物）；杂种；（不同事物的）混合物

参考例句：

• All these brightly coloured hybrids are so lovely in the garden. 花园里所有这些色彩鲜艳的杂交花真美丽。 来自辞典例句
• The notion that interspecific hybrids are rare is ill-founded. 有一种看法认为种间杂种是罕见的，这种看法是无根据的。 来自辞典例句

13 skull   

n.头骨；颅骨

参考例句：

• The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
• He fell out of the window and cracked his skull.他从窗子摔了出去，跌裂了颅骨。

14 apparently   

adv.显然地；表面上，似乎

参考例句：

• An apparently blind alley leads suddenly into an open space.山穷水尽，豁然开朗。
• He was apparently much surprised at the news.他对那个消息显然感到十分惊异。

15 pneumonia   

n.肺炎

参考例句：

• Cage was struck with pneumonia in her youth.凯奇年轻时得过肺炎。
• Pneumonia carried him off last week.肺炎上星期夺去了他的生命。

16 petroleum   

n.原油，石油

参考例句：

• The Government of Iran advanced the price of petroleum last week.上星期伊朗政府提高了石油价格。
• The purpose of oil refinery is to refine crude petroleum.炼油厂的主要工作是提炼原油。