2006年VOA标准英语-Study Suggests Climate Change Killed Off I

By David McAlary
Washington
10 May 2006

There is new evidence in the case of the missing woolly mammoth¹. In fact, several species of large mammals in addition to the mammoth went missing at the end of the last ice age more than 10,000 years ago, and scientific detectives have been seeking an explanation for their extinction². The new evidence points to a suspect other than human hunters, but that probably will not end the debate.

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"Oh give me a home

Where the buffalo³ roam,

Where the deer and the antelope⁴ play . . ."

Mammuthus columbi    
  
This traditional cowboy song pays homage⁵ to some of the large game found in North America. Had it been written 13,000 years ago, it might have mentioned the woolly mammoth, giant beaver⁶, saber-toothed tiger, wild horse, or a variety of other very large native animals that became extinct soon after. The extinction affected⁷ 75 percent of North America's big mammals. Scientists have long debated whether the cause was climate change or hunting by the human newcomers from Asia.

New scientific dating of 600 bones from that era from Alaska and Canada's Yukon Territory, including bones of humans, suggests that the warming climate was the culprit. University of Alaska scientist Dale Guthrie says it was a time when the landscape was changing from frigid⁸ grassland⁹ preferred by the large species to something less hospitable¹⁰ to them.

"What happened during this changeover time was that more moisture and warmer temperatures allowed trees and tundra¹¹ to move in, a very unproductive landscape for large mammals but very dense¹² greenery," said Dale Guthrie.

The study of the bones' ages, published in the journal Nature, shows that the woolly mammoth was already declining in number when humans arrived in North America from Siberia over the Bering Strait, which was still frozen at the time. The research also points out that wild horses died off 1,000 years earlier than the mammoth.

"So if you think of it as a really potent¹³ superkiller society coming in cleaning out all the animals, you would expect the mortality to be synchronous," he said.

Guthrie also notes that wild horse bones have never been found in early human hunting sites in North America. Abundant remains¹⁴ of bison and elk¹⁵ have been found, indicating they were the ones most hunted. Yet they did not become extinct.

"So that again says something about the human overkill theory," noted¹⁶ Guthrie. "It makes it seem less plausible¹⁷."

But others cling to the belief that humans forced the large mammal disappearance¹⁸, not only in North America, but everywhere. University of Arizona geo-scientist Paul Martin has long described how the pattern of large animal extinctions coincides with human expansion and big-game hunting technologies.

"The arrival of the first people into a landmass [has] everything to do with the extinction of large animals at that time in that landmass," said Paul Martin.

Supporting this view is the dating of several burial sites of big Australian land mammals, reptiles¹⁹, and birds in 2002. It revealed that the animals died off about 46,000 years ago, a few thousand years after humans arrived. That was far earlier than the North American extinctions. University of Melbourne researcher Richard Roberts says climate change cannot be the explanation for the loss of this so-called megafauna. If it were, extinctions would have occurred simultaneously²⁰ everywhere.

"All over the world, New Zealand, Madagascar, North America, South America - all of these islands and continents had megafauna that now no longer exist, and the only related theme is that people arrived at different points in time at each of those places," said Richard Roberts. "At all of these different points in time, soon after people arrived, the megafauna went extinct."

At the University of Alaska, Dale Guthrie agrees that animals are vulnerable to human colonization²¹ and does not discount the notion that prehistoric²² hunters might have decimated some populations of game. But he insists that people should not be singled out for blame.

"The story is more complex than any simplistic idea," he said. "So to have one simple solution to all of extinctions seems to be rather unwise."

1 mammoth   

n.长毛象；adj.长毛象似的，巨大的

参考例句：

• You can only undertake mammoth changes if the finances are there.资金到位的情况下方可进行重大变革。
• Building the new railroad will be a mammoth job.修建那条新铁路将是一项巨大工程。

2 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

3 buffalo   

n.(北美)野牛；(亚洲)水牛

参考例句：

• Asian buffalo isn't as wild as that of America's. 亚洲水牛比美洲水牛温顺些。
• The boots are made of buffalo hide. 这双靴子是由水牛皮制成的。

4 antelope   

n.羚羊；羚羊皮

参考例句：

• Choosing the antelope shows that China wants a Green Olympics.选择藏羚羊表示中国需要绿色奥运。
• The tiger was dragging the antelope across the field.老虎拖着羚羊穿过原野。

5 homage   

n.尊敬，敬意，崇敬

参考例句：

• We pay homage to the genius of Shakespeare.我们对莎士比亚的天才表示敬仰。
• The soldiers swore to pay their homage to the Queen.士兵们宣誓效忠于女王陛下。

6 beaver   

n.海狸，河狸

参考例句：

• The hat is made of beaver.这顶帽子是海狸毛皮制的。
• A beaver is an animals with big front teeth.海狸是一种长着大门牙的动物。

7 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

8 frigid   

adj.寒冷的，凛冽的；冷淡的；拘禁的

参考例句：

• The water was too frigid to allow him to remain submerged for long.水冰冷彻骨，他在下面呆不了太长时间。
• She returned his smile with a frigid glance.对他的微笑她报以冷冷的一瞥。

9 grassland   

n.牧场，草地，草原

参考例句：

• There is a reach of grassland in the distance.远处是连绵一片的草原。
• The snowstorm swept the vast expanse of grassland.暴风雪袭击了辽阔的草原。

10 hospitable   

adj.好客的；宽容的；有利的，适宜的

参考例句：

• The man is very hospitable.He keeps open house for his friends and fellow-workers.那人十分好客，无论是他的朋友还是同事，他都盛情接待。
• The locals are hospitable and welcoming.当地人热情好客。

11 tundra   

n.苔原，冻土地带

参考例句：

• The arctic tundra is at the top of the world around the North Pole.北极冻原是指北极点周边的地区，是世界最高的地方。
• There is a large amount of methane gas under the Siberian tundra.西伯利亚的冻土地带之下有大量的甲烷气体。

12 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

13 potent   

adj.强有力的，有权势的；有效力的

参考例句：

• The medicine had a potent effect on your disease.这药物对你的病疗效很大。
• We must account of his potent influence.我们必须考虑他的强有力的影响。

14 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

15 elk   

n.麋鹿

参考例句：

• I was close enough to the elk to hear its labored breathing.我离那头麋鹿非常近，能听见它吃力的呼吸声。
• The refuge contains the largest wintering population of elk in the world.这座庇护所有着世界上数量最大的冬季麋鹿群。

16 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

17 plausible   

adj.似真实的，似乎有理的，似乎可信的

参考例句：

• His story sounded plausible.他说的那番话似乎是真实的。
• Her story sounded perfectly plausible.她的说辞听起来言之有理。

18 disappearance   

n.消失，消散，失踪

参考例句：

• He was hard put to it to explain her disappearance.他难以说明她为什么不见了。
• Her disappearance gave rise to the wildest rumours.她失踪一事引起了各种流言蜚语。

19 reptiles   

n.爬行动物，爬虫( reptile的名词复数 )

参考例句：

• Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
• Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》

20 simultaneously   

adv.同时发生地，同时进行地

参考例句：

• The radar beam can track a number of targets almost simultaneously.雷达波几乎可以同时追着多个目标。
• The Windows allow a computer user to execute multiple programs simultaneously.Windows允许计算机用户同时运行多个程序。

21 colonization   

殖民地的开拓，殖民，殖民地化； 移殖

参考例句：

• Colonization took place during the Habsburg dynasty. 开拓殖民地在哈布斯堡王朝就进行过。
• These countries took part in the colonization of Africa. 这些国家参与非洲殖民地的开发。

22 prehistoric   

adj.（有记载的）历史以前的，史前的，古老的

参考例句：

• They have found prehistoric remains.他们发现了史前遗迹。
• It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。