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第四十八篇 Researchers Discover Why Humans Began Walking Upright

Most of us walk and carry items in our hands every day. These are seemingly simple activities tllat the majority of us don't question. But an international team of researchers, including Dr. Richmond from GW's Columbian College of Arts and Sciences, have discovered that human walking upright, may have originated millions of years ago as art adaptation to carrying scarce, high-quality resources.The team of researchers from the U. S. , England, Japan and Portugal investigated the behavior of modem day chimpanzees as they competed for food resources, in an effort to understand what ecological settings would lead a large ape～one that resembles the 6 million-year old ancestor we shared in common with living chimpanzees-to walk on two legs.

"These chimpanzees provide a model of the ecological conditions under which our earliest ancestors might have begun walking on two legs, " said Dr. Richmond.

The research findings suggest that chimpanzees switch to moving on two limbs instead of four in situations where they need to monopolize a resource. Standing on two legs allows them to carry much more at one time because it flees up their hands.Over time, intense bursts of bipedal activity4 may have led to anatomical changes that in turn became the subject of natural selection where competition for food or other resources was strong.

Two studies were conducted by the team in Guinea.The first study was conducted by the team in Kyoto University’s "Outdoor laboratory" in a natural clearing in Bossouo Forest. Researchers allowed the wild chimpanzees access to different combinations of two different types of nut-the oil palm Nut , which is naturally widely available, and the coula nut, which is not, the chimpanzees' behavior was monitored in three situations: (a)when only oil palm nuts were available, (b)when a small number of coula nuts were available, and(c)when coula nuts were the majority available resource.

When the rare coula nuts were available only in small numbers. the chimpanzees transported more at one time. Similarly, when coula nuts were the majority resource, the chimpanzees ignored the oil palm nuts altogether. The chimpanzees regarded the coula nuts as a more highly-prized resource and competed for them more intensely.

In such high-competition settings, the frequency of cases in which the chimpanzees startedmoving on two legs increased by a factor of four. Not only was it obvious that bipedal movement allowed them to carry more of this precious resource, but also that they were actively trying to move as much as they could in one go by using everything available—even their mouths.

The second study, by Kimberley Hockings of Oxford Brookes University, was a l4-month study of Bossou chimpanzees crop-raiding, a situation in which they have to compete for rare and unpredictable resources. Here, 35 percent of the chimpanzees' activity involved some sort of bipedal movement, and once again, this behavior appeared to be linked to a clear attempt to carry as much as possible at one time.

词汇：

scarce aaj. 缺乏的，不足的；稀有的

bipedal adj. 二足的

chimpanzee n. 黑猩猩

anatomical adj. 解剖的

ape n. 无尾猿；类人猿

coula nuts(coula也可写作cola或kola)可乐果

注释：

1. GW’S Columbian College of Arts and Sciences：乔治·华盛顿大学哥伦比亚艺术与科学学院。乔治·华盛顿大学(George Washington University)的英文简称为GW, 是美国顶尖的私立大学之一，于l821年建校，位于美国首都华盛顿。

2. ecological settings：生态环境

3. bipedal activity：双足活动

4. anatomical change：解剖学上的变化

5. Kyoto University：京都大学，是继东京大学之后成立的疆本第二所国立大学，于l897年建校。京都大学主要校区位于日本历史名城京都市。

6. Bossou：博苏，几内亚的一个地名。博苏森林生活着黑猩猩群落。

7. oil palm nut：油棕榈坚果

8. increased by a factor of four：增加了四倍

9. in one go：一口气

10. Oxford Brookes University：牛津布鲁克斯大学，刽立于1865年，是英国最具特色的综合性大学之一。牛津布鲁克斯大学位于世界学术名城——牛津。这里学风浓郁、精英荟萃，历来为求学圣地。

练习：

1. Which of the following statements is NOT true according to the first two paragraphs?

A. Many people question{he simple human activities of walking and carrying items.

B. Chimpanzee’s behaviors may suggest why humans Walk on two legs.

C. Human walking upright is viewed as all adaptation to carrying precious resources.

D. Our ancestors’ecological conditions resembled those of modem—day chimpanzees'.

2. Dr.Richmond conducted the experiment with the purpose of finding

A. when humans began walking on two legs.

B. what made our ancestors walk upright.

C. what benefits walking upright brought to our ancestors.

D. how walking upright helped chimpanzees monopolize resources.

3. Kyoto University’s study discovered that chimpanzees

A. regarded both types of nut as priced resources.

B. preferred oil palm nuts to coula nuts.

C. liked coula nuts better than oil palm nuts.

D. ignored both types of nut altogether.

4. Why did the chimpanzees walk on two limbs during Kyoto University’s experiment?

A. Because they imitated the human way of walking just for fun.

B. Because they wanted to please the researchers to get more coula nuts from them.

C. Because they wanted to get to the nut-rich forest faster by walking that way.

D. Because they Wanted to carry more nut with two free limbs.

5. What call we infer from the reading passage ?

A. Chimpanzees are in the same process of evolution as our ancestors Were.

B. Chimpanzees are similar to humans in many behaviors.

C. Walking oil two limbs and walking on four limbs each have their advantages.

D. Human walking On two legs developed as a means of survival.

答案与题解：

1. A 第一段第一句和第二旬说明，大多数人对人类直立行走习以为常，并不质疑这种习惯。而A的内容正好与此相反，所以是答案。其他选项所述内容均可从第一段和第二段推断出来。

2. B 文章报道，科学家通过实验证实黑猩猩直立行走是为了解放前肢，让前肢搬运对其生命至关重要的资源，从而推断出人类祖先也经历了从四足到二足的进化过程。科学家想通过对黑猩猩的实验解释人类直立行走的成因。所以B是答案，A、C、D选项不是科学家进行研究的目的。

3. C 第五段明白无误地描述了黑猩猩全然不顾油棕榈坚果(ignored the oil palm nuts altogether)，集中精力抢运可乐果。所以C是答案， B、C、D的内容不符合文章原意。

4. D黑猩猩用后胺直立行走，搬运资源的效率提高了四倍。选项D符合原意，是答案。选项A、B、C的内容文章中没有提到，所以不是答案。

5. D了解了通篇文章的意思，就会选择选项D。人类直立行走是受生态环境所迫，是人类生存的一种手段，直立行走是自然选择的结果。选项A和C的内容文章中没有涉及。文章中有选项B的内容，但它不是文章的主旨。