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 that 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 an adaptation to carrying scarce, high- quality resources. The team of researchers from the U. S., England, Japan and Portugal investigated the behavior of modern-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 frees up their hands. Over time，intense bursts of bipedal activity 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 Bossou 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 started moving 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 一 even their mouths.

The second study, by Kimberley Hockings of Oxford Brookes University, was a 14-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.

詞匯：

scarce adj.缺乏的，不足的；稀有的

chimpanzee n.黑猩猩

ape n.無尾猿; 類人猿

bipedal adj. 二足的

anatomical adj.解剖的

coula nuts( coula也可寫作cola或kola)可樂果

注釋：

1.GW's Columbian College of Arts and Sciences:喬治o華盛頓大學哥倫比亞藝術與科學學 院。喬治·華盛頓大學（George Washington University)的英文簡稱為GW，是美國頂尖的私立大學之一，于1821年建校，位于美國首都華盛頓。

2.ecological settings: 生態環境

3.bipedal activity：雙足活動

4.anatomical chaiige: 解剖學上的變化

5.Kyoto University:京都大學，是繼東京大學之后成立的日本第二所國立大學，于I897年建校。京都大學主要校區位于日本歷史名城京都市。

6.Bossou: 博蘇,幾內亞的一個地名。博蘇森林生活著黑猩猩群落。

7.oil palm nut: 油棕櫚堅果

8.increased by a factor of four:增加了四倍

9.in one go: -口氣

10.Oxford Brookes University: 牛津布魯克斯大學，創立于1865年，是英國最具特色的綜合性大學之一。牛津布魯克斯大學位于世界學術名城--牛津。這里學風濃郁、精英薈萃，歷來為求學圣地。

練習：

1.Which of the following statements is NOT true according to the first two paragraphs? A Many people question the 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 an adaptation to carrying precious resources.

D Our ancestors' ecological conditions resembled those of modern-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 die nut-rich forest faster by walking that way.

D Because they wanted to carry more nuts with two free limbs.

5.What can 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 on two limbs and walking on four limbs each have their advantages.

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

答案與題解：

1.A第一段第一句和第二句說明，大多數人對人類直立行走習以為常,并不質疑這種習慣。而A的內容正好與此相反，所以是答案。其他選項所述內容均可從第一段和第二段推斷出

2.B 文章報道，科學家通過實驗證實黑猩猩直立行走是為了解放前肢，讓前肢搬運對其生命至關重要的資源，從而推斷出人類祖先也經歷了從四足到二足的進化過程。科學家想通過對黑猩猩的實驗解釋人類直立行走的成因。所以B是答案，A、C、D選項不是科學家進行研究的目的。

3.C第五段明白無誤地描述了黑猩猩全然不顧油棕櫚堅果（ignored the oil palm nuts altogether),集中精力搶運可樂果。所以C是答案，B、C、D的內容不符合文章原意。

4.D黑猩猩用后肢直立行走，搬運資源的效率提高了四倍。選項D符合原意，是答案。選項 A、B、C的內容文章中沒有提到，所以不是答案。

5.D 了解了通篇文章的意思，就會選擇選項D。人類直立行走是受生態環境所迫，是人類生存的一種手段，直立行走是自然選擇的結果。選項A和C的內容文章中沒有涉及。文章中有選項B的內容，但它不是文章的主旨。

參考譯文：

第四十八篇 研究人員發現人類開始直立行走的原因

我們大多數人每天都走路而且手里搬著東西。這樣的活動看似太簡單，大多數人沒有疑問。但是一個國際研究者（包括喬治o華盛頓大學哥倫比亞藝術與科學學院的Richmond博士）團隊已經發現了人類直立行走可能源于數百萬年以前適應搬運稀有的、高質量的資源。這些來自美國、英國、日本和葡萄牙的研究者研究了當代黑猩猩爭搶食物時的行為特征，試圖對什么樣的生態環境竟然導致大猿（一種我們與現存的黑猩猩一樣的600萬年前的祖先）直立行走作出解釋。

"這些黑猩猩居住的生態環境和我們最早的祖先開始直立行走時是相同的，" Richmond博士說。研究結果顯示，當黑猩猩需要獨占一種資源時，它們就從四肢行走轉換為直立行走。由于直立行走可以解放它們的雙手，這使得它們能搬更多的東西。久而久之，雙足活動的強烈爆發可能導致了解剖學上的變化，因此這種變化也就成為自然選擇的主題，在那種情況下，對食物或其他 資源的爭奪是十分激烈的。

有兩項研究是在幾內亞完成的。第一項研究是在京都大學博蘇森林的一塊天然空地--"室外實驗室"進行的。研究者們允許森林里的黑猩猩能得到兩種不同的堅果，一種叫油棕櫚堅果，自然界隨處可見，一種叫可樂果，自然環境中不常見。人們監控黑猩猩在下列三種情形下的行為：(a)只有油棕櫚堅果；（b)只有少量的可樂果，大多數是油棕櫚堅果;(c)大多數是可樂果，少數是油棕櫚堅果。

當稀有的可樂果數量很少時，黑猩猩一次就會拿得多。同樣，當大部分是可樂果時，黑猩猩對油棕櫚堅果根本視而不見。黑猩猩認為可樂果才是珍貴的資源，并為得到可樂果激烈競爭。

處于這種激烈競爭的環境中，黑猩猩直立行走的頻率增加了四倍。很顯然，雙足行走可以使它們拿走更多的稀有資源，而且，為了盡可能地一口氣多拿，它們積極利用可用到的任何方法，甚至嘴巴。

第二項研究是在牛津布魯克斯大學的Kimberley Hockings進行的。該研究歷時14個月，主題是博蘇的黑猩猩搶劫糧食，場景是它們不得不為稀有和不可預知的資源競爭。在這項研究中，黑猩猩35%的活動是直立行走。而這一次研究再一次證實了黑猩猩的直立行走與它們試圖一次搬走盡可能多的東西有關。

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（責任編輯：vstara）