Why Humans Walk On Two Legs
A team of scientists that studied chimpanzees trained to use treadmills has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it required less energy than getting around on all fours.
“When our earliest ancestors started walking on two legs, they took the first steps toward becoming human,” said lead researcher Michael Sockol of UC Davis1. “Our findings help answer why.” Sockol worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to “knucklewalk” on all fours on the sort of treadmill found in most gyms.
The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out, the scientists collected metabolic and other data that allowed them to calculate which method of locomotion used less energy and why. The team gathered the same information for four adult humans walking on a treadmill.
The researchers found that human walking used about 75 percent less energy and burned 75 percent fewer calories than quadrupedal and bipedal2 walking in chimpanzees. They also found that for some but not all of the chimps, walking on two legs was no more costly than knucklewalking.
“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling. For three chimps, bipedalism3 was more expensive, but for the other two chimps, this wasn’t the case. One spent about the same energy walking on two legs as on four. The other used less energy walking upright.” These two chimps had different gaits and anatomy than their knucklewalking peers.
Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation which natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Fossil and molecular evidence suggests the earliest ancestors of the human family lived in forested areas in equatorial Africa in the late Miocene era some 8 to 10 million years ago, when changes in climate may have increased in distance between food patches. That would have forced our earliest ancestors to travel longer distances on the ground and favored those who could cover more ground using less energy.
“This isn’t the complete answer,” Sockol said. “But it’s a good piece of a puzzle humans have always wondered about: How and why did we become human? And why do we alone walk on two legs?” (435 words)
詞匯：
chimpanzee n. 黑猩猩(又作
chimp )calorie n. 卡(路里)，小卡
biped n 二足動(dòng)物
treadmill n. 踏輪;踏車(chē);單調(diào)工作gait n. 步態(tài)，步法
coax v. 哄，哄勸anatomic adj. 解剖(學(xué))的
knucklewalk v. 用膝關(guān)節(jié)走路Q(chēng)uadruped n. 四足動(dòng)物
metabolic adj.(新陳)代謝的Miocene n.& adj. 中新世(的)
locomotion n. 運(yùn)動(dòng)(力)
注釋?zhuān)?BR> 1. UC Davis ：加州大學(xué)戴維斯分校。UC是University of California (加利福尼亞大學(xué))的縮寫(xiě)，該校有多個(gè)分校，UC Davis是其中一個(gè)。Davis以前是UC Berkeley分校的農(nóng)學(xué)院，后來(lái)獨(dú)立出來(lái)。Davis是一個(gè)大學(xué)城，很小的城市，Davis校園基本就構(gòu)成了這個(gè)城市。
2. quadrupedal and bipedal：quad-：構(gòu)詞詞素，是“四”的意思;bi-:構(gòu)詞詞素，是“二”的意思;ped-：構(gòu)詞詞素，是“腳”的意思;-al是構(gòu)成形容詞的后綴，表示“...的”。因此，quadrupedal意為“四足動(dòng)物的”，bipedal意為“二足動(dòng)物的”。
3. bipedalism：系bipedal(二足動(dòng)物的)的對(duì)應(yīng)名詞，這里后綴-ism表示“特征”、“特性”。
練習(xí)：
1. What did Michael Sockol and his team find out in their study of chimpanzees?
A) The evidence why chimpanzees can be trained to use treadmills.
B) The evidence why our apelike ancestors came to walk on four legs.
C )The evidence why our apelike ancestors came to walk on two legs.
D) The evidence why chimpanzees can be trained to walk on two legs.
2. Which of the following best interprets the meaning of“While the chimps worked out, ….”(the first sentence of the third paragraph)?
A) While the chimps worked in the lab….
B) While the chimps exercised in the gym….
C) While the chimps tried to figure out what they should do….-
D) While the chimps tried to understand the instructions….
3. What was the result of the finding, according to Paragraph 5?
A) Three chimps used more energy walking on two legs.
B) One chimp used less energy walking on two legs.
C) One chimp used about the same energy walking on two legs as on four.
D) All of the above.
4. What was true of the hypothesis of the research?
A) Our apelike ancestors were anatomically different but had the same gaits.
B) Bipeds with natural selection had an advantage over quadruped.
C) Our apelike ancestors could adapt to different climate changes due to genetic variation.
D) Bipeds had an advantage over quadrupeds due to changes in the environment.
5. What does fossil and molecular evidence tell us about our earliest ancestors.
A) They experienced more climate changes than we do today.
B) Due to changes in climate, they were forced to travel between food patches.
C) They could cover more ground than their quadrupedal peers because they used less energy.
D)They could travel longer distances on the ground than those who could use less energy.
參考答案：
1.C.該題可以利用文章主題內(nèi)容直接判斷答案，也可以利用問(wèn)題句及被選項(xiàng)中的特征結(jié)構(gòu)及細(xì)節(jié)信息結(jié)構(gòu)(加粗字體內(nèi)容)共同作為答案線索， 在文章中查找答案相關(guān)句：
(可能的考點(diǎn)句)A team of (一組)scientists (科學(xué)家)that studied chimpanzees trained to use treadmills (跑步機(jī))has gathered(收集，集合) new evidence (證據(jù))suggesting(表明)that our earliest (初期的)apelike(象猿人的) ancestors(象猿人的) started(開(kāi)始) walking on two legs because(因?yàn)? it required(需要， 要求) less(較少的) energy(能量)than getting around (到處走動(dòng))on all fours(四肢). (一組研究被訓(xùn)練學(xué)習(xí)使用跑步機(jī)的黑猩猩的科學(xué)家們發(fā)現(xiàn)了一些新的證據(jù)：我們的人猿祖先開(kāi)始直立行走是因?yàn)閮蓷l腿比四條腿行走省力)
“When our earliest ancestors started walking on two legs, they took the first steps toward becoming human,” said lead(領(lǐng)導(dǎo)) researcher(研究帶頭人) Michael Sockol of UC Davis1. “Our findings help answer why.” Sockol worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to “knucklewalk” on all fours on the sort of treadmill found in most gyms.
根據(jù)第一段的內(nèi)容(一組研究被訓(xùn)練學(xué)習(xí)使用跑步機(jī)的黑猩猩的科學(xué)家們發(fā)現(xiàn)了一些新的證據(jù)：我們的人猿祖先開(kāi)始直立行走是因?yàn)閮蓷l腿比四條腿行走省)可以直接判斷C是答案。
2.B. 首先找到這個(gè)結(jié)構(gòu)在文章中的位置，然后借助其所在句子的句意或上下文內(nèi)容判斷答案。
(第3段)The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out, the scientists(科學(xué)家) collected(收集， 聚集) metabolic(新陳代謝的) and other data(數(shù)據(jù)) that allowed(允許) them to calculate(計(jì)算出) which method(方法) of locomotion(運(yùn)動(dòng)， 移動(dòng)) used less energy(能量) and why. The team gathered the same information for four adult humans walking on a treadmill.
2. B worked out句子中的含義是“運(yùn)動(dòng)，鍛煉”的意思，所以選擇 B。
3.D. 利用被選項(xiàng)中的特征結(jié)構(gòu)(加粗文字內(nèi)容)作為答案線索，在文章中查找答案相關(guān)句：
(可能的考點(diǎn)設(shè)置句)(第5段)“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling. For three chimps, bipedalism(兩足動(dòng)物/具有兩足動(dòng)物特征) was more expensive(昂貴的， 花費(fèi)的) (與選項(xiàng)A內(nèi)容一致), but for the other two chimps, this isn’t the case(情況). One (代詞， 指代one chimp)spent about the same energy(能量) walking on two legs as on four(與選項(xiàng)C一致). The other(指剩下的一個(gè)黑猩猩) used less energy walking upright(豎直地，垂直的， 正直的).(與選項(xiàng)B一致)”These two chimps had different gaits and anatomy than their knuckle walking peers.
第五段的第三、第四和第五句提供了答案。bipedalism was more expensive的意思是：兩足行走消耗更多的體能。walking upright的意思是：直立行走，即兩足行走。
4.D.利用問(wèn)題句及被選項(xiàng)中的細(xì)節(jié)信息詞語(yǔ)(加粗字體內(nèi)容)共同作為答案線索， 在文章中查找答案相關(guān)句:
“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling.(第5段答案相關(guān)句) For three chimps, bipedalism3 was more expensive, but for the other two chimps, this wasn’t the case. One spent about the same energy walking on two legs as on four. The other used less energy walking upright.” These two chimps had different gaits and anatomy than their knucklewalking peers.
(可能的考點(diǎn)設(shè)置句)(第6段)Taken(拿， 拿走, 占領(lǐng), 獲得) together(一起), the findings(研究發(fā)現(xiàn)) provide support for (為...提供了支持)the hypothesis (假設(shè))that anatomical (解剖學(xué)上的)differences(差異)affecting gait existed among(在...之中) our earliest apelike ancestors(與A不一致), and that these differences(差異) provided(提供) the genetic variation(遺傳變異) which natural selection (自然選擇)could act on(對(duì)...起作用)when changes in the environment(環(huán)境) gave bipeds(兩足動(dòng)物) an advantage over(優(yōu)于...的優(yōu)勢(shì)) quadrupeds(四足動(dòng)物)(該部分內(nèi)容與選項(xiàng)D結(jié)構(gòu)和用詞一致， 因此D是答案).
第六段告訴了我們研究的兩個(gè)假設(shè)：一種假設(shè)：猿人祖先在解剖學(xué)意義上存在著差異，這一差異影響了它們的步態(tài);另一種假設(shè)：這些差異為自然選擇所決定的遺傳變異提供了可能性，而環(huán)境變化使得兩足行走的猿人比起四足行走的猿人更有優(yōu)勢(shì)。因此B是答案。
5.C. 利用問(wèn)題句及被選項(xiàng)中的細(xì)節(jié)信息結(jié)構(gòu)(字體加粗文字)共同作為答案線索，在文章中查找答案相關(guān)句
(第4題答案相關(guān)句)Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation which natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Fossil(化石的) and molecular (分子的)evidence(證據(jù)) suggests(顯示) the earliest ancestors(祖先) of the human family lived in forested(被森林所覆蓋的) areas in equatorial(近赤道的) Africa(非洲) in the late(遲的，末期的) Miocene era (中世紀(jì)末期)some(大約) 8 to 10 million years ago(以前), when changes in climate may have increased the distance between food patches. That would have forced(強(qiáng)迫) our earliest ancestors(早期的祖先)(問(wèn)題句中的核心結(jié)構(gòu)) to travel longer distances(距離) on the ground and favored(贊成，幫助， 有利于) those who could cover(通過(guò)) more ground using less energy. (C中的cover more ground的近義結(jié)構(gòu)travel longer distance , less energy都出現(xiàn)這個(gè)句子中，因此可能C是答案)。
“This isn’t the complete answer,” Sockol said. “But it’s a good piece of a puzzle humans have always wondered about: How and why did we become human? And why do we alone walk on two legs?”
倒數(shù)第二段提供了問(wèn)題的答案。travel longer distances用的是比較級(jí)，這里是將兩足行走的猿人與上文中四足行走的猿人做比較。those who could cover more ground using less energy指的是上文提到的與四足行走的猿人相比，體能消耗較小的兩足行走猿人。其他選擇都不是正確說(shuō)法。
A team of scientists that studied chimpanzees trained to use treadmills has gathered new evidence suggesting that our earliest apelike ancestors started walking on two legs because it required less energy than getting around on all fours.
“When our earliest ancestors started walking on two legs, they took the first steps toward becoming human,” said lead researcher Michael Sockol of UC Davis1. “Our findings help answer why.” Sockol worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to “knucklewalk” on all fours on the sort of treadmill found in most gyms.
The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out, the scientists collected metabolic and other data that allowed them to calculate which method of locomotion used less energy and why. The team gathered the same information for four adult humans walking on a treadmill.
The researchers found that human walking used about 75 percent less energy and burned 75 percent fewer calories than quadrupedal and bipedal2 walking in chimpanzees. They also found that for some but not all of the chimps, walking on two legs was no more costly than knucklewalking.
“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling. For three chimps, bipedalism3 was more expensive, but for the other two chimps, this wasn’t the case. One spent about the same energy walking on two legs as on four. The other used less energy walking upright.” These two chimps had different gaits and anatomy than their knucklewalking peers.
Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation which natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Fossil and molecular evidence suggests the earliest ancestors of the human family lived in forested areas in equatorial Africa in the late Miocene era some 8 to 10 million years ago, when changes in climate may have increased in distance between food patches. That would have forced our earliest ancestors to travel longer distances on the ground and favored those who could cover more ground using less energy.
“This isn’t the complete answer,” Sockol said. “But it’s a good piece of a puzzle humans have always wondered about: How and why did we become human? And why do we alone walk on two legs?” (435 words)
詞匯：
chimpanzee n. 黑猩猩(又作
chimp )calorie n. 卡(路里)，小卡
biped n 二足動(dòng)物
treadmill n. 踏輪;踏車(chē);單調(diào)工作gait n. 步態(tài)，步法
coax v. 哄，哄勸anatomic adj. 解剖(學(xué))的
knucklewalk v. 用膝關(guān)節(jié)走路Q(chēng)uadruped n. 四足動(dòng)物
metabolic adj.(新陳)代謝的Miocene n.& adj. 中新世(的)
locomotion n. 運(yùn)動(dòng)(力)
注釋?zhuān)?BR> 1. UC Davis ：加州大學(xué)戴維斯分校。UC是University of California (加利福尼亞大學(xué))的縮寫(xiě)，該校有多個(gè)分校，UC Davis是其中一個(gè)。Davis以前是UC Berkeley分校的農(nóng)學(xué)院，后來(lái)獨(dú)立出來(lái)。Davis是一個(gè)大學(xué)城，很小的城市，Davis校園基本就構(gòu)成了這個(gè)城市。
2. quadrupedal and bipedal：quad-：構(gòu)詞詞素，是“四”的意思;bi-:構(gòu)詞詞素，是“二”的意思;ped-：構(gòu)詞詞素，是“腳”的意思;-al是構(gòu)成形容詞的后綴，表示“...的”。因此，quadrupedal意為“四足動(dòng)物的”，bipedal意為“二足動(dòng)物的”。
3. bipedalism：系bipedal(二足動(dòng)物的)的對(duì)應(yīng)名詞，這里后綴-ism表示“特征”、“特性”。
練習(xí)：
1. What did Michael Sockol and his team find out in their study of chimpanzees?
A) The evidence why chimpanzees can be trained to use treadmills.
B) The evidence why our apelike ancestors came to walk on four legs.
C )The evidence why our apelike ancestors came to walk on two legs.
D) The evidence why chimpanzees can be trained to walk on two legs.
2. Which of the following best interprets the meaning of“While the chimps worked out, ….”(the first sentence of the third paragraph)?
A) While the chimps worked in the lab….
B) While the chimps exercised in the gym….
C) While the chimps tried to figure out what they should do….-
D) While the chimps tried to understand the instructions….
3. What was the result of the finding, according to Paragraph 5?
A) Three chimps used more energy walking on two legs.
B) One chimp used less energy walking on two legs.
C) One chimp used about the same energy walking on two legs as on four.
D) All of the above.
4. What was true of the hypothesis of the research?
A) Our apelike ancestors were anatomically different but had the same gaits.
B) Bipeds with natural selection had an advantage over quadruped.
C) Our apelike ancestors could adapt to different climate changes due to genetic variation.
D) Bipeds had an advantage over quadrupeds due to changes in the environment.
5. What does fossil and molecular evidence tell us about our earliest ancestors.
A) They experienced more climate changes than we do today.
B) Due to changes in climate, they were forced to travel between food patches.
C) They could cover more ground than their quadrupedal peers because they used less energy.
D)They could travel longer distances on the ground than those who could use less energy.
參考答案：
1.C.該題可以利用文章主題內(nèi)容直接判斷答案，也可以利用問(wèn)題句及被選項(xiàng)中的特征結(jié)構(gòu)及細(xì)節(jié)信息結(jié)構(gòu)(加粗字體內(nèi)容)共同作為答案線索， 在文章中查找答案相關(guān)句：
(可能的考點(diǎn)句)A team of (一組)scientists (科學(xué)家)that studied chimpanzees trained to use treadmills (跑步機(jī))has gathered(收集，集合) new evidence (證據(jù))suggesting(表明)that our earliest (初期的)apelike(象猿人的) ancestors(象猿人的) started(開(kāi)始) walking on two legs because(因?yàn)? it required(需要， 要求) less(較少的) energy(能量)than getting around (到處走動(dòng))on all fours(四肢). (一組研究被訓(xùn)練學(xué)習(xí)使用跑步機(jī)的黑猩猩的科學(xué)家們發(fā)現(xiàn)了一些新的證據(jù)：我們的人猿祖先開(kāi)始直立行走是因?yàn)閮蓷l腿比四條腿行走省力)
“When our earliest ancestors started walking on two legs, they took the first steps toward becoming human,” said lead(領(lǐng)導(dǎo)) researcher(研究帶頭人) Michael Sockol of UC Davis1. “Our findings help answer why.” Sockol worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to “knucklewalk” on all fours on the sort of treadmill found in most gyms.
根據(jù)第一段的內(nèi)容(一組研究被訓(xùn)練學(xué)習(xí)使用跑步機(jī)的黑猩猩的科學(xué)家們發(fā)現(xiàn)了一些新的證據(jù)：我們的人猿祖先開(kāi)始直立行走是因?yàn)閮蓷l腿比四條腿行走省)可以直接判斷C是答案。
2.B. 首先找到這個(gè)結(jié)構(gòu)在文章中的位置，然后借助其所在句子的句意或上下文內(nèi)容判斷答案。
(第3段)The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out, the scientists(科學(xué)家) collected(收集， 聚集) metabolic(新陳代謝的) and other data(數(shù)據(jù)) that allowed(允許) them to calculate(計(jì)算出) which method(方法) of locomotion(運(yùn)動(dòng)， 移動(dòng)) used less energy(能量) and why. The team gathered the same information for four adult humans walking on a treadmill.
2. B worked out句子中的含義是“運(yùn)動(dòng)，鍛煉”的意思，所以選擇 B。
3.D. 利用被選項(xiàng)中的特征結(jié)構(gòu)(加粗文字內(nèi)容)作為答案線索，在文章中查找答案相關(guān)句：
(可能的考點(diǎn)設(shè)置句)(第5段)“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling. For three chimps, bipedalism(兩足動(dòng)物/具有兩足動(dòng)物特征) was more expensive(昂貴的， 花費(fèi)的) (與選項(xiàng)A內(nèi)容一致), but for the other two chimps, this isn’t the case(情況). One (代詞， 指代one chimp)spent about the same energy(能量) walking on two legs as on four(與選項(xiàng)C一致). The other(指剩下的一個(gè)黑猩猩) used less energy walking upright(豎直地，垂直的， 正直的).(與選項(xiàng)B一致)”These two chimps had different gaits and anatomy than their knuckle walking peers.
第五段的第三、第四和第五句提供了答案。bipedalism was more expensive的意思是：兩足行走消耗更多的體能。walking upright的意思是：直立行走，即兩足行走。
4.D.利用問(wèn)題句及被選項(xiàng)中的細(xì)節(jié)信息詞語(yǔ)(加粗字體內(nèi)容)共同作為答案線索， 在文章中查找答案相關(guān)句:
“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling.(第5段答案相關(guān)句) For three chimps, bipedalism3 was more expensive, but for the other two chimps, this wasn’t the case. One spent about the same energy walking on two legs as on four. The other used less energy walking upright.” These two chimps had different gaits and anatomy than their knucklewalking peers.
(可能的考點(diǎn)設(shè)置句)(第6段)Taken(拿， 拿走, 占領(lǐng), 獲得) together(一起), the findings(研究發(fā)現(xiàn)) provide support for (為...提供了支持)the hypothesis (假設(shè))that anatomical (解剖學(xué)上的)differences(差異)affecting gait existed among(在...之中) our earliest apelike ancestors(與A不一致), and that these differences(差異) provided(提供) the genetic variation(遺傳變異) which natural selection (自然選擇)could act on(對(duì)...起作用)when changes in the environment(環(huán)境) gave bipeds(兩足動(dòng)物) an advantage over(優(yōu)于...的優(yōu)勢(shì)) quadrupeds(四足動(dòng)物)(該部分內(nèi)容與選項(xiàng)D結(jié)構(gòu)和用詞一致， 因此D是答案).
第六段告訴了我們研究的兩個(gè)假設(shè)：一種假設(shè)：猿人祖先在解剖學(xué)意義上存在著差異，這一差異影響了它們的步態(tài);另一種假設(shè)：這些差異為自然選擇所決定的遺傳變異提供了可能性，而環(huán)境變化使得兩足行走的猿人比起四足行走的猿人更有優(yōu)勢(shì)。因此B是答案。
5.C. 利用問(wèn)題句及被選項(xiàng)中的細(xì)節(jié)信息結(jié)構(gòu)(字體加粗文字)共同作為答案線索，在文章中查找答案相關(guān)句
(第4題答案相關(guān)句)Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation which natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Fossil(化石的) and molecular (分子的)evidence(證據(jù)) suggests(顯示) the earliest ancestors(祖先) of the human family lived in forested(被森林所覆蓋的) areas in equatorial(近赤道的) Africa(非洲) in the late(遲的，末期的) Miocene era (中世紀(jì)末期)some(大約) 8 to 10 million years ago(以前), when changes in climate may have increased the distance between food patches. That would have forced(強(qiáng)迫) our earliest ancestors(早期的祖先)(問(wèn)題句中的核心結(jié)構(gòu)) to travel longer distances(距離) on the ground and favored(贊成，幫助， 有利于) those who could cover(通過(guò)) more ground using less energy. (C中的cover more ground的近義結(jié)構(gòu)travel longer distance , less energy都出現(xiàn)這個(gè)句子中，因此可能C是答案)。
“This isn’t the complete answer,” Sockol said. “But it’s a good piece of a puzzle humans have always wondered about: How and why did we become human? And why do we alone walk on two legs?”
倒數(shù)第二段提供了問(wèn)題的答案。travel longer distances用的是比較級(jí)，這里是將兩足行走的猿人與上文中四足行走的猿人做比較。those who could cover more ground using less energy指的是上文提到的與四足行走的猿人相比，體能消耗較小的兩足行走猿人。其他選擇都不是正確說(shuō)法。