GWD－31－20、21、22、23

Passage three

Anthropologists once thought that the ancestors of modern humans began to walk upright because it freed their hands to use stone tools, which they had begun to make as the species evolved a brain of increased size and mental capacity. But discoveries of the three-million-year-old fossilized remains of our hominid ancestor Australopithecus have yielded substantial anatomical evidence that upright walking appeared prior to the dramatic enlargement of the brain and the development of stone tools.

Walking on two legs in an upright posture (bipedal locomotion) is a less efficient proposition than walking on all fours (quadrupedal locomotion) because several muscle groups that the quadruped uses for propulsion must instead to (?) provide the biped with stability and control. The shape and configuration of various bones must likewise be modified to allow the muscles to perform these functions in upright walking. Reconstruction of the pelvis (hipbones) and femur (thighbone) of “Lucy”, a three-million-year-old skeleton that is the most complete fossilized skeleton from the australopithecine era, has shown that they are much more like the corresponding bones of the modern human than like those of the most closely related living primate, the quadrupedal chimpanzee. Lucy’s wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which (?) evolved to form the larger birth canal needed to accommodate the head of a large-brained human infant. By contrast, the head of Lucy’s baby could have been no larger than that of a baby chimpanzee.

If the small-brained australopithecines were not toolmakers, what evolutionary advantage did they gain by walking upright? (Line 50) One theory is that bipedality evolved in conjunction with the nuclear family: monogamous parents cooperating to care for their offspring. Walking upright permitted the father to use his hands to gather food and carry it to his mate from a distance, allowing the mother to devote more time and energy to nurturing and protecting their children. According to this view, the transition to bipedal walking may have occurred as long as ten million years ago, at the time of the earliest hominids, making it a crucial initiating event in human evolution.

20: the passage suggests that proponents of the theory mentioned in lines 50-54 (One theory is … offspring) assume that which of the following steps in human evolution occurred most recently?

A: development of a nuclear family structure

B: transition from walking on all fours to walking upright

C: dramatic enlargement of the brain

D: use of the hands to gather and carry food

E: modification of propulsive muscles to provide stability and control in locomotion

21: the passage suggests that, in comparison with the hominid australopithecines, modern humans are

A: less well adapted to large group cooperation

B: less well adapted to walking upright

C: more agile in running and climbing

D: more well suited to a nuclear family structure

E: more well suited to cooperative caring for their offspring

22: According to the passage, the hominid australopithecine most closely resembled a modern human with respect to which of the following characteristics?

A: brain size

B: tool making ability

C: shape of the pelvis

D: method of locomotion

E: preference for certain foods

23: the primary purpose of the passage is to

A: present an interpretation of the chronological relationship between bipedal locomotion and certain other key aspects of human evolution

B: compare the evolutionary advantages and disadvantages of bipedal locomotion to those of quadrupedal locomotion

C: argue that the transition to a nuclear family structure was a more crucial step in human evolution than was the development of stone tools

D: analyze anatomical evidence of bipedal locomotion to show that the large brain of modern humans developed at a later stage of evolution than was previously believed

E: use examples of muscle and bone structure to illustrate the evolutionary differences between modern humans, australopithecines, and chimpanzees

我的答案：

20 C

21 B

22 D

23 B

23题我第一次做的时候选了A，后来又读了一遍，发现B更好一点。。。因为我觉得第一段更像一个介绍性的开场，只是为了切入主题。。。

请大家讨论

GMAT31-20、21、22、23

Passage three

Anthropologists once thought that the ancestors of modern humans began to walk upright because it freed their hands to use stone tools, which they had begun to make as the species evolved a brain of increased size and mental capacity.
曾认为，古人类大脑发展的同时学习使用工具，后来则开始直立行走。

But discoveries of the three-million-year-old fossilized remains of our hominid ancestor Australopithecus have yielded substantial anatomical evidence that upright walking appeared prior to the dramatic enlargement of the brain and the development of stone tools.
但考古发现表明先直立行走，继而大脑发展、运用工具。

第一段提出问题。

Walking on two legs in an upright posture (bipedal locomotion) is a less efficient proposition than walking on all fours (quadrupedal locomotion) because several muscle groups that the quadruped uses for propulsion must instead to (?) provide the biped with stability and control.
两足移动低效，因为肌肉用以进行平衡而非提供推进力了。

The shape and configuration of various bones must likewise be modified to allow the muscles to perform these functions in upright walking.
骨骼也需相应调整。

Reconstruction of the pelvis (hipbones) and femur (thighbone) of “Lucy”, a three-million-year-old skeleton that is the most complete fossilized skeleton from the australopithecine era, has shown that they are much more like the corresponding bones of the modern human than like those of the most closely related living primate, the quadrupedal chimpanzee.
Lucy的髋骨和大腿骨更近于现代人类。

Lucy’s wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which (?) evolved to form the larger birth canal needed to accommodate the head of a large-brained human infant.
Lucy的髋骨较人类宽扁，更适合双足行走，人类的髋骨则为生育大头后代的需要而变圆了。

By contrast, the head of Lucy’s baby could have been no larger than that of a baby chimpanzee.
Lucy的孩子的头部不会大于大猩猩孩子的头部。

第二段展开说明古人类双足行走的骨骼特点。

If the small-brained australopithecines were not toolmakers, what evolutionary advantage did they gain by walking upright? (Line 50)
如果不是使用工具者，那为什么要直立行走呢？

One theory is that bipedality evolved in conjunction with the nuclear family: monogamous parents cooperating to care for their offspring.
一种理论是和家庭形式有关。

Walking upright permitted the father to use his hands to gather food and carry it to his mate from a distance, allowing the mother to devote more time and energy to nurturing and protecting their children.
可以让父母更好地采集食物、照顾幼儿。

According to this view, the transition to bipedal walking may have occurred as long as ten million years ago, at the time of the earliest hominids, making it a crucial initiating event in human evolution.
这样，直立行走可能很早就开始了。

第三段给出一个可能的理论说明。一夫一妻。。。采集食物。。。直立行走。。。脑容增大/使用工具。

20: the passage suggests that proponents of the theory mentioned in lines 50-54 (One theory is … offspring) assume that which of the following steps in human evolution occurred most recently?

A: development of a nuclear family structure

B: transition from walking on all fours to walking upright

C: dramatic enlargement of the brain

D: use of the hands to gather and carry food

E: modification of propulsive muscles to provide stability and control in locomotion

21: the passage suggests that, in comparison with the hominid australopithecines, modern humans are

A: less well adapted to large group cooperation

B: less well adapted to walking upright

C: more agile in running and climbing

D: more well suited to a nuclear family structure

E: more well suited to cooperative caring for their offspring

22: According to the passage, the hominid australopithecine most closely resembled a modern human with respect to which of the following characteristics?

A: brain size

B: tool making ability

C: shape of the pelvis

D: method of locomotion

E: preference for certain foods

23: the primary purpose of the passage is to

A: present an interpretation of the chronological relationship between bipedal locomotion and certain other key aspects of human evolution

B: compare the evolutionary advantages and disadvantages of bipedal locomotion to those of quadrupedal locomotion

C: argue that the transition to a nuclear family structure was a more crucial step in human evolution than was the development of stone tools

D: analyze anatomical evidence of bipedal locomotion to show that the large brain of modern humans developed at a later stage of evolution than was previously believed

E: use examples of muscle and bone structure to illustrate the evolutionary differences between modern humans, australopithecines, and chimpanzees

我的答案CBDA

版主NN, 我对第23题有点疑问

我觉得文章更像一篇新老观点对比的文章, 所以觉得好像D更合理

好像还是A好些

D 只讲到BRAIN 片面了