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# Anthropologists once thought that the ancestors of modern humans began

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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
1
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Question 1

nikitathegreat wrote:
GMATNinja - Can you please explain the primary purpose of the passage and Q1?

­To answer primary purpose questions, first think through the structure of the passage. Why did the author write each paragraph?

Here's a structural breakdown of this passage:

• Paragraph 1: The author introduces an old theory. This theory held that humans started making stone tools, and then began walking on two legs so their hands would be free to use those tools. Then, the author undermines this old theory. He/she says that the timeline is all wrong -- in fact, people started walking on two legs BEFORE they made stone tools.
• Paragraph 2: The author provides more info to undermine the old theory. He/she talks about fossils that support the idea that bipedalism happened BEFORE stone tools.
• Paragraph 3: The author introduces a new theory to explain why people started walking on two legs: so that parents could better care for their young as part of a nuclear family. The author then discusses what this theory could mean for the timeline of human evolution.

Overall, then, the author is mainly interested in using the timeline of various events in human evolution to explain why we started walking on two legs.

Let's see how the answer choices stack up:
Quote:
A. present an interpretation of the chronological relationship between bipedal locomotion and certain other key aspects of human evolution

This looks pretty good! The author discusses the timeline of stone tool usage and the formation of the nuclear family, and uses this timeline to interpret the relationship of these things to bipedalism. Keep (A) for now.
Quote:
B. compare the evolutionary advantages and disadvantages of bipedal locomotion to those of quadrupedal locomotion

The author does discuss the advantages and disadvantages of walking on two legs, but that's not his/her primary purpose. He/she is much more interested in the timeline of various components of human evolution, and how that answer the question of why we move to bipedalism. Eliminate (B).
Quote:
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

The author says that the nuclear family structure was a "crucial" step in human evolution, but he/she never compares this to the importance of the development of stone tools. That component could be just as crucial. We don't get a comparison of importance, we only get a relative timeline of events. For that reason, we can eliminate (C).
Quote:
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

Lucy's bones don't suggest that our large brains developed LATER than was previously believed -- they just show that bipedalism developed EARLIER than was previously believed. Early anthropologists could be 100% correct about the timeline of brain growth, but wrong about when we transitioned to two legs. (D) is out.
Quote:
E. use examples of muscle and bone structure to illustrate the evolutionary differences between modern humans, australopithecines, and chimpanzees

­Again, this just doesn't capture the main purpose of the passage. The author talks about different bone and muscle structures in these various species, but his/her primary purpose is to use timelines to explain why we became bipedal. Eliminate (E).

(A) is the correct answer to question 1.­
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
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Official Explanation

RC62100.01-20

2. The passage suggests that proponents of the theory mentioned in lines 35–38 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

Inference

The passage states that fossilized remains provide anatomical evidence that upright walking, which required a modification of propulsive muscles to provide stability and control in locomotion, occurred before the dramatic enlargement of the brain.

Proponents of the theory mentioned in lines 35–38 argue that walking upright may have evolved alongside the nuclear family structure because it allowed for cooperative caring for infants, which would have required the use of hands to gather and carry food. Thus, the dramatic enlargement of the brain was the most recent of the developments listed among the answer options.

A. Proponents of the theory mentioned in lines 35–38 hold that the dramatic enlargement of the brain occurred more recently than the development of walking upright, which happened alongside the development of a nuclear family structure.

B. Proponents of the theory mentioned in lines 35–38 hold that the dramatic enlargement of the brain occurred more recently than the transition from walking on all fours to walking upright.

C. Correct. Proponents of the theory mentioned in lines 35–38 hold that the dramatic enlargement of the brain was the most recent of these developments to occur.

D. Proponents of the theory mentioned in lines 35–38 hold that the dramatic enlargement of the brain occurred more recently than the use of hands to gather and carry food, which occurred alongside the development of walking upright.

E. Proponents of the theory mentioned in lines 35–38 hold that the dramatic enlargement of the brain occurred more recently than the modification of propulsive muscles to provide stability and control in locomotion, which is a key factor in the development of walking upright.

The correct answer is C.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
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Official Explanation

RC62100.01-30

3. 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

Supporting idea

The passage directly states that australopithecines walked upright (used bipedal locomotion), as human beings do.

A. The passage states that the dramatic enlargement of the brain among hominids occurred after the australopithecine era; it follows that the size of the australopithecine brain did not closely resemble that of the modern human brain.

B. The passage states that stone-tool-making ability did not develop until some time after the australopithecine era. The passage suggests that study of Australopithecus indicates that there is substantial evidence that upright walking appeared prior to . . . stone tools.

C. The passage specifies notable differences in shape between the australopithecine pelvis and the pelvis of modern human beings.

D. Correct. As noted above, the passage indicates that australopithecines walked upright, or used bipedal locomotion, as modern human beings do.

E. The passage does not indicate the types of foods preferred by australopithecines.

The correct answer is D.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
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Official Explanation

RC62100.01-40

4. 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

Inference

The information needed to answer this question is contained in the second paragraph. This is the only place in the passage where comparisons between australopithecines and modern human beings occur; the passage points out (1) that the pelvis and the femur of australopithecines are more similar to those of modern humans than they are to those of chimpanzees, the most closely related living primate, and (2) that the pelvis of australopithecines is better suited for bipedal locomotion than is the pelvis of modern humans.

A. The passage makes no mention of large-group cooperation.

B. Correct. As discussed above, the passage notes that the modern human pelvis is less suited for bipedal locomotion than was the australopithecine pelvis. This suggests that, in comparison with australopithecines, modern humans are less well adapted to walking upright.

C. The fact that australopithecines were better suited for walking upright than modern humans are would suggest if anything that australopithecines would also be better suited than humans to running and climbing (rather than vice versa). Regardless, the passage provides no clear evidence of whether modern humans or australopithecines were more agile.

D. In the third paragraph, the passage suggests that australopithecines may have been physically well suited to a nuclear family structure. The passage gives no information as to whether australopithecines were more or less physically well suited to such a structure than are modern humans.

E. In the third paragraph, the passage suggests that australopithecines may have been physically well suited to cooperative caring for their offspring. The passage gives no information as to whether they were more or less physically well suited to such caring than modern humans.

The correct answer is B.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
eybrj2 wrote:
⠀⠀⠀⠀⠀⠀⠀⠀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
(5)⠀⠀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
(10) 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
(15) 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
(20) 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
(25) 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
(30) 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
(35) gain by walking upright? 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
(40) 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,
(45) making it a crucial initiating event in human evolution.

1. 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

RC62100.01-10

2. The passage suggests that proponents of the theory mentioned in lines 35–38 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

RC62100.01-20

3. 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

RC62100.01-30

4. 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

RC62100.01-40

5. The theory mentioned in lines 35–38 suggests that which of the following was true for the hominid ancestors of modern humans before they made the transition to walking upright?

A. Their brains were smaller than the brains of present-day chimpanzees.
B. They competed rather than cooperated in searching for food.
C. Their mating patterns and family structure were closer to those of present-day chimpanzees than to those of modern humans.
D. Males played a more significant role in child rearing than they played after the transition to walking upright.
E. Females' ability to nurture and protect their offspring was limited by the need to find food for themselves.

RC62100.01-50

I think there is an issue with statistics of the questions. I mean accuracy and corresponding percentage of correct/incorrect answers.
For example , %age correct for Question no. 4 option B is only 4%, this means only 4% of people clicked that option, but when I see correct/wrong accuracy it shows 50%-50%. Please have a look. This can be seen in mostly GMAT advanced questions IMO.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
1
Kudos
AkshdeepS wrote:
eybrj2 wrote:
⠀⠀⠀⠀⠀⠀⠀⠀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
(5)⠀⠀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
(10) 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
(15) 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
(20) 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
(25) 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
(30) 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
(35) gain by walking upright? 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
(40) 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,
(45) making it a crucial initiating event in human evolution.

1. 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

RC62100.01-10

2. The passage suggests that proponents of the theory mentioned in lines 35–38 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

RC62100.01-20

3. 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

RC62100.01-30

4. 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

RC62100.01-40

5. The theory mentioned in lines 35–38 suggests that which of the following was true for the hominid ancestors of modern humans before they made the transition to walking upright?

A. Their brains were smaller than the brains of present-day chimpanzees.
B. They competed rather than cooperated in searching for food.
C. Their mating patterns and family structure were closer to those of present-day chimpanzees than to those of modern humans.
D. Males played a more significant role in child rearing than they played after the transition to walking upright.
E. Females' ability to nurture and protect their offspring was limited by the need to find food for themselves.

RC62100.01-50

I think there is an issue with statistics of the questions. I mean accuracy and corresponding percentage of correct/incorrect answers.
For example , %age correct for Question no. 4 option B is only 4%, this means only 4% of people clicked that option, but when I see correct/wrong accuracy it shows 50%-50%. Please have a look. This can be seen in mostly GMAT advanced questions IMO.

This happens when OA has been changed later on, when OA gets changed the statistics get distorted and that is the main reason.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
hello, can you kindly provide a better explanation for Q1. I cant rule out option D, though I found option A to be equally good.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
1
Kudos
I am not an expert but I can share my 2 cents thought on this problem with you.
The first part of option D is fine "analyze anatomical evidence of bipedal locomotion". However, the second part just mentions small detail about the passage "to show that the large brain of modern humans developed at a later stage of evolution than was previously believed".
So A is a sure winner.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
GMATNinja Can you please assist in understanding the logic behind Q No. 2 here
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
Can anyone explain why D is wrong in Question 5? The father is now focused on obtaining food post bipedal evolution and now mother is rearing the infants. What am I missing?
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
permitted the father to
⠀⠀⠀ use his hands to gather food and carry it to his mate
(40) from a distance, allowing the mother to devote more
⠀⠀⠀ time and energy to nurturing and protecting their
⠀⠀⠀ children.
VeritasKarishma This is for question 5.
How can we infer option E here? May be the father was just being friendly and the Female's ability was not limited.
E. Females' ability to nurture and protect their offspring was limited by the need to find food for themselves.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
3
Kudos
akash7gupta11 wrote:
permitted the father to
⠀⠀⠀ use his hands to gather food and carry it to his mate
(40) from a distance, allowing the mother to devote more
⠀⠀⠀ time and energy to nurturing and protecting their
⠀⠀⠀ children.
VeritasKarishma This is for question 5.
How can we infer option E here? May be the father was just being friendly and the Female's ability was not limited.
E. Females' ability to nurture and protect their offspring was limited by the need to find food for themselves.

The passage clearly says that the father gathering food "allowed" the mother to devote more time to nurture and protect. So food gathering was something that limited her 'nurture and protect time' previously. Now when the father started doing it, she had more time.
So option (E) is correct.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
1
Kudos
sunny91
Just like you, I had to decide between A and D

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

The passage starts with:
Anthropologists once thought that the ancestors of modern humans began to walk upright because it freed their hands to use stone tools.

Both A and D are true but "D" although it is true, it is narrow in scope.
This is a type of Trap in Primary Purpose Questions, giving you true answers but narrow in scope and doesn’t give broader perspective. I eliminated this answer choice on this basis.
A is a broader choice and True as well.

I eliminated "D" as
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
6
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1
Bookmarks

Question 2

gdatta wrote:
GMATNinja Can you please assist in understanding the logic behind Q No. 2 here

Quote:
2. The passage suggests that proponents of the theory mentioned in lines 35–38 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

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."

However, new evidence showed that humans began walking upright long before their brains got bigger. So it is not possible that humans started walking upright in order to use stone tools, because their mental capacity was not yet big enough to make/use stone tools!

The theory mentioned in question #2 addresses this issue by coming up with another explanation: "bipedality evolved in conjunction with the nuclear family."

So, the timeline of that theory goes something like this:
• Humans evolved to walk on two legs at the same time as they evolved to live as nuclear families
• THEN, their brains began to grow and they started using stone tools

In the answer choices, we are looking for the most recent step in human evolution:
Quote:
A. Development of a nuclear family structure
B. Transition from walking on all fours to walking upright

As discussed above, these two things happened in conjunction with one another. Hmm, that makes it difficult to say which one would come more recently. Eliminate (A) and (B).

Quote:
C. Dramatic enlargement of the brain

This definitely happened AFTER humans developed a nuclear family structure and transitioned to walking upright, so we can feel good about getting rid of (A) and (B). Let's keep (C) for now, and see whether anything more recent comes along.

Quote:
D. Use of the hands to gather and carry food

Proponents of the new theory believed that the whole reason that humans evolved to walk upright was to gather and carry food, so this development must have occurred with the transition from walking on all fours to walking upright. That puts (D) at the same time as (A) and (B), which occurred BEFORE (C). (D) is out.

Quote:
E. Modification of propulsive muscles to provide stability and control in locomotion

This is mentioned in the passage as a REQUIREMENT for transitioning from walking on all fours to walking upright. So, this certainly could not occur after humans made that transition. That means that (E) definitely occurred before (C).

We're left with (C) as the most recent development, and (C) is the correct answer to question #2.

Question 5

gmatapprentice wrote:
Can anyone explain why D is wrong in Question 5? The father is now focused on obtaining food post bipedal evolution and now mother is rearing the infants. What am I missing?

Quote:
5. The theory mentioned in lines 35–38 suggests that which of the following was true for the hominid ancestors of modern humans before they made the transition to walking upright?

The theory states that "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."

Can we infer from this that, when they walked on all fours, "males played a more significant role in child rearing than they played after the transition to walking upright"?

Not really. It is possible that quadrupedal males helped with child rearing, but it's also possible that they were deadbeat dads and just left the mothers to raise the kids solo. Mothers would not have had as much time and energy to nurture their children, but that does not mean that fathers actually helped them out -- maybe it was just a tough life for quadrupedal moms, who had to both gather food and raise the kids.

The theory in lines 35-38 doesn't suggest that males helped more with child rearing before they became bipedal, so (C) is out.

I hope that helps!
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
Can you please explain in q1 (Primary purpose) why is option C incorrect?

Thanks
Kritika
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
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kri93 wrote:
Can you please explain in q1 (Primary purpose) why is option C incorrect?

Thanks
Kritika

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

Support for this statement cannot be found in this passage, nowhere in the passage the author is arguing that the "nuclear family structure is more crucial than stone tools"

argument has been made only for "bipedal walking was a crucial event".

the transition to bipedal walking may have occurred as long as ten
⠀⠀⠀ million years ago, at the time of the earliest hominids,
(45) making it a crucial initiating event in human evolution.
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Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
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Hi - For 3, why not C ?

Reviewing the OA solution posted, the OA solution says there are notable differences in shape between the australopithecine pelvis and the pelvis of modern human beings.

However, doesn't the red font below indicate the australopithecine pelvis and the pelvis of modern human beings are actually similar (what's the red font below then saying?)

Reconstruction of the pelvis (hipbones) and
(20) 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
(25) 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
(30) large-brained human infant.
Re: Anthropologists once thought that the ancestors of modern humans began [#permalink]
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