According to a theory advanced by researcher Paul Martin, the wave of

Question

According to a theory advanced by researcher Paul Martin, the wave of species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans. However, anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them.  Nor were extinctions confined to large animals: small animals, plants, and insects disappeared , presumably not all through human consumption. Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene. Still, Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians, arguing that humans have produced local extinctions elsewhere. But, according to historian Richard White, even the attribution of secondary responsibility may not be supported by the evidence. White observes that Martin's thesis depends on coinciding dates for the arrival of humans and the decline of large animal species, and Krech, though aware that the dates are controversial, does not challenge them; yet  recent archaeological discoveries  are providing evidence that the date of human arrival was much earlier than 11,000 years ago.    1 
 Q1: Which of the following is true about Martin’s theory, as that theory is described in the passage?

(A) It assumes that the Paleoindians were primarily dependent on hunting for survival. 
(B) It denies that the Pleistocene species extinctions were caused by climate change. 
(C) It uses as evidence the fact that humans have produced local extinctions in other situations. 
(D) It attempts to address the controversy over the date of human arrival in North America. 
(E) It admits the possibility that factors other than the arrival of humans played a role in the Pleistocene extinctions.

2 
 Q2: In the last sentence of the passage, the author refers to “ recent archaeological discoveries ” (lines 36-37) most probably in order to

(A) refute White’s suggestion that neither Maritn nor Krech adequately account for Paleoindians’ contributions to the Pleistocene extinctions 
(B) cast doubt on the possibility that a more definitive theory regarding the causes of the Pleistocene extinctions may be forthcoming 
(C) suggest that Martin’s, Krech’s, and White’s theories regarding the Pleistocene extinctions are all open to question 
(D) call attention to the most controversial aspect of all the current theories regarding the Pleistocene extinctions 
(E) provide support for White’s questioning of both Martin’s and Krech’s positions regarding the role of Paleoindians in the Pleistocene extinctions

3 
 Q3: Which of the following, if true, would most weaken Krech’s objections to Martin’s theory?

(A) Further studies showing that the climatic change that occurred at the end of the Pleistocene era was even more severe and widespread than was previously believed 
(B) New discoveries indicating that Paleoindians made use of the small animals, plants, and insects that became extinct 
(C) Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras 
(D) Researchers’ discoveries that many more species became extinct in North America at the end of the Pleistocene era than was previously believed 
(E) New discoveries establishing that both the arrival of humans in North America and the wave of Pleistocene extinctions took place much earlier than 11,000 years ago

4 
 Q4: The passage suggests that Krech would be most likely to agree with a theory of the Pleistocene species extinctions that

(A) included climate change as one of the causes of the extinctions
(B) incorporated a revised date for human arrival in North America
(C) eliminated the Paleoindians as a factor in the extinctions
(D) identified a single cause for the extinctions
(E) emphasized the role of hunting in causing most species extinctions

5 
 5. The passage mentions the extinction of species other than large animals (see highlighted text) Nor were extinctions confined to large animals: small animals, plants, and insects disappeared ] most probably in order to

(A) suggest that the Paleoindians were responsible for more extinctions than Martin's theory assumes
(B) provide support for the speculation that humans arrived in North America significantly earlier than the end of the Pleistocene era
(C) point out the only area in which Martin, Krech, and White agree concerning the circumstances of the Pleistocene extinctions
(D) cite additional evidence tending to support Krech's conclusions about the role of humans in the Pleistocene extinctions
(E) raise a question about the logical consistency of Krech's view of Martin's theory

anairamitch1804 · Accepted Answer

1) Martin just said the extinction was caused by early humans . He doesn’t give any information about what the humans did with the animals. For all we know there could have been a hunting competition or something. So the food piece is n’t supported in the passage. As for B, I agree it can be a bit confusing but arrived at it simply by eliminating other choices."Krech also contradicts Martin’s exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed".This implies that martin's theory EXCLUDED CLIMATE CHANGE as an explanation to extinction. Hence B.
2)"White observes that Martin’s thesis depends on coinciding dates for the arrival of humans and the decline of large animal species, and Krech, though aware that the dates are controversial, does not challenge them; yet recent archaeological discoveries are providing evidence that the date of human arrival was much earlier than 11,000 years ago". As there is an evidence discovered by archaelogical department which support's the position of White. Hence E.
3)Martin's theory – cause of extinction- Arrival of humans (paleoindians)
Krech Objection-"no evidence of hunting by paleoindians,.. not just large animals but small animals, plants and insects too vanished- not through human consumption we need to weaken any of above mentioned objections. Looking at option B it clearly weakens the objection.

Raksat · Answer

TIME: 7 minutes

1. Excerpt from the passage:  Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene 
This means Martin proposed that  climate change was not a factor in the extinction  that occurred at the end of the Pleistocene.
Hence B
2. Excerpt from the passage:  White observes that Martin's thesis depends on coinciding dates for the arrival of humans and the decline of large animal species, and Krech, though aware that the dates are controversial, does not challenge them 
The last line of the passage provides additional support to white's theory that arrival humans had no role in the extinction. If the recent discoveries are true then humans had arrived much earlier than the time frame accepted by Martin and Krech. Therefore, we can infer that it is unlikely that humans had contributed to the extinction as envisioned by the researchers.
Hence E
3. Excerpt from the passage:  Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption 
Option B weakens the above statement. If option B is correct then we could assume that humans indeed played a far greater role than what Krech thought, and hence weakens krech opposition to martin theory. 
option B is the correct answer.
4. A ( straight and obvious)
Krech already states in the passage that  " asserting that widespread climatic change did indeed occur at the end of the Pleistocene"
 
5. Excerpt from the passage:  Anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them. Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption 
Thus the statements above support the Krech theory that humans didn't play a primary role in the extinction, but rather a secondary role.
Hence D

aquaria · Answer

For 1), are we supposed to take Martin's  exclusion  of climate change in his theories as  "denial" ? It seems a little problematic.

Seems possible that Martin's exclusion of climate change may just be a situation where he thinks it isn't the most important factor (so he didn't see any reason to include it in his theory), rather than a flat out denial of climate change's impact on the extinction of Pleistocene species. And you can't categorically say that exclusion = denial.

It's like saying a zoologist who doesn't include climate change in their theory as to why the dodo bird went extinct DENIES the impact climate change (may) have had on our feathered friend's extinction.

Skywalker18 · Answer

Even I had views similar to those of aquaria as quoted above and ended up choosing A, though the word 'primarily' in A is a little strong.

According to a theory advanced by researcher Paul Martin, the wave of species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans.  However, anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them.   -  From the bolded part, can't we infer that Paleoindians hunted large animals at least in a few areas and that this idea is a part of Martin's theory ?

Q1: Which of the following is true about Martin’s theory, as that theory is described in the passage?

(A) It assumes that the Paleoindians were primarily dependent on hunting for survival. - I agree that primarily is a little strong here.
(B) It denies that the Pleistocene species extinctions were caused by climate change. - As per Martin, the wave of species extinctions can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans, but this fact DOES NOT mean that there were no other causes.

AjiteshArun  ,  GMATNinja  ,  MagooshExpert  ,  GMATGuruNY  ,  VeritasKarishma  ,  DmitryFarber  , ChiranjeevSingh  , RonPurewal  ,  workout  , other experts -please enlighten

ChiranjeevSingh · Answer

Hello,

As usually the case, when you select an incorrect option, you have committed at least two errors in reasoning: your reasoning for rejecting the correct option and your reasoning for selecting the incorrect option both are wrong. So is the case here.

No, we cannot infer this. The bolded part is pointed out by Krech. We don't even know whether Martin knew about or considered human hunting. (If you think that since Martin is attributing species extinctions to the arrivals of humans, he must be considering human hunting, I'll not agree with you. Species extinctions may not be a result of human hunting; extinctions may be a result of humans' playing with or destroying the nature, as is the case currently). Besides, if you ask me whether we can consider the bolded part a part of Krech's theory, I'll NOT say 'yes'. Why? Because Krech is just pointing out a fact. This is not his theory. However, frankly, it'll be difficult to reject it completely because Krech's theory might be based on this fact. But can you say that the facts on which your theory is based are part of your theory? I don't think so.

Aquaria's reasoning is incorrect because of the way he interprets 'exclusion' as used in the passage. If you think 'exclusion' just means that Martin did not study or consider climate change, the statement 'Krech also contradicts Martin's exclusion' wouldn't make any sense. How can you contradict the fact that someone did not study factor X? (Well, you can. However, that will lead to a very different meaning) You can, however, contradict the fact that X was not a factor in Y. Also, the statement "I am excluding climate change as an explanation for extinctions" does mean that I don't think climate change was the cause for extinctions. However, if I say that 'I am excluding climate change from my study", then it means that I'm not considering 'climate change' in my study. However, in this case, somebody contradicting my exclusion wouldn't make sense.

GMATGuruNY · Answer

to exclude a theory  =  to RULE OUT that theory .
From the passage:
 Martin's exclusion of climatic change as an explanation. 
In other words:
Martin RULES OUT CLIMATE CHANGE as an explanation for the wave of species extinctions at the end of the Pleistocene era.
Thus, option B is a valid inference:
 Martin's theory denies that the Pleistocene species extinctions were caused by climate change.

B

rish2708 · Answer

Can anyone please help me why option C is wrong for Q3?
Per my understanding, Krech makes two assertions:
I he refutes Martin's claim about human predation

II He makes a claim that climate can explain the extinction.

I had tough time choosing between option b and option c and lastly chose option c because I thought if the climate reason is not present, surely it weakens the claim of Krech to include another factor in the extinction.

Please help me where I am wrong in my reasoning.

Regards,
Rishav

Posted from my mobile device

GMATGuruNY · Answer

Author:  X did  indeed  happen. 
Here, the usage of  indeed  conveys the following:
Some people doubt that X actually happened.
The author believes that X did INDEED happen.

Passage:
 Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did  indeed  occur at the end of the Pleistocene. 
Here, the usage of  indeed  conveys the following:
Some people -- among them, most likely Martin -- doubt that widespread climactic change occurred at the end of the Pleistocene.
Krech believes that widespread climactic change did INDEED occur at the end of the Pleistocene.

Which of the following, if true, would most weaken Krech’s objections to Martin’s theory?

Option C:
 Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras. 
This information SUPPORTS Krech's contention that climactic change did INDEED occur at the end of the Pleistocene and thus does NOT weaken his argument.
Eliminate C.

sonalchhajed2019 · Answer

Hi,

For Question 3 I selected the choice C.

Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras

The reason for the same was that may be climate change was not responsible. There were such changes in the past and then extinctions did not occur. So probably factors other than climate change were responsible and this I thought is a better contradiction as compared to B.

Please let me know if my reasoning is correct. And why is B a better answer as compared to C.

Thank You 
Sonal

zoezhuyan · Answer

dear,  GMATGuruNY ,  ChiranjeevSingh ,  GMATNinja ,  SajjadAhmad ,  GMATNinjaTwo ,  bm2201

I still Cann't get why B is correct on Q3. I just know other options are not weaken. 
please help.
Which of the following, if true, would most weaken Krech’s objections to Martin’s theory?

(A) Further studies showing that the climatic change that occurred at the end of the Pleistocene era was even more severe and widespread than was previously believed 
(B) New discoveries indicating that Paleoindians made use of the small animals, plants, and insects that became extinct 
(C) Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras 
(D) Researchers’ discoveries that many more species became extinct in North America at the end of the Pleistocene era than was previously believed 
(E) New discoveries establishing that both the arrival of humans in North America and the wave of Pleistocene extinctions took place much earlier than 11,000 years ago

thanks in advance.

GMATGuruNY · Answer

Passage;
 According to Martin, the extinctions can be directly attributed to the arrival of humans. However,    small animals, plants, and insects disappeared, presumably not all through human consumption .

Which of the following, if true, would most weaken Krech’s objections to Martin’s theory?

B:  New discoveries indicating that Paleoindians made use of the small animals, plants, and insects that became extinct. 
In other words, human consumption COULD have been responsible for the disappearance of small animals, plants and insects, WEAKENING the red portion of Krech's argument.

B

zoezhuyan · Answer

dear GMATGuruNY, in case of my misunderstanding, I need a further confirmation.

in the passage, Krech contends that humans did not hunt the small animals, plants, and insects disappeared, right?
in choice B, new evidence shows that human did hunt the small animals, plants, and insects that disappeared. 
it seems B directly says the evidence cited by Krech is wrong.

for me, it is too directly weaken evidence, a approach is different from CR section of GMAT.

I need your opinion.

thanks in advance.

GMATGuruNY · Answer

Krech:
 Small animals, plants, and insects disappeared,  presumably  not all through human consumption 
Note the usage of the word in red.
 presumably  =  likely but NOT KNOWN FOR CERTAIN .
Implication:
Krech does not know for certain whether humans used the small animals, plant and insects that disappeared.
Option B states that humans DID in fact use these things, weakening's Krech's contention that humans were not responsible for the the wave of extinctions 11,000 years ago.

mSKR · Answer

In this passage, students seem to struggle with Q1 but I got others right except 4th ; 
Please suggest error in my reasoning.
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Krech says 2 things:
1. climate condition could be one reason for extinction of species 
2. doesn’t agree completely with human as cause of their extinction (presumably not all through human consumption but humans have produced local extinctions elsewhere.

If included climate change as one reason then still doubt hovers whether humans were also cause of exintiction . If in option it had included as the only cause then probably doubts would have been over and it could be one of the strongest reason to agree.

Krech doesn’t agree completely with Paleoindians as a factor in the extinctions but if some theory says that Paleoindians were not cause of extinction, then he would have been very delighted because:
1. it would support theory that maybe climate could be one of the reasons for extinction
2. Extinction might have produced local extinction elsewhere was only secondary reason and he was not completely convinced that humans caused extinction with the following 2 statements

1.  Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption 
2.  that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them .

AjiteshArun · Answer

Hi  imSKR ,

1. Martin: humans were the  primary  cause of the extinctions ("the... extinctions... can be directly attributed to... humans")
2. Krech: humans were the  secondary , but not primary, cause of the extinctions ("Still, Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians")
3. White: even secondary may not be correct ("even the attribution of secondary responsibility may not be supported by the evidence")

So it's better to look at Krech's position as "Paleoindians were  not the  primary  cause of the extinctions ". This is different from saying that Krech doesn't consider humans a cause of the extinction. So (2) is: "humans were the  secondary  , but not primary,  cause of the extinctions". Let's take a look at that statement:

Humans were the secondary cause of the extinctions.

How likely is it that someone who agrees with "humans were the secondary cause of the extinctions" would agree with "humans were not in any way responsible for the extinctions"? That person would agree with "humans were not the primary cause of the extinctions", but not with "humans were not a factor in the extinctions".

GMATNinja · Answer

Question 3

Let’s consider (C):

All that (C) tells us is that widespread climate change occurred in previous and subsequent eras. Sure, the extinctions that took place at the end of the Pleistocene era did not take place in previous eras, but we don’t know whether similar species existed in similar conditions in those eras. It’s possible that the climate change at the end of the Pleistocene era was more severe or that the combination of climate change and the arrival of Paleoindians led to the extinction of many species. Krech simply argues that climate change took place and could bear at least some of the responsibility for the extinctions. Even with (C), this is still possible. So, (C) does not weaken Krech’s argument, and we can eliminate it.

And here’s (B):

This directly contradicts Krech’s implied argument that the extinction of small animals, plants, and insects cannot be attributed to the arrival of Paleoindians. By showing how Paleoindians could, in fact, be responsible for the extinction of these species, (B) weakens Krech’s argument. So, (B) is correct.

I hope that helps!

DrWho · Answer

Hi  GMATNinja  ,  AjiteshArun ,  MagooshExpert  ,  VeritasKarishma  ,  DmitryFarber  ,  ChiranjeevSingh  ,  RonPurewal

Between B and E,

Krech had 2 objections:
1. Extinctions were not confined to large animals and humans did not hunt smaller animals
2. Climate change not only had an impact but also was the primary reason.

B addresses #1.
However, doesn't E address #2?
If human arrival and extinction took place way before it was thought earlier, doesn't it imply that the new timeline does not match with climate change? (Kretch says "widespread climatic change did indeed occur at the end of the Pleistocene")

So, Istn't E a better option since it address that primary objection of Krech?

KarishmaB · Answer

Martin : Species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans. (Humans arrived at that time and hunted animals). Blame humans for extinction.

Krech : Extinctions happened even where humans were not hunting. Also humans were not hunting small animals. Climate is responsible too. Humans may have secondary responsibility.
Krech says nothing about dates.

White : Humans may not even have secondary responsibility. They arrived much earlier than 11000 yrs ago.

What is Krech's objection to Martin's theory? That even where humans did not hunt, animals went extinct. And that small animals etc went extinct too (presumably humans consumed large animals). So we cannot blame humans.

What will weaken Krech's objection? That humans used small animals etc in some way too. So this will explain how humans can be responsible for extinction of most animals. Answer (B)

Krech's objection to Martin's theory had nothing to do with dates. He knew that dates were controversial but he did not object on those grounds. We need to weaken Krech's objection only. So any data on dates will not weaken Krech's objections because Krech did not object on the dates.

DrWho · Answer

Thanks for the response  VeritasKarishma !

I'm still not getting one point.

As per your quotes,
" Krech : Extinctions happened even where humans were not hunting. Also humans were not hunting small animals. Climate is responsible too. Humans may have secondary responsibility.
Krech says nothing about dates. "

Krech says nothing about dates -> True. He said that climate change was responsible, and this climate change occurred at the end of Pleistocene.

Quoting exactly from passage,
"Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene"

By saying that extinction occurred before the end of the Pleistocene, we are implying that the climate change Krech is referring above, was not responsible for the extinction.

Question 1) What is the gap in the above logic?

Regarding the dates, passage states:
"Krech, though aware that the dates are controversial, does not challenge them" 
"archaeological discoveries are providing evidence that the date of human arrival was much earlier than 11,000 years ago"

From the above statements, it seems like the date of human arrival is controversial. Sure, if humans arrived early and "extinction and climate change" occurred at the same time, we can say that the climate change caused the extinction. But option E also predates extinction. 
It says "human arrival and extinction" occurred at the same time. Climate change occurred later.

Question 2) What is wrong with the above interpretation?

According to a theory advanced by researcher Paul Martin, the wave of

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According to a theory advanced by researcher Paul Martin, the wave of

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