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

Passage;
According to Martin, the extinctions can be directly attributed to the arrival of humans. However, [Krech contends that] 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.

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.

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.

In this passage, students seem to struggle with Q1 but I got others right except 4th ;
Please suggest error in my reasoning.
AjiteshArun , GMATNinja , MagooshExpert , GMATGuruNY , VeritasKarishma , DmitryFarber , ChiranjeevSingh , RonPurewal , workout , other experts -please enlighten




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.

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".

I had the same reasoning. Can any expert give their two cents on this?
Chiranjeevi GMATNinja

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!

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?

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.

+1 I had the same question. Option C helps us weaken the position that climate change led to extinctions - since if it had, then extinctions would have happened before the Pleistocene era. Sure it could have been gradual (hence not the most correct answer). But I felt it was much better than Option B - Even if Humans made use of these species - it doesn't help us justify that it was the ONLY reason for it's extinctions since the passage clearly states "Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably NOT ALL through human consumption"

Regarding C, it says that climate "change" occurred not only at the end of the Pleistocene era but also in the previous era. For eg. in previous era it went from cold to hot and in Pleistocene it went from hot to extreme hot. Maybe species could handle hot climate but not extremely hot climate.

B does cover a loophole. Krech says "Extinctions were not confined to large animals and humans did not hunt smaller animals". So, we don't know how they became extinct.

With B, you can say that like large animals, smaller animals were also hunted till extinction by humans

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?

DrWho - You are missing a critical point - The question says
"What would most weaken Krech’s objections to Martin’s theory?"

The question is not asking what will weaken Krech's theory. We need to weaken Krech's objection to Martin's theory.

What is Krech's objection to Martin's theory?
Martin's theory says that humans arrived and caused extinction of animals.
Krech says, "Martin, you are wrong. Extinctions happened even where humans were not present and extinctions of small animals also happened though humans did not hunt smaller animals."

Now, how do we weaken what Krech told Martin? By saying, "Krech, guess what, even if humans did not consume small animals, they used them for other things. So your point to Martin is not valid."


Martin excluded climate change from his theory i.e. did not say whether climate change could be responsible or not. We are not given that Martin said that climate change cannot be responsible. We are only given that he excludes it from his explanation. Krech brought up the point of climate change. He said that climate change could have a role to play since it happened at the end of that period.

We could go on to say, "Krech, by the way, you are wrong too. Both, arrival of humans and extinction of animals happened much before the end of that period."
But this would be how we will object to Krech's theory. This is not how we will object to Krech's objection of Martin's theory.

Hope the distinction is clear.

GMATNinja For question 1 listed here, although the other options are farfetched, doesn't Option B also make a considerable jump in saying that Martin 'denied' that the extinctions were caused by climate change? The passage only says that he 'excluded' that as one of the reason.

Another question, what role does the first line play in the passage? 'A theory advanced by Martin' Does this mean he added his bits to an existing theory or did he present a theory that wasn't prevalent as such by providing additional evidence?

Question 1

There isn't a huge difference in meaning between "exclude" and "deny" in this context. Both words tell us that Martin rejected the theory that climate change caused the extinctions. So it is accurate to say that Martin's theory "denies that the Pleistocene species extinctions were caused by climate change." And, as you've mentioned, the other answer choices are just plain wrong.

(B) is the correct answer for question #1.

As for the first sentence: to "advance" a theory means to advocate for that theory and to put it into discussion. We don't know the exact origins of the theory -- Martin could have developed it himself, or he could have developed it in collaboration with others, or he could have merely tweaked the work of other researchers.

We DO know that he is arguing for that particular theory, and this is the most important detail to understand as you work through the passage. We have Martin's view on one side, and then we see how that view is challenged or supported by Krech and White.

I hope that helps!

Hi, GMATNinja, generis, @VeritasKarishma,@mikemcgarry , request your insights on question 1 here.

according to paragraphs :
" 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,"

can this mean that Paul Martin denies other reasons such as climate change. and what do we mean by primary reason and directly attributed as given in paragraphs, does these mean that they were the only reasons.

Question 1

If something is the "primary reason" for an event, we can't say that it is the ONLY reason for that event. There could be other factors that contributed to a lesser extent.

Luckily, there is another piece of the passage that tells us exactly what Martin thought about climate change:

"Krech also contradicts Martin's exclusion of climatic change as an explanation [for the wave of species extinctions]..."

Here, we learn that Martin specifically excluded climatic change as an explanation. So, we know that Martin's theory "denies that the Pleistocene species extinctions were caused by climate change."

(B) is the correct answer to question 1.

I hope that helps!