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605-655 Level|   Grammatical/Rhetorical Construction|   Parallelism|                              
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In answer choice (A) there is a problem with modification. (A) is implying that our ancestors greatly reduced their own numbers (this is incorrect because it was the event that greatly reduced ancestors). When we have an independent clause followed by a participle phrase (one that starts with a gerund and serves as an adjective clause), the participle phrase modifies the subject of the sentence.

In non-grammarese: 'ancestors' is the subject of the independent clause, 'at some time...' and because of the comma after event, we have the incorrect meaning. It was not the ancestors but an event that 'reduced their numbers.'

Therefore, we want to make sure that it is clear that 'event' is 'greatly reducing the numbers.' One way to fix that is by using the relative pronoun 'that.' In (B), we have 'an event that greatly reduced their numbers' that does a good job of correcting the error in (A).

Therefore (B) is the answer.
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Thanks for the great explanation.
I just wanted to ask, is the rule for participle only valid of -ing modifiers or it is also true for other participle modifiers such as -ed modifiers?
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Some anthropologists believe that the genetic homogeneity evident in Updated on: 26 Aug 2021, 22:59
Originally posted by CrackverbalGMAT on 26 Jun 2021, 05:22.
Last edited by CrackverbalGMAT on 26 Aug 2021, 22:59, edited 2 times in total.
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Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.


(A) at some time in the past our ancestors suffered an event, greatly reducing their numbers

(B) that at some time in the past our ancestors suffered an event that greatly reduced their numbers

(C) that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced

(D) some time in the past our ancestors suffered an event from which their numbers were greatly reduced

(E) some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,


The sentence says that- Some anthropologists believe that the genetic homogeneity is the result of a “population bottleneck”--
The second part explains “population bottleneck”
The clue to solving this question is - what greatly reduced their numbers? An event. Therefore we need the relative pronoun “that” to modify events.
This leaves us with option B.

Ancestors did not suffer an event in order to (intention) reduce their numbers. This eliminates options C and E.

In option A, the participial modifier- greatly reducing modifies the preceding clause and not “event”. Eliminate A.
B is the answer.


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A at some time in the past our ancestors suffered an event, greatly reducing their numbers ------ A hyphen is not the tool to connect two ICs.
B that at some time in the past our ancestors suffered an event that greatly reduced their numbers -------- ‘that ’ is the right connector ---correct choice.
C that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced ------- altered notion; it looks as if the ancestors suffered a calamity in order to reduce their numbers.
D some time in the past our ancestors suffered an event from which their numbers were greatly reduced -------- conjugation of two ICs with hyphenation is wrong.
E some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly, ------ same as in D
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GMATNinja @egmat- I request for clarity on use of hyphenation here and in general for GMAT
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daagh
A at some time in the past our ancestors suffered an event, greatly reducing their numbers ------ A hyphen is not the tool to connect two ICs.
B that at some time in the past our ancestors suffered an event that greatly reduced their numbers -------- ‘that ’ is the right connector ---correct choice.
C that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced ------- altered notion; it looks as if the ancestors suffered a calamity in order to reduce their numbers.
D some time in the past our ancestors suffered an event from which their numbers were greatly reduced -------- conjugation of two ICs with hyphenation is wrong.
E some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly, ------ same as in D
GMATNinja @egmat- I request for clarity on use of hyphenation here and in general for GMAT
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Hyphens are pretty darn versatile. They can function like commas and introduce modifiers. They can function like colons and connect clauses.

So rather than agonizing about all the things the hyphen might do, ask yourself what it seems to be doing here, logically. And it seems to be introducing a modifier offering more info about a "population bottleneck." Beyond that, I wouldn't think much about the hyphen.

For more, check out this video on GMAT punctuation.
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Can we take following learning from this question?

dash or hyphen are flexible. They can be used as comma, semi colon, colon . Which one to use in which sceanroes depends on the meaning context. the key is in the part followd by dash or hyphen should make sense. The part can be clause, dependent clause, modifier, phrase, words.


please confirm experts: AjiteshArun GMATNinja EMPOWERgmatVerbal CrackVerbalGMAT EducationAisle GMATRockstar


some reference links:
https://gmatclub.com/forum/what-is-dash ... ml#p816454
https://gmatrockstar.com/2014/01/11/gra ... nd-a-dash/
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mSKR
Can we take following learning from this question?

dash or hyphen are flexible. They can be used as comma, semi colon, colon . Which one to use in which sceanroes depends on the meaning context. the key is in the part followd by dash or hyphen should make sense. The part can be clause, dependent clause, modifier, phrase, words.


please confirm experts: AjiteshArun GMATNinja EMPOWERgmatVerbal CrackVerbalGMAT EducationAisle GMATRockstar


some reference links:
https://gmatclub.com/forum/what-is-dash ... ml#p816454
https://gmatrockstar.com/2014/01/11/gra ... nd-a-dash/
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Hi mSKR,

I don't spend any time on hyphens and short (en) dashes in my classes, but I'll put my thoughts down here:

We shouldn't think of hyphens and dashes as being interchangeable. Hyphens are used in some compound nouns/compound adjectives/compound verbs (like heat-exchange network) and in some words with a prefix (like ex-prime minister).

As for dashes, you could also go through this post, though it looks at only longer (em) dashes. Shorter dashes (en dashes) are used mainly to indicate a range (like 2018–2020).
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My problem
Is the sentence structure "... believes that S + V ––– that S + V" interchangable with "... believes that S + V, and that S + V"?

Original OG sentence:
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation.

My revision:
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck," and that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation.

Thanks for answering!
Best regards,

Iris :heart
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irisjojojo
My problem
Is the sentence structure "... believes that S + V ––– that S + V" interchangable with "... believes that S + V, and that S + V"?

Original OG sentence:
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation.

My revision:
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck," and that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation.

Thanks for answering!
Best regards,

Iris :heart
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I don't think these two mean quite the same thing. The hyphen seems to be introducing a modifier offering more info about a "population bottleneck" in the original sentence (as explained earlier).

But in the revised version we have a parallel list: "Some anthropologists believe (1) that the genetic homogeneity evident in the world's people is the result of a "population bottleneck," and (2) that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation."

This makes it seem like the anthropologists believe TWO separate and distinct things, and that's not quite right. The second thing in the list is NOT something else that the anthropologists believe. Instead, the second thing simply clarifies the first thing. So I think the hyphen is more appropriate given the context.

I hope that helps!
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Hi,

Just a quick observation on Option A: at some time in the past our ancestors suffered an event, greatly reducing their numbers; the part 'at some time in the past', isn't this a prepositional phrase? if so how can a clause follow a preposition? Would that not be a reason to eliminate option A.

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Abheek
Hi,

Just a quick observation on Option A: at some time in the past our ancestors suffered an event, greatly reducing their numbers; the part 'at some time in the past', isn't this a prepositional phrase? if so how can a clause follow a preposition? Would that not be a reason to eliminate option A.

Regards
AD
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Hi Abheek,

The subject-verb pair doesn't really follow the preposition. In A (in B as well), it's not really as if a subject-verb pair is acting as the object of the preposition. Instead, we're looking at a modifier that's isn't part of the "skeleton" of that part of the sentence. We could even move the modifier around if we wanted to.

1. ... that (at some time in the past) our ancestors suffered an event that greatly reduced their numbers...
or
2. ... that our ancestors suffered an event (at some time in the past) that greatly reduced their numbers...
or
3. ... that our ancestors suffered (at some time in the past) an event that greatly reduced their numbers...
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Abheek
Just a quick observation on Option A: at some time in the past our ancestors suffered an event, greatly reducing their numbers; the part 'at some time in the past', isn't this a prepositional phrase? if so how can a clause follow a preposition? Would that not be a reason to eliminate option A.
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There are numerous official examples, where a clause follows a prepositional phrase.

An example:

In two letters to the historian Tacitus, the nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius.

Notice that in the above sentence as well, a "clause" (the nephew of Pliny the Elder wrote the only eyewitness account of the great eruption of Vesuvius) follows a "prepositional phrase" (In two letters to the historian Tacitus).

Note that when a prepositional phrase appears towards the beginning of a clause, the prepositional phrase generally acts as an adverbial modifier.

p.s. Our book EducationAisle Sentence Correction Nirvana discusses modifier issues related to "prepositional phrases", their application and examples in significant detail. If you or someone is interested, PM me your email-id; I can mail the corresponding section.
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Referesher :

"sometime"
Adverb : (one word) means at an indefinite or unstated time in the future,
"occasionally, now and then"
"at some point in time in the future or the past"
Adjective, "sometime" means occasional or former.

"some time" (two words) means
"a period of time.", it refers to a span of time
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Hi AjiteshArun,

Following up from your comment, Let me share how I read prepositions and their function in a sentence.

A preposition can modify a noun or a verb depending on the structure.

Ex. In 1947, India attained its sovereignty

In 1947 is modifying the verb attained and is not part of the Independent Clause: India attained its sovereignty

The same could be expressed as In 1947 India attained its sovereignty - in this case we have dropped the ',' however the portion 'In 1947' is still acting as the same function.

In the same way, can we read the option (A) in the OG:

at some time in the past our ancestors suffered an event

Regards
Abheek
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Abheek
Hi AjiteshArun,

Following up from your comment, Let me share how I read prepositions and their function in a sentence.

A preposition can modify a noun or a verb depending on the structure.

Ex. In 1947, India attained its sovereignty

In 1947 is modifying the verb attained and is not part of the Independent Clause: India attained its sovereignty

The same could be expressed as In 1947 India attained its sovereignty - in this case we have dropped the ',' however the portion 'In 1947' is still acting as the same function.

In the same way, can we read the option (A) in the OG:

at some time in the past our ancestors suffered an event

Regards
Abheek
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Hi Abheek,

That's absolutely correct: we can insert a pair of commas there if we want to (I used round brackets instead of commas in my previous post).

1. —at some time in the past, our ancestors suffered an event...
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The Official Guide for GMAT Review 2017

Practice Question
Question No.: SC 736
Page: 695
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.

A at some time in the past our ancestors suffered an event, greatly reducing their numbers
B that at some time in the past our ancestors suffered an event that greatly reduced their numbers
C that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced
D some time in the past our ancestors suffered an event from which their numbers were greatly reduced
E some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,
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Sorry if it’s a stupid question or if it’s not the right place to ask, but from which book does your image come from?

Posted from my mobile device
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Can we eliminate option A on the basis that it doesn???t have ???that??? after the dash?
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Can we eliminate option A on the basis that it doesn???t have ???that??? after the dash?
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Having the "that" after the dash definitely helps convey the meaning in a clear and logical way (as mentioned in this post), but I certainly wouldn't call the missing "that" a definitive error in (A) -- it's more of a small vote in favor of (B) over (A).

Luckily, we have a couple of other votes against (B), as explained here and here.

Because (B) is a BETTER option, we can eliminate (A).

I hope that helps!
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Dear Friends,

Here is a detailed explanation to this question-
macjas
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.


(A) at some time in the past our ancestors suffered an event, greatly reducing their numbers

(B) that at some time in the past our ancestors suffered an event that greatly reduced their numbers

(C) that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced

(D) some time in the past our ancestors suffered an event from which their numbers were greatly reduced

(E) some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,


Show Spoiler
Attachment:
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Attachment:
06.jpg
Attachment:
07.jpg
Attachment:
08.jpg

Meaning is crucial to solving this problem:
Understanding the intended meaning is key to solving this question; the intended meaning of the crucial part of this sentence is that at some time in the past our ancestors suffered an event that greatly reduced their numbers.

Concepts tested here: Meaning + Grammatical Construction

A: This answer choice alters the meaning of the sentence through the phrase "greatly reducing their numbers"; the construction of this phrase illogically implies that our ancestors suffered an event, and as a result, they greatly reduced their own numbers; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

B: Correct. This answer choice uses the phrase "event that greatly reduced their numbers", conveying the intended meaning - that our ancestors suffered an event, and that event greatly reduced their numbers.

C: This answer choice alters the meaning of the sentence through the phrase "so that their numbers were greatly reduced"; the construction of this phrase illogically implies that our ancestors suffered an event for the purpose of greatly reducing their numbers; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

D: This answer choice alters the meaning of the sentence through the phrase "from which their numbers were greatly reduced"; the construction of this phrase leads to an incoherent meaning; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

E: This answer choice alters the meaning of the sentence through the phrase "so as to reduce their numbers greatly"; the construction of this phrase illogically implies that our ancestors suffered an event for the purpose of greatly reducing their numbers; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

Hence, B is the best answer choice.

Additional Note: Some students may believe that Options A, D, and E are incorrect because they use a dash to join independent clauses, however, a dash can be used to carry out the roles of a colon, one of which is introducing an independent clause that explains a preceding independent clause, as is the case here. The independent clauses that follow "Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck" are meant to explain what is meant by a "population bottleneck".

All the best!
Experts' Global Team
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My only query is why do we need ''that'' after a dash. Isn't this incorrect? I understand that ''that'' act as a subordinating conjunction, so either use ''that'' without ''dash'' or use ''dash'' without ''that''. Why we need both? This was my analysis.

Can you please let me know what's wrong with this analysis?

Regards
Vighnesh
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Some anthropologists believe that the genetic homogeneity evident in 03 Mar 2022, 05:47
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VIGHNESHKAMATH
ExpertsGlobal5
Dear Friends,

Here is a detailed explanation to this question-
macjas
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—at some time in the past our ancestors suffered an event, greatly reducing their numbers and thus our genetic variation.


(A) at some time in the past our ancestors suffered an event, greatly reducing their numbers

(B) that at some time in the past our ancestors suffered an event that greatly reduced their numbers

(C) that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced

(D) some time in the past our ancestors suffered an event from which their numbers were greatly reduced

(E) some time in the past, that our ancestors suffered an event so as to reduce their numbers greatly,


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Meaning is crucial to solving this problem:
Understanding the intended meaning is key to solving this question; the intended meaning of the crucial part of this sentence is that at some time in the past our ancestors suffered an event that greatly reduced their numbers.

Concepts tested here: Meaning + Grammatical Construction

A: This answer choice alters the meaning of the sentence through the phrase "greatly reducing their numbers"; the construction of this phrase illogically implies that our ancestors suffered an event, and as a result, they greatly reduced their own numbers; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

B: Correct. This answer choice uses the phrase "event that greatly reduced their numbers", conveying the intended meaning - that our ancestors suffered an event, and that event greatly reduced their numbers.

C: This answer choice alters the meaning of the sentence through the phrase "so that their numbers were greatly reduced"; the construction of this phrase illogically implies that our ancestors suffered an event for the purpose of greatly reducing their numbers; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

D: This answer choice alters the meaning of the sentence through the phrase "from which their numbers were greatly reduced"; the construction of this phrase leads to an incoherent meaning; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

E: This answer choice alters the meaning of the sentence through the phrase "so as to reduce their numbers greatly"; the construction of this phrase illogically implies that our ancestors suffered an event for the purpose of greatly reducing their numbers; the intended meaning is that our ancestors suffered an event, and that event greatly reduced their numbers.

Hence, B is the best answer choice.

Additional Note: Some students may believe that Options A, D, and E are incorrect because they use a dash to join independent clauses, however, a dash can be used to carry out the roles of a colon, one of which is introducing an independent clause that explains a preceding independent clause, as is the case here. The independent clauses that follow "Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck" are meant to explain what is meant by a "population bottleneck".

All the best!
Experts' Global Team


My only query is why do we need ''that'' after a dash. Isn't this incorrect? I understand that ''that'' act as a subordinating conjunction, so either use ''that'' without ''dash'' or use ''dash'' without ''that''. Why we need both? This was my analysis.

Can you please let me know what's wrong with this analysis?

Regards
Vighnesh
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Hello VIGHNESHKAMATH,

We hope this finds you well.

As mentioned, here the dash plays the role of a colon, conveying that "that at some time...greatly reduced their numbers" provides an explanation for or elaborates upon the preceding clause.

We hope this helps.
All the best!
Experts' Global Team
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Some anthropologists believe that the genetic homogeneity evident in 15 Apr 2022, 20:02
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KarishmaB AndrewN DmitryFarber ExpertsGlobal5
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A couple of foundation questions -

1. Can we have IC as a non-essential modifier? If not, then can we reject option A basis this rule in the following question?
Understanding – IC(our ancestors suffered)

2. Can we have IC as a subject?
Ex(a). That GMATclub is the best forum for GMAT preparation is a well known fact.(Correct)
Ex(b). GMATclub is the best forum for GMAT preparation is a well known fact.(Will this be correct? here IC - 'GMATclub is the best forum' is acting as a subject)
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