Some anthropologists believe that the genetic homogeneity evident in

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

Hello Everyone!

While it seems that the original question came with a pretty thorough explanation, let's see if we can figure out how you would tackle this question if you found in on the GMAT! To get started, let's look at the original question, and highlight any major differences in orange:

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,

After a quick glance over the options, there are a couple things we can focus on:

1. at some time / that at some time / that sometime / some time
2. Their endings (intended meaning)

Let's start by taking a closer look at #1 on our list: how to begin! We know that the phrase starts directly after an em dash, so we need to follow the rules concerning em dashes. In this sentence, the em dash is used to show that what follows is a more detailed explanation of a "population bottleneck." You could replace the em dash with the phrase "in other words" and it should still make sense because both the original explanation and the "rewording" of it should be parallel:

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,

We can eliminate options A, D, & E because they don't have the word "that" to create a parallel structure to the original explanation.

Now that we only have 2 options to choose from, let's add in the rest of the sentence and check for other problems:

(B) 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.

This is CORRECT! It uses parallel wording by starting both explanations with the word "that." It also uses parallel structure to list the two things that were greatly reduced: their numbers / our genetic variation. It uses the structure "greatly reduced X and Y," where X and Y were both written using parallel structure (pronoun + noun).

(C) Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"—that sometime in the past our ancestors suffered an event so that their numbers were greatly reduced and thus our genetic variation.

This is INCORRECT! While it does use parallelism to start both explanations with "that," there is a parallelism problem later on:

their numbers were greatly reduced and thus our genetic variation = X was greatly reduced and Y = NOT PARALLEL

To fix it, we would have to repeat the verb:

their numbers were greatly reduced and thus our genetic variation was greatly reduced = X was greatly reduced and Y was greatly reduced = PARALLEL

There you have it - option B is the correct choice because it uses parallel structure throughout the sentence!


Don't study for the GMAT. Train for it.

Dear Friends,

Here is a detailed explanation to this question-

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

COMMA + VERBing should refer to the SUBJECT of the preceding clause. In A, reducing seems to refer to our ancestors, implying that OUR ANCESTORS were greatly reducing their numbers. The intended meaning here is that an EVENT greatly reduced their numbers. Eliminate A.

So that (in C) and so as (in E) imply PURPOSE. The result is a strange meaning: that our ancestors suffered for the PURPOSE of reducing their numbers. Not the intended meaning. Eliminate C and E.

In D, which seems to refer to an event, implying that our ancestors' numbers were reduced FROM an event -- a nonsensical meaning. Eliminate D.

The correct answer is B.

Hi,
I am bit confused about your explanation, I thought that a participle phrase (gerund) will modify the entire independent clause - in this case the fact that "our ancestors suffered an event"
Example (Taken from MGMAT just to make sure I don't introduce something estrange):
Crime has recently decreased in our neighborhood, leading to a rise in property values

I may be missing something in your explanation, so it will be great if you can expand a bit more on it.

I originally had chosen A, not thinking about the required parallelism: Anthropologist believed that x - that y. I didn't think it made sense to make those two clauses parallel because of the lack of 'and', and thus I figured that the clause after the dash ('=') was just emphasizing the definition of a 'population bottleneck'.

I hope this thread is not to old.

Thanks,

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 some time 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,

Meaning: Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck". Population bottleneck – an event that occurred sometime back in the past which greatly reduced their numbers and thus our genetic variation.

Option A) “greatly reducing their numbers” – Verb-ing modifier comma separated, so presenting (modifying) more information about the preceding clause “at some time in the past our ancestors suffered an event” which is incorrect as the event reduced their numbers.

Option C) so that presents reason which is incorrect.

Option D) “from which” is incorrect. The correct sentence would be “some time in the past our ancestors suffered an event that greatly reduced their numbers”.

Option E) “so as” provides an intent.

My confusion is “that” in Option B)
that should replace “population bottleneck”
So the sentence becomes “population bottleneck at some time in the past our ancestors suffered an event that greatly reduced their numbers” – doesn’t look correct to me.

I know after the hyphen “-” the modifier comes which provides more information about the preceding noun.

Can you please clarify about the usage of hyphen?

Dear Kinjal,

Thank you for your query.

The punctuation mark referred to by you is technically called a “dash”. Yes, it has a slightly less fancy name than the “hyphen”.

Moving on, the dash can be used in multiple ways. In the sentence at hand, it has been used to elaborate on what the author has mentioned before the dash. If you observe, the portion after the dash not only expands on the “bottleneck” bit but also on how the genetic homogeneity is the result of the mentioned bottleneck. Accordingly, if I were to draw a parallel structure it would be something on the following lines:

Mariana believes that altruism exists even in today’s day and age — that people can help others without any selfish motives is not an idea that is too unrealistic to exist in a society that thrives on rewarding individualism.

In the example sentence above, the portion after the dash reiterates the point stated earlier while elaborating a bit more on the same. Not only does it tell you more about the concept of altruism, as perceived by the author, but also about the whole statement made earlier. This is very similar to how the dash has been used in the correct choice of the question referred to by you in your post.

Of course, the above question does not limit the universe of the uses of this punctuation mark. You can also use the dash in various other forms, but the idea remains the same: to separate parts of the sentence while adding information. To enhance your understanding, you could refer to some other OG questions in your research - OG 13: Q#98 & Q#132.

Hope that helps!

Regards,
Neeti.

I have some follow up questions about the following sentence:

Mariana believes that altruism exists even in today’s day and age — that people can help others without any selfish motives is not an idea that is too unrealistic to exist in a society that thrives on rewarding individualism.

1) The sentence after the hyphen modifies "altruism" but also the author adds more information. So "altruism" need not be close to the hyphen as possible. One of the rule which comes to my mind was usage of Noun+Noun modifier. It is very versatile in the application because it can modify any part of the sentence and also modify the whole preceding phrase. Can you please confirm if same is the case with hyphen usage.
2) The reason why I am asking you is because, in OG 13 Question # 138 - Correct Option
"Although heirloom tomatoes, grown from seeds saved during the previous year, appear less appetizing than most of their round and red supermarket cousins—they are often green and striped, or have plenty of bumps and bruises—heirlooms are more flavorful and thus in increasing demand."
The noun is closest to the hyphen.
OG 13 Question # 98 - Correct Option.
"Ranked as one of the most important of Europe's young playwrights, Franz Xaver Kroetz has written 40 plays; his works—translated into more than 30 languages—are produced more often than those of any other contemporary German dramatist.
The noun is closest to the hyphen.

Dear Kinjal,

Since you have cited your analysis for the mentioned two official questions to raise a query about the example sentence, let me address your analysis first:

Your analysis:
in OG 13 Question # 138 - Correct Option
"Although heirloom tomatoes, grown from seeds saved during the previous year, appear less appetizing than most of their round and red supermarket cousins—they are often green and striped, or have plenty of bumps and bruises—heirlooms are more flavorful and thus in increasing demand."
The noun is closest to the hyphen.

My comments:
Per your analysis, the portion between the two dashes — they are often green and striped, or have plenty of bumps and bruises— modifies red supermarket cousins. My question is does this modification make logical sense? If we take this modification in to consideration, we are effectively saying that the comparatively appealing, red supermarket cousins are:
1. green and striped
2. and have plenty of bumps and bruises

Please reconsider the structure of the sentence, keeping in mind the logical meaning that the author wants to convey. I am sure you’ll be able to see the role dash plays in this sentence and the example sentence then.

Your analysis:
OG 13 Question # 98 - Correct Option.
"Ranked as one of the most important of Europe's young playwrights, Franz Xaver Kroetz has written 40 plays; his works—translated into more than 30 languages—are produced more often than those of any other contemporary German dramatist.
The noun is closest to the hyphen.

My comments:

In the above sentence, the purpose of the author is indeed to modify “his works” and this is the precise reason that the author has inserted the modifier here. There is nothing else before the dash here (taking in to account only the portion after the semi-colon). So, the point about the noun being closest to the dash is not relevant in this case.

In all, as pointed to you in my earlier post, the idea behind using the dash is the same: separating parts of a sentence while adding more information.

Hope the above discussion helps!

Regards,

Neeti.

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 some time in the past our ancestors suffered an even 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 even so as to reduce their numbers greatly



i have 2 doubts in this question
1)that greatly reduced their numbers and thus our genetic variation.
how is this parallel ?? that.... numbers is an IC, clause while the 2nd part is a phrase.
please help.

2)OG says that at some time or adverb sometime is needed and some time in option c is incorrect.

can u please explain why is it so ??

Hi Sid,

Thanks for your posting your doubt here.

This is the structure of Choice B: ...at some time in the past our ancestors suffered an event that greatly reduced
a. their numbers and
b. thus our genetic variation

The noun entities "their numbers" and "our genetic variation" are grammatically parallel to each other. Now, "thus" is an adverb, a modifier, that presents the effect of an action. It's placement before the second entity DOS NOT violate the grammatical parallelism in any way. Hence, the parallelism is all correct in Choice B.

Now, "sometime" is not the same as "some time". The former means "at some point in time" while the other means "a little time". Let's take two very simple examples here:

1. Sometimes, i visit the public library.
2. Please give me some time to finish this question.

That's the reason why "some time" is incorrect in Choice C.

Hope this helps.
Thanks.
SJ

I agree with in all points, that's a great explanation. But regarding D, I think, that both D and B have the same meaning -> from which and that actually have the same meaning, and both sentences explain that an Event reduced the numbers of ..... D is just wordier than B, it also lacks THAT and AT before some time.

D has a parallelism issue. Notice that the sentence ends with a phrase after and: thus our genetic variation.

Hence, there should be a phrase before the and. However, in D, there is a clause before and: their numbers were greatly reduced.

In contrast, B says: ...an event that greatly reduced X and Y.
x: their numbers
Y: thus our genetic variation

X and Y are both phrases.

egmat
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.

I still dont get why A is not correct ?
"ing" plays 2 role first is describing the action with subject and second it can be an effect of a cause mentioned earlier in the clause.
here why cant "greatly reducing their numbers and thus our genetic variation" be an effect of " ancestors suffering from event "
It can mean " ancestors suffered from event and thus suffering from that event led to reducing their....blabla " clear cause and effect.
if "ing" can play second role clearly why one has to check for the first role "ing" plays( i.e. describing with subject) ??
If option A is incorrect it has to be some other reason.
thanks

Without "that", the latter clause ( " at some time....greatly reduced their numbers") does not have much meaningful bearing to the first clause as the author intended. It is required to establish that the scientists believe even the latter clause and hence "that" is required to be repeated.

ccooley : I was wondering if you could help me with the following doubts?
1) I am having a hard time understanding how A break the parallelism and why is 'that' required to maintain it. I am referring to OG explanation here.
2) How would you define grammatically what role is dash playing here? I researched use of dash as per grammar rules but didnt find any other example similar to this question.
Thanks

1. The author requires to convey that the fact that "at some time in the past our ancestors suffered an event that greatly reduced their numbers..." is believed by "some anthropologists". Without "that", the sense would be as though the author is expressing his own belief , not the anthropologists' belief.

2. Dash is versatile in use and can play the role of a comma, semicolon or a colon. Dash here plays the role of a colon(:) - the colon can be used to provide further explanation for what comes before it. The dash, as a replacement of a colon, plays the same role here.