KarishmaB AndrewN DmitryFarber ExpertsGlobal5
GMATNinja

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)

By the way, don't look for 'rules'. It all depends on context and that is why it makes you think afresh every time.
For your point 2, I would say that I prefer (a) over (b). (b) is confusing and you have to run through the entire sentence to make sense of what is being said.

ChrisLele and ExpertsGlobal5
Option A uses construction ', + verb ing' which indicates cause effect relation / verb ing will modify preceding verb, so reducing can modify suffered and it is also correct to look at it in the light of cause - effect relation. Why are we saying it means that ancestors reduced themselves. Why don't we apply , + verbing rules over here ?

Hello experts,
I eliminated A and C, on the basis of "-that", As far as I knew, when we use dash (-), It explains any part of a sentence, for ex, a single word or verb or complete clause etc.

but this is new, If author wanted to maintain a parallelism between believe and at some time, he could've done so by simply using only "that". why is he being so fancy with -?

Hence I thought its simple is explaining the term "population bottleneck"(which makes sense), SO I liked D , but it fails to maintain parallelism in the end, then finally I chose A, knowing that ,ing is modifying subject and is wrong.

So why exactly the need of -That??

How to know weather "-" is explaining a part of a sentence or its maintaing a parallelism with clause or a verb?

Dear Experts,

What does the role of "the first THAT" in choice (B)?
Why do we have to put "that" in (B)?

The em-dash used to provide more info about a "population bottleneck". Thus, What does the role of "the first THAT" in choice (B)?
Why do we have to put "that" in (B)?

Importantly, the stuff after the dash is ••NOT•• an explanation of just the phrase 'population bottleneck'! It's an explanation of the entire preceding sentence. I.e., it explains more specifically why/how "the genetic homogeneity evident in the world's people is the result of a 'population bottleneck'".

We can make a relative judgment between the choices with only one "that" (A, D, E) and those with a second "that" in front of the explanation (B and C).
In B and C, this relationship is clear and unambiguous.
In ADE, on the other hand, this rl is not at all clear. In those versions of the sentence, a typical reader will FIRST try the simplest, more straightforward, and most compactly contained interpretation—meaning that a typical reader will first misinterpret the stuff after the dash as explaining only the phrase 'population bottleneck', and will have to go back and re-read the sentence in order to understand it.
So, the version with two "that"s is definitely OBJECTIVELY SUPERIOR to the version with only one "that". eliminate ADE.

Thank you for your explanation RonTargetTestPrep!

Now I understand that : the stuff after the dash is ••NOT•• an explanation of just the phrase 'population bottleneck'!

However, what is the role or "that" after the em-dash? I mainly used the last that to eliminate others choices, especially the choices containing -ing.
I don't understand what "that" after the em-dash does. I thought "that" after the em-dash acts as a pronoun but it doesn't (If I correctly understand your explanation).

Option A : at sometime in the past our ancestors suffered an event, greatly reducing their numbers

??? greatly reducing their numbers??? : will this not act as modifier for the suffering?

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.

Thank you for this. I am still confused on why the "that" is required here following the dash.

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

I have the same question. the ing modifier is modifying the entire clause - ancestors suffering an event, and that suffering led to reduction

I have the same question. the ing modifier is modifying the entire clause - ancestors suffering an event, and that suffering led to reduction

I have the same question. the ing modifier is modifying the entire clause - ancestors suffering an event, and that suffering led to reduction

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