Neuroscientists, having amassed a wealth of knowledge over the past

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 this sentence is that neuroscientists are now drawing solid conclusions about how the human brain grows and how babies acquire language, and over the past twenty years they have amassed a wealth of knowledge about the human brain and its development from birth to adulthood.

Concepts tested here: Meaning + Grammatical Construction

• The introduction of the present participle ("verb+ing"- “drawing” in this case) after comma generally leads to a cause-effect relationship.

A: Correct. This answer choice acts upon the subject - "Neuroscientists" - with the independent verb "are now drawing" to form a complete thought, leading to a complete sentence. Further, Option A uses the phrases "having amassed a wealth of knowledge over the past twenty years" and "are now drawing", conveying the intended meaning - that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the development the human brain undergoes from birth to adulthood, and as a separate action, they are now drawing solid conclusions about how the human brain grows and how babies acquire language.

B: This answer choice fails to form a complete sentence; "having amassed" is part of a modifying phrase, and "are now drawing" is part of a dependent clause, meaning there is no independent verb to act upon the subject - "Neuroscientists". Further, Option B alters the meaning of the sentence through the phrase "development from birth to adulthood over the past twenty years"; the construction of this phrase incorrectly implies that over an unspecified amount of time neuroscientists have amassed a wealth of knowledge about the development the human brain underwent over the past twenty years, specifically, from birth to adulthood; the intended meaning is that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the development the human brain undergoes from birth to adulthood.

C: This answer choice fails to form a complete sentence; "amassing" is a present participle acting as a noun modifier, and "are now drawing" is part of a dependent clause, meaning there is no independent verb to act upon the subject - "Neuroscientists". Further, Option C alters the meaning of the sentence through the phrase "development from birth to adulthood over the past twenty years"; the construction of this phrase incorrectly implies that over an unspecified amount of time neuroscientists have amassed a wealth of knowledge about the development the human brain underwent over the past twenty years, specifically, from birth to adulthood; the intended meaning is that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the development the human brain undergoes from birth to adulthood.

D: The sentence formed by this answer choice alters the meaning of the sentence through the phrase "now drawing solid conclusions"; the use of the "comma + present participle ("verb+ing" - "drawing" in this sentence)" construction incorrectly implies that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the human brain and its development from birth to adulthood, and as a result, they are now drawing solid conclusions about how the human brain grows and how babies acquire language; the intended meaning is that neuroscientists are now drawing solid conclusions about how the human brain grows and how babies acquire language, and, as a separate action, over the past twenty years they have amassed a wealth of knowledge about the human brain and its development from birth to adulthood; remember, the introduction of the present participle ("verb+ing"- “drawing” in this case) after comma generally leads to a cause-effect relationship.

E: The sentence formed by this answer choice alters the meaning of the sentence through the phrase "now drawing solid conclusions"; the use of the "comma + present participle ("verb+ing" - "drawing" in this sentence)" construction incorrectly implies that over the past twenty years, neuroscientists have amassed a wealth of knowledge about the human brain and its development from birth to adulthood, and as a result, they are now drawing solid conclusions about how the human brain grows and how babies acquire language; the intended meaning is that neuroscientists are now drawing solid conclusions about how the human brain grows and how babies acquire language, and, as a separate action, over the past twenty years they have amassed a wealth of knowledge about the human brain and its development from birth to adulthood; remember, the introduction of the present participle ("verb+ing"- “drawing” in this case) after comma generally leads to a cause-effect relationship.

Hence, A is the best answer choice.

To understand the concept of "Comma + Present Participle for Cause-Effect Relationship" on GMAT, you may want to watch the following video (~3 minutes):



All the best!
Experts' Global Team

Im no expert but this is what I think

B. The new placement of the prepositional phrase "over the past twenty years" changes the meaning of the sentence. Instead of modifying the verb amassed it now seems to modify adulthood.

C. The way this sentence is constructed suggest a compound predicate, but the first part of the sentence has no working verb. Amassing by itself does not function as the verb of the sentence - its a modifier. If you have mahattans sc they tell you that words connected by AND should be parallel.

D. Like B. D also has a shift in meaning. By getting rid of the word ARE the phrase "now drawing solid conclusions about the human brain grows and how babies acquire language." acts more like a modifier. Put this phrase in front and you'll see the change in meaning.

E. E has the same problem as D.

The correct answer A is grammatical - there isnt anything wrong with it.

Hi Mugdha,

Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

Once again, I would say that you have done a good job in analyzing this one. However, the clause split for this one is not accurate. Let's look at the clauses in this sentence:

Cl. 1: Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about
Cl. 2: how the human brain grows and
Cl. 3: how babies acquire language.

Since we cannot have a clause without an SV pair, the additional information cannot be identified as a clause because it does not have a Subject and a Verb.

I would never advise to skip the additional information completely while doing the PoE. The best way to answer questions where answer choices confuse us is to stay focused on the meaning of the sentence. You have understood the intended meaning of this sentence alright. Now let's compare that meaning with the meaning that we get from choices D and E.

Choice D: Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, - Per this choice, now the focus (main point) of the sentence is that Neuroscientists have amassed a lot of knowledge... However, per the original sentence, the focus of the sentence is that Neuroscientists are now drawing conclusions... This choice shifts the focus of the sentence completely. The main point of the sentence in Choice A is now an additional information in this choice. On this basis, we can eliminate this answer choice.

Choice E: Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood, - Incorrect for the same reason as explained above.

So keep the intended logical meaning of the sentence as the main guide while doing the PoE.

Hope this helps.
Thanks.
Shraddha

Hi @honchos,

I'm assuming you meant that the subject 'neuroscientists' would have two verbs. However, 'are' is not present in options D and E, so the verb 'are drawing' becomes the modifier 'drawing' in these options.

Before we get to the problem in options D and E, let’s look at the intended meaning of choice A. Remember we need to first thoroughly understand the original sentence so that we can properly gauge the other answer choices.

Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

This sentence indicates the following:
• Over the past 20 years, neuroscientists have collected a lot of knowledge about 2 things - brain and its development
• Neuroscientists are now drawing conclusions about 2 things - growth of human brain and acquiring language.
Key things to notice:

Two actions are being discussed:
a. In the past, scientists collected information
b. Now in the present context, scientists are drawing conclusions

Now let’s take a look at choice D:

Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, now drawing solid conclusions about how the human brain grows and how babies acquire language.

Let’s focus on the sequencing of tenses in this sentence. For this, I will omit “now” for now. We will bring this back after this bit of discussion.

Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, drawing solid conclusions about how the human brain grows and how babies acquire language.

Let’s read this sentence now and see what meaning it communicates.
• Over the past 20 years, neuroscientists have collected a lot of knowledge about 2 things.
• The verb-ing modifier can either present result of preceding clause or elaborate on the preceding clause. Let’s see which meaning is logical here:

o Elaborating - They collected a lot of knowledge in the past by drawing solid conclusions about 2 things.
 This seems illogical since one does not collect information by drawing conclusions.

o Result - They collected a lot of knowledge in the past and this led to them drawing solid conclusions.
 This seems rather logical. After they collected knowledge, they were able to draw solid conclusions.

But notice one very important thing. In this sentence, both the actions appear to have taken place in the past. The information was collected in the past and the conclusions were also drawn in the past.

Now bring back your understanding of choice A. Per choice A, collection took place in the past but the conclusions were being drawn in the present.

So this is the first reason for rejecting choice D - the shift in the meaning of the sentence.

Now let’s bring back the word “now”. This word interferes with the logical sequence of actions established in choice D. The logical sequence as we determined was that both actions took place in the past, but the presence of “now” forces the second action to take place in present, thereby creating a conflict.

And lastly, there is a focus shift in choice D.

Note that modifiers typically do not present the main point of the sentence: they only give additional information. In the original sentence, the subject of the main clause is “Neuroscientists” and the verb is “are drawing”. So, the intended focus is to say that neuroscientists are now drawing solid conclusions about something. This focus is now shifted to the collection of information.

So, in conclusion:

It’s very important to understand the meaning of the original sentence so that you can assess answer choices in the appropriate light. Remember, grammar is a tool to help you communicate ideas. But there is no use of learning about grammar rules if you do not pay attention to what it is that you have to communicate using these tools.

I hope this helps!

Regards,
Meghna

Hi htskumar,

I'll leave the boys at egmat to explain their answer further for you, but see if I can help with your second question

OG12 says, The final descriptor in present tense, now drawing conclusions...does not fit the opening clause, which is in present perfect tense (have amassed a wealth...) ----> What does this exactly mean?

This means that 'have amassed a wealth' is an event that happened in the past in an action that is completed(past perfect tense if you will), but the 'now drawing conclusions' is happening now (present tense). In interpreting the meaning of the sentence, this does not make sense.

The correct answer (A) moves from 'having amassed' to 'now drawing' this is more correct, 'having done some thing I now do something else'

Does that help?

James

Hi Saurabh,
Thank you for posting your query here.


There are two problems with option D, as Meghna explained above:

1. Shift in Focus: In the original sentence the information that neuroscientists have amassed a wealth of knowledge is given in the form of a modifier. Also, it seems that the main point that the sentence wants to convey is what scientists are doing now after they have already amassed a wealth of knowledge. Now, option D shifts the focus of the sentence to the modifier part. So, this is an error.

2. Also, per the original sentence the neuroscientists have completed the action of amassing the wealth over a duration of 20 years. The verb-ing modifier "drawing" presents the result of this clause that the action of amassing the wealth of knowledge has resulted in drawing some conclusions. As we know, the verb-ing modifier takes the tense of the preceding clause in such cases. So, per this choice the conclusions are being drawn for the last 20 years. However, the presence of the word "now" interferes with the logical sequence of the actions because it indicates that the action of drawing conclusions is taking place in the present. So, there is a conflict in the meaning.


Now, the explanation provided by the OG in this case states something else. Here, the verb-ing modifier "drawing" modifies the preceding clause, not the preceding noun "adulthood".



Hope this helps!
Regards,
Deepak

There is some doubt about this structure that since having amassed is an adverbial modifier, it should modify the previous clause and since there is no clause before the said modifier, but only a noun, this structure is inherently wrong.
IMO, this is not a correct perception.
Now let's look at this structure.

Can we now argue that this structure is wrong because there is no clause before the modifier?
The point is the verb + ing modifier, which we assumed, as an adverbial modifier becomes an adjective modifier when placed in the beginning of the clause.
The issue in question---
1. Neuroscientists, having amassed a wealth of knowledge over the past twenty years --- is actually --
--Having amassed a wealth of knowledge over the past twenty years, Neuroscientists --
Therefore, per se, that part is legal.

Hello Everyone!

Let's tackle this question, one issue at a time, to find the correct answer quickly! First, here is the original question, with the major differences between the options highlighted in orange:

Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the human brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,

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

1. Where to place the phrase "over the past twenty years"
2. How each option begins (modifiers, non-essential phrases, verbs)

Let's start with #1 on our list: where to place the phrase "over the past twenty years." This phrase is meant to modify, or add more detail, to some part of this sentence, but which part? WHAT was done over the past 20 years? Let's take a closer look at each option, and figure out the best location for that phrase:

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the human brain and its development from birth to adulthood, are --> OKAY
It's clear that what happened over the past 20 years was researchers amassing a wealth of knowledge, so let's keep this one for later.

(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are --> WRONG
This is misleading because it suggests that the phrase "over the past 20 years" is modifying "development from birth to adulthood." The research isn't over the past 20 years of someone's life - the research was collected over the past 20 years.

(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are --> WRONG
Again, this is misleading because it suggests that the research covers the brain development over 20 years of a person's life, which isn't the intended meaning. It's supposed to say that the research was collected over the span of 20 years.

(D) Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood, --> OKAY
It's clear that the research was collected over a span of 20 years, so let's keep this one for later.

(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood, --> WRONG
While this isn't grammatically incorrect, it does change the meaning of the original sentence slightly. By putting the phrase "over the past twenty years" in between commas, it's now a non-essential clause. By making this an "optional" phrase, we are saying that the length of time it took to amass this information isn't important. We would argue that it is important because it adds more detail to the idea that it took 20 years to gather all the information, and that neuroscientists are ONLY NOW figuring out what to do with all the information.

We can eliminate options B, C, and E because they place the phrase "over the past twenty years" in the wrong place.

Now that we're only left with 2 options, let's take a closer look at each one to determine which is the best choice. To make this easier, I've included the remaining part of the sentence at the end:

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the human brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

This is CORRECT! The phrase "over the past twenty years" is in the best location to create clarity and provide accurate information. The non-essential modifier, "...having amassed...to adulthood" uses the right punctuation and doesn't create any problems with verb tenses.

(D) Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood, now drawing solid conclusions about how the human brain grows and how babies acquire language.

This is INCORRECT for a couple reasons. First, it uses the present perfect "have amassed," which means that neuroscientists started looking for knowledge in the past and are still looking for it today. This isn't true. They collected all the information in the past, and they are done looking for it - they've moved on to drawing conclusions about brain development based on what they already found! Second, the modifier "now drawing solid conclusions..." sounds like it's in the wrong place, or needs to be worded more clearly to show that it's talking about the neuroscientists drawing conclusions. It's not technically wrong, but it could be confusing to readers.

There you have it - option A was the best choice after all!


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

Hi Meghna,

Neuroscientists,having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about the human brain grows and how babies acquire language.

A)Neuroscientists,having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are

B)Neuroscientists,having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years,and are

C)Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years,and are

D)Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood,

E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood ,

This sentence has three clause.
clause 1 : Neuroscientists,(subject)
having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,(verb-ing modifier that modifies Neuroscientists)
are (verb) now drawing solid conclusions about
Clause 2 : how the human brain grows and
Clause 3 : how babies acquire language.(clause 2 and 3 are parallel)

there is nothing wrong with the above sentence. but we should reject all the other choices for good reasons.
Choice B) this choice is wrong because a comma +and is used before "are", implying that there is another verb before "are" in the sentence. however, there is no other verb in the sentence.
choice C) it has the same problem as choice B. In addition the placing of the modifier "over the past twenty years" changes the meaning. Now the reader conclude that the development of the brain was over past twenty years
choice D) I do not find any thing wrong with this choice. this choice says that Neuroscientists
have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, now drawing solid conclusions about how the human brain grows and how babies acquire language.
In this sentence the verb -ing form modifies entire preceding clause and expresses the result of Neuroscientists action which is having amassed a wealth of knowledge.
Choice E) Same analysis as for choice D.

what is wrong with my analysis for choices D and E?

Hi Hero8888, you are correct! Having + Past Participle basically depicts an action that completed before the main verb in the sentence. Hence,

i) If the main verb is in past, Having + Past Participle acts like past perfect
ii) If the main verb is in present (as is the case in option A here), Having + Past Participle acts like present perfect


These type of Present participles (are now drawing solid conclusions..) should depict simultaneous result of the previous clause (For example: Peter met with an accident, sustaining severe injuries). Option D does not represent this scenario and is hence, incorrect.

You have the right idea here. The "amassing" logically came before the "drawing," and choice (A) expresses that logical meaning in a perfectly clear way.

That said, you could argue that the neuroscientists made some conclusions WHILE they were in the process of amassing the knowledge. In that case, "drawing" could make sense as a modifier for the main clause in (D) and (E): "Neuroscientists have amassed...".

But if that's the interpretation we want, we'd have to drop the "now" to make it clear that the "amassing" and the "drawing" are overlapping actions. The "now" seems to separate the "drawing" and the "amassing" on the timeline, and that throws a wrench in an otherwise plausible interpretation.

Choice (A) avoids this issue by using "drawing" as a verb instead of a modifier: the drawing is happening now, and the amassing happened before that. The meaning is perfectly clear and logical, making (A) a much better choice. (For more on "-ing" verbs vs modifiers, check out this article.)

I hope that helps!

Neuroscientists,having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about the human brain grows and how babies acquire language.

A)Neuroscientists,having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are

B)Neuroscientists,having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years,and are
No verb for Neuroscientists
C)Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years,and are. No verb for Neuroscientists

D)Neuroscientists have amassed a wealth of knowledge over past twenty years about the brain and its development from birth to adulthood, "drawing " is modifying what "adulthood"

E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood , "drawing " is modifying what "adulthood"



Note correct SV pair: Neuroscientists are

Present participle modifiers (-ing modifiers) can work the same way any other modifier does: modifying the noun touching the modifier. In addition, these modifiers may also be used to modify either the preceding clause or the subject of the preceding clause.

Oh no; without a comma, the having + past-participle structure is always incorrect on GMAT.

You might want to remember this. Let me know and I can dig out an official example in this regard.

This is what your response was in a previous post

Choice D: Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood: Incorrect. In this choice, "now drawing" acts as a comma + verb-ing modifier. The focus on the main information here has shifted from " are now developing" in the original sentence to "have amassed". In the original sentence, the action that is primary is "now developing" and "amassing knowledge" comes as an additional information. This choic reverses that order by making the main action additional information and the additional information into the main action. This is a clear shift in the intended meaning.


Can you please explain if the rule that you have explained before is valid for this question?

This thread has undergone a great length of discussion by many contributors and let me add a little more to it.

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are --- the modifier " having amassed a wealth of knowledge…. are" can only modify neuroscientists as there is no other eligible plural noun in the clause. One does not expect the brain and its development to amass knowledge. This is the best choice

(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are --- This is a fragment, the first part lacking a verb b

(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are. --- same flaw as in B.

(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, ---
1. Over the "past" twenty years is a closed chapter. There is no indication that the scientists are continuing to amass knowledge. Therefore, "have amassed" is not appropriate in the context.
2. It gives a twisted meaning that drawing conclusions is an inferior act of amassing wealth. nay. 'Drawing conclusions' is as equal and weighty as amassing knowledge and therefore needs an active verb. The step-motherly modifier status for the drawing part is a significant error.
.
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood --- same modifier error as in D.

I'm not sure what Deepak meant by:

As we know, the verb-ing modifier takes the tense of the preceding clause in such cases.