Neuroscientists, having amassed a wealth of knowledge over the past

Hi EducationAisle!

OA: 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.

Question: Usualy in GMAT SC "having ..." takes past perfect. But I also know that -ing modifier takes the tense of the main verb. Can we infer that in this case"having" is in present perfect, not in past perfect?
Otherwise how to justify usage of past perfect instead of simple construction such as: Neuroscientists, amassed a wealth..., are now drawing.
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About option 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.

Question: Is the only problem of this option that it shifts focus from main action "are now drawing solid conclusions" to "have amassed a wealth of knowledge'? Otherwise the sentence sounds pretty (grammatically and logically) correct.

Thanks!

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.

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.

Another interesting point I would like to add here is that, VErb+ing denotes an action that is happening at the same time as the action of the main clause.(Do ignore my comparison if incorrect, I am trying to ace it)

He went to college, driving 50kms.-> here the act of driving is happening at the time of "going to college".

One can not say He went to college, now driving 50 kms. That'd be incorrect.

egmat, do correct me if I am wrong.

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.

at experts,


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

is above the rule... can i have few more gmac questions in this.. ( especially taking the past tense, as verb ing is a present participle, how it can take past tense or any other tense)

advanced thanks for your response

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.

AjiteshArun , egmat , experts

"The information was collected in the past and the conclusions were also drawn in the past.". ( please look at the usage of the same in the quote in red colour).

its not only Mr. Deepak from egmat, as in the quoted Ms. Meghna from egmat also using the same. i think they both are mentioning in that option the verbing modifier is taking the tense of the previous clause.

so is this a rule that verbing modifier takes the tense of the previous clause? Please enlighten me on this with reference to other OG question.

Thanks

A) Only answer which respects both tense parallelism & right modifying (Neuroscientists, clause, are): OA for sure!

B) Little meaning confusion which will be repeated in other answers (makes it seem like they amassed info about only the adulthood), + addition of "and" doesn't convey meaning as sharply as A does: incorrect.

C) Same as B but with progressive verb (amassing), no comma to separate the neuroscientists to the action they have accomplished, + "are" which won't bring a lot of meaning to the sentence: incorrect!

D) E and this are almost the same, except that D doesn't separate the subject from the action, which decreases the efficiency of the sentence's meaning

E) Wrong placement of the comma, clause formed but which distorts the information conveyed in the sentence: incorrect!

(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 - CORRECT SENTENCE

(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 - it did not take 20 years to gain this knowledge

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

(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,

D and E are disconnected from the rest of the sentences

A

Use the 'slash and burn' method. Between the commas we have a large descriptor. Remove it and we see that we are really only dealing with 'Neuroscientists are...". No other option makes sense with the descriptor removed.

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Hi professor

“Have amassed “ is present tense. The tense is the same as “NOW”. Why we cannot use “ Now drawing” as result?

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VeritasKarishma : Can you please give the proper explaination for elimination of D, because

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.


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

how come , D is making illogical sense , since i feel its cause and effect ,

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

There are two actions involved in this sentence -
Neuroscientists have amassed a wealth of knowledge
Neuroscientists are now drawing conclusions (from the wealth of knowledge)

One is not effect of another. The wealth of knowledge has enabled the scientists to draw conclusions but they are still performing that action.

If you mean to say that drawing conclusions should be participle (effect of amassing knowledge) then that is incorrect. It is a separate action.

Look at how a participle is used:
The principal stepped on to the podium, silencing the students.

Here the principal is not silencing the students. When he stepped on the podium, it led to silencing of the students.

But in our sentence, the scientists have amassed knowledge and are now drawing conclusions - separate actions.

So you need a verb with "drawing conclusions". Hence (D) is incorrect.

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 - Neuro scientists are drawing something - Conveys meaning well.

(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, - Non-underlined portion drawing modifies the entire preceding clause .
Actually drawing conclusions is the main point here but it is potrayed as effect - incorrect

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

Dear Experts,
I read all the responses suggesting the explanation why D/E is incorrect, but I am still not confident on eliminating it.

I see the posts from egmat in which it is said - "Present perfect tense verb is also used when the there is no definite time frame of the action OR the action has finished in the past but the effect of which continues in the present"
https://gmatclub.com/forum/fossils-of-t ... 77781.html
https://e-gmat.com/blogs/verbs-tenses/

If present perfect tense can be used in such cases, I feel this is not in-line with how daagh has eliminated D


I agree to VeritasKarishma explanation , but not sure if D is incorrect just because of "now drawing..." rather than "drawing...".

May I request you to help me getting a better reason to eliminate D.