Sentence Correction

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.

dhaval.shownkani wrote: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.

Semicolon and period are preferred.

On the GMAT, a DASH at the end of a sentence will typically serve to introduce an APPOSITIVE: a noun form serving to explain or define a preceding noun form.

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.
Here, the two that-clauses function as NOUNS.
Each serves as a direct object of believe, as follows:
Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck."
These anthropologists believe that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation.

The that-clause in red is in apposition to the first that-clause, explaining WHY the first that-clause (that genetic homogeneity is the result of a "population bottleneck") is what some anthropologists believe.

I don't understand the application of parallelism here. Most of the questions with appositives that I have seen are something like the below.

Thelonious Monk, the jazz pianist and composer,
produced a body of work that was rooted both..

What if the sentence was something like - Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"- a phenomena bla bla.. There would have been no need for parallelism then right ?


(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,

Hi Mitch because following is not an Independent clause "that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation", can we safely conclude that two Independent clauses cannot be connected by a hyphen?

bonetlobo wrote:Hi Mitch because following is not an Independent clause "that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation", can we safely conclude that two Independent clauses cannot be connected by a hyphen?

Hi bonetlobo,

Two independent clauses, in my opinion, can never be connected with a hyphen. Hyphen, in GMAT, as mentioned by Mitch above is only as an modifier (in general - appositive in this case).

Other ways to join two clauses are as under:
1. Using a AND or COMMMA + AND.
2. Using a semicolon. However, in this case the second clause must be dependent on first one.

Everyone, please feel free to add to the list.

dhaval.shownkani wrote:I don't understand the application of parallelism here. Most of the questions with appositives that I have seen are something like the below.

Thelonious Monk, the jazz pianist and composer,
produced a body of work that was rooted both..

What if the sentence was something like - Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck"- a phenomena bla bla.. There would have been no need for parallelism then right ?

APPOSITIVES are noun forms that appear side-by-side, with the second serving to explain or define the first.

Some anthropologists believe that the genetic homogeneity evident in the world's people is the result of a "population bottleneck", a catastrophic event that greatly reduces the size of a population.
Here, a catastrophic event is in apposition to a "population bottleneck," serving to explain that a "population bottleneck" is a type of catastrophic event.
While this sentence is correct, it does not fully convey the intended meaning of the SC above.
The purpose of the second that-clause in the OA above is not merely to define "population bottleneck" but to explain why anthropologists hold the belief conveyed by the first that-clause (that genetic homogeneity is the RESULT of a "population bottleneck").

ZEUGMA is a rhetorical construction in which parallel structures are governed by the SAME WORD, PHRASE OR CLAUSE.
In many cases, the parallel structures will NOT be linked by a conjunction.
The OA above is an example of zeugma.

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.
Here, the two that-clauses are governed by the same verb (believe).
Each serves as a direct object for this verb.
The two that-clauses are linked not by a conjunction but by a dash.
The lack of a conjunction implies that the second that-clause is serving to explain the first.
For this reason, we can consider the second that-clause an APPOSITIVE for the first.

Other official examples of zeugma:

The hognose snake puts on an impressive bluff, hissing and rearing back, broadening the flesh behind its head the way a cobra does.
Here, the two modifiers in red are not linked by a conjunction.
Both are governed by the preceding clause, serving to express HOW the hognose snake puts on an impressive bluff.

So dogged were Frances Perkins' investigations of the garment industry, so persistent her lobbying for wage and hour reform, that Alfred E. Smith and Franklin D. Roosevelt recruited Perkins.
Here, the two so-clauses are not linked by a conjunction.
Both are governed by the following that-clause.
The following meanings are conveyed:
So dogged were Frances Perkins' investigations that Alfred E. Smith and Franklin D. Roosevelt recruited Perkins.
So persistent [was] her lobbying that Alfred E. Smith and Franklin D. Roosevelt recruited Perkins.

bonetlobo wrote:Hi Mitch because following is not an Independent clause "that at some time in the past our ancestors suffered an event that greatly reduced their numbers and thus our genetic variation", can we safely conclude that two Independent clauses cannot be connected by a hyphen?

To my knowledge, no OA has ever employed a single dash to link two independent clauses.
However, TWO DASHES may serve to interject an independent clause into the MIDDLE of a sentence.
SC132 in the OG13:
Although heirloom tomatoes appear less appetizing than most of their supermarket cousins -- thev often have plenty of bumps and bruises -- heirlooms are more flavorful.
Here, two dashes serve to interject an independent clause into the middle of the sentence.
In this usage, the two dashes function like parentheses, serving to interject a parenthetical thought into the middle of the sentence.

dear experts,
thanks for your patient to my question.

I am a little confused about this statement's conclusion
1/ this conclusion includes two events ?

Charging each household a fee for each pound of trash it puts out for collection will induce residents to reduce the amount of trash they create ; this charge will therefore protect the remaining county parkland

because I figure out there is a colon btw last 2 sentences, generally, colon means parallelism, so i think there are two events in conclusion , reduce trash and protect remaining parkland





2/ does charge cause reduce and cause protect parkland
or
charge causes reduce, then reduce causes protect parkland

Charging each household a fee for each pound of trash it puts out for collection will induce residents to reduce the amount of trash they create ; this charge will therefore protect the remaining county parkland

here is a word "therefore" implying a conclusion, charge therefore protect parkland,
reading it some times, i feel charge is not the direct cause which causes protect parkland, but i am not sure.

please help to clarify.

thanks a lot
have a nice day
>_~

GMATGuruNY wrote:The two that-clauses are linked not by a conjunction but by a dash.

Hi Mitch,

as read this thread, talking about two THAT clause connection,
I recalled my unanswered post about two complete sentence connection without conjunction


it will be appreciate if you can help answer the following topic.
https://www.beatthegmat.com/sc-two-compl ... 92578.html

thanks in advance
have a nice weekends.

>_~

GMATGuruNY wrote:The two that-clauses are linked not by a conjunction but by a dash.

Hi Mitch,

as read this thread, talking about two THAT clause connection,
I recalled my unanswered post about two complete sentence connection without conjunction


it will be appreciate if you can help answer the following topic.
https://www.beatthegmat.com/sc-two-compl ... 92578.html

thanks in advance
have a nice weekends.

>_~