Ancient hunter-gatherers developed instincts that

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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 ancient hunter-gatherers developed instincts that stigmatized selfishness and encouraged voluntary cooperation both within the group and with outsiders.

Concepts tested here: Meaning + Verb Forms + Grammatical Construction + Idioms + Awkwardness/Redundancy

• Information that is vital to the core meaning of the sentence cannot be placed between commas.
• Semicolons and the “comma + conjunction” construction are used to link two independent clauses; commas are used to link an independent clause with a dependent one; commas cannot be used to join two independent clauses.
• The introduction of the present participle ("verb+ing"- “encouraging” in this case) after the comma generally leads to a cause-effect relationship.
• “both A and B" or "A as well as B" are the correct usages; A and B must be parallel and comparable.
• “not only A but also B” is the correct, idiomatic usage; A must be parallel to B.
• The simple past tense is used to refer to actions that concluded in the past.

A: This answer choice incorrectly places information that is vital to the core meaning of the sentence – the fact that ancient hunter-gatherers' instincts encouraged voluntary cooperation as well – between commas; remember, information that is vital to the core meaning of the sentence cannot be placed between commas. Further, Option A uses the needlessly wordy phrase “whether it be within the group or”, leading to awkwardness and redundancy. 

B: This answer choice alters the meaning of the sentence through the phrase “encouraging voluntary cooperation as well”; the use of the “comma + present participle (“verb+ing” - “encouraging” in this sentence)” construction incorrectly implies that ancient hunter-gatherers' instincts stigmatized selfishness, and as a result encouraged voluntary cooperation as well; the intended meaning is that ancient hunter-gatherers' instincts stigmatized selfishness, and as a separate action encouraged voluntary cooperation as well; remember, the introduction of the present participle ("verb+ing"- “encouraging” in this case) after comma generally leads to a cause-effect relationship. Further, Option B incorrectly uses the unidiomatic construction “both A (“within the group”) but also B (“with outsiders”); remember, “both A and B" or "A as well as B" are the correct usages; A and B must be parallel and comparable.

C: This answer choice incorrectly uses the present participle ("verb+ing"- “encouraging” in this case) to refer to an action that concluded in the past; remember, the simple past tense is used to refer to actions that concluded in the past.

D: This answer choice incorrectly uses conjunction (“and” in this case) to join two independent clauses - “Ancient hunter-gatherers developed instincts that stigmatized selfishness” and “they encouraged voluntary cooperation”; remember, semicolons and the “comma + conjunction” construction are used to link two independent clauses; commas are used to link an independent clause with a dependent one; comma cannot be used to join two independent clauses. Further, Option D uses the needlessly indirect phrase “whether it be within the group”, leading to awkwardness and redundancy.

E: Correct. This answer choice uses the phrase “and encouraged voluntary cooperation”, conveying the intended meaning – that ancient hunter-gatherers' instincts stigmatized selfishness, and as a separate action encouraged voluntary cooperation as well. Further, Option E correctly uses the simple past tense verb “encouraged” to refer to an action that concluded in the past. Additionally, Option E avoids the grammatical construction error seen in Option A, as it places no information between commas. Moreover, Option E avoids the grammatical construction error seen in Option D, as it includes only one independent clause. Option E also correctly uses the idiomatic construction “not only A (“within the group”) but also B (“with outsiders”)”; “not only A but also B” is the correct, idiomatic usage; A must be parallel to B. Besides, Option E is free of any awkwardness or redundancy.

Hence, E is the best answer choice.

To understand the concept of "Simple Tenses" on GMAT, you may want to watch the following video (~2 minutes):



To understand the use of punctuations on GMAT, you may want to watch the following video (~10 minutes):



To understand the concept of "Comma Plus Present Participle for Cause-Effect Relationship" on GMAT, you may want to watch the following video (~2 minutes):



All the best!
Experts' Global Team