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Question

Difficulty: Very hardSingle-Sentence Inferences

Read the following excerpt from an academic treatise on archaic human genomics:

"While nineteenth-century palaeoanthropologists inferred hominin migration vectors exclusively from morphological variations in fossilized crania, recent high-throughput sequencing of archaic nuclear DNA from Pleistocene dental calculus demonstrates that although phenotypic diversification in Neanderthal lineages frequently correlated with geographic isolation, inter-lineage gene flow persisted across ecological barriers previously assumed to be insurmountable."

Statement: Based on the excerpt provided, Neanderthal populations separated by major environmental barriers were not completely genetically isolated from one another during the Pleistocene epoch.

Answer: Answer

Answer

True. The sentence explicitly confirms that genetic exchange (gene flow) continued between Neanderthal lineages despite major ecological barriers, directly supporting the conclusion that these populations were not entirely genetically isolated.
The correct assessment is True because the sentence explicitly establishes that genetic transfer (gene flow) continued between Neanderthal lineages across ecological barriers, directly proving that geographic division did not cause total genetic separation.

Step-by-Step Solution

1
Analyze the structural pivots and main clauses of the sentence.
Identified the concession clause ('although phenotypic diversification... correlated with geographic isolation') and the primary factual assertion ('inter-lineage gene flow persisted across ecological barriers...').
Single-sentence GMAT inference questions require isolating the core claim from qualifying clauses.
2
Evaluate the logical implication of 'gene flow persisted across ecological barriers'.
'Gene flow' means genetic transfer between populations; 'persisted across barriers' means the barriers did not block genetic exchange entirely.
Direct deduction requires mapping the sentence's technical terminology to the evaluated statement's claim.
3
Compare the deduced meaning to the statement under evaluation.
The statement asserts that populations separated by environmental barriers were 'not completely genetically isolated,' which matches the sentence's assertion that gene flow persisted.
Confirm that no outside knowledge or unwarranted extrapolation is required to hold the statement as strictly true.

Key Concept

Single-Sentence Inferences
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Topics

Single-Sentence Inferences

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