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Difficulty: HardMethod of Reasoning

Paleogeneticist: Critics argue that the extinction of Pleistocene megafauna across northern Eurasia was driven exclusively by abrupt climatic warming rather than human hunting pressure. However, this view fails to withstand scrutiny. Ice-core records establish that northern Eurasia underwent dozens of equally abrupt warming oscillations during earlier interglacial epochs without triggering widespread megafaunal collapse. Furthermore, recent radiometric dating demonstrates that megafaunal extinctions across distinct subregions coincided precisely with the documented arrival of anatomically modern humans, regardless of the local climatic conditions. Therefore, climatic warming alone is insufficient to account for the extinctions, and human hunting pressure was a decisive factor.

Based on the passage, arrange the logical stages of the paleogeneticist’s argument into the sequential order in which they establish the ultimate conclusion.

  1. 1Stating the opposing claim that abrupt climatic warming was the exclusive cause of megafaunal extinctions.
  2. 2Citing historical paleoclimate data showing that previous warming episodes did not precipitate extinction events.
  3. 3Introducing chronological evidence demonstrating that regional extinctions correlated with human migration irrespective of local climate.
  4. 4Inferring the intermediate conclusion that sudden climatic warming alone cannot account for the extinction pattern.
  5. 5Deducing the final conclusion that human hunting pressure was a decisive factor in driving the extinctions.

Answer

The correct logical sequence begins with identifying the opposing thesis, advances through negative comparative evidence and positive chronological correlation, derives the intermediate conclusion rejecting climate exclusivity, and concludes with the primary claim that human hunting was decisive.
The argument follows a classic LSAT refutation-and-alternative structure: it first delineates the opposing causal hypothesis, provides two independent empirical premises (historical paleoclimate data and regional human arrival chronologies), derives an intermediate conclusion denying the sufficiency of the rival cause, and culminates in the final conclusion affirming the author's preferred causal factor.

Step-by-Step Solution

1
Identify the target hypothesis framed by the author.
The argument opens by establishing the critics' position that abrupt climate warming was the sole cause of the extinctions.
Before an indirect refutation can occur, the specific claim under scrutiny must be isolated.
2
Analyze the empirical counter-evidence challenging the target hypothesis.
Ice-core records are introduced showing earlier warming episodes that lacked corresponding megafaunal extinctions.
This establishes that climate warming is not historically sufficient on its own to produce widespread collapse.
3
Examine the affirmative evidence for the alternative causal mechanism.
Stratigraphic and radiometric data confirm that regional collapses aligned with human arrival rather than local climate shifts.
This supplies the positive empirical linkage necessary to attribute causal weight to human presence.
4
Identify the intermediate conclusion derived from the combined premises.
The author infers that climatic warming alone is insufficient to explain the extinctions.
This sub-conclusion directly resolves the initial critique by invalidating the exclusivity of the opposing explanation.
5
Identify the ultimate conclusion supported by the sub-conclusion and affirmative evidence.
The author concludes that human hunting pressure played a decisive role in the extinction event.
This serves as the overarching conclusion of the passage, drawing upon the totality of the preceding deductive steps.

Key Concept

Method of Reasoning: Logical Progression in Multi-Premise Refutations
Estimated Time:1m 30s
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Method of Reasoning

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