Logical Reasoning

PT6 · S2 · Q12 By dating fossils of pollen

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By dating fossils of pollen and beetles, which returned after an Ice Age glacier left an area, it is possible to establish an approximate date when a warmer climate developed.

Given that ...

The return of pollen and beetles to an area helps us approximate when a warmer climate returned (following an Ice Age)

and that ...

In one area, the beetle evidence suggests that the warm climate returned immediately after the glacier melted

Why is it that

In that area, the pollen evidence makes it seem like it took a long time after the glacier melted for the warm climate to come back?

Goal

We need four storylines to explain why the beetle record and pollen record give us different approximations for this one glacial area. (we'll eliminate those four answers)

A storyline might provide a distinction between this glacial area and others.

It might provide a distinction between the pollen method and the beetle method, maybe beetles always return prior to pollen.

It could help us answer the question,

Or, it could help us answer the question,

12.

Each one of the following, if true, helps to explain the apparent discrepancy except:

  1. Cold-weather beetle fossils can be

    Resolves Paradox

    This explains the discrepancy. If cold-weather beetles can be mistaken for warm-weather beetles, the insect record may falsely suggest warm climate appeared earlier than it actually did. The pollen record could then be the accurate one. Discrepancy resolved.

    8% picked this

  2. Warm-weather plants cannot establish themselves

    Resolves Paradox

    This explains the discrepancy. If beetles arrive in a new environment faster than warm-weather plants do, the insect record will register warm conditions before the pollen record does — even if both records are accurate. Discrepancy resolved.

    6% picked this

  3. Beetles can survive in a

    Resolves Paradox

    This explains the discrepancy. If beetles can survive in a barren postglacial area by scavenging, beetles can be present right after the glacier leaves even when the climate isn't warm yet. The insect record then falsely suggests warm climate, while the pollen record (which depends on actual warm conditions) accurately shows warm climate developed later.

    9% picked this

  4. Since plants spread unevenly in

    Resolves Paradox

    This explains the discrepancy. If plants spread unevenly and gaps in the pollen record can be misread as no growth, the pollen record may underestimate when warm-weather plants actually arrived. So warm climate could have developed earlier than the pollen record suggests, lining up with the beetle record. Discrepancy resolved.

    6% picked this

  5. Correct

    Beetles are among the oldest

    Why this is right

    This is the answer that does NOT resolve the discrepancy. The age of beetles as a species (vs. plant species) doesn't bear on whether either record is accurate or on the rate at which beetles vs. plants arrive in a postglacial area. The discrepancy is about the timing of climate change as recorded by two different fossil sources — not about evolutionary age. This fact is irrelevant to the puzzle.

    Skill tested: Paradox · how this choice captures the argument's function is the move to repeat next time.

    71% picked this

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