Logical Reasoning

PT11 · S2 · Q2 Sea turtles nest only

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Sea turtles nest only at their own birthplaces.

Curious Fact

How do sea turtles find their way back to their birthplace, 15-30 years later when they're ready to nest?

Hypothesis (i.e. Explanation)

Newborn sea turtles learn the smell of their birth environment, and that smell is what stimulates them to return to nest 15 to 30 years later.

Evaluate

We know when we see "hypothesis" in the question stem that it will be this Explain Curious Fact style of causal argument.

The two pressure points for such an argument are 1) alternate explanations (for the curious fact) 2) plausibility (of the author's hypothesis)

How else might the turtle find its way back? Maybe it uses the stars as a guide? Maybe there's some current of water in the ocean that takes them there?

How plausible is it that they smell their way home? Are they always within smell-range of their birthplace? Does each birthplace have a distinct scent?

Goal

On Evaluate, we basically consider whether a potential answer to any of the answer choice's toss-ups could Weaken. (You can also validate that the oppose answer would strengthen, but it suffices to find the answer that could most weaken)

So let's look for an answer that would address an alternate means of how they find their way back or one that addresses the underlying plausibility of the "smell your way home" hypothesis.

2.

Which one of the following would be most important to know in evaluating the hypothesis in the passage?

  1. how long the expected life

    Unrelated to Goal

    The hypothesis is about what triggers the return migration, not how long turtles live. Lifespan information doesn't help us evaluate whether smell is the trigger. Knowing turtles live 50 vs. 80 years tells us nothing about whether smell guides their navigation.

    1% picked this

  2. what the maximum migratory range

    Unrelated to Goal

    This could maybe be relevant to the plausibility of the author's hypothesis. If the smell from their birthplace only drifts about 10 miles but they migrate 100 miles away, that would make it hard to believe the hypothesis. But just knowing how far they migrate doesn't really help on its own, unless there's some common sense number we all know about how far smells travel.

    5% picked this

  3. whether many beaches on which

    Unrelated to Goal

    Whether some hatching beaches have been destroyed doesn't help us evaluate the smell hypothesis. Even if many beaches were lost, the question of whether smell is the return trigger for turtles whose beaches still exist remains unanswered.

    2% picked this

  4. Correct

    whether immediately before returning to

    Why this is right

    This gets at the plausibility of the hypothesis. If we answered this answer choice by saying, "YES, when sea turtles start their way back to their birthplace, they are beyond the range of it being perceptible to smell their birthplace", then the hypothesis collapses. There's no way that the smell of their birthplace could trigger their return home, if they're beyond the perceptible range of their birthplace when they begin that voyage. You can't be triggered by something imperceptible. You have to perceive it to be triggered by it.

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

    92% picked this

  5. whether both sexes of sea

    Unrelated to Goal

    Whether both sexes are involved in the nesting process doesn't bear on the navigation mechanism. The hypothesis is about how turtles find their way back; gender involvement in nest-building or guarding is a separate question.

    0% picked this

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