Q10 - Giant ground sloths began disappearing

by **ohthatpatrick** Tue Jul 09, 2019 2:27 pm

Question Type:
Strengthen (the belief)

Stimulus Breakdown:
CURIOUS FACT: why did giant sloths start disppearing (and ultimately go extinct) from the Americas 10k years ago, around the end of last ice age?
SCIENTISTS' EXPLANATION: the arrival of human beings shortly before that moment is what caused the sloths' decline.

Answer Anticipation:
Whenever we're assessing a CURIOUS FACT / AUTHOR'S EXPLANATION type paragraph, we ask ourselves
1. How ELSE could we potentially explain the curious fact?
2. How plausible is the Author's Explanation?

To strengthen, we could either rule out an alternate explanation (i.e. "sloths were NOT killed off by the climate change brought on by the ice age") or bolster the plausibility of the author's explanation (i.e. "humans hunted sloths" / "humans gave sloths incurable diseases" / "in the parts of America where there WEREN'T humans, sloths still survived")

Strengthen answers usually increase the plausibility of the author's story, and the most typical form is covariation (no cause / no effect ... or more cause / more effect).

Correct Answer:
E

Answer Choice Analysis:
(A) This WEAKENS the plausibility of the scientists' story

(B) This is neutral. We only care about these giant sloths and nothing in the "humans did it" hypothesis has any common sense connection to giant vs. medium vs. small.

(C) This WEAKENS (slightly) by hinting at an alternate story. Maybe humans didn't doom sloths; maybe it was sloths' inability to adapt to the new post-Ice Age climate.

(D) That's great, Other Large Mammals that Went Extinct, but not helpful in terms of assessing whether humans killed giant sloths.

(E) YES. Covariation (no cause, no effect) for the win, yet again. This shows that when there were NOT humans (isolated), there WERE sloths (survived). But yet when there WERE humans (arrived), the sloths no longer survived.

Takeaway/Pattern: This is the most expected answer when you're strengthening a causal hypothesis: some form of "where the supposed cause is absent, the effect is absent" or more evidence that "where the supposed cause is present, the effect is present"

#officialexplanation