PT154 S1 Q15 ExplanationIn the winter, ravens survive

Answer choices, explained

1. A

   Only One Alternative1% picked this

   He proposed two alternative hypotheses, each of which would explain a

   Heinrich does propose an alternative hypothesis. He thinks, "the ravens aren't enlisting other ravens to go eat a carcass together because they're generous and altruistic, it's because if they were on their own they'd get chased away by a mated pair that's claimed the carcass."

   1%
2. B

   Correct87% picked this

   His investigation partially confirmed prior observations but led to a radical reinterpretation

   Why this is right

   Yikes, what an answer. We can sign off on the accuracy of the idea that his investigation partially confirmed prior observations. Prior observation -- "according to many reports", ravens recruit more ravens to eat a carcass. Heinrich's meat experiment partially corroborates this, since juvenile ravens assembled in groups to try to eat the meat "carcass". This means that the phenomenon of ravens recruiting other ravens to go eat a carcass is the opposite of altruism. Rather than being a selfless act of sharing, a juvenile raven is asking other ravens for help (for selfish reasons, because the juvenile can't eat the carcass unless he shows up with a gang of friends). Since this alternate explanation is completely self-interested, instead of selfless, we could say it's radically different, but certainly no one would love that type of strong wording on a first pass.

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

   87%
3. C

   Out of Scope: proposed theory7% picked this

   He proposed a theory and then proceeded to confirm it

   There's nothing in the text that suggests he proposed any theory prior to setting out his meat test. All we know is that "this seemingly altruistic behavior struck him as being worthy of investigation".

   7%
4. D

   Opposite: same conclusion2% picked this

   He used different methods from those used in earlier studies but arrived at

   The earlier conclusion was that ravens were just being altruistic. He did not arrive at that same conclusion. He concluded that the raven enlisting other ravens actually had a selfish motive: they were too puny on their own to displace the mated pair that had already claimed the meat.

   2%
5. E

   Out of Scope: replicated previous studies3% picked this

   His investigation replicated previous studies but yielded a more limited set

   We never heard about any previous studies, nor were we given any suggestion that Heinrich replicated anyone else's methodology.

   3%