#20- Galanin is a protein found in the brain. In an

[Chandler H]

Hello,
I'm confused on how (A) weakens/ "may hurt" the argument. If the cravings do not always lead to choosing fatty foods, how can we use that to weaken the causal relationship between galanin and fatty foods since choosing foods comes after craving foods?

Hi Lemonade42,

(A) weakens the argument because the author concludes that galanin causes rats to crave fatty foods. The author's evidence is that rats who choose to eat fatty foods have higher galanin levels. However, if (A) is true, then it weakens the link between the author's conclusion and this first piece of evidence, because the conclusion talks about "craving" while the evidence talks about "choosing." It is possible to choose fatty foods but not crave them, and vice versa.

Hope that helps!

[berrysugar]

I'm confused how (E) suggests that the causal relationship in the conclusion is reversed. I chose (E) because rats that metabolize fat less efficiently would need more fatty foods relatively, and thus have high concentrations of galanin, resulting in them to crave for more fatty foods.

[Luke Haqq]

Hi berrysugar!

The conclusion of this stimulus is the final sentence: "These facts strongly support the conclusion that galanin causes rats to crave fatty foods." The facts are the study mentioned in the stimulus, which found that rats who preferred fatty foods had higher levels of galanin in their brains.

In reading this, I wondered about the possibility that perhaps eating the fatty food itself produced galanin. If this were true, it'd weaken the conclusion that galanin causes rats to crave fatty food. Answer choice (D) strengthens the answer choice by eliminating this possibility--according to that answer choice the levels of galanin in their brains was higher before they ate the foods. This strengthens the causal claim that galanin causes the craving for fatty foods.

Perhaps it would be better to say that answer choice (E) is out of scope more than showing a reversed relationship. It seems out of scope because metabolism isn't mentioned in the stimulus. Even if some rats metabolize fat less efficiently and develop more galanin in their brains as a result, there's still the question of whether the fatty foods cause the increase of galanin or whether instead the galanin already exists prior to eating and causes the cravings for fatty foods.