Q17 - Dietary researcher: A recent study

[LSAT-Chang]

Could someone help me with this problem?
I was down to (A) and (D) and I picked (A) -- the correct answer, but when I went back and read it, I thought it was actually the opposite of what we wanted.

So here is our core:

The doctor's belief that North Americans' life spans can be extended is not supported. Why? Because lab animals tend to eat much more than animals in their natural habitats, so restricting their diet merely brings their caloric intake back to natural, optimal levels and reinstates their normal life spans. SO basically, the lives of these lab animals have not been really "extended" but rather just brought back to "normal" level.

So when I read (A), it says "North Americans, on average, consume a higher number of calories than the optimal number of calories for a human diet" -- so if this were true, then these North Americans normally consume higher number of calories (just like the lab animals eating much more than animals in natural habitat), so even if they were to reduce the calories, it wouldn't "extend" their life but rather just make it to "normal life spans", since they are just eating more that shortens their life spans, so if they reduced their intake, it would just bring it to "normal" and not necessarily "LONGER" lives. Does this make sense?

If we had (D), "some north americans who follow reduced-calorie diets are long-lived" then wouldn't it go against the conclusion since it is giving evidence that at least "some" who did reduce-calorie intake lived LONG.

[timmydoeslsat]

I have read over your post and will incorporate your questions and concerns in my post as I go over this problem.

Core:

Recent study showed that lab animals fed reduced calorie diets lived longer than those that did not.
+
Lab animals tend to eat more than animals in natural habitat. Restricting the diet is just bringing the calorie level back to normal and reestablishes the normal life span.

----> Idea of reduced calorie diets for North Americans to extend lifespan is not supported


It is important to realize that strengthen and weaken questions are often assumption questions in disguise at times. Stating a necessary assumption will necessarily strengthen an argument. Expecting a sufficient assumption on a strengthen question is like waiting for Elvis to walk into your local truck stop for a side pancakes.

Weaken questions can also go after assumptions. It can basically use a negated version of to hurt the argument.

In this case of our core, we notice that a conclusion is reached about human diets and extending life, but we have NO evidence associated with this idea do we?

This argument IS ASSUMING that North Americans are not currently acting like the lab animals in the fact that they eat more than what nature calls for.

Answer choice A: North Americans, on average, consume a higher number of calories than the optimal number of calories for a human diet.

This would weaken the idea that the conclusion IS NOT SUPPORTED. This adds MORE support to the idea that reducing calories can extend life. The researcher's last sentence of "restricting their (lab animals) diets merely brings their caloric intake back to nature/optimal levels and then their life spans" is used as evidence that the idea of extending NA human life by reduced calories is unsupported.


Answer choice D does not address extending life. This is giving us a fact that gives us no insight as to whether they live longer than most North Americans either. It may be the case that people who do not follow reduced calorie diets are long-lived too.

[LSAT-Chang]

In this case of our core, we notice that a conclusion is reached about human diets and extending life, but we have NO evidence associated with this idea do we?

This argument IS ASSUMING that North Americans are not currently acting like the lab animals in the fact that they eat more than what nature calls for.

Answer choice A: North Americans, on average, consume a higher number of calories than the optimal number of calories for a human diet.

This would weaken the idea that the conclusion IS NOT SUPPORTED. This adds MORE support to the idea that reducing calories can extend life. The researcher's last sentence of "restricting their (lab animals) diets merely brings their caloric intake back to nature/optimal levels and then their life spans" is used as evidence that the idea of extending NA human life by reduced calories is unsupported.

Hey timmy!
I followed through everything except the stuff I quoted above.. I'm thinking the exact opposite of what you are thinking so please help correct me if you can see where I went wrong..

So I agree with you 100% that we have no evidence about humans in this argument that supports the idea that "NA life spans cannot be extended" -- so the evidence that comes after that conclusion is what the author uses to support this conclusion about HUMANS. RIght? Okay so what I'm thinking is this (I think it is the total opposite of what you wrote above):

The author is ASSUMING that NA life spans cannot be extended BECAUSE NA humans tend to eat much more than normal human comsumption and so reducing their consumption just brings life back to the natural, optimal levels of normal life spans so this is actually NOT extending human life -- but just bringing it back to normal!

And (A) seems to be exactly what I wrote above. If this were true, then the author's position is supported.. this is the exact assumption that I posted above. I'm so confused -- what am I not understanding? I have the author's conclusion correctly down "that NA life cannot be extended" and the reason for this is about lab animals -- so we have to assume that NA humans are like this lab animals in that they consume way more than their natural counterparts so just merely reducing their diet is just bringing their life span back to normal...

[maryadkins]

The mice on diets are living longer than the other mice. Some people say this means humans should diet too if they want to live longer, but that's not right because the mice on diets are actually eating NORMAL amounts and living NORMAL lifespans (for mice). What does that mean? The other lab mice are eating too much and living shorter than normal life spans.

What's the problem with this? Like timmydoeslsat points out, what if North Americans are also eating too much and not living "normal" lifespans for humans (which, by the way, are a much bigger group than just North America), because they freakin' eat so much?

Then, just like the lab rats, we can extend their lifespans--beyond where they are currently--by bringing them back to a normal diet. Just because the (excessively caloric) average North American diet is "average" doesn't make it a "normal" human diet. And just because potential to increase their lifespan means it'll just bring them back to a "normal" lifespan doesn't mean we're not extending it. We're just extending it beyond its current place.

Any clearer?

[chike_eze]

I see. Thanks for the explanation Timmy + Mary!

To make (D) work, we would modify it thus: "Some North Americans who follow reduced-calorie diets live longer than those who don't"

(D) is wrong because "... are long lived" does not compare "reduced-calorie" group to "not reduced-calorie" group.

[LSAT-Chang]

And just because potential to increase their lifespan means it'll just bring them back to a "normal" lifespan doesn't mean we're not extending it. We're just extending it beyond its current place.

Any clearer?

YES! Thank you so much Mary!! It took me a while to understand that "extending" life spans could just mean extending it from the current place, so basically, if North Americans were consuming so much food, and this was what led them to have shorter life spans, by reducing the caloric intake, we could sure extend that short life span to become the "normal" life span. Great!

[csunnerberg13]

just a quick question about answer choice E, which troubled me for a while...

Is the issue with E basically just that it is not strong enough? We could know that some animals have a strong correlation between diet and longevity, but it's still only some animals...so humans/mice could be excluded from this and then it would have no bearing on the argument?

[foralexpark]

just a quick question about answer choice E, which troubled me for a while...

Is the issue with E basically just that it is not strong enough? We could know that some animals have a strong correlation between diet and longevity, but it's still only some animals...so humans/mice could be excluded from this and then it would have no bearing on the argument?

(E) has "some species of animals"

but this is out of scope. conclusion is about the rats and how they are similar to humans (north americans) and this is based on HUGE assumption.

So even if this was true (for example, elephants and dolphins and so forth),, this would say anything about the rats and humans

[maryadkins]

(E) has "some species of animals"

but this is out of scope. conclusion is about the rats and how they are similar to humans (north americans) and this is based on HUGE assumption.

So even if this was true (for example, elephants and dolphins and so forth),, this would say anything about the rats and humans

Yes!

[GeneW]

What's wrong with C? Would it weaken the argument if animal studies don't apply to humans?

Does "Not all" not weaken it enough? Thank you.

[maryadkins]

Let me do a breakdown of the answer choices since we seem not to have done that, yet!

Like a true diva, I will begin by quoting myself:

The mice on diets are living longer than the other mice. Some people say this means humans should diet too if they want to live longer, but that's not right because the mice on diets are actually eating NORMAL amounts and living NORMAL lifespans (for mice). What does that mean? The other lab mice are eating too much and living shorter than normal life spans.

What's the problem with this? Like timmydoeslsat points out, what if North Americans are also eating too much and not living "normal" lifespans for humans (which, by the way, are a much bigger group than just North America), because they freakin' eat so much?

Then, just like the lab rats, we can extend their lifespans--beyond where they are currently--by bringing them back to a normal diet. Just because the (excessively caloric) average North American diet is "average" doesn't make it a "normal" human diet. And just because potential to increase their lifespan means it'll just bring them back to a "normal" lifespan doesn't mean we're not extending it. We're just extending it beyond its current place.

That is why (A) is correct.

(B) is out of scope. It compares two groups that both have low-calorie diets. The only difference between them is that one has a high-FAT diet. This whole argument is about calories, not fat.

(C) is too vague. If not all important scientific results are based on lab animals, so what? Some still are, and maybe this is one of them.

(D) is wrong because, as Chike noted below:

(D) is wrong because "... are long lived" does not compare "reduced-calorie" group to "not reduced-calorie" group.

(E) is vague. Some species, okay. What about humans? We have no idea.

[GeneW]

Thank you, Mary. Just came across the reply. Somehow, the email alert for replies didn't work.

[contropositive]

i read the entire post about answer choice A and D. Although, I still did not understand the explanations above. After through analysis of why I had eliminated A, I realized whatever way you attack A, it will still weaken the author's point and strengthen the doctors belief which is the side we want to be on.

Here is my thought process:


Reduced-calorie diets does not extend life spans (particularity North Americans)

Why?


Because laboratory animals, which were used as support for doctor's belief about reduced-calorie diet and life span, eat more than non-laboratory animals which makes them have shorter life spans.

+

Reducing laboratory animals' calorie diet is going to bring them back to natural diet their supposed to have and reinstate their normal life spans



A strengthens the doctors' belief about North Americans life span because the doctors could argue,

"true, laboratory animals doe eat more and restricting their diets will bring back their natural diet and thereby their normal life spans which is longer than the one they have now due to eating so much. So by saying North Americans consume more than the natural human diet, then North Americans are just like our lab animals that eat more. Restricting North Americans diet will bring back their natural diet and normal life span just like the lab animals."

But I am having difficulty letting go of D. In my Manhatten LR 4th edition book, I see that there are 3 wrong answer choices on weakening question types. Does D fall under "unclear impact on conclusion?" I think D is wrong because the word "some" could me one to all. if its one it doesn't really weaken anything. its vague.

Any other helpful explanations for D?


for the two other people asking about C and E.

C) irrelevant. Not all scientific results have important implications on human health? okay but we were never speaking of all scientific results anyway. Also, it could strengthen the author's point. He could put that into his evidence - kind of like a booster.

E) irrelevant. we are not just talking about animals. we want something to speak of humans and animals.

[ganbayou]

Hi,

I thought D is not good enough because "some" can be too small and it is not sufficient to attack conclusion. Is this understanding correct? Or can "some" statement weaken or strengthen arguments?
Or if D say "...longer lived" it can be the answer as well?
Actually I did not like all answer choices at first because although A provides the same condition for North American as the laboratory animals, NA and the animals can have differences as well and that can have influence, so I thought that would not lead to the same consequence...or did I think too much?

Thank you

[maryadkins]

First of all, to this question:

I thought D is not good enough because "some" can be too small and it is not sufficient to attack conclusion. Is this understanding correct? Or can "some" statement weaken or strengthen arguments?

GREAT question. Yes, "some" is a problem in (D) for the exact reason you noted. And while rarely, "some" in an answer choice can be a correct answer to a Strengthen or Weaken question, more often than not it indicates that there's a BETTER answer choice in the mix.

And yes, this would fall under "unclear impact on conclusion."

Which leads me to your other question about (A):

Actually I did not like all answer choices at first because although A provides the same condition for North American as the laboratory animals, NA and the animals can have differences as well and that can have influence, so I thought that would not lead to the same consequence...or did I think too much?

I mean, right. But it still weakens the argument by providing a similarity between the two scenarios that the researcher claims doesn't exist. The fact that it doesn't totally destroy the argument is okay—it just has to "most weaken" as the question asks.