Q22 - Paleontologists recently discovered teeth

[jacqueline.niba]

Hi everyone. I was working on this problem and picked B as my answer instead of D. My thinking was that B provided an alternative explanation why the teeth were small. Could anyone help explain why B is wrong?

[ManhattanPrepLSAT1]

The argument concludes that woolly mammoths living on the island were smaller on average than those that lived elsewhere. Why? Because the teeth of adult woolly mammoths found on the island were 25 percent smaller on average than adult woolly mammoth teeth that have been found elsewhere.

Correct Answer
The issue in this argument is about relative proportions. If the size of a woolly mammoth’s teeth is a good indication of the overall size of a woolly mammoth then the argument’s conclusion would be validly drawn _ best expressed in answer choice (D).

Incorrect Answers
(A) undermines the relationship between tooth size and body size by introducing variability.
(B) protects the argument from the issue of tooth wear, but is not enough to ensure the conclusion is properly drawn.
(C) is irrelevant to the argument as the evidence establishes that the teeth found on the island belong to adult woolly mammoths.
(E) protects the argument from the possibility that discrepancy in size of teeth is a product of the woolly mammoths on island having somewhat different teeth than the those found elsewhere. However, defending the argument from this possible weakness is not enough to ensure the conclusion.

[elizabeth.r.casanova]

Hi mshermn! Given the question called for identifying a sufficient assumption, I was able to cleanly prephrase "average teeth size is proportional to average body size." After I answered D), I went back through the answers to identify why each answer choice was incorrect. As I read B) again, I had a question regarding what it does to the argument if the question task changed:

-Would this be considered an appropriate answer to a necessary assumption question? I can't decide because if you negate B), the argument doesn't seem to fall apart, as long as the significant change in tooth size occurred among all woolly mammoths.

-Or, would this be more of an appropriate answer to a necessary assumption question: The amount of tooth wear resulting in significant change in tooth size among the adult woolly mammoths on the Arctic island did NOT differ from the amount of tooth wear among the adult woolly mammoths elsewhere.

I may be looking way too into this. Please let me know when you get a chance. Thank you kindly!

[ManhattanPrepLSAT1]

Wow! Great work. I'm truly impressed. Absolutely, answer choice (B) is close to a necessary assumption. But you're right. As long as the wear on teeth was uniform across all woolly mammoths in general, it wouldn't matter if that wear was significant or not. Now consistent - on the other hand - is important. Because if the woolly mammoths on the island were susceptible to unnatural wear, then the conclusion in the argument couldn't be reached.

Again, great work!

[elizabeth.r.casanova]

Thank you for the rapid response and confidence booster!

[timsportschuetz]

I chose E for this question. I stumbled on a question very similar to this: PT 36 Section 1 #18. Basically, the conclusion of this question is qualified by "Provided that the teeth are representative of their respective population...". Since we HAVE to prove the conclusion, the most important item to validate is that these teeth are actually representative of woolly mammoths. Answer choice E does exactly that!!!

Why in the world is this not a credited answer choice?

[tommywallach]

Hey Tim,

Answer choice (E) does not actually give us that. Answer choice (E) tells us that these mammoths had the same NUMBER and VARIETY of teeth as other mammoths. This does not allow us to conclude that their teeth are smaller on average than the teeth of mammoths that lived elsewhere. All it tells us is that they had the same number of teeth in their mouth, and the teeth different in the same ways (i.e. there were bicuspids and molars, etc.).

-t

[timsportschuetz]

Hi Tommy,

Thank you for your prompt and always valued responses! Honestly, I am not a thick-headed person and always consider alternatives! However, on this one, I must say that my logic is still sound. The argument's conclusion is specifically qualified by stating "provided...." THEN this is true. Well, no matter how detailed and or categorically answer E supports and/or proves this qualifying statement, it will allow the conclusion to be properly draw. By stating that the teeth had the same number and variety, the argument now has the evidence needed to remove the qualifier for the stated conclusion. I realize that there may be a million other ways to prove the representative nature of teeth, however, only one is needed.

I must be missing a crucial detail here...

[tommywallach]

Hey Tim,

I definitely didn't accuse of being less than brilliant, but your logic here is no good.

This is about SIZE of teeth.

Answer choice (E) is about NUMBER and TYPE of teeth.

As an example: I have 32 teeth, with 8 molars, 4 bicuspids, etc.

A gorilla might have: 32 teeth, with 8 molars, 4 bicuspids, etc.

But the fact that we have the same NUMBER and TYPE of teeth does not determine if the gorilla ITSELF is LARGER than I am. We don't know that BODY size is directly related to TOOTH size.

Make more sense?

-t

[timsportschuetz]

Got it! Thanks for sticking with me on this one... . So, lets assume that [E] said: "the teeth found on the island have similar structural proportions and chemical make-up to other mammoth populations around the world."

Would the above make it more feasible? Answer [E], as stated on the test, would not show that the teeth are representative of other mammoth teeth around the world because having a similar number and variety of teeth states NOTHING about the actual teeth being representative of other mammoths themselves; correct?

[tommywallach]

Hey Tim,

Glad to help! You're posting so much good stuff on our forums these days!

However, I still feel you're missing the flaw in the argument. The problem isn't about whether these mammoths are representative of ALL mammoths. The question is about whether an animal's teeth grow in proportion with the size of the animal. We don't need to reference "other mammoth populations around the world," because even if we did, we STILL don't know if bigger animals have bigger teeth.

Make sense?

-t

[timsportschuetz]

Thank you Tommy! Overt-thinking this stupid question! Am happy to report that all the hard work is paying off! Started a few months ago averaging -8 to -9 on each LR section. I averaged only -2 on the last 8 PT's! So, considering my rather pathetic abilities on the RC sections (usually -5 to -8), I should be able to score in the mid 160s or high 160s!

Again, thank you for all of your help!

[tommywallach]

I can't imagine any part of your performance will be "pathetic," given all the deep thought you're putting into stuff on this forum. I bet you'll be happily surprised on test day! : )

-t