#22 - Paleontologists recently discovered teeth from several

[Administrator]

Complete Question Explanation

Justify the Conclusion. The correct answer choice is (D)

This Justify stimulus concludes that woolly mammoths that lived on the island were smaller on average than those that live elsewhere. This conclusion is drawn from the fact that the teeth of the mammoths on the island were smaller on average than other adult mammoth teeth that were found elsewhere. To connect these two ideas and prove that the mammoths were in fact smaller on average, you must find an answer choice that links tooth size with actual mammoth size (show that the two are related and that teeth are indicative of overall size).

Answer choice (A): Showing that mammoths’ average tooth and body size can vary significantly does not prove that the island mammoths were smaller on average based on their smaller teeth.

Answer choice (B): The fact that the mammoth teeth found were not smaller due to tooth wear does not connect mammoth size to tooth size, so it cannot prove the conclusion.

Answer choice (C): The conclusion is about mammoths found on the island, so an answer choice about mammoths found elsewhere cannot be correct.

Answer choice (D): This is the correct answer choice. If mammoth size is always proportional to tooth size then mammoths with smaller teeth would be smaller than mammoths with larger teeth, and the conclusion would be true.

[jrc3813]

Is B a necessary assumption? It rejects the idea that the teeth might be smaller due to wear. If we're linking tooth size to body size then all other explanations for tooth size variation must be rejected.

I realize this is a justify the conclusion question, but I was just curious if the test makers will sometimes throw in a necessary assumption to throw people off sometimes.

[Emily Haney-Caron]

Hi jrc,

Nope! B is actually irrelevant. Presumably, the same tooth wear would occur across populations, especially since the teeth are smaller on average (so presumably including adult mammoth teeth from mammoths of different ages). Do you see why that makes B not a necessary assumption here?

[jrc3813]

Hi jrc,

Nope! B is actually irrelevant. Presumably, the same tooth wear would occur across populations, especially since the teeth are smaller on average (so presumably including adult mammoth teeth from mammoths of different ages). Do you see why that makes B not a necessary assumption here?

I think so. It's because it's referring to tooth size across the entire mammoth population including the non-islanders? If B had read "tooth wear specific to the isolated island did not result in significant change in tooth size" that would have been a necessary condition? I think that's how I interpreted the answer choice.

[AthenaDalton]

Hi JRC,

Yes, the fact that answer choice (B) specifies that it's concerned with "tooth wear that occurs in many animals" does eliminate it from being relevant for the island fossil study of mammoth teeth -- it uses broad terms to capture not just mammoths but many other species. If the answer choice were specifically targeted to the mammoth population found on the island, as you suggest, it could be a necessary condition.

Good luck!

Athena Dalton

[egarcia193]

Hi,

I choose answer choice E because I saw that in the conclusion it talked about mammoths that lived on the island and E is the only answer choice that talks about the mammoths actually living on the island so I thought by connecting that Rouge term with that answer choice it was correct.

Why is E wrong the explanation does not include why E is a wrong choice and did I mess up by relying too much on the word lived in the conclusion?

Thanks

[Luke Haqq]

Hi egarcia193,

It's good that you're thinking about the potential "rogue" elements. But in this case, the fact about where they lived--whether on the isolated Arctic island or elsewhere--isn't the essential assertion undergirding the conclusion. Rather, the conclusion is: these recently discovered teeth are evidence that mammoths on this island are smaller than other mammoths. If mammoths on the Arctic island have the same number of teeth or variety of teeth as (E) supposes--that doesn't justify the conclusion that these mammoths are smaller than others. If (E) were true, it would still be unclear why the recent discovery of teeth shows the mammoth's on the Artic island to be smaller than others.