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#26 - Fossilized teeth of an extinct species of herbivorous
Posted: Fri Jan 21, 2011 12:00 am
by Administrator
Lesson 5, Page 5-4, Question 5
Posted: Tue Jan 05, 2016 7:47 pm
by Blueballoon5%
Although I got the right answer, I found the stimulus to be confusing. The student center states that the author assumes this conditional statement: "no phytoliths --> not part of diet." How did the author indicate this assumption (although it does make sense). But in a purely mechanical sense (with sufficient/necessary indicators), the conclusion seems to have two necessary indicators: "Since
only phytoliths from certain species of plants are found on the teeth, the apes' diet
must have consisted only of those plants."
Please help
Re: Lesson 5, Page 5-4, Question 5
Posted: Wed Jan 06, 2016 6:49 pm
by Robert Carroll
Blue,
"Since" indicates a premise. Part of that sentence is evidence for the conclusion at the end. Thus:
found on teeth
certain plant species
And the conclusion:
apes' diet
certain plant species
This conclusion would follow if we could add the conditional:
apes' diet
found on teeth
And indeed, answer choice (B) says that.
An assumption is not something the author makes explicitly. Thus, there is no place to look in the stimulus for it. It's that the author's argument makes no sense
unless the author is tacitly assuming the assumption we're looking for. The conclusion does not follow from the premise. The author didn't make a bad argument for no good reason. Thus, the author assumed the connection in answer choice (B), but did not explicitly state it.
Robert Carroll
Re: #26 - Fossilized teeth of an extinct species of herbivor
Posted: Thu Aug 04, 2016 11:14 am
by lexigibbs
I dont understand how the answer for this cannot be C. The explanation of why it isnt C doesnt click in my head. The passage states " since ONLY phytoliths from certain species of plants are found on the teeth, the apes' diet MUST have consisted ONLY of those plants." C states that each toothed examined had phytoliths of the SAME plant species, this connects with saying that ONLY phytoliths from certain species of plants are found on the teeth. Answer B says plants of every type left phytoliths but it says ONLY phytoliths from certain species...
I dont understand
Thank you!
Lexi Gibbs
Re: #26 - Fossilized teeth of an extinct species of herbivor
Posted: Thu Aug 04, 2016 5:57 pm
by Shannon Parker
Hi Lexi,
Answer Choice (C) only states that the phytoliths were found on every tooth examined, it does not address the existence of other plants in the herbivore's diet. As the explanation above demonstrates, the only answer choice that addresses the complete diet of the herbivore, "every type eaten." By providing the link between the whole diet and phytoliths left on the teeth, it supports the conclusion.
Hope this helps clear it up some.
~Shannon
Re: #26 - Fossilized teeth of an extinct species of herbivor
Posted: Fri Aug 05, 2016 5:08 pm
by Adam Tyson
I'll add my two cents here on what's wrong with answer C, and it's the difference between "that's all we found" and "we found all of that everywhere."
Let's forget about phytoliths and ancient apes - let's make this more personal. Let's talk about college freshmen. First time away from home, mom not there to cook them a good dinner, the cafeteria isn't cool, so what do they do? They live on mostly pizza and ramen noodles and snickers and monster. Mostly, but not exclusively.
Now, you're a scientist, and you uncover the remains of some college freshmen, and you study their teeth to find out what they ate. You find pizza, and snickers, and ramen, and monster, and nothing else, so you conclude that that's all they ever ate. What's wrong with this conclusion? It ignores the possibility that they brushed their teeth and removed all traces of something - maybe they had mac and cheese at the cafeteria the day before they died, or maybe they went home and had some green beans and baked chicken with Mom and Dad the prior weekend. I suppose it's possible they drank some beer, but probably not, since they were freshman and underage and of course they would not do that. But maybe. Maybe they ate something, maybe some apples, that miraculously left no trace in their teeth - it all went down the hatch without leaving any evidence that it was ever there.
So there is the problem - just because all we found was the junk food doesn't prove that all they ate was the junk food.
So what about C? Does it matter that they found pizza on some teeth, and snickers on other teeth, and ramen on some other teeth, but not every tooth had each thing on it? Pizza on the molar, snickers on the bicuspid, monster on the tonsils, etc. - is that a problem? Not at all - they never said that the food they ate left exactly the same stuff on each and every tooth. It's about the cumulative findings - we found a total of four foods on the teeth, not necessarily four things on each tooth.
Chew on that explanation a while and see if you can digest it!
Now I feel like I need to brush my teeth. Or eat a snickers. See ya!
Re: #26 - Fossilized teeth of an extinct species of herbivorous
Posted: Thu Mar 09, 2023 10:13 am
by nivernova
how can we negate C)?
Re: #26 - Fossilized teeth of an extinct species of herbivorous
Posted: Thu Mar 09, 2023 1:01 pm
by Adam Tyson
There are a lot of options for doing that, nivernova. Here are a few:
"Not every tooth examined had phytoliths of the same plant species on it as each of the other teeth."
"Different teeth had different phytoliths."
"Some teeth had phytoliths that were not on some other teeth."
"It's not true that each of the teeth examined had phytoliths of the same plant species on it as all the other teeth."
Negation isn't necessarily a mechanical process with only one right answer. It's just about denying the truth of the answer choice. The Assumption is something that the author must believe is true. Negation is just a way of saying "but what if this is not true?" When you do that to the correct answer, the argument falls apart, because the author needed it to be true. When you negate the wrong answers, those negations won't matter, because the author didn't need them to be true.