Fossilized teeth of an extinct

Answer choices

1. A

   Too Strong: none3% picked this

   None of the plant species that left phytoliths on the apes’ teeth has

   Would it matter to the author's argument if at least one of the plant species that left phytoliths no longer exists? Of course not. When the author sees that phytoliths from plants A, B, and C are found on the apes' fossilized teeth, she assumes that the apes ate plants A, B, and C, when the ape was still alive. But since this ape has gone extinct, it may have lived a long time ago and so it's perfectly plausible that some of the plants the ape ate have also gone extinct in the meantime.

   3%
2. B

   Correct75% picked this

   Plants of every type eaten by the apes left phytoliths on

   Why this is right

   Conditionally, this would look like this: If ape ate plant ? phytolith of plant X of type X would be left on their teeth The contrapositive of this rule will feel a lot like the author's reasoning move: If phytolith of plant X ? then ape didn't isn't on their teeth eat plant X Alternatively, we could assess that this answer works by negating it and seeing that it turns into an objection. NEGATION: some of the plants eaten by the apes did not leave phytoliths on their teeth. That would be a big objection to the author's reasoning. That would allow us to argue that the apes' diet included some plants that were found on their teeth.

   Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

   75%
3. C

   Too Strong: each / same / all17% picked this

   Each of the teeth examined had phytoliths of the same plant species on it as

   This is an extreme idea that every single tooth had the full suite of phytoliths. The author doesn't need that to be true. Say that the only phytoliths we found were from plants A, B, and C (so the author assumes that the apes only ate plants A, B, and C). Does it need to be true that on the apes' molars, there was A/B/C, and on the apes' incisors there was A/B/C? Or would the argument still work if we found A/B on the molars and C on the incisors? It would work either way. In either case, the author could surmise that the ape was definitely eating A, B, and C. (it might chew different plants with different parts of its mouth, and so it might not be that all plants show up on all teeth). Since the negation doesn't weaken, it can't be a necessary assumptino.

   17%
4. D

   Out of Scope: other extinct apes3% picked this

   Phytoliths have also been found on the fossilized teeth of apes of

   This argument is only about one extinct species of herbivorous great ape. The author doesn't need to assume anything about any other species on Earth.

   3%
5. E

   Too Strong1% picked this

   Most species of great ape alive today have diets that consist of a fairly narrow

   Too Strong: most Out of Scope: apes today This argument is only about one extinct species of herbivorous great ape. The author doesn't need to assume anything about modern apes. And the threshold of at least 51% is not important to this (or almost any) argument. The word "most" is wrong 99% of the time that we see it on Necessary Assumption.

   1%