Q3 - About two million years ago

[sumukh09]

Can someone go over this question, please? Wrong answer analysis and the like? Thanks

Btw this is question number 3

[ohthatpatrick]

I found this pretty tough to visualize at first and had to read it several times.

Essentially, 2 million years ago a lake formed. The lake existed for about half a million years. So the lake stopped existing 1.5 million years ago. We found some human bones at the bottom of the dried up lake.

Thus, the author concludes, humans were living near that lake during the timeframe the lake existed, between 1.5 - 2 million years ago.

Do you see any gaps there?

When arguments deal with fossil evidence / archeological findings / old specimens, etc. there's almost always some assumption of "where we found it = where it came from".

Here the author is assuming that since we found these human bones at the bottom of a lake that existed 1.5 - 2 mya, then humans existed near this lake 1.5 - 2 mya.

Let's look at answer choices and just keep judging their relevance to the premise/conclusion.

(A) This is extreme, which is dangerous for Necessary Assumption. Does the author need to assume there were NO other lakes in the same area? If there WERE other lakes in that area would it hurt his conclusion? Nope.

(B) This would somewhat strengthen the author's hypothesis that humans lived near this lake when it existed. But does the author HAVE to assume the lake contained fish? If the lake did NOT contain fish, would that hurt the author's argument? No, he was never saying that the lake provided sustenance. He's only saying that since we found human bones in the lake, we know humans lived in the area when the lake existed.

(C) This deals with whether there are any human bones in the lava. Does the author need to assume anything about what was or wasn't in the lava? Not really. If we negate this answer, it's saying that there WERE human bones in the lava. That would just suggest that humans were living in this area 2 million years ago when the lava came. That doesn't hurt the conclusion. If anything, it may help it.

(D) Do the author have to assume that the human bones found in the lake were a result of drowning? No. Cause of death is out of scope. If the lake were too shallow to drown in, that wouldn't kill the author's conclusion.

(E) Does the author have to assume that the bones were in the lake prior to the lake drying up? When did the lake dry up? 1.5 million years ago. The author thinks that finding human bones in the lake is evidence that humans lived around there between 1.5-2 mya. So, yes, the author is assuming that these human bones were in the lake during that period.

If we negate (E), it's saying that the bones weren't at the bottom of the lake until AFTER the lake dried up. That means that the bones weren't in the lake during the 1.5 - 2 mya time period of the conclusion. So negating (E) would severely hurt the argument, telling us that this is the correct answer.

To simplify this argument in retrospect, we're getting this:
Prem: human bones found at the bottom of a lake that existed between 1.5 - 2 mya
Conc: humans lived around the lake during that time period.

Assumption: the bones existed during that time period.

Hope this helps. Let me know if you still have questions.

[AshleyT786]

Why is E a problem when negated? Is it saying that the bones may have been deposited there AFTER the lake dried up?