#6 - A primate jawbone found in Namibia in southern Africa

[Administrator]

Complete Question Explanation

Assumption. The correct answer choice is (B)

The stimulus reports that what is probably a jawbone of a forest-dwelling primate has been found in Namibia, and concludes that the dry, treeless expanses in that area must have replaced forests.

The argument leaps from what is probable to what is certain, and excludes a number of possibilities. Perhaps the jawbone of the ape was transported to the area in some fashion. Perhaps there was an intervening type of landscape. Since you are asked to identify an assumption, you should look for either the leap from the probable to the certain or for one of the many ignored possibilities.

Answer choice (A): The argument does not need to assume anything about modern apes, since the argument concerns apes 10 to 15 million years ago.

Answer choice (B): This is the correct answer choice. The certainty that the forest-dwelling ape lived in Namibia makes it more likely that Namibia was forested, and if the ape had not lived in Namibia, the ape's fossil might not help prove that Namibia was once forested. For the jawbone to be evidence of the ecology at one time in Namibia, it is necessary that the relevant animal be somehow associated with Namibia.

Answer choice (C): The argument states that the fossil is 10 to 15 million years old, but the argument does not need to assume that no older fossils exist. Actually, if older fossils of apes existed in Namibia, that could improve the argument.

Answer choice (D): Since the researchers deliver their data only concerning ancient apes, similarities to modern apes are irrelevant.

Answer choice (E): The stimulus does not concern whether the apes themselves triggered the collapse of the forest ecology. This choice confuses the issue, and is incorrect.

[safia.sayedi]

Hi there,

i am still confused about this question - i understand why the correct answer is correct, but isn't it already mentioned in the stimulus that the jawbone was found in Namibia ? usually necessary assumptions are unstated premises..so i don't understand how the correct answer is something that has already been stated in the stimulus....

[Jeff Wren]

Hi safia,

This is a great example of how important it is to read everything on the LSAT very carefully because every word matters.

The stimulus states that the jawbone of a primate was found in Namibia. This does not necessarily mean that the primate itself actually lived in Namibia. For example, perhaps the jawbone was originally found in a completely different region and was carried back to Namibia to be used as a tool or decorative art, etc..

Answer B states that the ape itself lived in/near Namibia. In other words, Answer B is making the assumption that, since the jawbone was found in Namibia, that means that the ape that the jawbone belonged to must have lived in/near Namibia as well. While this assumption might seem obvious, it does need to be made for the argument. Again, if the ape itself didn't ever live in/near Namibia and the jawbone got there some other way, then the argument falls apart.