tribui
MartyMurray
B. Dental remains of some of the early humans without the grooves have been found at places where the available grass could have been suitable for tooth picking during their lifetimes.
The fact that grass suitable for tooth picking may have existed where early humans' teeth did not have the grooves doesn't tell us whether the grooves were caused by use of grass for cleaning teeth. After all, it's not the case that all early humans must have used the available resources in the same way. It's likely that some early humans didn't use grass to clean their teeth.
Eliminate.
MartyMurray, I would think that for an "evaluate" question, the answer choice does not have to strongly prove or disprove the conclusion, so in this case it only needs to affect ie. strengthen or weaken the hypothesis.
For B: - if that info is true, it would weaken the hypothesis a little since there's remains without grooves where there's grass available, so maybe the grass does not cause the grooves. Again, there could be many other factors, but all else being the same, shouldn't it weaken the hypothesis?
- If the info is false ie. negation, that would strengthen the hypothesis a little, as you already explained.
I can see the same pattern for E. So in this case I'm struggling to see why E is better than B at all. Can someone help?
Notice that the conclusion of the argument is about the cause of the grooves in teeth in which the grooves are present. Some people say that cause of the grooves is not tooth picking, but this one anthropologist has proposed that picking with abrasive grass stalks caused the grooves.
So, it doesn't really weaken the argument to say, "Dental remains of some of the early humans without the grooves have been found at places where the available grass could have been suitable for tooth picking during their lifetimes," because it's fairly clear that picking with abrasive grass would cause grooves. After all, picking one's teeth with something abrasive would result in tooth wear.
So, the fact that some abrasive grass was present where the teeth do not have grooves shows only that those people did not pick their teeth with grass, not that picking with grass is not the cause of the grooves. Right?
Here's a similar example.
Let's say that we found a tree that had been cut down by an animal. We see beavers in the same area. So, we hypothesize that a beaver cut down the tree. The fact that other trees are still standing where beavers are present would not mean that the tree that had been cut down had not been cut down by a beaver. It would just mean that the beaver had not cut down every tree.
So, this is a similar situation. We don't need all teeth where grass was present to have grooves in order to conclude that grass caused the grooves in teeth that do have grooves.
Thus, the answer to (B) neither weakens nor strengthens the argument.