allenh wrote:Orangutan, a species of Pondigae, is an ape with long reddish hair that comes from Borneo and Sumatra and is able to walk upright in trees by using two arms to keep balance. Since the ape, human, and other primates have the same ancestors called Ampipithecus, we can reach the conclusion that, instead of the past hypothesis that humans learned how to walk upright in grassland, they were able to walk upright long before they arrived in grassland.

Which of the following, if true, most seriously weakens the argument above?

A. Except for orangutan and human, other primates cannot walk upright in trees until today.

B. Walking upright in trees needs outstanding balance ability and also needs forest as habitat and settlement for both orangutan and human

C.Grassland is not an absolutely treeless environment so that primates can settle on trees in grassland

D. The walking speed of human is faster than that of other primates except the orangutan

E. There is no existing evidence to demonstrate that humans are able to walk upright in trees.



I picked E , cuz I believe that the conclusion is the last sentence, "humans learned how to walk upright in grassland......before they arrived in grassland". Therefore, the best way to weaken the argument is to reject the fact.

OA:C

However, the OA suggests a counter-example. The counter example used here, I think, does not work because the stimulus did not mention all the primates can walk in the tree but simply suggests that humans can walk in trees...
I am a bit confused and I would really appreciate some help, thank you!!

Hi, lets look at the argument here: all the premises and the conclusion

Orangutan, a species of Pondigae, is an ape with long reddish hair that comes from Borneo and Sumatra and is able to walk upright in trees by using two arms to keep balance. Since the ape, human, and other primates have the same ancestors called Ampipithecus, we can reach the conclusion that, instead of the past hypothesis that humans learned how to walk upright in grassland, they were able to walk upright long before they arrived in grassland.

Orangutan, a type of ape is able to walk upright on trees keeping two arms in balance ---> Now since, Ampipithecus is the ancestor of apes, humans and other primates ----> conclusion: humans had learned to walk upright much before they arrived on grassland.

Our aim is to weaken this conclusion, how do we do that?
We need to prove that humans may have learned to walk much much later than their arrival on grassland as well and the possibility of orangutans learning this only recently (maybe in the past 90-100 years). So grassland NEED NOT be the criteria for walking upright. So basically we need something that counters this timeline of events and my suggestions are hypothetical events that can weaken the conclusion:
Timeline:
Orangutan can walk upright ----> So humans evolved from the ancestor shared by orangutans -----> They could walk upright before their arrival on grassland.

A. Except for orangutan and human, other primates cannot walk upright in trees until today - Alright, so O and H can walk upright in trees and other primates can't - does this suggest WHEN H might have picked this trait of walking upright? No.

B. Walking upright in trees needs outstanding balance ability and also needs forest as habitat and settlement for both orangutan and human. Our discussion isn't about HOW to walk upright in trees.


C.Grassland is not an absolutely treeless environment so that primates can settle on trees in grassland - Okay, now lets break this up and see what its saying: Grassland HAS trees ---> So it very likely or possible that primates (group includes: O, H and other primates) still lived on trees, even after their arrival on grassland. This definitely DOES NOT SUGGEST WHEN H picked up the trait of walking upright, BUT MOST DEFINITELY KILLS the assumption that H might have learned it BEFORE arrival to Grassland or EVEN shortly after arriving on grassland as they are as equally likely to have lived on trees. Maybe they developed this trait later on. When they developed isn't important. Whats important is the arg's claim fails.


D. The walking speed of human is faster than that of other primates except the orangutan - Speed isn't the topic of discussion here.

E. There is no existing evidence to demonstrate that humans are able to walk upright in trees. - Nothing here to demonstrate whether H can walk upright in trees. What if there was, if you could show humans can walk upright in trees - Does it point out the timeline to us as to when H picked up this trait?? No. Hence E is eliminated.

So Answer = C

What is the source of this question (just asking for the benefit of all readers )

I hope my explanation is right and helps you come out of the confusion

Cheers
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