The golden toad of Costa Rica, whose beauty and rarity inspired an unusual degree of human interest from a public generally unconcerned about amphibians, may nevertheless have been driven to extinction by human activity. In the United States, a public relations campaign raised money to protect the toad’s habitat in Costa Rica, establishing the Monteverde Cloud Forest Preserve in 1972. However, setting aside habitat was not enough to save the species. The toad's demise in the late 1980s was a harbinger of further species extinction in Costa Rica. Since that time, another twenty of the fifty species of frogs and toads known to once inhabit a 30 square kilometer area near Monteverde have disappeared.

Between one third and one half of the world’s amphibian species—including frogs, toads, and salamanders—have declined or disappeared. Scientists hypothesize that the more subtle effects of human activities on the world's ecosystems, such as the accretion of pollutants, the decrease in atmospheric ozone, and changing weather patterns due to global warming, are beginning to take their toll. Perhaps amphibians - whose permeable skin makes them unusually sensitive to environmental changes - are the biological harbingers of the natural world, giving humans early notification of the deterioration, if not destruction, of our ecosystem.

It can be inferred from the discussion of amphibians that
(A) only thirty species of frogs and toads remain in Costa Rica
(B) relatively few non-amphibious animals have permeable skin
(C) most have either already become extinct or are in danger of extinction
(D) humans do not usually take signals of environmental deterioration seriously
(E) the extinction of so many amphibian species supports the contention that humans are responsible for the situation

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without mentioning the supposed correct answer, i would appreciate some help on qualifying E.

E - the 1st para states that
The golden toad of Costa Rica, whose beauty and rarity inspired an unusual degree of human interest from a public generally unconcerned about amphibians, may nevertheless have been driven to extinction by human activity.

the 2nd para states that
Between one third and one half of the world’s amphibian species—including frogs, toads, and salamanders—have declined or disappeared. Scientists hypothesize that the more subtle effects of human activities on the world's ecosystems, such as the accretion of pollutants, the decrease in atmospheric ozone, and changing weather patterns due to global warming, are beginning to take their toll. Perhaps amphibians - whose permeable skin makes them unusually sensitive to environmental changes - are the biological harbingers of the natural world,...

from reading the above, doesn't the the extinction support the contention that humans are responsible?

_________________
Ashish
Share not just why the right answer is right, but also why the wrong answers are not.

Ashish, before we proceed, it is important to obtain the correct answer for future students who will read this thread. Please provide, thanks!

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Jamie Nelson
ManhattanGMAT Instructor

B is the correct answer, as per the CAT explanation.

_________________
Ashish
Share not just why the right answer is right, but also why the wrong answers are not.

i had another inference question for the same RC.

The passage implies that:
a. many amphibians are not considered particularly beautiful
b. the Monteverde Cloud Forest Preserve was not large enough to protect the golden toad
c. only Costa Rican amphibians living near Monteverde have disappeared since the 1980s
d. if amphibians did not have permeable skin, then they could not act as biological harbingers
e. scientists believe that the decline of amphibian populations reflects a threat to human populations

i am confused between a. and d. this is how i synthesized both choices --

explanation for d.

the sentence in the 2nd para, Perhaps amphibians - whose permeable skin makes them unusually sensitive to environmental changes, means
-the permeable skin makes amphibians unusually sensitive to environmental changes
-if it were not for the permeable skin, then the amphibians would not be more sensitive to environmental changes than other animals are
-and thus could not possibly act as biological harbingers
-ancillary inference: most other animals besides amphibians are not as sensitive to environmental changes

explanation for a.

the 1st sentence of the passage, The golden toad of Costa Rica, whose beauty and rarity inspired an unusual degree of human interest from a public generally unconcerned about amphibians, means
-the public don't normally care about amphibians (unconcerned)
-but the the golden toad was so beautiful and rare that it generated an unusual level of human interest
-meaning amphibians other than the golden toad are not as beautiful and rare for people to become interested in them

i feel both are equally good. could you please clarify?

a similar, BUT not the same, question is discussed here as well:
post49599.html

_________________
Ashish
Share not just why the right answer is right, but also why the wrong answers are not.

Whenever we draw an inference we have to stick very, very close to what is stated in the passage and not go too far with what we infer.

Here's the part of the passage I find relevant to eliminating E:

Between one third and one half of the world’s amphibian species—including frogs, toads, and salamanders—have declined or disappeared. Scientists hypothesize that the more subtle effects of human activities on the world's ecosystems, such as the accretion of pollutants, the decrease in atmospheric ozone, and changing weather patterns due to global warming, are beginning to take their toll.

What we find out here is that a lot of the amphibians have declined or disappeared . . . but we don't know WHEN this happened. It could have happened over the last several million years, when human activity could not have really impacted the ecosystem. Notice also the word "beginning" in the last paragraph . . . this implies that going forward humans may be responsible for amphibian decline, but does not give us enough information to conclude that we have been responsible for the decline all along. This is a very tricky distinction.

_________________
Jamie Nelson
ManhattanGMAT Instructor

Ashish, for your second question, the OA is A, correct?

I think D once again takes things too far to be an inference . . . if the toad did NOT have permeable skin they could NOT be biological harbingers. We don't know this. Maybe amphibians have some other characteristic that would still allow them to serve as biological harbingers. Always beware of extreme wording on inference questions . . . it's just too easy to disprove extreme wording.

_________________
Jamie Nelson
ManhattanGMAT Instructor

absolutely, Jamie.
E is very subtle here. but again, it says:
supports the contention that humans are responsible

this is somewhat like a CR argument, where the conclusion/contention (because scientists hypothesize) is humans are responsible for the extinction and we need to find a strengthener that merely makes this conclusion, if not certain, more likely.

the strengthener is in the passage that states
scientists hypothesize: human actions --> env damage
env damage --> affects permeable skin of amphibians
amphibian skin gauges --> deterioration of env

SO, yeah -- it's quite possible humans ARE responsible.

the 1st para gives a background with the example of the forest preserve and how amphibian species -- toads and frogs -- have disappeared. then in 2nd para, it tries to analyze and thus, puts forth the scientists' theory.

the beginning merely implies that the problem has gotten worse enough to attract attention -- a wake up call if you will. i don't think it would mean that now we've become responsible.

simply put -- all E is asking that if amphibians are declining, then can one read the passage and infer whether humans have a hand anywhere? E also doesn't seem too extreme/strong for elimination.

_________________
Ashish
Share not just why the right answer is right, but also why the wrong answers are not.

yes, A is the OA. sorry, i missed this time!

'm partly convinced on this one :)
looking at the excerpt again:
Perhaps amphibians - whose permeable skin makes them unusually sensitive to environmental changes - are the biological harbingers of the natural world
-so we no for sure that the permeable skin is what makes (or one of the many possible things that make?) amphibians unusually sensitive to environmental changes. do you agree?
-and thus, the amphibians act as biological harbingers

SO, this means that it is the permeability of the skin --> that makes amphi sensitive to env changes --> and they act as precursors to natural world, etc.
and if, the permeable skin was removed, they possibly couldn't do the above i.e. act as harbingers?

_________________
Ashish
Share not just why the right answer is right, but also why the wrong answers are not.

I would agree that the permeable skin is a quality that enables the amphibians to act as harbingers. However, that is not the only possible quality that would enable them to act as harbingers; even if they did not have the permeable skin they may have some other feature that would allow them to act as harbingers.

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Jamie Nelson
ManhattanGMAT Instructor

Instructors kindly clear this!

It can be inferred from the discussion of amphibians that
(A) only thirty species of frogs and toads remain in Costa Rica
(B) relatively few non-amphibious animals have permeable skin
(C) most have either already become extinct or are in danger of extinction
(D) humans do not usually take signals of environmental deterioration seriously
(E) the extinction of so many amphibian species supports the contention that humans are responsible for the situation

How can "B" be the correct answer for this. No where in the passage non-amphibious animals. How can we simply assume about their skin?

Should C be the correct answer?

manisjce, please read the first half of this thread--it has to do with your question. Then let us know if you need further help.

_________________
Jamie Nelson
ManhattanGMAT Instructor