Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur. Secretions of these millipedes have been...
GMAT Critical Reasoning : (CR) Questions
Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur. Secretions of these millipedes have been shown to contain two chemicals that are potent mosquito repellents, and mosquitoes carry parasites that debilitate the capuchins. The rubbing behavior is rare except during the rainy season, when mosquito populations are at their peak. Therefore monkeys probably rub millipedes into their fur only because doing so helps protect them against mosquitoes.
Which of the following would be most useful to determine in order to evaluate the argument?
Passage Analysis:
| Text from Passage | Analysis |
| Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur. |
|
| Secretions of these millipedes have been shown to contain two chemicals that are potent mosquito repellents, and mosquitoes carry parasites that debilitate the capuchins. |
|
| The rubbing behavior is rare except during the rainy season, when mosquito populations are at their peak. |
|
| Therefore monkeys probably rub millipedes into their fur only because doing so helps protect them against mosquitoes. |
|
Argument Flow:
The argument starts with an observed behavior, then provides scientific evidence about why this behavior could be beneficial, adds timing evidence that supports this theory, and concludes that mosquito protection must be the sole reason for the behavior.
Main Conclusion:
Capuchin monkeys rub millipedes into their fur only because it protects them from mosquitoes.
Logical Structure:
The author uses a combination of chemical evidence (millipedes repel mosquitoes) and behavioral timing evidence (happens most during mosquito season) to support the claim that mosquito protection is the exclusive reason for this behavior. However, the conclusion assumes this is the 'only' reason without ruling out other possible benefits.
Prethinking:
Question type:
Evaluate - We need to find information that would help us determine whether the conclusion is valid. This means looking for assumptions the argument makes that we could test.
Precision of Claims
The argument makes specific claims about frequency (behavior is rare except during rainy season), causation (monkeys rub millipedes ONLY because of mosquito protection), and effectiveness (chemicals are potent repellents).
Strategy
Since this is an evaluate question, we need to identify the key assumptions the argument makes and think of scenarios that would either strengthen or weaken the conclusion when taken to extremes. The conclusion claims mosquito protection is the ONLY reason for this behavior. We should think about what information would help us test whether there might be other reasons or whether the mosquito protection explanation is actually correct.
Whether the two chemicals provide protection for millipedes against their predators. This focuses on how the chemicals benefit the millipedes themselves, which doesn't help us evaluate whether mosquito protection is the only reason capuchins use them. The millipedes' own survival strategies are irrelevant to understanding the monkeys' behavior.
Whether this type of millipede is found in other parts of the world. The geographic distribution of millipedes doesn't help us determine if mosquito protection is the exclusive reason for the rubbing behavior. We need information about the relationship between the behavior and its supposed cause, not about where millipedes live.
Whether other animals rub insects into their fur. While this might provide some context about animal behavior patterns, it doesn't specifically help us evaluate whether capuchins use millipedes only for mosquito protection. Other animals' behaviors don't directly test our argument's causal claim.
Whether millipedes are only readily available during rainy season. This directly tests a key assumption in the argument. If millipedes are only available when mosquitoes are abundant, then the timing correlation could be explained by availability rather than intentional mosquito protection. If millipedes are available year-round but monkeys still choose to use them primarily during mosquito season, this would strongly support the mosquito protection theory. This information is crucial for evaluating whether the behavioral timing proves the argument's conclusion.
Whether other accessible insects contain mosquito-repelling chemicals. While interesting, this doesn't directly help evaluate the current argument about millipede use. Even if other insects have similar properties, this doesn't tell us whether mosquito protection is the only reason for the specific millipede-rubbing behavior we're analyzing.