Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pressure. This likelihood...
GMAT Critical Reasoning : (CR) Questions
Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pressure. This likelihood also holds for westernized Black Africans when compared to White Africans. Researchers have hypothesized that this predisposition in westernized Blacks may reflect an interaction between western high-salt diets and genes that adapted to an environmental scarcity of salt.
Which of the following statements about present-day, westernized Black Africans, if true, would most tend to confirm the researchers' hypothesis?
Passage Analysis:
| Text from Passage | Analysis |
| Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pressure. |
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| This likelihood also holds for westernized Black Africans when compared to White Africans. |
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| Researchers have hypothesized that this predisposition in westernized Blacks may reflect an interaction between western high-salt diets and genes that adapted to an environmental scarcity of salt. |
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Argument Flow:
The passage starts with a health fact (Black Americans have twice the high blood pressure risk), then shows this same pattern exists elsewhere (westernized Black Africans vs White Africans), and finally presents researchers' theory about why this happens (genes + diet interaction).
Main Conclusion:
Researchers believe that westernized Blacks' higher blood pressure rates come from an interaction between Western high-salt diets and genes that evolved to handle salt scarcity.
Logical Structure:
This isn't really a complete argument - it's more like setting up a hypothesis that needs testing. The evidence (same pattern in America and Africa) supports the idea that something systematic is going on, and the researchers' gene-diet theory attempts to explain what that something might be.
Prethinking:
Question type:
Strengthen - We need to find information that would make the researchers' hypothesis more believable or credible
Precision of Claims
The hypothesis claims that westernized Blacks have genes adapted to low-salt environments that react poorly to high-salt Western diets, causing higher blood pressure rates
Strategy
To strengthen this hypothesis, we need evidence that supports the gene-diet interaction theory. We should look for information that shows: 1) westernized Black Africans actually do consume high-salt Western diets, 2) their ancestors lived in low-salt environments, 3) non-westernized Black Africans don't show the same high blood pressure rates, or 4) the genetic adaptation to salt scarcity is real and measurable
This perfectly strengthens the hypothesis. If Black Africans descended from peoples in Senegal and Gambia (where salt was historically available) have low blood pressure, this supports the idea that genetic adaptation to salt scarcity is the key factor. These populations wouldn't have developed the problematic genes since they never faced salt scarcity, so they don't experience elevated blood pressure even with Western diets. This creates the exact contrast the hypothesis predicts.
This doesn't help the hypothesis at all. Simply stating that high salt consumption in Africa is a health problem doesn't tell us anything about the genetic component or why westernized Blacks specifically are more susceptible. This could apply to any population consuming too much salt.
This is irrelevant to the hypothesis. What White Africans do about their salt consumption doesn't provide any evidence about whether Black Africans have genes adapted to salt scarcity. The researchers' theory is specifically about genetic differences, not behavioral responses to health concerns.
This seems supportive at first glance, but it actually doesn't strengthen the hypothesis about westernized Blacks. The Yoruba's low blood pressure could be explained by their current low-salt traditional diet rather than proving anything about genetic adaptation. We need information about how populations react to Western high-salt diets, not traditional low-salt diets.
This directly contradicts what would strengthen the hypothesis. If there are no significant differences in salt metabolism between populations with different historical salt access, then the genetic adaptation theory becomes much less plausible. This would weaken rather than strengthen the researchers' hypothesis.