PrepTest 110, Section 2, Question 17
Dietary researcher: A recent study reports that laboratory(84 more words not shown)
Which one of the following,(9 more words not shown)
- ANorth Americans, on(17 more words not shown)
- BNorth Americans with(16 more words not shown)
- CNot all scientific(15 more words not shown)
- DSome North Americans(6 more words not shown)
- EThere is a(11 more words not shown)
Reading the argument
A result in laboratory animals doesn't automatically tell us what will happen to people. So the researcher's objection is worth hearing. The animals were overeating, and cutting their calories merely brought them back to a normal intake and a normal lifespan. That would be a poor reason to expect an animal already eating the right amount to live longer by eating less.
But what if North Americans are overeating too? Someone with easy access to fast food might routinely eat more than they otherwise would.
Then the researcher's explanation could apply to people just as well as to the animals. If people are currently eating more than is optimal, reducing their intake might also remove something that is shortening their lives. We don't need the diet to stretch anyone's life beyond its natural limit; restoring a normal lifespan would still mean living longer than they otherwise would.
What we’re looking for
The question asks us to weaken the researcher's argument. I'd look for that parallel: North Americans, like the laboratory animals, are currently consuming more calories than is optimal. That would challenge the reason for dismissing the study's relevance to them.
Working the answers
- ACorrect
This supplies exactly the parallel we wanted. The researcher's explanation is that the animals benefited because they started above their optimal calorie intake. A says North Americans, on average, also start above the optimal intake for humans. That makes the animal study more relevant to the doctors' recommendation.
This doesn't prove that reducing calories will extend every North American's life. It does undermine the researcher's attempt to dismiss the recommendation on the ground that the animals were simply correcting excessive intake. Humans may have the same problem to correct.
- B
Both groups of people here are already eating low-calorie diets. The difference is how much fat those diets contain. That might matter for comparing the diets, but it doesn't address the researcher's objection to using the animal study as evidence for reducing calorie intake.
- C
Sure, animal studies aren't the source of every useful discovery about human health. But this argument concerns whether one particular animal study supports a particular recommendation. The existence of other kinds of research doesn't show that this study applies to North Americans.
- D
Living a long time while following a reduced-calorie diet doesn't show that the diet extended anyone's life. These people might have lived just as long without it. We need a reason to challenge the researcher's explanation of the study, and a few long-lived dieters don't tell us whether people share the animals' problem of excessive intake.
- E
A connection between diet and longevity in animals is already consistent with everything the researcher says. The researcher accepts that restricting these animals' food extended their lives; the dispute is over what that result supports about humans. Another general statement about animals doesn't bridge that gap.
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