Self-study
Dietary researcher: A recent study reports that laboratory animals that were fed reduced-calorie diets lived longer than laboratory animals whose caloric intake was not reduced. ██ █████████ ████ ███████ ███ ██████████ ███████████████ ██████ ██ ███ ██████ ████ █████ ██████████ ████ █████ ███ ███████ ██ █████████ ████████ ████ ██████████ ██ ███ ██████████ ██████████ ███████ ████ ██ ███ ████ ████ ████ ███████ ██ █████ ███████ █████████ █████ █████ ██ █████ ██████ █ ███████ ████ ███████████ ███████████ █████ █████ ██████ ██████ █████ ███████ ██████ ████ ██ ████████ ███████ ██████ ███ ██████████ █████ ██████ ████ ██████
Summarize Argument
The researcher concludes the study does not support recommending North Americans eat fewer calories to extend their lives. Why not? Because unnaturally calorific laboratory diets are the reason a reduced-calorie diet increased longevity in the study.
Notable Assumptions
The researcher assumes that North Americans’ diets are more in line with their natural calorie intake than the diets of laboratory animals. Furthermore, she assumes the animals studied had a pre-diet calorie intake typical for laboratory animals.
17.
Which one of the following, ██ █████ █████ ████ ██████ ███ ███████ ████████████ █████████
a
North Americans, on ████████ ███████ █ ██████ ██████ ██ ████████ ████ ███ ███████ ██████ ██ ████████ ███ █ █████ █████
This challenges the assumption that the laboratory animals’ unnaturally high calorie intake makes them dissimilar from North Americans. If North Americans consume more calories than optimal, then they are similar to laboratory animals in that way, not different.
b
North Americans with █████████ ███████████ █████ █████████ ████ █ ███████ ████ ██████████ ████ █████ █████████ ████ ████████ ███████████ ██████
This relationship between fat intake and life expectancy does not imply that the study’s findings can be correctly extended to North Americans. The researcher does not say fat intake was examined separately from calorie intake.
c
Not all scientific ███████ ████ ████ █████████ ████████████ ███ █████ ██████ ███ █████ ██ ███████ ██ ██████████ ████████
This states that some studies with implications for human health do not involve laboratory animals, not that studies of laboratory animals must or usually have implications for human health.
d
Some North Americans ███ ██████ ███████████████ █████ ███ ███████████
This does not say North Americans who eat fewer calories are tend to live longer—it’s possible North Americans on normal diets are more likely to be long-lived than those on reduced-calorie diets.
e
There is a ██████ ███████████ ███████ ████ ███ █████████ ██ ████ ███████ ██ ████████
This does not specify which type of diet increases longevity or identify the species in question. This may support doctors making some dietary recommendation to increase longevity, but not the one described on the basis of the study.