Agricultural societies cannot exist without staple crops. Several food plants, such as kola and okra, are known to have been...
GMAT Critical Reasoning : (CR) Questions
Agricultural societies cannot exist without staple crops. Several food plants, such as kola and okra, are known to have been domesticated in western Africa, but they are all supplemental, not staple, foods. All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams. Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.
Which of the following is an assumption on which the argument depends?
Passage Analysis:
| Text from Passage | Analysis |
| Agricultural societies cannot exist without staple crops. |
|
| Several food plants, such as kola and okra, are known to have been domesticated in western Africa, but they are all supplemental, not staple, foods. |
|
| All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams. |
|
| Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there. |
|
Argument Flow:
The argument moves from a general rule (agricultural societies need staple crops) to specific facts about western Africa (they domesticated supplemental plants but got all staple crops from elsewhere) to reach a conclusion about what would help us date the earliest agricultural societies there.
Main Conclusion:
Discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.
Logical Structure:
The logic works like this: Since agricultural societies require staple crops (premise 1), and western Africa had no native staple crops but got them from elsewhere starting with rice and yams (premises 2&3), then finding when rice and yams arrived would tell us the earliest possible date for agricultural societies there (conclusion). The argument assumes that rice and yams were indeed the very first staple crops to arrive.
Prethinking:
Question type:
Assumption - We need to find what the argument must assume to be true for the conclusion to follow logically
Precision of Claims
The argument makes specific claims about timing (rice and yams were the first staple crops), necessity (agricultural societies cannot exist without staple crops), and scope (all recorded staple crops in western Africa were introduced from elsewhere)
Strategy
To find assumptions, we need to identify ways the conclusion could fall apart while keeping all the stated facts intact. The conclusion says that finding when rice and yams were introduced would establish the earliest date for agricultural societies. For this to work, we need to think about what gaps exist between the premises and conclusion that must be filled
This directly addresses a critical gap in the argument. The argument concludes that finding when rice and yams were introduced would establish the earliest date for agricultural societies. But what if western Africans had developed their own staple crops earlier and then stopped growing them once rice and yams arrived? If that happened, agricultural societies could have existed before rice and yams were introduced, completely undermining the conclusion. The argument must assume this scenario didn't occur - that there were no earlier staple crops that were later abandoned. This is a necessary assumption because without it, we cannot be confident that rice and yams truly mark the earliest possible date for agricultural societies.
This goes too far beyond what the argument needs to assume. The argument doesn't need to assume that no native plants could potentially serve as staple crops - it only needs to establish that rice and yams were the first staple crops actually used. Even if some native plants had the potential to be staples, as long as they weren't actually developed into staple crops before rice and yams arrived, the conclusion still holds. The argument is about what actually happened historically, not about theoretical agricultural possibilities.
This deals with agricultural societies outside of western Africa, but the argument's conclusion is specifically about western Africa. Whether rice and yams were staples elsewhere has no bearing on when agricultural societies could have first arisen in western Africa. The argument doesn't depend on the agricultural history of other regions - it only cares about the sequence of events within western Africa itself.
This comparison of growing conditions is irrelevant to the argument's logic. The argument is about timing - when different crops were introduced and what this tells us about the earliest possible date for agricultural societies. Whether kola and okra are better suited to local conditions than rice and yams doesn't affect the reasoning about when staple crops (and therefore agricultural societies) first became possible in the region.
While this might seem relevant since it establishes a timeline, it's not necessary for the argument. The argument already tells us that kola and okra are supplemental foods, not staples, so the exact timing of their domestication relative to rice and yams doesn't matter. Since agricultural societies require staple crops (not supplemental ones), knowing when kola and okra were domesticated doesn't change the conclusion about when agricultural societies could have first emerged.