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# Agricultural societies cannot exist without staple crops. Several food

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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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Evidence 1: Agricultural societies cannot exist without staple crops
Evidence 2: the recorded staple crops grown in western Africa were introduced from elsewhere
Evidence 3: Rice and yams were the first recorded staple crops.
Conclusion: If we discover when rice and yams rice and yams were introduced into western Africa we will be able to know when agricultural societies arose in Western Africa.

D and E are irrelevant. C is out of scope. Only A and B remain. If B is not true the argument is still valid. However A is necessary since if the had developped, then the agricultural period would have started before and the prediction of the author would be correct.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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The argument evaluation:
Agr societies cannot exits without SC (staple crops)
K and O plants are known to have been domesticated in WA, but they are all supplemental, not SC
All recorded SC grown in WA were introduced from else where at some unknown date, with R and Y.
=> Discovering R and Y in WA will find the earliest date at which Agr societies have arisen

The conclusion here lacks the gap between the Staple Crop, Rice, Yam, and Arg societies. Choice A fills this gap. If not:

People in western Africa DEVELOPED staple crops that they stopped cultivating once rice
and yams were introduced. => the agriculture societies will develop sooner than when the rice and yam were cultivated.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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Hi,

I can certainly try.

People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.

Here is A, with I think the 2 tricky bits in red.

It is sort of a double negative. So when you see something like that you need to take each section separately:

1) People in western Africa did not develop staple crops
- So people didn't do something

2) they stopped cultivating once rice and yams were introduced.

- This is what they didn't do

With this split it becomes clearer.

They didn't stop growing something else prior to rice and yams being introduced.

In the context of the question, this is certainly an assumption. I.e. if they were growing something prior to rice and yams they could still have been an agricultural society.

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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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?

A. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced
B. There are no plants native to western Africa that, if domesticated, could serve as staple food crops.
C. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa
D. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are
E. Kola and okra were domesticated in western Africa before rice and yams were introduced there.

after i finished the passage, My rethinking was : the conclusion "discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there" would not be true if Western Africa have another staple corps before getting the rice and rams. so my assumption was: Western Africa didn't plant other staple plants before receiving the Rice and Yams. but i couldn't find something similar to my rethinking among the answer choices. My problem was : the way they wrote answer A is very weird so i couldn't realize that "A" is the same as my rethinking.

Answer A : "People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced"
i couldn't understand this phrase "that they stopped cultivating"

Any advice to how can i understand unclear answers in future ?

thanks
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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Agricultural societies cannot exist without staple crops...................fact

Several food plants are known to have been domesticated in western Africa,butthey are all supplemental, not staple, foods.

All therecorded staple cropsgrown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams............so they are the primary ones

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?

A. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.............that portion is a bit confusing but note that this choice explains that there are no native staple crops in western Africa prior to rice and yams introduction.

B. There are no plants native to western Africa that, if domesticated, could serve as staple food crops..........One more strong contender. ...................I got stuck between options A and B. Opted for B but found amazing reasons from prashant's and Ron's explanations below.

(B) On negation this statement becomes:
There are SOME plants native to western Africa that, if domesticated, could serve as staple food crops.

Even if there were/are some plants that are staple crops and are native to Western Africa, we don’t know whether these staple crops were planted before the plantation of rice/yams by the agricultural societies, or after staple crops rice/yams were introduced in Western Africa. If it was the former case then it would weaken the conclusion and hence can be a valid assumption. If it is the latter case, then it’s not going to affect the conclusion anyway. Since we don’t know of this information, so this can’t be an assumption - since an assumption is something that must be true for the conclusion to be valid.

Ron: you can also kill B using the negation test.

if you negate B, you get:
There are plants native to western Africa that, if domesticated, could serve as staple food crops.

"ok, great!
but (according to the passage) no one has actually domesticated any of them, so i don't care." the argument is not affected at all. (remember that, when an actual assumption is negated, the argument should be completely destroyed/invalidated.)

C. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa..........we are only aware that they were introduced in western Africa from somewhere else. It does not have to be true that they were staple crops of that region.

D. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are........We dont have to assume this since it is ok even if they are a bit less suited in comparison.

E. Kola and okra were domesticated in western Africa before rice and yams were introduced there.............Does not matter since they are supplemental groups and not staple crops.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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It is always better to simplify the argument -

Premise 1 - Agricultural Societies --> Staple Crops
Premise 2 - Rice and yam --> First Staple Crops in Africa

Conclusion - Time when rice and yam were introduced --> Start of Agricultural Societies in W.Africa

Let us look at each of the answer options -

A - let us negate this answer option.
"people developed staple crops before rice and yam were introduced" - this statement weakens the conclusion. If this were indeed true, then it is entirely possible that agricultural societies developed before the time when rice and yam were introduced.

B - even if there are plants that could be domesticated to be staple crops, we do not know whether they were ever domesticated.
Negating this option does not weaken the argument.

C - Not relevant.
We are only concerned with what happened in Western Africa.

D - Does not mean that kola and rice are/were used as staple foods. This answer option, thus, has no impact on the argument.
(If they were indeed used as staple foods, this could weaken the argument).

E - "Domesticated" is not the same as "staple foods".
We are concerned with whether they were staple crops or not.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
nakib77 wrote:
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?

A. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.
B. There are no plants native to western Africa that, if domesticated, could serve as staple food crops.
C. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.
D. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.
E. Kola and okra were domesticated in western Africa before rice and yams were introduced there.

The fact: All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams.

The missing information: People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.

Conclusion:Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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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?

* For assumption questions, I like to find the Conclusion, then NEGATE the A/C to BREAK the Conclusion!
- Conclusion: discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

A. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.
- Rewrite: People in western Africa developed staple crops that they stopped cultivating once rice and yams were introduced.This means we discovered that rice and yams cannot determine the earliest date at which agri societies could have arisen

B. There are no plants native to western Africa that, if domesticated, could serve as staple food crops.
- Rewrite: There are plants native to western Africa that, if domesticated, could serve as staple food crops. Out of scope. Does not give us info to determine the earliest date agri societies could have arisen

C. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.
- Rewrite: Rice and yams were not grown as staple crops by the earliest agricultural societies outside of western Africa. Out of scope. Why do we care about agri societies OUTSIDE of western Africa?

D. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.
- Rewrite: Kola and okra are not better suited to growing conditions in western Africa than domesticated rice and yams are. Out of scope. Again, does not give us info to determine the earliest date agri societies could have arisen

E. Kola and okra were domesticated in western Africa before rice and yams were introduced there.
- Rewrite: Kola and okra were not domesticated in western Africa before rice and yams were introduced there. Out of scope. Kola and okra not our concern: they are not staple crops. So we don't care about them at all.

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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
Why is B incorrect? It says there were no plants native to Africa. So the people there didn't have a staple food source till then.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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ajtmatch wrote:
Why is B incorrect? It says there were no plants native to Africa. So the people there didn't have a staple food source till then.

The author of the passage concludes that "discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there." His/her evidence for this argument is that "all the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams."

So, we are looking for a statement that shows that the first staple crops are the same as the first recorded staple crops -- namely, rice and yams. Keeping this in mind, take another look at answer choice (B):
Quote:
There are no plants native to western Africa that, if domesticated, could serve as staple food crops.

This answer choice is telling us that in western Africa there are absolutely no plants that could possibly be used as staple food crops. If this were true, it would mean that the first staple food crop must have been introduced from somewhere else. This is looking pretty good for the author's argument, right?

There is just one problem: answer choice (B) is not required for the conclusion to be true. An assumption is a piece of evidence that must be true in order for the author's argument to hold -- so (B) is not an assumption.

The conclusion doesn't require the total absence native plants that could be staple food crops as described in (B). Even if there were plants native to western Africa that could become staple food crops, we'd still have no idea whether anyone ever domesticated them. And that's the real issue: Which plants were first domesticated for use as staple food crops? Could it have been a plant that wasn't in the records?

You could say that this statement strengthens the argument, but we are not looking for a strengthener -- we are looking for an assumption. (B) is out.

Contrast this with answer choice (A):
Quote:
(A) People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.

This statement provides the missing link between the first recorded staple crops and the first staple crops, because it precludes the possibility of unrecorded staple crops at an earlier time. Answer choice (A) must be true in order for the argument to hold, so it is the correct option.

I hope that helps!
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
For assumption questions, it's important to find the conclusion of the argument:

Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

• Agricultural societies need staple crops to survive.
• All the recorded staple crops grown in western Africa were introduced from elsewhere.
• Discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

It's hard to think of scenarios for this one before jumping to the choices so let's get straight into it.

Quote:
(A) People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.

This tells us that people in western Africa did not develop staple crops. What type of staple crops? Staple crops that they stopped cultivating once rice and yams were introduced.

If we negative this choice we get: People in western Africa developed staple crops that they stopped cultivating once rice and yams were introduced.
If they developed staple crops but stopped once rice and yams were introduced, then our conclusion is shattered! A is a good one.

Quote:
(B) There are no plants native to western Africa that, if domesticated, could serve as staple food crops.

This isn't a necessary assumption. What if there were native plants that simply weren't domesticated? B is out.

Quote:
(C) Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.

Out of scope. We're looking for a necessary assumption that would precede our conclusion.

Quote:
(D) Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.

We can quickly eliminate -- we're concerned with rice and yams, not kola and okra.

Quote:
(E) Kola and okra were domesticated in western Africa before rice and yams were introduced there.

We can quickly eliminate -- we're concerned with rice and yams, not kola and okra.

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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
Hi Experts

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Why option C is not the answer?

My explanation for option C
All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams

Please have a look at the bolded part

And if we negate the answer C
Rice and yams were not grown as staple crops by the earliest agricultural societies outside of western Africa.

Then it will beak the premise. If Rice and yams were not grown as staple crop outside of western Africa then how it can be introduced from elsewhere??

I was confused between A and C . But end up marking answer as C
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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Vatsal7794

Careful--in your negation, you omitted the important word "earliest." We don't need to know what the very first staple crops were outside of Africa. We simply need to know that the introduction of rice and yams marks the first time that staple crops were grown in Africa. if it happened that 500 years earlier, people in Asia grew wheat or lentils or snozzberries, it doesn't change the reasoning about Africa.
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
Vatsal7794 wrote:
Why option C is not the answer?

My explanation for option C
All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams

Please have a look at the bolded part

And if we negate the answer C
Rice and yams were not grown as staple crops by the earliest agricultural societies outside of western Africa.

Vatsal7794 Note the word earliest in answer choice C. What if it wasn't the earliest, but rather the "second earliest"? We don't have information about the timeline here so I see no requirement for it to have been the earliest societies necessarily.
Similarly, note the phrase grown as staple crops in answer choice C. What if they were grown as something other than staple crops (e.g. supplemental foods)? That wouldn't destroy the argument either!
You chose to focus on one part of C in your negation (introduced from elsewhere), but that's not the only way to negate C.

Vatsal7794 wrote:
Then it will beak the premise. If Rice and yams were not grown as staple crop outside of western Africa then how it can be introduced from elsewhere??

Vatsal7794 An answer choice that casts doubt on a premise is never the right answer choice. It is always a trap answer. This is because a premise is, by definition, to be taken for granted.
Definition of premise:
a previous statement or proposition from which another is inferred or follows as a conclusion.
"if the premise is true, then the conclusion must be true"
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
It is already mentioned that staple crops cultivation began with Rice and Yam in Western Africa - "All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams."

Since this fact is already stated, why do we need an assumption that Rice and Yam were the first to be grown?
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
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Raghav9906 wrote:
It is already mentioned that staple crops cultivation began with Rice and Yam in Western Africa - "All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams."

Since this fact is already stated, why do we need an assumption that Rice and Yam were the first to be grown?

Notice that what you said and what the passage says are a little different from each other.

You said

staple crops cultivation began with Rice and Yam in Western Africa

The passage says

All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams.

The fact that "All the recorded staple crops grown in western Africa" were introduced from elsewhere and the fact that the first of "All the recorded staple crops grown in western Africa" were rice and yams does not mean that "staple crops cultivation began with Rice and Yam in Western Africa."

After all, there could be staple crops that are not "recorded" that were grown in western Africa before rice and yams.

Thus, for the evidence "All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams," to support the conclusion "discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there," requires the assumption "People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced."
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Re: Agricultural societies cannot exist without staple crops. Several food [#permalink]
Understanding the argument -
The author concludes that discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there. Why? Because
1. All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning with rice and yams.
2. 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
3. Agricultural societies cannot exist without staple crops.

What can be a potential weakness to the argument - What if it's correct that the "recorded crops" were introduced from elsewhere, but there are some "unrecorded crops" that the people were growing staple crops for thousands of years, and just when rice and yams got introduced, they stopped those crops? So, the correct date for agricultural societies' introduction will be if we can find when "those crops" were introduced and not when "rice and yams" were introduced. So, we need to shield the argument from this weakness.

Option Elimination -

(A) People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced. - ok

(B) There are no plants native to western Africa that, if domesticated, could serve as staple food crops. - This is a strengthener. But is it an assumption? Let's negate it. There are plants. But do we know if they were domesticated before introducing rice and yams or after? We don't know. So, the conclusion can still stay intact if they were introduced after "rice and yams." We are looking for an assumption whose negation will 100% shatter the conclusion, and we are not looking for a strengthener.

(C) Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa. - out of scope.

(D) Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are. - They are not even staple crops, as stated in the argument. Distortion.

(E) Kola and okra were domesticated in western Africa before rice and yams were introduced there. - They are not even staple crops, as stated in the argument. Distortion.
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