LR Question 24 Explanation, by LSATHacks
QUESTION TEXT: Biologist: Scientists have discovered fossilized bacteria in…
QUESTION TYPE: Role in Argument
CONCLUSION: Life may be able to begin under lots of difficult conditions.
REASONING: Earth is 4.6 billion years old. We found bacteria 3.5 billion years old. These bacteria had a long evolutionary history, indicating that they must have appeared during the harsh conditions following the Earth's formation.
ANALYSIS: The bacteria are 3.5 billion years old. But they had a long evolutionary history.
The question asks: why does the argument mention this fact? Well, it proves that the ancestors of the bacteria were very, very old. So old that they must have been around in the early day of Earth's history, when conditions were rough.
This lends support to the conclusion that life can arise under difficult conditions.
___________
- There is support for the claim that the bacteria had a long evolutionary history: they were complex. And this fact doesn't illustrate the conclusion (i.e. show an example of). Instead, this fact supports the conclusion.
- There is support for the claim that the bacteria have a long history: they are complex.
- CORRECT. The support for the claim is that the bacteria were complex. This is why we think they had a long evolutionary history. And this fact about history supports the claim that the bacteria evolved under difficult conditions. That in turn supports the conclusion that life all around the universe could evolve in difficult conditions.
- Nope. There is some support provided to this claim. But the claim about evolution also supports another claim: life evolved under difficult conditions.
- It's true that the claim about the bacteria's history supports a conclusion: the bacteria must have evolved during a difficult period. But this conclusion does support the main conclusion. The final sentence says “this suggests”, referring to the previous sentence.
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What is the role of the “However” in this question? Is it to throw the reader off, as however is usually indicative of an opposing viewpoint, but plays no purpose here?
The “however” is intended to highlight the seeming disparity between the fact that the Earth is only 4.6 billion years old, and the complexity of the fossils.
The fossils were found to be 3.5 billion years old and must have had a complex evolutionary history. The author is saying that one would think that Earth must be much older (than 3.5 billion years old) in order to facilitate the complexity of these fossils, “however”, it is only 4.6 billion years old.