Reading Comprehension

PT145 · S1 · P4 · Q27 Genetic Typos

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The French biologist Jean-Baptiste de Lamarck (1744–1829) outlined a theory of evolutionary change in 1809, 50 years before Darwin’s On the Origin of Species.

Topic

The revival of Lamarckian evolutionary theory through new research on heredity in the immune system.

Framework

Old / New; Present Debate

Main Point

Edward J. Steele and his team are challenging the widely dismissed Lamarckian theory of evolution by proposing that a mechanism in the immune system could allow acquired traits to be inherited, although most biologists remain skeptical due to lack of direct evidence. ( — End of P1 gives the core new idea, while P4 presents ongoing skepticism and the debate.)

P1: Introduction to Lamarck and Steele's Revival

Lamarck, a French biologist, suggested in 1809 that organisms could inherit traits acquired during their lifetimes. While this idea has been mostly laughed off by modern biologists, Edward J. Steele is now trying to bring Lamarckism back, claiming he’s found supporting evidence in how our immune system works.

P2: The Immune System’s Mutating Genes

This paragraph lays out the mystery of how the immune system adapts so quickly to new threats—partly by certain cells mutating their genes at an unusually high rate, creating "typos" as the DNA is copied to RNA. This enables the immune system to experiment with defenses on the fly.

P3: Steele’s Lamarckian Hypothesis and Its Mechanism

Here we get the details of Steele’s theory: he proposes that altered RNA is turned back into DNA (a process called "reverse transcription"), and suggests that viruses could carry this altered DNA into reproductive cells—potentially passing acquired traits to offspring.

27.

Suppose a scholar believes that the surviving text of a classical Greek play contains alterations introduced into the original text by a copyist from a later era. Which one of the following pieces of evidence bearing upon the authenticity of the surviving text is most analogous to the kind of evidence mentioned in the last paragraph of the passage?

  1. a copy of the original,

    Bad Match

    We were looking for "a distinct pattern of mutations that is concentrated in particular areas". This is saying, "Hey, we found the original text!" That would definitely allow us to resolve authenticity questions, but this doesn't match the passage at all. This would be like "directly observing evolutionary mechanisms", which the 4th paragraph told us never happens. This would be like if Steele said, "Well, we discovered a copy of the original DNA of hominids from 200,000 years ago, so we can just compare that DNA to current hominid DNA to figure out whether acquired traits have been copied in there".

    8% picked this

  2. a letter in which the

    Bad Match

    We were looking for "a distinct pattern of mutations that is concentrated in particular areas". This is saying, "Hey, the copyist confessed!" That would definitely allow us to resolve authenticity questions, but this doesn't match the passage at all. This would be like "directly observing evolutionary mechanisms", which the 4th paragraph told us never happens. This would be like if Steele said, "The RNA just signed a confession that said, 'yes, I sold the altered DNA to a virus, which then took it to the reproductive cells'." This is too literal and easy. The evidence in the final paragraph is circumstantial and involves some interpretation / guesswork.

    6% picked this

  3. an allegation by one of

    Bad Match

    We were looking for "a distinct pattern of mutations that is concentrated in particular areas". This is saying, "some other body part that works with RNA is giving us signs that RNA changed how DNA was written and those changed DNA instructions got reproduced." The evidence in the final paragraph comes from looking at the genes that carry instructions for immune system responses. It's looking at a subset of our DNA. It's hard to match that up with "one of RNA's contemporaries" (since RNA is the copyist in this metaphor). This answer is a little better than (A) and (B), since it still seems more like innuendo / suggestion, rather than outright proof. But it's a weaker match than the correct answer is for "distinct pattern of mutations concentrated in particular areas".

    10% picked this

  4. an account dating from the

    Bad Match

    We were looking for "a distinct pattern of mutations that is concentrated in particular areas". This is saying, "Hey, we found a quote from the original text that shows the surviving version has been changed." That would definitely allow us to resolve authenticity questions, but this doesn't match the passage. This would be like "we found a DNA sequence of this organism from a long time ago, and we can see that this snippet of DNA is different from the modern version".

    22% picked this

  5. Correct

    vocabulary in the surviving text

    Why this is right

    We were looking for "a distinct pattern of mutations that is concentrated in particular areas". This is our best option, though it's pretty poor. This is better than other answers because this involves looking at the text itself to see whether there are internal suggestions that things have changed / been adulterated. Steele is looking at subsets of DNA and seeing stuff within the genetic code that appears to be altered .. there's a signature, a cluster of distinct mutations that apparently stick out from the rest of those immune response genes. Similarly, this answer involves looking at the potentially altered text itself and finding within that some stuff that sticks out like a sore thumb: signature vocabulary that doesn't seem like part of the original code. This answer implies that what we're seeing in the surviving text is something typical of the later era but not typical of the original era. It's not super clear how that part of this answer matches Steele and colleagues, but presumably if they are able to pinpoint "a distinct pattern of mutations", then they must have a control group idea of what the DNA should look like if it were following the original form. Mutations are anomalies, and so it presupposes that you know what "normal" is in order for you to detect "abnormal".

    Skill tested: Application · how this choice captures the passage's function is the move to repeat next time.

    54% picked this

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