#13 - Must Be True, Subject Perspective

[8scn]

Hello

Why is E correct -- where in the passage does it say the biologists initially thought genes were inherited vertically? In lines 54-58, it says that horizontal transmission sheds light on the biologists’ thinking, but that just means they never considered horizontal transmission, not that they thought genes were inherited vertically.

[Adam Tyson]

The definitions of horizontal and vertical inheritance are found in the last paragraph of the passage. We learn there that horizontal inheritance "may well be the mechanism for inheritance of acquired characteristics that has long eluded biologists, and may eventually prove Lamarck's hypothesis to be correct." This relates back to the opening paragraph, which tells us that "[biologists] have long held that inheritance of acquired characteristics never occurs." In other words, they have not historically believed in horizontal inheritance. If they didn't believe that, then they must have believed in only vertical inheritance.

Hope that helped clear it up!

Adam Tyson
PowerScore LSAT Instructor

[yrresnik]

Hey why isn’t d also true. The passage never suggested the extant to which the biologists would have believed in “inheritance “

[KelseyWoods]

Hi yrresnik!

Answer choice (D) (like answer choice (B)) is something that biologists currently believe. Biologists currently believe that some but not all genes are inherited vertically because, as the last paragraph tells us, they now believe that horizontal inheritance occurs even though most inheritance is still vertical. So answer choice (D) cannot be something that biologists "no longer believe."

Hope this helps!

Best,
Kelsey

[tug59567]

I originally answered E but then left this question unanswered because I ran into a couple issues trying to validate answer choice E.

The parts of the passage I was referring to for evidence was the first paragraph ("But because biologists could find no genetic mechanism to make the transmission...") and the last paragraph (Such horizontal transmission may well be the mechanism for inheritance of acquired characteristics that has long eluded biologists...")

This issue I have with connecting the first and last paragraphs is that while the first paragraph is referring to the biologists original view that Lamarck's thesis was wrong, the last paragraph does not actually comment on how the new evidence has changed the biologists' views.

It feels wrong to assume that biologists have reacted to the new evidence when the author doesn't hint if they have or not. It doesn't even say if the biologists are aware of this new evidence! I don't see how we can assume that the biologists have the view point that genes are divided into two groups.

In conclusion, I talked myself out of this one because I thought it was wrong to assume that the biologists had adopted the new evidence. Furthermore, nothing in the passage mentions what biologists DO believe. It only mentions what they DO NOT believe, which is that Lamarck is wrong.

What am I missing??

Thank you and have a great day!

[Jeremy Press]

Hi tug,

I don't think you're missing anything, but I do think you're holding answer choice E to too high a standard. The question stem asks about what the passage "suggests," which means we're unlikely to find a direct statement validating the answer choice. Instead we're looking to see if we have the pieces in place from the passage to take the next reasonable step to what the answer choice says.

Take another look at the first paragraph, specifically these two sentences next to each other: "But because biologists could find no genetic mechanism to make the transmission of environmentally induced adaptations seem plausible, they have long held that inheritance of acquired characteristics never occurs. Yet new research has uncovered numerous examples of the phenomenon." The first of those sentences suggests a reason biologists have held such inheritance never occurs (a lack of evidence). The second of those sentences suggests that reason is disappearing (new research is uncovering evidence). In a sense it's almost like they give you the following pieces: A caused B (lack of evidence caused a lack of belief). A is going away (there's evidence now). What's the next logical step? Absence of cause means absence of effect. In other words, the new evidence suggests there will be biologists who believe in (horizontal) inheritance of acquired characteristics.

Is that inference 100% solid? No, but that's not the standard we're being held to here. When we're looking for something the passage "suggests," we get a little bit of wiggle room down from that 100% standard.

I hope this helps!

[Tajadas]

I am still not convinced with why the answer should be E, for similar reasons to tug. While Jeremy's response identifies a part of the passage that could suggest E, I'm put off by the phrase "they have long held that inheritance of acquired characteristics never occurs. " "Have" is in the present tense. This makes the reemergence of horizontal transmission seem brand-spanking-new, far from accepted by "many" biologists (especially when many == most). It could be that many biologists still hold that inheritance of acquired characteristics never occurs, either because they haven't seen this new evidence to the contrary or they have issues with the evidence.

The possibility that biologists don't agree with the evidence of horizontal transmission seems pretty strong to me because even though the author seems pretty confident in the text Jeremy posted, there are plenty of times where the author leaves things as way less certain. "The new evidence suggests that genes can be divided into two groups." "The evidence even appears to show that genes can be transmitted horizontally between organisms that are considered to be unrelated" "Some horizontal transmission may well be the mechanism for inheritance of acquired characteristics that has long eluded biologists".

I could believe that some biologists agree with horizontal transmission, but there's nothing in here that makes me think the tides of the biology community are shifting and most biologists agree. With these issues in mind, the "suggests" in the question stem is doing a lot of heavy lifting here. Is there something that I'm missing? How could I have changed my approach, so that these (in my opinion, totally justified) reservations don't drag me down in the future?

[Adam Tyson]

The first step, Tajadas, should be to adjust your understanding of the term "many." That term does NOT mean "most," and could be substantially less than half as long as it is a subjectively large number. Many people live in North America, for example, but that population is a far cry from most (I just looked up some stats that put the figure below 5% of the world's population). So the question should be whether these is at least some support that some large and growing number of biologists now believe that inheritance can happen horizontally instead of just vertically as was previously considered the standard position.

To add to the evidence cited earlier in this thread, it may help to notice that the research described in the second and third paragraphs goes beyond one study and one organism. It seems that there are many different studies reaching similar conclusions, and those would presumably be conducted by multiple biologists. Even the last sentence of the first paragraph supports this, saying that there are numerous examples, again suggesting a growing number of researchers coming to these conclusions.

Can we prove that there is a large enough number that "many" is an appropriate descriptor? I don't think so, but as Jeremy said, that is holding the answer to too high a standard. We don't need proof, but only a suggestion.

[BMM2021]

Hello,

I certainly appreciate the reasoning being provided for answer E above, I'm simply not sure how to arrive at that in a future, similar case.

In my understanding, nothing in the passage suggests that the many biologists whom we are told "have long held that inheritance of acquired characteristics never occurs" are aware of the "new research [/] evidence." This research could be the product of a single researcher ("experimenter") who never released the findings, and is thus also the author of the passage. Since there's nothing to preclude this possibility, I'm not sure why we would be comfortable believing that the evidence presented in the passage has changed the minds of many biologists.

On the other hand, the "But biologists..." sentence in the first paragraph seems to imply that at some point, some biologists were at least interested in determining if horizontal inheritance was possible, but upon finding no evidence, they abandoned the idea. That circumstance doesn't prove that any of those biologists believed that some genes could be inherited horizontally, but to me it's more intuitive that the biologists who tested the theory at one point believed it to be true but have since stopped believing it due to a lack of evidence than that the evidence cited in this passage is well known to biologists and they have since shifted their explicitly mentioned perspectives.

I'm not sure how one chooses between these two somewhat unfounded positions, unless we're to assume that the evidence cited by an author is always publicly available and adequately understood by the relevant population. Thanks for any help here.

[Rachael Wilkenfeld]

Hi BMM2021

We can assume that the research is generally known by experts in the field. This is because it is called research and not just an experiment. The research is published--that's how people know about it--and it's not unreasonable to assume that experts in a field follow the publications in that field.

Hope that helps!