A recent study concludes that prehistoric birds, unlike modern birds

Question

A recent study concludes that prehistoric birds, unlike modern birds, were cold-blooded. This challenges a widely held view that modern birds descended from warm-blooded birds. The conclusion is based on the existence of growth rings in prehistoric birds’ bodily structures, which are thought to be found only in cold-blooded animals. Another study, however, disputes this view. It concludes that prehistoric birds had dense blood vessels in their bones, which suggests that they were active creatures and therefore had to be warm-blooded.

Which one of the following, if true, would most help to resolve the dispute described above in favor of one party to it?

(A) Some modern warm-blooded species other than birds have been shown to have descended from cold-blooded species.
(B) Having growth rings is not the only physical trait of cold-blooded species.
(C) Modern birds did not evolve from prehistoric species of birds.
(D) Dense blood vessels are not found in all warm-blooded species.
(E) In some cold-blooded species the gene that is responsible for growth rings is also responsible for dense blood vessels

somyasneh · Answer

Hi could someone please explain why E?

mayankdgmat · Answer

(E) it explains why cold blood prehistoric bird have rings as well as dense blood vessels. This option is directly attacking "which suggests that they were active creatures and therefore had to be warm-blooded"

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unraveled · Answer

somyasneh 
HTHs. 
The two studies have different basis of concluding as highlighted in the blue text. How these two are related helps resolve the situation.

A recent study concludes that prehistoric birds, unlike modern birds, were cold-blooded. This challenges a widely held view that modern birds descended from warm-blooded birds. The conclusion is based on the  existence of growth rings in prehistoric birds’ bodily structures , which are thought to be found only in cold-blooded animals. Another study, however, disputes this view. It concludes that prehistoric birds had  dense blood vessels in their bones , which suggests that they were active creatures and therefore had to be warm-blooded.

Which one of the following, if true, would most help to resolve the dispute described above in favor of one party to it?

(A)  Some modern warm-blooded species other than birds  have been shown to have descended from cold-blooded species. - WRONG. Nothing as far as resolution is considered.
(B) Having growth rings is  not the only physical trait  of cold-blooded species. - WRONG. Then what!! It does nothing like A.
(C) Modern birds  did not evolve  from prehistoric species of birds. - WRONG. Totally goes against the passage.
(D) Dense blood vessels are  not found in all warm-blooded species . - WRONG. Similarities alike to A. Doing nothing.
(E) In some cold-blooded species the  gene  that is responsible for growth rings is  also responsible  for dense blood vessels - CORRECT. Altough POE helps, this choice does sets things right.  Exception case this may be. However, it does resolve the ambiguity.

Answer E.

mkeshri185 · Answer

E is clearly not the answer. Question has asked to find something which turn the debate to one side, and not BOTH SIDE. If gene is responsible for both sides, then it says both sides are right which in turn means both sides are true in their respective beliefs but that is not what the question has asked. Question is asking to support one party not BOTH

adhin31 · Answer

In the E option they have mentioned that the gene found in cold blooded species, so I think it supports the side of cold blooded species.

dr8t · Answer

Even I felt that option E is clearly not the answer until I reread the option. It suggests that "In some cold-blooded species the gene that is responsible for growth rings is also responsible for dense blood vessels". Had the option been that "In some species the gene that is responsible for growth rings is also responsible for dense blood vessels", then we would not have known which side it rolls on because rings indicate cold blooded and the blood vessels indicate warm blooded according to the argument. This settles the argument in favor of the cold blooded species also assuming that some cold blooded species also have dense blood vessels. This hidden assumption in the option is what makes this option so difficult to detect.

Atleast this is how I interpret this question.

mkeshri185

E is clearly not the answer. Question has asked to find something which turn the debate to one side, and not BOTH SIDE. If gene is responsible for both sides, then it says both sides are right which in turn means both sides are true in their respective beliefs but that is not what the question has asked. Question is asking to support one party not BOTH

Atleast this is how I interpret this question.

krrishabh96 · Answer

Honestly I think the key is realizing that the two studies *seem* contradictory only if you assume dense blood vessels automatically = warm-blooded.

The first study says prehistoric birds were cold-blooded because they had growth rings, which are associated with cold-blooded animals.

The second study pushes back by saying they had dense blood vessels, which usually suggests high activity levels and therefore warm-bloodedness.

Choice E basically connects those two things together. If in some cold-blooded species the same gene causes BOTH growth rings and dense blood vessels, then suddenly the evidence is no longer conflicting. A cold-blooded animal could still have dense blood vessels.

That weakens the second study’s conclusion and supports the first study’s interpretation.

So E doesn’t just weaken one side — it actually explains how both observations can exist at the same time.

dr8t · Answer

From what I understand the argument suggesting that dense blood vessels suggest the species were warm blooded does infact implies the relation. Option E challenges that implication. For most of the people, I think, who got this question wrong eliminated E thinking that it deepens the puzzle because it favours both the sides, thus they must have missed the cold blooded part in the option.

krrishabh96 · Answer

Yeah, I think that’s exactly where most people get trapped.
A lot of people read E and think: “Wait, this supports BOTH growth rings  and  dense blood vessels, so doesn’t that make the contradiction worse?”
But the important detail is the phrase  “in some cold-blooded species.” 
That completely changes the logic.
The second study is basically relying on:
dense blood vessels → warm-blooded
But if cold-blooded species can also develop dense blood vessels (because of the same gene tied to growth rings), then that implication weakens a lot.
So E actually resolves the dispute by showing that the two pieces of evidence are not mutually exclusive. Prehistoric birds could have had:
 
 growth rings 
 dense blood vessels 
 and still been cold-blooded.  
I honestly think many people eliminate E because they stop reading after “dense blood vessels” and mentally categorize it as evidence for the warm-blooded side.

A recent study concludes that prehistoric birds, unlike modern birds

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A recent study concludes that prehistoric birds, unlike modern birds