#19 - Anthropologist: It was formerly believed that

[Administrator]

Complete Question Explanation

Assumption. The correct answer choice is (C)

This anthropologist does not believe the hypothesis that Homo sapiens, the prehistoric ancestors of
modern day humans, bred with Neanderthals. The anthropologist’s skepticism is based on the fact
that DNA taken from the remains of Neanderthals is very different from the DNA of contemporary
humans:

• Premise: When the DNA of modern-day humans is compared with that of Neanderthals,
  they are very different.
  
  Conclusion: Therefore, Homo sapiens, the ancient ancestors of humans, must not have bred
  with Neanderthals.

The anthropologist’s leap here is pretty clear: based on a comparison with modern humans, a
conclusion is drawn about our ancient ancestors. The question stem asks for the assumption required
by the anthropologist’s conclusion; the right answer choice most likely ties modern human DNA
with ancient Homo sapiens DNA, so that information about modern humans can be applied to
analysis of ancient Homo sapiens.

Answer choice (A): If the anthropologist believed that there had been breeding between
Neanderthals and Homo sapiens, it would of course have been necessary to assume that there was
some cohabitation between the groups. This anthropologist, however, believes that there wasn’t such
interbreeding, so this assumption is not required.

Answer choice (B): The anthropologist does not take issue with the reliability of the DNA tests,
so the argument does not require living species’ samples to be more reliable. To confirm, the
Assumption Negation technique can be applied: the negated version of the right answer choice will
hurt the author’s argument.

The negated version of this choice, on the other hand, is as follows:

DNA testing of remains is not significantly less reliable that DNA testing on living species (in other
words, they have about the same degree of reliability).

Since this choice has no effect on the anthropologist’s argument, the assumption provided by this
choice is not required.

Answer choice (C): This is the correct answer choice. Its difficulty lies in the convoluted
language, but this choice provides that the anthropologist must be assuming that the DNA of ancient
humans wasn’t much more Neanderthal-like than the DNA of modern humans.

To confirm this to be the right answer choice, Assumption Negation can be used: The correct
answer choice to an Assumption question, when negated, will hurt the author’s argument. The
negated version of this answer choice is as follows: compared with modern humans, Homo sapiens’
DNA was significantly more similar to Neanderthal DNA. This negated version clearly refutes the
anthropologist’s conclusion, again confirming this choice to be the right answer.

Answer choice (D): The anthropologist does not believe that there was interbreeding between
Neanderthals and Homo sapiens, but that is not the same as assuming that the two were completely
isolated from one another.

To confirm, this choice can be negated, to see whether taking away this assumption would hurt the
author’s conclusion. The negated version of this choice would be:

“Neanderthals and Homo sapiens were NOT completely isolated from one another.”

Since the negated version does not help to show that there was interbreeding, it does not refute the
anthropologist’s belief that no such interbreeding took place.

Answer choice (E): The anthropologist argues that there was no interbreeding between Neanderthals
and Homo sapiens; this argument does not require the assumption that every single similarity
between two species’ DNA must come from interbreeding.

[netherlands]

Hi there PS,

I got this one correct mainly using the process of elimination. But would you mind explaining to me the actual reason this one is correct. I have my own idea of how the negation of this assumption could weaken the argument ( perhaps that which we think is a resemblance to Homo Sapiens is actually a resemblance to Neanderthals as well and we just didn't realize it bc we didn't know their dna was similar, or earlier descendants of Neanderthal and HS interbreeding had Neanderthal DNA qualities that faded over time as the they evolved into contemporary humans?) but would like to understand yours.


I mean I guess this just tells me that at some point there was interbreeding, but it just didn't transfer into modern human dna.

Thank you!

[David Boyle]

Hi there PS,

I got this one correct mainly using the process of elimination. But would you mind explaining to me the actual reason this one is correct. I have my own idea of how the negation of this assumption could weaken the argument ( perhaps that which we think is a resemblance to Homo Sapiens is actually a resemblance to Neanderthals as well and we just didn't realize it bc we didn't know their dna was similar, or earlier descendants of Neanderthal and HS interbreeding had Neanderthal DNA qualities that faded over time as the they evolved into contemporary humans?) but would like to understand yours.


I mean I guess this just tells me that at some point there was interbreeding, but it just didn't transfer into modern human dna.

Thank you!

Hello netherlands,

E is good because the stimulus assumes that it means something that contemporary DNA differs from Neanderthals'. But why would it mean anything, when the issue is "prehistoric Homo sapiens ancestors . . . interbre[eeding] with Neanderthals"?
"Prehistoric ancestors" is not necessarily the same thing as "contemporary"...but if we assume E, "The DNA of prehistoric Homo sapiens ancestors of contemporary humans was not significantly more similar to that of Neanderthals than is the DNA of contemporary humans", i.e., that the prehistoric DNA is not very different from contemporary DNA, then the two DNA's, prehistoric and modern Homo sapiens, *are* pretty much close to the same, which lets the stimulus make sense.
Also, what you say above about interbreeding, may not necessarily be true.

Hope this helps,
David

[Arindom]

Hi,

Could you explain why ans. choice A is incorrect? Unless Homo Sapiens live in the same time and same place, how could they interbreed? If they interbreed then only could DNA testing results be meaningful.

Thank you.

- Arindom

[Robert Carroll]

Arindom,

The anthropologist's conclusion is that interbreeding did not occur. If Homo sapiens and Neanderthals did not live at the same time and place, this would actually help the anthropologist's conclusion, so the anthropologist need not (and does not want to!) assume what answer choice (A) says. Answer choice (A) is an opposite answer.

Robert Carroll

[rneuman123@gmail.com]

Can you explain why e is wrong but c is correct? I thought that e seemed more clear because the stimulus said the tests were very different, so assumedly if there was a similarity, you could conclude that there was some interbreeding, even if only, say, 5%. And c's language is very confusing.

[Shannon Parker]

Hi there,

Can you explain why e is wrong but c is correct? I thought that e seemed more clear because the stimulus said the tests were very different, so assumedly if there was a similarity, you could conclude that there was some interbreeding, even if only, say, 5%. And c's language is very confusing.

The author's conclusion here is that there was not interbreeding, and therefore "E" is incorrect. If "significantly different," means that there is even a .01% similarity, and "E" were true (any similarity in the DNA of two species must be the result of interbreeding) then there would have to have been interbreeding.

Answer choice "C" is correct because if the DNA of prehistoric Homo sapiens ancestors of contemporary humans were significantly more similar to the DNA of neanderthals than the DNA of contemporary humans, it would weaken the argument by showing that contemporary humans were descendent from a class with a "significantly different" DNA, which is why the author says there was no interbreeding.

I know the wording of this question is a mouthful, but I hope this helps.

~Shannon

[rneuman123@gmail.com]

So, if I understand this correctly, C is saying that the prehistoric homo sapiens were more similar to contemporary humans than to the Neanderthals. Negating this assumption would hurt the author's argument by saying that the contemporary humans are more similar to the Neanderthal DNA than to the Homo sapiens. Did I get that right?

[Emily Haney-Caron]

Hi rneuman,

Not quite - that might be what's making this question a bit trickier for you. The wording here is awkward, and so it is easy to misread. However, what C is actually saying is that when you compare the DNA of Neanderthals to the DNA of prehistoric Homo sapiens ancestors, the two aren't more alike than the similarity between the DNA of Neanderthals and the DNA of contemporary humans. Why does that matter? Well, the stimulus is telling us that the DNA of contemporary humans and Neanderthals is different, and uses that to draw a conclusion about in-breeding between Neanderthals and prehistoric Homo sapiens ancestors. But what if the DNA of Neanderthals was much more similar to the DNA of prehistoric Homo sapiens ancestors than it is to contemporary humans? That might tell us that the DNA testing is less meaningful than we thoughts, since we already know that contemporary humans were descended from prehistoric Homo sapiens.

[rneuman123@gmail.com]

I think I get it now. If prehistoric humans were more similar to Neanderthals, it would question the argument, because contemporary humans are ancestors of prehistoric humans. Right?