Quote:
here what does "for only if" indicates?
I think the author is trying to communicate that the two groups could only have the same tools either if they faced the same daily challenges and met them in the same way or if they belong to the same species, since they did not face the same daily challenges, it must be true that the two groups belong to the same species
Hi @
StanindawHappy to discuss.
"only if" indicates a Necessary Condition.
For example:
Statement: Only if we exercise regularly, we stay fit.
Inferences:
- If we do not exercise regularly, we do not stay fit.
- If we are fit, we must be exercising regularly.
- If we exercise regularly, we may or may not stay fit. (We might be doing something else to offset the benefits of regular exercise.)
- If we are not fit, we may or may not be exercising regularly. (We might be doing something else to offset the benefits of regular exercise.)
So, "
only if they faced the same daily challenges and met them in the same way would they have used such similar tools."
Inference:
- If they did not face the same daily challenges and did not meet them in the same way, they would not have used similar tools.
- If they used similar tools, they must have faced the same daily challenges and met them in the same way.
Now, the author is saying that Neanderthals and Cro-Magnons used the same tools, therefore they were members of the same species. Using the same tools proves that they must have faced the same daily challenges and met them in the same way.
So,
- If they used similar tools, they must have faced the same daily challenges and met them in the same way.
- If they faced the same challenges and met them in the same way, they were members of the same species.
- So, if they used the same tools, they were members of the same species.
- Hence, even though there were minor morphological differences between the two, they were essentially the same species.
Choice B: The daily challenges with which an environment confronts its inhabitants are unique to that environment.
This has to be false, since even though Neanderthals and Cro-Magnons lived in different environments, they faced similar challenges and met them in similar ways using the same tools. Hence, B cannot be true. Clearly, the daily challenges were not unique to those environments, but were shared by those environments.
Choice D: Use of similar tools is required if members of two distinct groups of tool-making hominids are to be considered members of the same species.
We cannot say for sure that this is "required", but it "could" be true. We know having the same tools proves they are the same species. However, we do not know whether not having the same tools proves that they were not the same species. Hence, this statement is a possibility not a certainty.
Hope this helps.
Happy learning!
-Abhishek