The following appeared as part of a letter to the editor of a scientific journal.
"A recent study of eighteen rhesus monkeys provides clues as to the effects of birth order on an individual's levels of stimulation. The study showed that in stimulating situations (such as an encounter with an unfamiliar monkey), firstborn infant monkeys produce up to twice as much of the hormone cortisol, which primes the body for increased activity levels, as do their younger siblings. Firstborn humans also produce relatively high levels of cortisol in stimulating situations (such as the return of a parent after an absence). The study also found that during pregnancy, first-time mother monkeys had higher levels of cortisol than did those who had had several offspring."
Write a response in which you discuss one or more alternative explanations that could rival the proposed explanation and explain how your explanation(s) can plausibly account for the facts presented in the argument.
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This is a new GRE essay style: 'Write a response in which you discuss one or more alternative explanations...'. I know most users made mistakes.
I copy the ideas from this link:
https://www.testbig.com/comment/16566#comment-16566
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The goal of the statement is to prove:
The birth order can affect an individual's levels of stimulation.
Then it gives three assumptions:
(1) In stimulating situations (such as an encounter with an unfamiliar monkey), firstborn infant monkeys produce up to twice as much of the hormone cortisol, which primes the body for increased activity levels, as do their younger siblings;
(2) Firstborn humans also produce relatively high levels of cortisol in stimulating situations (such as the return of a parent after an absence).
(3) The study also found that during pregnancy, first-time mother monkeys had higher levels of cortisol than did those who had had several offspring."
So the alternative explanations could be:
1. Maybe not because of the birth order, but because first born infant monkeys, first-time mother monkeys and firstborn humans all belong to same biological species - primates.
2. The age difference can play a major role. Maybe different siblings produce different amounts of hormone cortisol.
3. Maybe it is related to particular situations because the conditions are like: meeting with an unfamiliar monkey, reunion with a parent after an absence, and first-time birth of baby monkeys.