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.
(Topic 2, AoA, Official Guide, Revised GRE)
- The argument has no explanation to believe that there exists any relationship between the characteristics of monkeys and humans.
- The study is based on only 18 rhesus monkeys which is too small and insignificant a number to be taken as a “clue” for any scientific phenomenon to be researched for an entire species.
- There is a possibility that the sample selected has given some aberrant result which if believed, will only lead to false interpretations.
- The argument says “firstborn infant monkeys produce up to twice as much of the hormone cortisol, …, as do their younger siblings”, but doesn’t talk about the number of monkeys that exhibit this characteristic. Is it all? Is it most? Is it few?
- No explanation about the habitat/ eating habits of the sample studied (the 18 rhesus monkeys) has been given. It is quite possible that all the 18 monkeys belonged to a particular kind of environment/ shared the same food habits that would result in the production of the similar amount of cortisol in them.
- The study seems to have overlooked the possibility of the presence of some other hormone/ physiological factor in the body of the “firstborns”, that might have had a balancing effect for cortisol.
- As about firstborn humans also producing relatively high levels of cortisol in stimulating situations, the author doesn’t back the statement by any statistics whatsoever about firstborn “humans”.
- The situation to study the stimulation level in the monkeys refers to meeting someone “unfamiliar” while that in case of the humans is stark opposite i.e. to meet someone as “familiar” as their parents. These opposite situations may be but also may NOT be taken to have the same effect.