2012gre范文：argument02

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.

中文翻译：

最近一项对恒河猴的调查揭示了出生顺序对于个体刺激水平的影响。调查显示在受到刺激的环境下（例如遇到一个不熟悉的猴子），头胎小猴的皮质醇分泌会翻倍，这样增加了它及其兄弟姐妹的身体灵活度。人类的头胎孩子在遇到刺激（例如父母外出回家）时也会分泌出相对浓度的皮质醇。研究同时还发现在怀孕期间，第一次为人母的猴子的皮质醇要比生过几次孩子后的猴子水平高很多。

写一篇回应，在其中讨论一个或数个可以和文中的解释相竞争的他种解释（原因），并说明你提出的解释是如何可信的解释和说明文中呈现的事实的。