"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.

The passage suggests that the birth order has some influence on the individual’s level of stimulation. The passage takes into consideration the assumption that the firstborn infant rhesus monkey produces up to twice the amount of cortisol during stimulating situations than their younger siblings. Apart from this, it is assumed that firstborn humans also show relatively high levels of cortisol in stimulating situations as compared to their younger counterparts. It also states that during pregnancy, the first-time mother monkeys had higher levels of cortisol as compared to those who already had several offspring. The argument is flawed in certain ways, and can be rivalled by certain arguments regarding hormones secreted in stimulating situations, the study conducted and comparison between pregnancy conditions of humans and monkeys.

The sole dependence on cortisol to depict the levels of stimulation is limiting and thus can lead to incomplete and inconsistent results. There may be other hormones, whose production results if used may correctly indicate the levels of stimulation. For instance, the flight-and-fight hormone adrenaline is used in humans in stressful scenarios such as fighting someone. This hormone may be secreted while encountering an unfamiliar belligerent monkey. In such a scenario, both adrenaline and cortisol might be secreted, and despite this one would still consider the latter as the deciding factor. Thus, solely relying on one hormone’s results may not give a complete picture of how much stimulation happens inside the brain.

There are certain limitations in the survey conducted. A short sample size has always led to incomplete results, as it doesn’t accommodate outliers in the dataset: data samples which are markedly different from those considered in the study, and thus would actually make a considerable impact in the result. The usage of eighteen rhesus monkeys may lead to limited results, and thus they may not be generalised. It’s possible that a case exists where the second-born monkey has more cortisol levels than the firstborn. The study also includes the research about humans and rhesus monkeys only, and thus generalization over the rest of the species might be incorrect, despite both of them being mammals.

The amount of cortisol levels in pregnant first-time monkeys, while more than those who already had several offspring, may not account for the those of a human mother. It could be possible that the human mother who already has had offspring could have higher levels of cortisol due to advancements in medical sciences and sufficient intake of nutrients. After pregnancy, a human can replenish its utilised resources in the body and can make up for any damage, thus maintaining the cortisol levels prior to pregnancy. A monkey, however, cannot do so. This argument holds strong and can rival, if not undermine, the above argument.

The argument is flawed and there are a lot of unstated assumptions. A more thorough study is necessary to make the writer’s argument acceptable, and because of this more compelling arguments can be presented.