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 situa

In this letter, the author concludes that birth order and even being mother for the first time can affect individuals' levels of stimulation by citing a study of eighteen rhesus monkeys. At the first glance, this may be a newly exciting scientific breakthrough, however, after examining the evidence provided by the author, several other alternative explanations to the same issue could undermine the reliability of the conclusion.

The initial problem with this argument is the possible flaws in the study cited by the author. According to the introduction of the study, its subjects are eighteen rhesus monkeys. Yet, there is not quite possible that a convincing result of a study can be generated merely based on eighteen subjects. Because the size of the sample in this study is not big enough, and the smaller the sample, the less reliable the study's conclusion. Besides, the sample are selected from rhesus solely. However, can rhesus monkeys be the representative of the whole monkey species? Common sense informs people that monkey species include a rather wide range in the nature, perhaps distinct species have different physical and biological functions which may lead to the opposite outcomes. What's more, the author fails to offer the detail information of those monkeys such as their age, sex and etc. And opposite sex can decide different responses to the same environment, as well as different age. Unless the author takes into account all those possible alternative explanations, the study cited in the letter can only undermine its reliability by its own.

Another hidden flaw in the letter is that, the author simply equates the situation of the birth order with that of fist-time being mother. The author assumes that, according to the study in which the fist born monkeys can generate a high level of cortisol so can first-time mother monkeys, the cause and effect of the high level of cortisol between the first born monkeys and first-time mother monkeys are the same. However, other alternative explanations may cast doubts on this assumption. Perhaps, the reason that those first-time mother monkeys generate such a high level of cortisol may not result from the need that they have to regulate their activity levels to confront the stimulating environment but a type of self-regulation to balance internal levels of hormones. This scenario, if true, would serve to weaken the author's conclusion.

Even though the two possibilities mentioned above are proved to be true, however, the author hastily assumes that there is no alternative explanations for the similar responses generated by monkeys and humans. However, merely resting the assumption on the unilateral and superficial phenomenon is unconvincing and cursory. Even though monkeys and humans are all mammals and there is some inherent relationship between them, however, they are still two independent and utterly distinct kind of species which means their physical functions and structures can be total different. Therefore, without providing well-rounded and scientific research of humans and ruling out these and other possible explanations behind it, the author's conclusion can not be reasonably established.

To sum up, the internally physical and biological functions of animals and humans are extremely intricate that there are still mysterious problems can not be fully solved and understood. The conclusion made by the author rests barely on an inaccurate study and superficial phenomena which are irresponsible and non-scientific. To strengthen the argument, years' researches and comparsons are required and also a rigorous attitude to science.