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 sit

In this argument the author claims that according to a research which is provided on the basis of a study on a specified number of rhesus monkey and the author concludes that there is an effect called “the effect of birth order” on individual’s cortisol level and then he related this to humans as they have affinity to monkeys. However, his reasons are not tenable nor convincing. In what follows I will delineate why I think so.

Although humans and monkeys have some common features and traits, there is still huge gap between them especially physiologically so an important item such as hormones levels cannot be concluded just by studying an special kind of animal. Furthermore, the level of all hormones changes during pregnancy especially the first one which may prompt the animal’s body to give birth more easily and keep it for other bearings. But, this cannot be a clue that humans have had such features or the high level of cortisol for many years as the author cites.

The author supposes that human firs-born babies have high level of cortisol according to the study in which certain animals are tested “rhesus monkey”. As we know the getting twice of the level of special hormone in newly born rhesus monkeys maybe specifically happened between this breed. Thus the author could not over generalize this item to other mammals neither to human race while still there is not enough study to support this claim.

The other frailty in the author’s claim is that the effect of birth order and the level of cortisol in first born monkeys is attenuated by confining the study to a limited number of monkeys. So he could not conclude that this can be a common feature in all animals or mammals. May be this happened just for a while or may be the high level of cotisol hormone in animal was due to the effect of being kept in a laboratory situation. Moreover, since the number of examined monkey are too short thus this conclusion cannot be cogent enough to make a sweeping statement for all humans.

In final analysis, the author’s surmise that human first- born child has more cortisol hormone than other siblings according to comparing him to other animals such as rhesus monkeys does not supported well enough to reach a wide conclusion. So if the author tends to enhance his theory , he should first boost the number of his samples and then divert it to other mammals. Besides, he should investigate scientific data of human blood test about cortisol hormone level at least for a decade and then compare them to support his hypothesis.