argument 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 stimulati

In the argument, the author attributes the high level of cortisol of infants in stimulating situation to birth order. Thus, firstborn infant will get more cortisol than its siblings. To bolster it , the author cites various evidences. However, a meticulous analysis will show that there could be many other alternatives to explain this situation that could not be eliminated before more evidence is provided.

First, in stimulating situations, much more amount of cortisol in firstborn monkeys may doesn't indicate that there is a relation with birth order and the level of hormone,perhaps much more cortisol is directed by their gender. As I know, female individuals usually contain more amount of hormone. For that matter, perhaps that all the firstborn monkeys served in experiment precisely are female, which does not refer in the argument. Thus, much more cortisol in those monkeys is caused by their gender rather than their birth order.

Second, the experiment is also not convincing to substantiate the argument when it comes to the firstborn humand.It's entirely possible that the firstborn human doesn't have playmates at home, so parents are their only friends. After a period time doesn't see their parents, they will be so excited and then produce more hormones when parents come home. In contrast, as for the later born infant, they use to play with their sisters or brothers,so maybe they don't mind whether their parents are at home or not.

Third,the first-time mother monkeys who have higher levels of hormone doesn't indicate that it will deliver to their infant monkeys. For first-time mother monkeys, they are really looking forward to being mothers and having their offsprings,thus their emotion will have a considerable impact on the high level of cortisol. Besides, perhaps some physical mechanisms that relate to pregnancy are so sensitive in first time mother monkeys that only a little change in their surrounding environment will stimulate the secretion of the hormone. However,in both of these case, the increase of the amount of cortisol may not transmit to their firstborn infant.

In sum, all these three examples can't attest the relationship with birth order and the level of hormone of cortiso. The results of the experiments can be explain by other means. So, to bolster the argument, the author should cites more evidence to ruling out other possible reasons, or it cannot convince me on it,