2 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 situ

The following letter presents a recent research that how a birth order affects an individual’s levels of stimulation. In addition, the author applies the explanation to human case. Even though firstborn infant monkey showed higher level of hormone cortisol than other younger siblings, there might be other theories that are possible. Since it does not provide information regarding sex of the monkey and human, that could be another explanation.

Let us consider biological age difference. The study shows that firstborn monkey produces higher level of cortisol. The firstborn monkey must be older and physically more mature than other siblings. For example, 1 year old monkey may be able to recognize his/her predators, and instantly knew he has to run away or alert to others. However, 6 month old monkey perhaps only recognizes predators as friends. Such as how much the monkeys recognize the danger, how they react to stimulation and so on. Thus, it could be the fact that all different siblings produce different amounts of hormone cortisol.

What about sexual difference? The fact does not provide information regarding sexual difference on the passage. Sex might be a key factor that helps explaining that the firstborn human and monkey infant have different hormone producing level regardless birth order. Either male or female might produce much more than the other sex. If the female monkey was only sample available for the research, this might only apply to female monkey, and vice versa. Again, it might be different in human babies; female has lower hormone level than male.

Because first-time mother monkey has higher level of hormone, does it make the firstborn baby produce more cortisol? This might have different explanation. The research also claims that first-time mothers have higher cortisol level than those who had babies several times. First-time trials are very difficult and nervous for some people, in other words, the neophyte must be more stimulated and could produce more hormones. If so, the first-time mother is nothing to do with the level of firstborn babies’ hormones.

Ultimately, the argument would have been strengthened if it provides more information regarding norms of the research such as sample, circumstances, and so on. The theory might be combination of everything, or the facts presented on the passage might not have enough or suitable evidences to explain the phenomenon. Thus, the argument is not valid and reliable since its evidence and assumptions are too weak to support the hypothesis as a concrete theory.