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

In this scientific journal author's conclusion about relation between production of the hormone cortisol and birth order is based on some observations. But none of them are strong enough to reach at that conclusion and the conclusion drawn in this argument remain unfounded. If author were to provide more evidence to support the finding, the argument would be much more effective.

To establish the relation between production of the hormone cortisol and birth order, author mentioned about the study of eighteen rhesus monkeys. 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. But here the sample size is too small to draw any general conclusion. Hormonal production can be also depends upon food and living condition of monkeys. It might be possible that their younger siblings eating habit is different from first born infant hence less production of hormone in younger sibling.

Author used humans as a second proof for his finding. He mentioned that Firstborn humans also produce relatively high levels of cortisol in stimulating situations (such as the return of a parent after an absence).But author has not discussed about the social condition of those children. It might be possible that those first born children were alone at home and those children do not have any other relatives other than their parents who can spend time with them. So after seeing their parents after long time they will certainly produce more hormone than other children who have many friends with whom they can play.

Author's third point is out of context to this argument there is no relationship between author's finding and the level of cortisol in first-time mother monkeys. Author's finding is about level of cortisol to birth order.

To sum up, The author fails to substantiate its claim that level of cortisol depends upon birth order , because facts used by him is not a general observation. It is very specific to draw this general conclusion. He should have considered large sample space of monkeys . Author should have mentioned about monkeys food quality and living condition, social life of human children etc to substantiate his finding.