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 conclusion that the author states that the cortisol hormone production levels depend on the order of birth and that in turn reflecting the difference of behavior in stimulating conditions cannot be validated on the given assumptions. There may be various explanations for such behavior in the infants.

Firstly, the first in born monkey will have the most experience and responsibility in the family. So they learn to try to protect the clan from strangers trying to invade or attack the clan. This concern regarding the stranger could be the reason for the increased responsiveness of the first born monkey that the young ones may not understand.

Similarly, as being the first born, it gets the complete care and support by the mother or both parents, in case of other mammals like humans. But the youth hat is born afterwards is also taken care by the older infant. So it is more obvious that the first child is more attached to his/her parents than the young ones. This helps us understand the high level of stimulation by the first born when they see their parents after a long time.

The author also states that the monkeys during their first pregnancy had higher levels of cortisol than the ones having several offspring. As seen in humans, all animals feel anxiety and various different emotions when they experience something new. In case of pregnancy, it is excitement and happiness that surrounds the mother. Also her affection and care for the first child will be more and she will take more sedulous steps in caring for it. This provides the explanation for the argument the author holds.

Thus we can conclude that the difference in cortisol hormonal levels is a fact among the offsprings, but the order cannot alone be responsible for it. The situation and emotional upbringing of the offsprings also play a role in it.