The answer to why these reactions are so ubiquitous lies in efficiency. Expending a few hundred calories to vomit is much more efficient than being crippled by a disease that will threaten a life for weeks. If there is even a small chance, approximately five percent to be precise, that the chemical in the stomach is toxic, then the body will initiate vomiting. Only when the toxin is below the five percent mark will the amount of calories expended be inefficient enough to cause the body not to vomit.
Does treating these beneficial symptoms actually harm chances for survival? Using morning sickness as an example, it is often dismissed as a superfluous reaction from oversensitive pregnant women. When put into the frame of natural selection however, the reason for morning sickness becomes apparent. Fetuses are especially vulnerable against pathogens,...
Morning sickness expels these dangerous pathogens from the body, thereby saving the fetus considerable harm. If the pregnant woman were to treat morning sickness, the fetus may be damaged irreparably. In fact "mothers with less morning sickness turn out to be more likely to have babies with birth defects." (Nesse 1995)
Treating these symptoms may actually be more harmful than allowing them to remain, but until solid research is done on the subject the idea will remain debatable. Coughing and runny noses do not physically endanger our health, and treating them may harm an individual more than not doing so.
Works Cited
Nesse, Randolph, (1995) Evolution and Healing: The New Science of Darwinian Medicine, the THES, http://psych.lmu.edu/hbesmedicine.htm, Accessed February 26, 2007
