As a young sprite, it occurred to me on one my visits to the family physician to ask, "Why do I cough when I'm sick? Does it help me get better?" To which he replied that, no coughing and sneezing does not help us get better when sick. Then I asked, "But all it does is spread the sick, right? Why would God make us do that when we're sick?" Dr. Keith was taken aback a little by this seemingly obvious and simple question. I don't remember his exact response, but I recall that his brushing away of my question that followed was the beginning of me realizing that doctors don't know as much about sickness as we, the untrained public, are lead to believe. Regardless of the incompetence of the medical profession, the question remains - why do we cough and sneeze when inflicted with a common virus? I have heard some postulate that it is a flawed attempt on our body's part to rid our system of the sickness - to expel as much of the virus in question as possible. Upon closer examination, this is obviously a silly answer. Our bodies do not in any way shape or form fight off an embedded illness by getting it out of our body. A disturbing scene comes to mind when one imagines a world in which blowing enough snot out will cure us: hospital wards and school nurses' offices filled with snot depositories where the ailed sit blasting mucus hours on end to rid themselves of their ailment. Indeed it is a disturbing world where the phrase "enough snot" has everyday parlance (although I think my sister would be happy, but I won't clarify that out of respect to her and common decency as well.)
But there is an answer, intrepid reader, and the rosetta stone of evolution offers it to us in its beautiful simplicity. It is a long standing debate as to whether viruses qualify as a form of life. There are unlike anything else in that they posses many traits held only by living things and yet are missing certain important qualifiers. This probably just reveals science's mistake in creating specific qualifiers to begin with - certainly if life sprung from non-life then something must exist between, and viruses are very likely the remaining spawn of some form of protolife. There are even now theories being advanced that viruses may be the ancient ancestors of all life as they do appear to be a potential missing link between the living and the inanimate. (For more on viruses as the source of life see The March 2006 issue of Discover magazine.) But my point being that viruses operate similarly to life are are clearly subject to the understood principles of evolution (in fact nonlife such as rocks and rock music are both subject to the same Darwinian principles, but more on that later.) Viruses have, without scientific argument, evolved their various traits and tendencies. But another word about snot before we go further.
Why do we produce snot at all? This I will explain only in brief. The body naturally produces mucus for two reasons: 1. for lubrication purposes (yes, yes, those lubrication purposes, wink, wink. And numerous other less filthy ones, you filthy minded filthy filths) and 2. to trap airborne dirt so that we don't breath it in nor ingest it. This is why when our allergies go haywire, lots of clear snot comes a-flowin out. Our body is overproducing mucus because it interprets the allergy in question as being a dangerous airborne nasty that it must stop with its garrison of boogers. So mucus is a good thing in the case of making certain things more slippery (Like the interior of our intestines. Why? What were you thinking of? Filthy filths.) and in catching, holding, and expelling dirt in the cleansing river that flows forth in the allergen-filled springtime or year-round should you be a smoker.
So why do we sneeze out buckets of snot not to mention sprays of virus-laden spit whenever we have a cold or flu? The answer is simple once one learns to look at it dynamically. Coughing and snotting all over the place when sick is NOT an adaptation that us humans have developed over the millennia to help cure ourselves. It IS an adaptation that viruses have gained to help themselves survive. Certain sicknesses trick our body into reacting in counterproductive ways so that the sickness can spread. Viruses, being extremely simple in makeup, can evolve faster than any multi-celled organism. Somewhere along the way, viruses discovered* this trait allowing them to spread and replicate far more efficiently than before. Everything (and I do mean everything) tries to create copies of itself one way or another. Life is in essence a big ebb and flow of various things trying to make more of themselves while competing with everything else trying to do the same. (Sheds some newly disturbing light on the Hasselhoffian Recusion, doesn't it?) Some virus way back in the days of yore mutated the ability to trick our mucus producing bodies into thinking that more mucus would help to get rid of the virus, when in fact all it does is spread the damnable thing. This simple behavioral trait is so effective that more and more viruses starting jumping on the snotty band wagon and surviving and replicating because of it.
We sneeze, in other words, because the virus wants us to sneeze so it can have more hosts to make more virus babies. It's no wonder, then, that we've all evolved an extreme aversion to anyone else sneezing on us and an extreme disgust with the snot of others. We're not nearly as disgusted with our own snot because our own snot will only ever contain viruses and bacteria already in our system. (This is also very much the reason why other people's farts are nasty and horrid, where-as smelling our own really ain't too bad.) Non airborne viruses and bacterial infections have similar adaptations - you shouldn't scratch your chicken pox, because the scratching causes minor tears in the skin which allows the pox to spread into those tiny open wounds. Chicken pox have evolved the trait of making us itch because it allows chicken pox to spread and continue to survive. I would bet a dollar and a doughnut that certain venereal diseases (if not all of them) make us more horny thus allowing themselves to spread more, although research on this is a little wanting at the moment.
So now you know, and knowing is half the battle GI Joe told me as a kid. The other half, I always guessed involved shooting people but the cartoon never really went into that.
*When I say that the virus "discovered" something I don't mean that there was a little Italian virus sea captain that landed on some phlegmy shore, stuck a flag in the snotty beach and declared that it belonged to Her Majesty Ebola. I simply mean that through the natural process of replication, variations and mutations occur and at some point one of these variations cause the host body for the virus to produce a lil' bit of snot and cough a bit, allowing that virus to spread a lil' better and so on and so forth. The process of evolution helped the virus's RNA "discover" the aforementioned adaptive trait. Although I would like it better if the cells in our body were like the Mayans and had to fight of the Spanish Viruses in glorious mucus battles which could then be adapted into a movie called "Apocasnoto."