This morning, I woke with a tedious sinus headache, along with a question, “What is pain, exactly?”

The headache wasn’t hard to explain. This is high ragweed season. I happen to be severely allergic to ragweed, which means that my body mistakes the presence of harmless ragweed pollen for a dangerous pathogen. All of my body’s defenses for surrounding and expelling a microscopic foreign invader  — including a massive histamine response – are currently in overdrive: watery eyes; scratchy throat, inflamed sinuses, and, above all, stuffed-up nose.

It’s not unusual, in ragweed season, despite the allergy medicine I take, for me to wake up with a headache, the result of pressure on my sinuses, which tend to get nice and swollen when I’m lying down.

This morning, as I popped a couple of Ibuprofins, I wondered about the purpose of that headache. If pain is an evolutionary response, something designed to safeguard the human animal from a harmful stimulus, what good is a sinus headache? 

But perhaps I should take a step back for a moment, and reconsider the first question: what is pain, exactly? The commonsense answer would seem to be, “I know it when I feel it,” which would register pain as something purely subjective, on the order of Supreme Court Justice Potter Stewart’s famous definition of pornography.

And, as a matter of fact, a standard clinical definition of pain is “whatever the experiencing person says it is, existing whenever he or she says it does.” This is why doctors ask patients that vexing question, “On a scale of 0 to 10, with 0 being no pain at all and 10 being the worst pain you ever felt, how bad is it?”

Doctors need a patient’s help in determining pain since it’s entirely in the eye of the beholder. For non-verbal patients, there are plenty of cues: an infant’s wailing, for instance; or, for elderly patients, so-called “guarding” or “shying” behavior.

But philosophy and medicine have been trying to get to the bottom of pain for thousands of years. Aristotle excluded pain from the list of the five senses, preferring to lump it together with pleasure in an emotive category, “passions of the soul.”

The fact that pain is not simply a physical problem was evident to the ancients. While a Who’s Who of scientists through the centuries – including eminent tourists from other fields, such as Rene Descartes — subjected the human body to ever finer experiments searching for the physical mechanism of pain, there were other underlying mysteries that needed to be explained, too. Why, for instance, were soldiers in the heat of battle often insensible to wounds, even very grave ones? And why, if pain was simply a matter of nerve endings, did the overwhelming majority of amputees feel something chillingly described as “phantom pain,” a piercing agony that seemed to originate in the missing limb?

The modern understanding of physical pain starts with a special class of “sensory fibers” in the body called nociceptors, which can be activated by three categories of stimulation: thermal, mechanical, or chemical. Or, in other words, by a burn; a trauma like a cut or a blow; or an assault by something like a chili pepper.

Let’s say you inadvertently touch the handle of a hot frying pan. Your skin quickly heats beyond the heat pain threshold of about 108 degrees Fahrenheit, which causes the nociceptor to fire off a quick message – “Ow!” – to an area at the base of the spinal chord designed to interpret and transmit this information to the brain. The signal ascends to the brain by way of the thalamus and into the cerebral cortex, which is where consciousness of the pain begins to dawn.

With consciousness comes an involuntary muscle response: “Get thee away from the pan!” Your hand flies back. Perhaps you blow on your fingers, or rub them, which has the effect of confusing, and thus lessening, the initial pain signal.

So the physical stimulus – in this case, the scorched finger – is almost instantly interpreted by the mind. This is where the psychological component of pain enters into the equation. Pain can be amplified by the mind — for instance by fear, as in the case of torture. Or it can be deadened, as in the case of the soldier too engrossed in battle to notice his wound.

Evolutionary biologists find the meaning of pain in its ability to alert us to an imminent danger. That scorched fingertip causes a sharp pain, and that warning causes the body to involuntarily draw back from the handle of the frying pan, which would cause a much more serious burn if we kept touching it. The worse the pain, the graver the danger; the graver the danger, the more urgent the body’s response.

That much makes sense to me. But what about my stupid sinus headache, or, on an infinitely more serious scale, the chronic pain associated with a disease like cancer. What’s the point of that pain? Or, put another way, what’s the point of pain when there’s nothing to be done about it?

This is where we find yet another layer in the story of pain: the cultural overlay. For some societies, the ability to overcome intense pain was the badge of manhood. One thinks of the Native American coming-of-age ceremony that involved piercing the initiate’s chest with wooden skewers, then hanging him from the skewers and slowly adding weights to his legs until he lost consciousness.

The idea behind such a seemingly sadistic ceremony was that pain is a fact of life, especially for a warrior. The man who could withstand the most pain was the most qualified to lead in battle — a somewhat dubious conclusion, it seems to me. Does anyone really think that Napoleon was thicker-skinned than his soldiers?

Our own cultural attitude towards pain is encoded in the English word itself, which ultimately derives from the ancient Greek for “penalty” or “punishment.” Americans tend to take that one step further. We think of pain not only as a punishment, but also an undeserved one, something to be alleviated as quickly as possible, by whatever means possible. This has led to a revolution in medicine, from that modern Godsend, surgical anesthesia, all the way down to those Ibuprofins I gobbled up.

But there’s a part of me that worries about how frightened we are, as a civilization, of pain. Pain is indeed a fact of life, but rarely a lethal one. Sometimes it simply has to be endured.

This column was published in the Perry Co Times on 22 September 2011

For more information, please contact Mr. Olshan at writing@matthewolshan.com