Stress is bad. You will receive this opinion about stress (or some variation of it) from almost anyone you ask. It is drummed into us from childhood onwards, with people pointing to almost any illness or unfortunate outcome and making the link to the unchecked presence of stress (among other things) in the unfortunate victims history. If only they had managed their stress better they solemnly intone, shaking their heads in dismay and warning, this could have been prevented. As a child I inwardly swore to never let stress into MY life as an adult, placing it along side stern messages to avoid heroin addiction, unprotected sex with multiple high-risk partners, and failure to tithe on Sundays.

So how did such a foul beast as stress creep into our collective experience? What purpose could there ever have been in the creation of the stress response, or does it simply belong to the same category as the Seven Deadly Sins (theyre not your fault just avoid them)?

The stress response, it turns out, is one of evolution's best tricks to ensure that human beings survive long enough to pass along their genes to the next generation. Let's take the example of a semi-mythical ancestor, the caveman. Imagine our caveman walking down a prehistoric trail in search of dinner, when from around a corner a hungry and ill-tempered overgrown cave bear appeared on the path. The caveman had two choices to pick from for a chance at survival. He could fight the bear and hope to kill it with a skillful blow, or he could run like crazy in the opposite direction. (Cavemen who opted for the third choice - holding still while the bear made a meal of them - had their genes quickly removed from the caveman gene pool.)

Whether the caveman chose to fight or run, his body's response to the stressful situation was identical. The perception of danger by his mind was converted to electrical signals that traveled along his nervous system to various organs in his body, which released hormones that prepared him to survive the short-term episode of danger. The sequence of events is still the same for people today. Biologists refer to it as the fight-or-flight reaction.

Epinephrine (also known as adrenaline) is released from the adrenal glands into the bloodstream. Within seconds, the pupils dilate to admit the maximum amount of light, the bronchioles dilate to admit the maximum amount of air, the heart rate increases, the blood pressure rises, blood vessels to deep muscles dilate at the same time as blood vessels to the skin constrict (to promote muscle movement and prevent blood loss in case of wounds), and alertness and sensitivity to the environment are at their maximum. Cortisol, the body's natural steroid, is also released by the adrenal glands as an aide to helping the body survive the short-term bout of extreme stress. In addition, the liver converts stored glycogen into a burst of glucose that floods the bloodstream and feeds the cells that are most active during the stress reaction. Blood flow is shunted away from areas of the body that are not required for short-term survival (such as the digestive tract) in order to ensure adequate pressure for those muscles and organs that will promote survival. This cascade of events has been so successful at keeping organisms alive through periods of danger that biologists find it in some form in almost every animal above the single-cell level of organization.

Let's assume that the caveman lived to tell the tale. He either killed the bear, or outran it (or at least ran faster than the cave man next to him, thus selecting for speed in the gene pool). He returned to the family cave, where his perception was that he was safe once more. The electrical signals from his brain that were triggering his endocrine organs to release stress hormones into his bloodstream slowed or stopped. His pupils, bronchioles, heart rate, blood pressure, blood flow distribution, and level of awareness all returned to their normal levels. He was able to eat a meal and digest it properly, and then fall into a well deserved slumber at the back of the cave.

Seen in this context, stress is recognized as an adaptive mechanism that is important for the survival of the human body during periods of short-term crisis. Where stress becomes a maladaptive response is when the mind perceives the environment as always stressful. We never get to the point where we are back to the cave. The body, unaware of whether our perceptions of the environment as stressful are appropriate or not, simply reacts with the same mechanisms that have been keeping people alive for countless generations. That doesnt always work well for us in todays world. More about that in the next article.

To review: cute stress has signs and symptoms which may include a racing heart beat, rapid breathing, palpitations, hyper-vigilance, muscular tension, pale skin (like a ghost), wide-eyed stare, and an inability to concentrate on abstract thoughts. In emergency situations these reactions serve to keep us alive, but they are not healthy for us over long periods of time.