I spent most of yesterday either in a plane or in an airport. It is my least favorite of pastimes, worse even than trips to the dentist or having the flu. During the roughly four hours of turbulence on the connecting flight from Chicago to Vancouver, I had ample time to contemplate my own death, and noticed that (as one might imagine) my palms were sweating. But why?
We have all heard of the "fight or flight" response, and I have no inclination to disagree with its apparent evolutionary origins. Even with a lack of scientific understanding, it makes sense - we perceive a threat and react to it by quickly (and basically unconsciously) sizing it up and deciding to either attack it or run from it. Certain physiological effects accompany this response: increased adrenaline in the bloodstream, rapid heart rate, shallow breath. But why also sweaty palms?
I wondered, as I sat there in 15F, why the palms of hands (or feet) should sweat at all - it's not a tremendously large surface area from which to cool ourselves, and having the surface which comes into contact with those things which we are trying to grip get damp and slippery seems massively counter-productive. Regardless of whether I "decide" on fighting or fleeing, I'd like for my hands and feet to remain reasonably dry and capable of retaining grip (be it of a tree limb or the ground or the neck of my enemy). Perhaps it is like certain other traits, a byproduct of the original trait which is being selected for by evolutionary processes. Consider, for example, tameness in dogs: the dog-like shape (floppy ears, drooping tail, etc) is actually a byproduct of the selection of tameness, and in itself has no direct consequence on evolutionary progress. There is also the case of certain human genetic traits being tied together in this fashion: a propensity for inherent intellect and a genetic predisposition to certain diseases, for instance. Sweating palms may be the same; our bodies flush with chemicals that give us the needed boost to run or attack, but which also, as a side effect, cause us to sweat profusely. I can only speculate.
In the end, I suppose, the lesson learned is that evolution is by no means an "elegant" process, and it does not produce "elegant" results. One should feel infinitely lucky to have reached the point that we have.
3 days ago