With all the info about the swine flu out there, I’ve seen several mentions of the fact that taking basic precautions like washing your hands often and taking care to not touch your mouth, nose, eyes with your dirty dirty hands will help protect you from infection.
This is absolutely true, and so it occurred to me to wonder why we touch ourselves on the face so much in the first place. Given that it can lead to infection by things that will kill you, there should be substantial evolutionary pressure selecting against it, yet people touch their faces constantly. There must be some reason the behavior continues to exist.
I have a few guesses, but no data to back them up.
The basic hand to mouth behavior is deeply ingrained because it’s important for ensuring that we feed ourselves.
During the vast majority of our evolution, there was nothing to wash with anyway, and since you had to feed yourself by hand, touching your mouth/face at other times didn’t add much to your chances of getting sick.
There isn’t a reason or purpose for anything evolutionarily (if that is a word).
The answer is that, apparently, touching one’s face does not have any significant disadvantage; i.e., it doesn’t prevent enough people from reproducing that it would be a trait that was eliminated from the gene pool. It also begs the question a bit, because it’s possible that what is left right now IS the result of people touching their faces, and that we are just touching our faces a lot less than all others that went before us. We might be the least touchy ancestors of all the people that came before us, and we don’t even know if it matters!
Isn’t it just a trifle silly that this is noted in essentially every thread concerning evolution? Reason or purpose, as the OP title makes clear, in this context refers to evolutionary advantage - something that improves reproductive success.
Yes, this is not strictly accurate for strict interpretations of “purpose”. But this way of speaking is in common use even by experts (e.g. Richard Dawkins).
Sure there is. We need a rectum able to accommodate stools of the texture dictated by our diet, and large enough to hold it for a reasonable length of time, to minimize the time we spend vulnerable in defecation. Any rectum not capable (with a bit of stretching) of having a cucumber shoved up it would also not be suitable for its primary function.
Maybe I wasn’t clear. I’m not asking about the evolutionary advantages of being able to touch your face. I’m asking about the evolutionary advantages of the behavior of compulsively touching your face.
Not touching your face for some length of time is actually difficult to do. And there appear to be valid evolutionary pressures that should keep us from that behavior (public health consensus is that touching your face results in increased mortality due to disease).
It seems to me that there would be advantages in being able to put food in your mouth, blow your nose, and get little foreign objects out of your eyes, and having hands able to touch the face makes all of that easier. But it’s all part of being able to touch almost any part of the body (except the middle of the back), and being able to keep it clean and fix minor injuries on the body, which again seems to me evolutionarily useful.
Pretty sure the OP is not asking why we can touch our face (obviously we need to to feed ourselves, wipe our brow of sweat, clear our eyes and half a dozen other advantageous things), but why people do touch their faces a lot even when they don’t need to. I know I rub my nose and scratch my brow or chin a lot as nervous gestures. Watch a group of people for a bit and you’ll see a lot of similar behavior, to the point where I suspect it is instinctual, which rases the OP’s question, why? It’s apparently harmful in at least one respect, since it speeds transmission of disease.
My guess, faces and hands are both very useful for communicating via body language, so putting the two togeather is even more so, to the point where the advantage to communication is more important then the disadvantage to hygene.
Desmond Morris believes that people touch their own faces in times of stress as a comforting action. In the absence of someone else (like a parent) holding the person, the person in a sense is trying to hold himself/herself.
Infectious diseases spread by “flu mechanisms” are a recent phenomena in the human realm, being side effects of animal husbandry and high-density human populations. In the big picture, people have been able to touch their faces all day long without contracting infectious diseases. Not anymore.
It would be more useful to develop some boilerplate about how the current existence of a behavior or body part doesn’t necessarily mean that behavior or body part gives an evolutionary advantage, but rather that that behavior or body part does not give an evolutionary disadvantage.