I asked this question in a recent post. If you look at people sitting in an audience, about one-third of them will be touching their mouth.
I had wondered about this for years. Somehow blogging about it helped. A few days ago I was on the subway. Of the persons sitting, the usual fraction were touching their mouth. Nobody standing was touching their mouth with their hands but now and then I noticed them purse or lick their lips.
Which suggested an answer to my question: We get a small amount of pleasure from touching our mouths. The pleasure declines after it is “harvested” and takes several minutes to become available again. This mechanism evolved because it kept our lips moist. At the time it evolved, people spent little time sitting. The pleasure was obtained by pursing or licking your lips, which moistened them. Predictions: 1. if you watch people whose hands are busy, they will purse or lick their lips roughly as often as people in an audience touch their mouths. 2. The more you lick or purse your lips, the less you will touch them with your hands. 3. The more you touch your lips with your hands, the less you will purse or lick them.
Pagophagia (compulsive ice eating) is similar. It is caused by anemia (too little iron). In the Stone Age, there was no ice. An intense desire to crunch something in your mouth would have led you to crunch bones. Bone marrow is high in iron. It’s another mechanism that worked well in the Stone Age but now malfunctions (not that there’s anything wrong with touching your mouth with your hand). My self-experimentation is all about this sort of thing. It’s easy to sit, so we don’t sleep well. It’s easy to be inside in the morning, so we don’t sleep well. It’s easy to eat breakfast, so we don’t sleep well. it’s easy to avoid faces in the morning, so we get depressed. And so on.
More. Andrew Sullivan‘s readers have other ideas: here and here. Thanks to Tyler Cowen.
“This mechanism evolved because it kept our lips moist.”
How does touching our lips w/ our hands keep them moist? More importantly, why is keeping them moist important?
I agree with your suggestion of periodicity and with licking taking over when we’re mobile. Both of these attributes, however, to me suggest a larger purpose – and I’d posit that moist lips are a great surface for capture of local microflora whether by contact with air (while mobile) or by direct sampling (with hands, while seated). Swallowing would then allow for a measured immune response and a constant re-adjustment of immune capability to the local microflora environment. Same goes for swallowing mucus from the nasal passages.
“How does touching our lips w/ our hands keep [our lips] moist?”
It doesn’t — just as chewing ice doesn’t cure an iron deficiency. Back in the Stone Age, with a different environment, the mechanism kept our lips moist because it caused us to touch our lips with our moist tongue.
“the mechanism kept our lips moist because it caused us to touch our lips with our moist tongue”
I’m still not sure I understand the connection between touching one’s mouth and maintenance of moist lips; wouldn’t touching a dry hand to your lips dry them further?
Accepting your reasoning, this still doesn’t explain *why* it’s so important for us to maintain moist lips.
I have found that licking my chapped lips dries them out further, causing more harm than if I left them alone, just as washing dry skin doesn’t restore moisture, it makes it worse. What the lips need is probably not water, its skin oil, right?
Kevin is exactly right- licking your lips will not keep them moist, it will dry them out. I am skeptical that touching your lips gets skin-oils on them and keeps them moist, but that is more probable than your opposite-world conclusion.
I have no idea what chapped lips need. Perhaps more oil. Perhaps something else. I’m talking about normal lips.
Yes. you are talking about normal lips and you are wrong about normal lips. There are no lips that licking makes moist, that is the bottom line. If you don’t believe me, do a little research, then revise your theory because it does not fit reality. Think about it. Would washing your hands really often keep your hands moist? No. It dries them out. Try washing your hands 100 times a day and see what happens to your hands, they will be destroyed.
If you bothered to google, you would find stuff like this:
https://www.wikihow.com/Make-Your-Lips-Smooth
https://www.ehow.com/how_2115815_cure-chapped-lips.html
https://www.carefair.com/Skincare/Tips_to_Stop_Biting_Your_Lip_1427.html
Looks like unanimous agreement- don’t lick your lips.
Btw, I have been watching people who are busy, and have not seen any lick their lips.
If you can find data — not just assertions — that support your idea, please post again.
i think that when i touch my own lips i often rub the ends, moving the moist buildup towards the middle of my lips. thus, my lips become more moist, even though moistening my lips in this fashion is not my intention, maybe it’s instinctive.
Hey Seth, Cliff is right. I have a nervous habit of licking my lips sometimes and all it does it dry them out during the day by removing the natural oils on the surface. After hours of licking my lips I have to start using lip balm! Maybe there’s a benefit to licking lips – but it ain’t keeping them lubricated!
Rob, maybe doing something 20 times is helpful but doing it 100 times is harmful. Maybe you’re licking your lips too much.
Touching one’s mouth may have a social meaning as well; in acting they say that touching your mouth or your head with your hands lowers your social status relative to other people in the room. I’ve never seen any data or experiments to test this though.
Seth, I think you’re now taking your conclusion and searching for somewhat tortured justifications for it – e.g., maybe 20 times is helpful but 100 times is harmful. As far as I know, it’s commonly held that licking your lips dries them out, and it’s consistent with my experience. If you disagree, why not try licking your lips various numbers of times per day and see if it keeps them moist?
It’s a nice theory you have, but I have to disagree a little.
I think the lip licking and lip touching has more to do with nervousness or interest in a person. We lick our lips and when we do so, they are for a little while moist and glistening, which is the same effect you get from lip gloss. It’s a way to draw attention to your mouth. I won’t go in to detail, but it is also a sort of reference to something else.
Also, by licking our lips, we show our tongue, or part of it, for a split second, which could be seen as another way of showing interest and wanting that someone to notice you.
The lip touching has the same use, to draw attention to our lips.
It’s a simple way of intentionally, but mostly unintentionally, show that you are interested in someone. It doesn’t have to be someone you’re in love with, just someone you just saw and found attractive/cute/sexy whatever.
Silent celiacs have an uncurable addication to iceberg lettuce when they exhibit when iron deficient. They may also chew on things — like clothes, anything close to their mouth. Autistic children are reported to exhibit the same thing. In celiac (wheat -intolerance), the gut becomes fenestrated (‘leaky’) and blood leaks out into the stools. Perhaps our bodies respond to ancient signals that defy our current understanding??
In the nutrition world this is known as ‘pica’.
Thanks for this post! This explains a lot that we observe.