Reactive behaviour questioned
Edna Graham, of Christchurch, asked:
Why is it that when a woman gets a surprise or shock she opens her mouth and covers it with a hand whereas a man does not?
Kirk Hamilton, a physiologist at the University of Otago, responded:
It is quite fascinating and entertaining when one goes to Dr Google to read what others suggest might be happening. The question reminds me about yawning and covering up my mouth. I was always told, as a child, that I had to cover my mouth when I yawned, otherwise, I could lose part of my ‘‘soul’’ or, even worse, ‘‘bad spirits’’ might enter my body while my mouth was open. Interestingly, some scientists believe that yawning aids in ventilation of the sinuses and can activate ‘‘selective brain cooling’’. But that is a different story.
I must state I did not find any anecdotal evidence that suggested a difference between women and men when experiencing an episode of surprise or shock. Though a number of suggestions certainly warrant further thought and consideration. One idea I came upon tantalised me as a scientist: When one is watching a television show and a sudden event happens that is scary, we will, including me, lunge backwards and quickly breathe inward and cover our mouth as an action of fear. This could be considered as a protective gesture for our own safety. In fact, our body may be preparing us for a ‘‘reactive behaviour’’ based on what initially ‘‘scared’’ us. So, I would compare this as a stimulusresponse and, some might suggest, the ‘‘fight or flight’’ scenario. If this is the case, then the response of a quick breath of air and covering one’s mouth could be considered as increasing the intake of oxygen for the potential demand of preparing muscles for a fight or runaway action. Could this be related to the scientists who suggested ventilation and brain cooling?
What about some of the other possibilities for explaining the coveringthemouth behaviour? There is thought that if someone is startled, then the reaction might be to be very quiet, thus covering the mouth so as to not make a noise. For instance, if an animal is being pursued by a predator, then being silent is a way to stay alive, though I doubt a mouse would display good etiquette of mouthcovering. Of course for humans, this would be silly unless you are ‘‘running from the law’’. But, for a fieldmouse being hunted by a harrier hawk, this would be a good defensive behaviour. Other suggestions by Dr Google include that it is polite behaviour to cover your mouth, analogous to sneezing; or hiding your feelings, or hiding your crooked teeth, or to cover your mouth because only dentists like to look at an open mouth, or some think it is a learned behaviour, or even to prevent flies from entering your mouth. I think I might stay with my idea of the ‘‘soul and the bad spirits’’. What about you?
Send questions to:
AskAScientist,
PO Box 31035, Christchurch 8444 Or email questions@askascientist.net