Teeth cause such dreadful problems in humans that interest in them by non-dentists would seem both unlikely and unhealthy. Who could get excited about tooth decay and gum disease? The physical reality of such apparently moribund structures is paralleled in our cultural perception of them. Diseased or not, the whole mouth is viewed as an unclean region of the body in most parts of the world, especially when it is crammed full of food. Parents, particularly in Western countries, often train children to keep their lips sealed when they are eating even though this is difficult to follow exactly and, indeed, little food seems to re-emerge if the instruction is disobeyed. It is debatable if this training is necessary. While it is possible to sit next to someone at a banquet and get sprayed with seafood, for example, from his or her mouth, the nutritive loss to the diner, represented by the sum of those fine particles, seems negligible compared to what is obviously going down their throat. This is a clear sign of the efficiency of the chewing process. The main reason, in fact, that food particles are expelled is that the person is talking while chewing. Talking involves the expiration of air and that is what pushes food particles forwards. This may seem a strange example but it makes a strong point: the thought of even catching sight of food that was, a moment previously, decorating a plate evokes visceral feelings (of a somewhat inside-out kind) rather than artistic ones.