People should be afraid of “germs”: the wrong kind of bacteria (not to mention viruses) will totally **** you up, or kill you.
On the other hand, people’s hygiene and sanitation methods are mostly totally detached from any real risk assessment or careful rational understanding. There are all kinds of nasty bacteria on the surface of your skin, and all over in the environment, pretty much all the time (indeed, bacteria already living on your body is the main source of infections when some wound breaks the skin), and rubbing your body with hand sanitizer all the time (for instance) accomplishes almost nothing.
The main model/metaphor people use for thinking about sanitation and personal hygiene is a “clean”/“dirty” or “pure”/“tainted” model. The way this model works, some things are dirty, and anything that touches those also becomes dirty, until it has been purified/cleaned. The purification is mostly a ritual; actual cleaning may be happening, but it’s of secondary importance. A critical aspect of this model is that the state of each thing is binary.
* * *
People apply this same model in many varied circumstances, some of which aren’t about “germs” per se.
To take one example, according to this model, whenever teeth touch food, they become unclean, and need to be “brushed” (the purification ritual), because if left in the unpure/dirty state, it’s thought that tooth decay will result.
When people actually brush their teeth, they often do a terrible job of it. The purpose of toothbrushing is to remove plaque that might build up in various odd corners of your teeth. Thus, brushing the easy front surfaces of the teeth accomplishes very little. But people manage to “brush their teeth” in 30 seconds sometimes. People also tend to brush their teeth right after eating, even though that has been shown to be worse for teeth than brushing teeth before eating (or alternately, a few hours later).
My personal model of toothbrushing is quite different: namely, I think the main predictor of tooth decay is diet, and suspect that someone who eats mostly vegetables and meat (rather than sugar or bread or rice or very acidic things) will probably end up with great teeth even if they only brush them once per week (or never), whereas someone who constantly chews gum, mostly drinks soda and fruit juice, and eats lots of processed food will be more likely to end up with cavities even if they brush religiously.
I only brush my teeth once every day or two (or sometimes 4, if I’m e.g. traveling), but I make sure to be thorough about it, getting all the built-up plaque out of the spaces between teeth, the area along the gumline, the “valleys” on the molars, and the back sides of the teeth (especially the back sides of the front bottom teeth seem to be tricky to get to with a toothbrush). In the mean time, I limit the amount of sugar and processed food in my diet, and I almost never drink soda or fruit juice.
* * *
Other examples of this broken pure/impure decision model: throwing away a whole piece of food at the first sign of mold, washing clothes after they’ve been worn “once” regardless of the circumstance, making sure to always wash the outside of fruit and vegetables before eating them but doing a half-assed job of it.
