What's the deal with toothbrushes?

I think oral hygiene has a longer history than you think it does. I think though that if you never brushed your teeth that you wouldn't know how they'd feel when clean. My old dentist told me that cavities are basically caused by two different kinds of bacteria, and that not all civilizations and ethnic groups carried it so the image of people with all their teeth rotting out at twenty isn't all that accurate.