Brush your teeth

(Note: I’ve been answering questions on Quora for a while, and this one has proved to have a “long tail”: it’s been slowly, but consistently, getting voted up. SO I’m putting it here for archival purposes.)

Q: For hundreds of thousands of years, humans did not brush their teeth. What happens if I stop altogether? At what point does my mouth start to take care of itself? Animals don't brush their teeth; how do they pull it off?

A: You can’t expect your mouth to “take care of itself” the way ancient humans did. Modern humans in advanced industrial societies have a different bacteria and different diet (probably more sugars and other carbohydrates) than ancient humans.

Ancient humans tended to have good dental health. Two research papers published in 2013 both suggest that human cavities started to take off about 10,000 years ago – roughly about the same times as we were moving to agriculture. They show this in part by comparing modern to ancient bacteria that live in our mouths.

• Evolutionary and population genomics of the cavity causing bacteria Streptococcus mutans
• Sequencing ancient calcified dental plaque shows changes in oral microbiota with dietary shifts of the Neolithic and Industrial revolutions

Even if you could go back to the ancient diet, you are not going to be able to get the ancient bacteria to live in your mouth – they are long gone.

Just brush your teeth.

External links

For hundreds of thousands of years, humans did not brush their teeth. What happens if I stop altogether?