Where do teeth bacteria come from?

[MajesticQ]

Do they come from us? If so, how come we have bacteria that's bad for us? Shouldn't have evolution dealt with them already if they're bad for us, and why are they there to begin with?

[mith]

Why does no one realize that bacteria can evolve also?

[MajesticQ]

I don't know, but can we get back on topic? Can anyone answer my questions?

[stopherlogic]

Well I know that Lactobacillus is one species guilty of causing tooth decay and this is used in the production of food. Lactobacillus is actually of benefit to us in our gut flora where it out-competes other organisms.

[MrMistery]

the symbiosis between humans and teeth bacteria evolved long before tooth decay was a problem, because the life span of humans was so much shorter.
Basically, why you have bacteria in your mouth is because that bacteria can outcompete other bacteria that would be harmful(as in cause disease). That is generally why you have bacteria all around your body(well, except the ones in your large intestine, those do other stuff too).

Andrei.

[canalon]

And unless you sterilize everything that comes into your mouth, you won't prevent bacteria from installing there.