Ambient light on without asking?

When I view a polygon from the front and the light is behind it the polygon is never black (0.0, 0.0, 0.0), more dark gray. There seems to be some kind of ambient light. I never enabled one. How do I switch this off? glDisable(GL_LIGHT0-8) doesn't work.

-- Thomas

[Bob]

The default scene amblient light is (0.2, 0.2, 0.2, 1.0). You can change it with glLightModelfv and GL_LIGHT_MODEL_AMBIENT.