Something that has hit bottom can go no lower.

VOA: special.2009.09.20

VandeBerg says he and his colleagues go out of their way to use lower forms of animals before experimenting on chimpanzees.

VOA: standard.2010.02.16

"We have to go to the best centers and try to identify specific practices at these centers that could be exported to lower performing centers."

VOA: standard.2010.07.14