Devolution, de-evolution, or backward evolution is the notion that a species can change into a more "primitive" form over time. In terms of modern biology, the term is a misnomer for that concept because it presumes that there is a preferred hierarchy of structure and function, and that evolution must mean "progress" to "more advanced" organisms. That confusion is based on two conceptual errors: the idea that evolution is supposed to make species more "advanced", as opposed to "primitive"; and the idea that some modern species that have lost functions or complexity accordingly must be degenerate forms of their ancestors. Its use is therefore mainly historical apart from its use by creationists.