The Naturalistic evolution theory (or unguided evolution) posits the view that new species of life came into being as a result of natural causes only, that is, without any supernatural intervention (compare Creationism). Put this way, it makes a crucial distinction between the more general or vague formulations espoused by proponents of Evolution. The primary claim of Evolution is that human beings "have developed over millions of years from less advanced forms of life". The secondary claim is that science can explain this process satisfactorily in terms of natural forces and processes.