forms have developed from simpler forms by a series of gradual steps. Evolution, Biological The development of more complex biological forms from less complex forms. Evolution, Naturalistic The idea that evolution has proceeded by means of immanent laws within the physical universe; it is simply a matter of atoms, motion, time, and chance. Evolution, Theistic The view that God began the creation with a de novo act and then worked from within the process of evolution to produce the desired results.