It is supposed that mutations in genes of organism occur accidentally, but genetic fixations of the mutant species into all members of an organic species progress selectively. Directed protein evolution through the genetic fixation with the aim of the final goal as the molecular basis of organic evolution has always been progressing in tandem with the decrease of the degree of freedom of protein structure. This is evident in the continuous deceleration of the evolutionary amino acid substitution rate in protein. This seems to demonstrate the existence of the directed selection in also molecular evolution. In addition, it is supposed that directed protein evolution progresses by mainly the self-selection of organisms, and that the primary motive force of this self-selection is the stabilizing force with the aim of the final goal of the maximal stable condition of the non-equilibrium dynamic balance and harmonization of energy at the individual level of the organic species. Therefore, the primary factor of organic evolution is the self-selection of the organism itself, and the evolutionary factors of competition and symbiosis with the other species appear to be secondary.