In a previous publication [1] the author described the base rivalry in monotonous DNA sequences and their effect on the DNA repair mechanism. As described in the article, during the monotonous sequence replication, energies appear theoretically to increase with a progressive replication fork up to the quantum mechanical energy level n=2 because of the base rivalry, and these rivalry energies affect the bond strength between the complementary bases. If there is a tautomeric base pair in the replication position where the rivalry energy is large enough, then in this position an irreparable mutation will occur, since the DNA repair mechanism cannot repair that error because too much binding energy. Thus a mutation (caused by base rivalry) can occur only on condition that a transition of a base pair into its tautomeric form is happened. It is remarkable that this transition likewise can occur by the effect of base rivalry energy. The base rivalry - energy which has an effect on a normal base pair provokes a tunnel process in its hydrogen bond, and produces the tautomeric form. After whose replication a different, irreparable base pair develops from the tautomeric base pair, when the rivalry - energy leads into a very strong hydrogen bond. This happens, however, by chance and in the following we will compute the probabilities of such accidental events. The result of these calculations is the equation (32) which could be useful for the theory of evolution and besides for clearing up of virus mutations. It is remarkable that follows from these calculations that the length of DNA increases itself in the course of evolution (section 7).