Proteins have evolved in terms of their structure to achieve quasi-perfection in their respective functions. The process of evolution is simple in principle: spontaneous mutations occur randomly at low frequency (1/10⁶) in nucleic acids sequences, and their resulting modified products are most often abortive, unless they convey a functional advantage to the organism hosting them. In this case the mutated sequence tends to be more frequent than the old one in the offsprings through mere competition. The results of such a process represent the basis for the divergence of species according to Darwin. Its consequences are in fact quite complex, and include:

• achieving stable structure for proteins in their own cellular evironment (aqueous or membranal);
• efficient function (catalytic, regulatory or structural) as independent entities;
• improved functionality in cooperation with other molecules/structures of the cell.