The evolution of function appears to have proceeded from a primordial catalyst with little specificity to a highly specific one. As specificity increased, the need to exclude water created a need for flexibility, and flexibility in time led to regulation through induced conformational changes. Induced conformational changes in multisubunit proteins then produced cooperativity. Each of these properties is subject ot fine tuning by modification of the protein structure. The function of the enzyme is itself tuned to high efficiency by the evolution of these interrelated functions.