Ribonuclease A(RNASE A) superfamily is one of the model systems for studying new gene origin and functional innovations in evolutionary biology. Remarkably, gene duplications have been found in many members of RNASE A superfamily, and the functional differentiations of the duplicated genes have been demonstrated to be driven by the adaptive(positive) selection. In this review, we summarize the researches on the evolutionary patterns of RNASE A genes in different species, especially the recent researches at ...