Evolution and function of de novo originated genes.

De novo origination has recently been appreciated to be an important mechanism contributing to the origin of genes. Evidence indicates that de novo originated genes can evolve important and even essential functions rapidly. We present an "adaptation following neutrality" process to explain the evolution of essential function of new genes. How new de novo originated genes become involved in pathways and interact with other old genes, and the exact functions of these new genes, however, remains largely undocumented. Examinations of the function of de novo origin and the function of noncoding RNA genes should become more frequent and appreciated in the future studies.