Genetic information is stored in DNA and transcribed as mRNA. The mRNA is usually translated into proteins. However, it has long been known that mRNA can also be reverse transcribed to DNA and integrated back into the genome. Such cases are referred to as retrogenes. In an article, a team from the Max Planck Institute for Evolutionary Biology in Plön and the Zoological Institute of the Chinese Academy of Sciences in Beijing now reports that this process was previously underestimated by at least a factor of one thousand and that it is an important new mutation mechanism.