RNA editing is thought to be just one way that humans get more out of their 30,000 genes than, say, a fruit fly does with 13,600 or a roundworm does with 19,100. Those creatures have more primitive editing machinery, said the paper’s senior author, Kazuko Nishikura of Philadelphia’s Wistar Institute.

And they have much less of what is sometimes misleadingly called “junk” DNA - a region of the genome that does not produce proteins but nevertheless appears to play a key role in the diversity of life. The new paper is one of numerous recent finds in the booming field of RNA research. In the early days of genetic study, RNA was seen basically as a messenger for its cousin, DNA, carrying instructions to direct the manufacture of proteins.

But other kinds of RNA have since been discovered, including some that regulate or turn off certain genes, playing a role in embryonic development and - when things go awry - in diseases such as cancer. Last year’s Nobel Prize in medicine was awarded to scientists who pioneered a related field called RNA interference. And RNA is now thought to be even older than DNA, with some saying it served as the genetic blueprint for the earliest forms of life.