Much like your four-year-old nephew, RNA can only read three-letter combinations. Called codons, these three DNA-base-pair groups form the phrases that RNA translates into the 21 amino acids that underlie all life. But now, University of Cambridge researcher Jason Chin has engineered more literate RNA, capable of reading codons composed of four base pairs. This expands the possible number of codons from 64 to 320, and opens the door for a whole new line of artificial amino acids.