But here’s the thing. Even without knowing the structure of active Cas9, scientists have already started modifying the protein. Such is the pace of Crispr/Cas9 research, which has exploded since the first paper to show its DNA-editing potential in 2012. As scientists have raced to use the system to modify pigs, mosquitoes, mice, and even in one case, nonviable human embryos, others have been working on making it better—so good that it could one day be used to cure diseases in humans.