A mutational timer is built into the chemistry of DNA

Scientists have discovered that DNA contains a kind of built-in timer that clocks the frequency with which mutations occur. They show that DNA bases can shape-shift for a thousandth of a second, transiently morphing into alternative states that allow the molecule’s replication machinery to incorporate the wrong base pairs into its double helix. Such mismatches, though rare, serve as the basis of genetic changes that drive evolution and diseases like cancer.