For palaeontologists, DNA is infuriatingly fragile. Its long chains begin to break apart shortly after death, destroying valuable information about the deceased parent organism. Unlike bones, footprints and even faecal matter, which can comfortably survive—in fossilised form—for millions of years, DNA rarely lasts much more than a hundred. In recent decades scientists have discovered that some exceptionally well-preserved bodies do still have readable fragments of genetic code hundreds of thousands of years after death. But these have been tiny scraps. They lack much of the valuable information that an intact genome provides.