DNA is the genetic code that provides the biological instructions for every living species, but not every bit of DNA helps the species survive. Some pieces of DNA are more like parasites, along for the ride and their own survival.

To translate DNA into proteins, the building blocks of life, many of these selfish DNA elements have to be removed from the genetic code. Doing so enables the body to produce the wide diversity of proteins that allow for complex life, but the process can also lead to health problems, like some kinds of cancer.

University of California, Santa Cruz researchers are studying the ways that these genetic elements hide and make copies of themselves, so they can propagate within a species’ DNA, or even hop from one species to an unrelated one in a process called horizontal gene transfer.