Scientists have directly controlled animals before, but these approaches tend to either require surgery or only work with critters at certain stages in their lives. Researchers might have a more powerful technique in store, however: they've managed to control fruit flies' heartbeats through laser pulses. The approach relies on optogenetics, or modifying the genes of animals to produce materials that respond to light. In this case, the team tweaked flies' heart cells to produce light-sensitive proteins. After that, it was just a matter of zapping the hearts to make them beat on command, whether the flies were larvae or full-grown insects.