How can cicadas eat nothing but tree sap for 17 years? How do endosymbiotic relationships evolve? What do bacteria-insect symbioses teach us about the evolution of mitochondria and chloroplasts? On this episode, Art and Marty talk with John McCutcheon, an evolutionary biologist at the University of Montana. John studies symbioses between bacteria and cicadas—exploring what each partner provides for the other, how cicadas transmit bacteria to their offspring, and what the consequences are for the evolution of bacterial genomes (hint: they are extreme!). This research raises basic questions about what an individual even is.