"Predator" bacteria (green) surround "prey" bacteria (red) in this petri dish version of the Serengeti. Rather than eating their prey, however, predator cells release a chemical that activates a suicide gene in the prey. Prey cells also release a chemical, but one that promotes survival of the predators. Researchers genetically programmed the cells to "communicate" with each other in this way and function as a synthetic ecosystem. The artificial system acts as an experimental model and can help us understand behaviors in more complex, natural ecosystems. Courtesy of Hao Song, Duke University.