Harvard University epidemiologist Marc Lipsitch has become a prominent voice in the debate over studies that create potentially dangerous new flu viruses that critics fear could escape from laboratories and cause a pandemic. This past July, Lipsitch organized 18 scientists who crafted a statement calling for governments to curtail these controversial studies until risks and benefits can be thoroughly weighed. It drew an online response a few days later from an opposing alliance of researchers who support the experiments. Still, to Lipsitch's surprise, they gave a little ground: They agreed that researchers needed to publicly air the issues. The turn of events highlights how Lipsitch, a one-time philosophy major turned biologist, has recently shown a knack for being in the right place at the right time, with a message and data that have helped shape the conversation.