In 2011, Yoshihiro Kawaoka reported that his team had engineered a pandemic form of the bird flu virus. Bird flu, also known as H5N1, has infected infected nearly 700 people worldwide and killed more than 400. But it hasn’t yet gained the ability to jump easily from human to human. Kawaoka’s research suggested that capability might be closer than anyone had imagined. His team showed that their virus could successfully hop from ferret to ferret via airborne droplets. In addition to scaring the bejesus out of many, Kawaoka’s controversial study, and a similar study by Ron Fouchier in the Netherlands, also sparked a debate about the wisdom of engineering novel and potentially deadly pathogens in the lab.