Americans Edward Lewis and Eric Wieschaus will share the $1 million Nobel Prize in Medicine with German Christiane Nuesslein-Volhard. The three were recognized for work on genetic studies that could help explain birth defects and miscarriages. All three used that classroom staple, the fruit fly, as the basis of their experiments. "They found the genetic master control system for taking a fertilized egg and turning it into a fruit fly embryo," says medical writer Christine Gorman. Because the system exists in other species, she adds, "it explains a lot about the development of human embryos as well."