The Guardian has a profile interview with aging researcher Cynthia Kenyon: “Cynthia Kenyon: ‘The idea that ageing was subject to control was completely unexpected’”.
This finding built on her earlier research, but to the rest of the scientific community, "the idea that ageing was subject to control was completely unexpected," Kenyon says, before struggling to find the words to describe how she felt when she realised the magnitude of the discovery. "It was very profound because you look at these worms, and the normal worms are dying, and the worms in this other culture dish are young. And you think: 'Oh my God, they should be dead.' It was like finding something that shouldn't be. It makes your hair stand up." Then came a second realisation: "You just think, 'Wow. Maybe I could be that long-lived worm.'"
Kenyon’s story is a great one, because it illustrates how a productive research path can depend on one serendipitous observation.