"No, no," Levine said earnestly. "I'm quite serious. What if the dinosaurs did not become extinct? What if they still exist? Somewhere in an isolated spot on the planet."

"You're talking about a Lost World," Malcolm said, and heads in the room nodded knowingly. Scientists at the Institute had developed a shorthand for referring to common evolutionary scenarios. They spoke of the Field of Bullets, the Gambler's Ruin, the Game of Life, the Lost World, the Red Queen, and Black Noise. These were well-defined ways of thinking about evolution. But they were all -

"No," Levine said stubbornly. "I am speaking literally."

"Then you're badly deluded," Malcolm said, with a dismissive wave of his hand. He turned away from the audience, and walked slowly to the blackboard. "Now, if we consider the implications of the edge of chaos, we may begin by asking ourselves, what is the minimal unit of life? Most contemporary definitions of life would include the presence of DNA, but there are two examples which suggest to us that this definition is too narrow. If you consider viruses and so-called prions, it is clear that life may in fact exist without DNA…"

At the back of the room, Levine stared for a moment. Then, reluctantiv he sat down, and began to make notes.

The Lost World Hypothesis

The lecture ended, Malcolm hobbled across the open courtyard of the Institute, shortly after noon. Walking beside him was Sarah Harding, a young field biologist visiting from Africa. Malcolm had known her for several years, since he had been asked to serve as an Outside reader for her doctoral thesis at Berkeley.

Crossing the courtyard in the hot summer sun, they made an unlikely pair: Malcolm dressed in black, stooped and ascetic, leaning on his cane; Harding compact and muscular, looking young and energetic in shorts and a tee shirt, her short black hair pushed up on her forehead with sunglasses. Her field of study was African predators, lions and hyenias. She was scheduled to return to Nairobi the next day.