“Prions,” Malcolm said, from the other side of the boat.
Levine looked blank.
“Prions,” Harding said, “are the simplest disease-causing entities known, even simpler than viruses. They’re just protein fragments. They’re so simple, they can’t even invade a body—they have to be passively ingested. But once eaten, they cause disease: scrapie, in sheep; mad-cow disease; and kuru, a brain disease in human beings. And the dinosaurs developed a prion-disease called DX, from a bad batch of sheep protein extract. The lab battled it for years, trying to get rid of it.”
“You’re saying they didn’t?”
“For a while, it seemed as if they did. The dinosaurs were flourishing. But then something happened. The disease began to spread. The prions are excreted in feces, so it is possible—”
“Excreted in feces?” Levine said. “The compys were eating feces. . . .”
“Yes, the compys are all infected. The compys are scavengers; they spread the protein over carcasses, and other scavengers became infected. Eventually, all the raptors were infected. Raptors attack healthy animals, not always successfully. One bite, and the animal becomes infected. And so, bit by bit, the infection spread through the island again. That’s why the animals die early. And the rapid die-off supports a much larger predator population than you would expect—”
Levine was visibly anxious. “You know,” he said, “one of the compys bit me.”
“I wouldn’t worry,” Harding said. “There may be a mild encephalitis,
but it’s usually just a headache. We’ll get you to a doctor in San José.”
Levine began to sweat. He wiped his forehead with his hand. “Actually, I don’t feel very good at all.”
“It takes a week, Richard,” she said. “I’m sure you’ll be fine.”
Levine sank back in his seat unhappily.
“But the point,” she said, “is that I doubt this island will be able to tell you very much about extinction.”
Malcolm stared back at the dark cliffs for a moment, and then began to speak. “Maybe that’s the way it should be,” he said. “Because extinction has always been a great mystery. It’s happened five major times on this planet, and not always because of an asteroid. Everyone’s interested in the Cretaceous die-out that killed the dinosaurs, but there were die-outs at the end of the Jurassic and the Triassic as well. They were severe, but they were nothing compared to the Permian extinction, which killed ninety percent of all life on the planet, on the seas and on the land. No one knows why that catastrophe happened. But I wonder if we are the cause of the next one.”
“How is that?” Kelly said.
“Human beings are so destructive,” Malcolm said. “I sometimes think we’re a kind of plague, that will scrub the earth clean. We destroy things so well that I sometimes think, maybe that’s our function. Maybe every few eons, some animal comes along that kills off the rest of the world, clears the decks, and lets evolution proceed to its next phase.”
Kelly shook her head. She turned away from Malcolm and moved up the boat, to sit alongside Thorne.
“Are you listening to all that?” Thorne said. “I wouldn’t take any of it too seriously. It’s just theories. Human beings can’t help making them, but the fact is that theories are just fantasies. And they change. When America was a new country, people believed in something called phlogiston. You know what that is? No? Well, it doesn’t matter, because it wasn’t real anyway. They also believed that four humors controlled behavior. And they believed that the earth was only a few thousand years old. Now we believe the earth is four billion years old, and we believe in photons and electrons, and we think human behavior is controlled by things like ego and self-esteem. We think those beliefs are more scientific and better.”
“Aren’t they?”
Thorne shrugged. “They’re still just fantasies. They’re not real. Have you ever seen a self-esteem? Can you bring me one on a plate? How about a photon? Can you bring me one of those?”
Kelly shook her head. “No, but . . .”
“And you never will, because those things don’t exist. No matter how seriously people take them,” Thorne said. “A hundred years from now, people will look back at us and laugh. They’ll say, ‘You know what people used to believe? They believed in photons and electrons. Can you imagine anything so silly?’ They’ll have a good laugh, because by then there will be newer and better fantasies.” Thorne shook his head. “And meanwhile, you feel the way the boat moves? That’s the sea. That’s real. You smell the salt in the air? You feel the sunlight on your skin? That’s all real. You see all of us together? That’s real. Life is wonderful. It’s a gift to be alive, to see the sun and breathe the air. And there isn’t really anything else. Now look at that compass, and tell me where south is. I want to go to Puerto Cortés. It’s time for us all to go home.”