The Valley
"This is going extremely well," Levine said, rubbing his hands together. "Far beyond my expectations, I must say. I couldn't be more pleased."
He was standing in the high hide with Thorne, Eddie, Malcolm, and the kids, looking down on the valley floor below. Everyone was sweating inside the little observation hut; the midday air was still and hot. Around them, the grassy meadow was deserted; most of the dinosaurs had moved beneath the trees, into the cool of the shade.
The exception was the herd of apatosaurs, which had left the trees to return to the river, where they were now drinking once again. The huge animals clustered fairly tightly around the water's edge. In the same vicinity, but more spread out, were the high-crested parasaurolophasaurs; these somewhat smaller dinosaurs positioned themselves near the apatosaur herd.
Thorne wiped sweat out of his eyes and said, "Why, exactly, are you pleased?"
"Because of what we're seeing here," Malcolm said. He glanced at his watch, and wrote an entry in his notebook. "We're getting the data that I hoped for. It's very exciting."
Thorne yawned, sleepy in the heat. "'Why is it exciting? The dinosaurs are drinking. What's the big deal?"
"Drinking again," Levine corrected him. "For the second time in an hour. At midday. Such fluid intake is highly suggestive of the thermoregulatory strategies these large creatures employ."
"You mean they drink a lot to stay cool," Thorne said, always impatient with jargon.
"Yes. Clearly they do. Drink a lot. But in my view, their return to the river may have another significance entirely."
"Which is?"
"Come, come," Levine said, pointing. "Look at the herds. Look how they are arranged spatially. We are seeing something that no one has witnessed before, or even suspected, for dinosaurs. We're seeing nothing less than inter-species symbiosis."
"We are?"
Yes," Levine said. "The apatosaurs and the parasaurs are together. I saw them together yesterday, too. I'll bet that they're always together, when they're out on the open plain. Undoubtedly you are wondering why."
"Undoubtedly," Thorne said.
"The reason," Levine said, "is that the apatosaurs are very strong but weak-sighted, whereas the parasaurs are smaller, but have very sharp vision. So the two species stay together because they provide a mutual defense. just the way zebras and baboons stay together on the African plain. Zebras have a good sense of smell, and baboons have good eyesight. Together they're more effective against predators than either is alone."
"And you think this is true of the dinosaurs because…"
"It's rather obvious," Levine said. "Just look at the behavior. When the two herds were alone, each clustered tightly among themselves. But when they're together, the parasaurs spread out, abandoning their former herd arrangement, to form an outer ring around the apatosaurs. Just as you see them now. That can only mean that individual paras are going to be protected by the apatosaur herd. And vice versa. It can only be a mutual predator defense."
As they watched, one of the parasaurs lifted its head, and stared across the river. It honked mournfully, a long musical sound. All the other parasaurs looked up and stared, too. The apatosaurs continued to drink at the river, although one or two adults raised their long necks.
In the midday heat, insects buzzed around them, Thorne said, "So where are the predators?"
"Right there," Malcolm said, pointing toward a stand of trees on the other side of the river, not far from the water.
Thorne looked, and saw nothing.
"Don't you see them?"
"No."
"Keep looking. They're small, lizard-like animals. Dark brown. Raptors," he said.
Thorne shrugged. He still saw nothing. Standing beside him, Levine began to eat a power bar. Preoccupied with holding the binoculars, he dropped the wrapper on the floor of the hide. Bits of paper fluttered to the ground below.
"How are those things?" Arby said.
"Okay. A little sugary."
"Got any more?" he said.
Levine rummaged in his pockets and gave him one. Arby broke it in half, and gave half to Kelly. He began to unwrap his half, carefully folding the paper, putting it neatly in his pocket.
"You realize this is all highly significant," Malcolm said. "For the question of extinction. Already it's obvious that the extinction of the dinosaurs is a far more complex problem than anyone has recognized."
"It is?" Arby said.
"Well, consider," Malcolm said. "All extinction theories are based on the fossil record. But the fossil record doesn't show the sort of behavior we're seeing here. It doesn't record the complexity of groups interacting."
"Because fossils are just bones," Arby said.
"Right. And bones are not behavior. When you think about it, the fossil record is like a series of photographs: frozen moments from what is really a moving, ongoing reality. Looking at the fossil record is like thumbing through a family photo album. You know that the album isn't complete. You know life happens between the pictures. But you don't have any record of what happens in between, you only have the pictures. So you study them, and study them. And pretty soon, you begin to think of the album not as a series of moments, but as reality itself. And you begin to explain everything in terms of the album, and you forget the underlying reality.
"And the tendency," Malcolm said, "has been to think in terms of physical events. To assume that some external physical event caused the extinctions. A meteor hits the earth, and changes the weather. Or volcanoes erupt, and change the weather. Or a meteor causes the volcanoes to erupt and change the weather. Or vegetation changes, and species starve and become extinct. Or a new disease arises, and species become extinct. Or a new plant arises, and poisons all the dinosaurs. In every case, what is imagined is some external event. But what nobody imagines is that the animals themselves might have changed-not in their bones, but their behavior. Yet when you look at animals like these, and see how intricately their behavior is interrelated, you realize that a change in group behavior could easily lead to extinction."
"But why would group behavior change?" Thorne said. "If there wasn't some external catastrophe to force it, why should the behaviour change?"
"Actually," Malcolm said, "behavior is always changing, all the time. Our planet is a dynamic, active environment. Weather is changing. The land is changing. Continents drift. Oceans rise and fall. Mountains thrust up and erode away. All the organisms on the planet are constantly adapting to those changes. The best organisms are the ones that can adapt most rapidly. That's why it's hard to see how a catastrophe that produces a large change could cause extinction, since so much change is occurring all the time, anyway."
"In that case," Thorne said, "what causes extinction?"
"Certainly not rapid change alone," Malcolm said. "The facts tell us that clearly."
"What facts?"
"After every major environmental change, a wave of extinctions as usually followed-but not right away. Extinctions only occur thousands, or millions of years later. Take the last glaciation in North America. The glaciers descended, the climate changed severely, but animals didn't die. Only after the glaciers receded, when you'd think things would go back to normal, did lots of species become extinct. That's when giraffes and tigers and mammoths vanished on this continent. And that's the usual pattern. It's almost as if species are weakened by the major change, but die off later. It's a well-recognized phenomenon."
"It's called Softening Up the Beachhead," Levine said. "And what's the explanation for it?"
Levine was silent.
"There is none" Malcolm said. "It's a paleontological mystery. But I believe that complexity theory has a lot to tell us about it. Because if the notion of life at the edge of chaos is true, then major change pushes animals closer to the edge. It destabilizes all sorts of behavior. And when the environment goes back to normal, it's not really a return to normal. In evolutionary terms, it's another big change, and it's just too much to keep up with. I believe that new behavior in populations can emerge in unexpected ways, and I think I know why the dinosaurs - "