Maria diplomatically deferred to her husband. “Sergei? As project director, what do you think?”

“I think that Ms. Janos has offered a solution that we can all live with.”

“There's a quid pro quo,” she said. “Maybe you can help me with my project.”

“My apologies,” Dr. Sato said. “We've been so self-absorbed with our own issues that we've become impolite. What exactly do you hope to find here?”

“An answer to the riddle of the mammoth.”

“The Pleistocene extinction?” Maria said.

Karla nodded. “Picture this island twenty thousand years ago. The land outside our tent was green with vegetation. The earth shook with the thunder made by the feet of vast herds of Mammuthus. These creatures stood up to fourteen feet tall, making them the largest of all the elephants. Their great herds roamed the ancient world, going back more than three million years. They were in North America, from North Carolina to Alaska, in most of Russia and Europe, and even in Britain and Ireland. But by eight thousand B.C., they were nearly gone, except for remnants here and there. The herds of mammoths vanished, along with hundreds of other species, leaving their frozen bones to puzzle scientists like us.”

“The extinction is one of the greatest mysteries in the world,” Maria said. “Mammoths, mastodons, saber-toothed tigers—all disappeared from the face of the earth ten to twelve thousand years ago, along with nearly two hundred other species of large mammals. Millions of animals died on a global scale. What do you hope to find here?”

“I'm not sure,” Karla said. “As you know, there are three theories explaining the extinction. The first is that the Clovis people hunted them to extinction.”

“The main problem with that theory is that it doesn't explain the extinction in the rest of the world,” Arbatov said.

“There is also no fossil evidence to support this idea, so we move on to theory two, that a killer virus swept through the mammal populations of the world.”

“So you think the virus theory is the most plausible?” Dr. Sato said.

“Yes and no. I'll get back to it after we discuss the third theory, drastic climate change. Near the end of the period, the weather changed suddenly. But that theory has a big hole in it. Creatures on a number of islands survived. They would have died out if the extinction were weather related.”

“So if it wasn't overhunting, or a virus or climate change, what was it?” Sergei said.

"The argument has always boiled down to two schools of thought.

Catastrophism, which says that a single event or a series of events caused the extinction. And uniformism, which maintains that extinction happened over a long period of time, from a number of causes."

“Which are you, a catastrophist or a uniformist?” Arbatov said.