“Until then,” said Ponter, making his decision, “yes, I would be glad of your company.”

Mary Vaughan’s lab at York University was much as she had left it—not surprisingly, since, despite all the things that had happened to her, it had only been twenty-three days since she’d last been here.

Daria Klein—one of Mary’s grad students—had clearly been in repeatedly during Mary’s absence, though. Her work area had been rearranged, and the chart on the wall showing her sequencing of the ancient Egyptian Y chromosome she was working on had many more spaces filled in.

Arne Eggebrecht of the Pelizaeus Museum in Hildersheim, Germany, had recently suggested that an Egyptian body purchased from an old Niagara Falls tourist attraction might in fact have been Ramses I, founder of the line that contained Seti I, Ramses II (the one portrayed by Yul Brynner in The Ten Commandments ), Ramses III, and Queen Nefertari. The specimen was now housed in Atlanta’s Emory University, but DNA samples had been sent to Toronto for analysis; Mary’s lab was world-renowned for its success in recovering ancient DNA, a fact that had led directly to her involvement with Ponter Boddit. Daria had made considerable progress on the putative Ramses in Mary’s absence, and Mary nodded approvingly.

“Professor Vaughan.”

Mary’s heart jumped. She turned around. Atall, thin man in his midsixties was standing in the lab’s doorway. His voice was deep and rough, and he had a Ronald Reagan pompadour.

“Yes?” said Mary. She felt her stomach knotting; the man was blocking the only way out of the room. He was wearing a dark gray business suit, with a gray silk tie, its knot loosened. After a moment, he stepped forward, pulled out a thin silver business-card case, and proffered a card to Mary.

She took it, embarrassed to see that her hand was shaking as she did so. It said:

SYNERGY GROUP

J. K. (Jock) Krieger, Ph.D.

Director

There was a logo: a picture of the Earth, divided neatly in half. On the left half, the oceans were black and the landmasses white, and on the right half the opposite color scheme was used. The street address given was in Rochester, New York, and the e-mail address ended in “.gov,” signifying a U.S.-government operation.

“What can I do for you, Dr. Krieger?” asked Mary.

“I’m the director of the Synergy Group,” he said.

“So I see. I’ve never heard of it.”

“No one has yet, and few will, ever. Synergy is a U.S. government think tank that I’ve been putting together over the last couple of weeks. We’re modeled more or less on the RAND Corporation, although on a much smaller scale—at least at this stage.”

Mary had heard of RAND, but really didn’t know anything about it. Still, she nodded.

“One of our principal sources of funding is the INS,” said Krieger. Mary lifted her eyebrows, and Krieger explained: “The U.S. Immigration and Naturalization Service.”

“Ah,” said Mary.

“As you know, the Neanderthal incident caught us—caught everybody—with their pants down. The whole thing was over practically before it had even begun, and for the first few days we’d just dismissed it as another crazy tabloid story—like finding Mother Teresa’s face in a prune Danish, or a Bigfoot sighting.”

Mary nodded. She hadn’t believed it herself at the outset.

“Of course,” continued Krieger, “it may be that the portal between our universe and the Neanderthal one might never reopen. But, in case it ever does, we want to be ready.”

“We?”

“The United States government.”

Mary felt her back stiffen slightly. “The portal opened on Canadian soil, and—”

“Actually, ma’am, it opened a mile and a quarter beneath Canadian soil, at the Sudbury Neutrino Observatory, which is a joint project of Canadian, British, and American institutions, including the University of Pennsylvania, the University of Washington, and the Los Alamos, Lawrence Berkeley, and Brookhaven National Laboratories.”

“Oh,” said Mary. She hadn’t known that. “But the Creighton Mine, where SNO is located, belongs to Canada.”

“More precisely, it belongs to a Canadian publicly traded corporation, Inco. But, look, I’m not here to argue sovereignty issues with you. I just want you to understand that the United States has a legitimate interest in this matter.”

Mary’s tone was frosty. “All right.”

Krieger paused; he clearly felt he’d gotten off on the wrong foot. “If the portal between our world and the Neanderthal world ever reopens, we want to be ready. Defending the portal doesn’t seem too difficult. As you may know, the Twenty-second Wing Command of the Canadian Forces, based at North Bay, has been charged with securing the portal against invasion or terrorist attacks.”

“You’re kidding,” said Mary, although she suspected he wasn’t.

“No, I’m not, Professor Vaughan. Both your government and mine are taking all this very seriously.”

“Well, what’s this got to do with me?” asked Mary.

“You were able to identify Ponter Boddit as a Neanderthal based on his DNA, correct?”

“That’s right.”

“Would the test you did be able to identify every Neanderthal? Could it reliably tell if any given person was a Neanderthal or a human?”

“Neanderthals are human,” said Mary. “We’re congeners; we all belong to the genus Homo. Homo habilis, Homo erectus, Homo antecessor—if you believe that’s a legitimate species—Homo heidelbergensis, Homo neanderthalensis, Homo sapiens. We’re all humans.”

“I concede the point,” said Krieger, with a nod. “What should we call ourselves to distinguish us from them?”

“Homo sapiens sapiens,” said Mary.

“Not very catchy, is it?” replied Krieger. “Didn’t I hear someone call us Cro-Magnons? That’s got a pleasant ring to it.”

“Technically, that term refers to a specific population of anatomically modern humans from the Upper Paleolithic of southern France.”

“Then I ask again: what should we call ourselves to distinguish us from the Neanderthals?”

“Well, Ponter’s people had a term for fossil humans from their world that looked like us. They called them Gliksins. It would be an appropriate parity: we call them by a name that really refers to their fossil ancestors, and they call us by a name that really refers to our fossil ancestors.”

“Gliksins? Is that what you said?” Krieger frowned. “All right, I guess that will do. Can your DNA technique reliably distinguish between any Neanderthal and any Gliksin?”

Mary frowned. “I doubt it. There’s a lot of variation within species, and—”

“But if Neanderthals and we Gliksins are different species, surely there are genes that only they have, or only we have. The genes that give them those browridges, for instance.”

“Oh, lots of us Gliksins have browridges. They’re very common among males from Eastern Europe, for instance. Of course, the doubly arched Neanderthal one is quite distinctive, but…”

“Well, what about those triangular projections into their nasal cavities?” asked Krieger. “I’ve heard that they are truly diagnostic of a Neanderthal.”

“Yes, that’s right,” said Mary. “I suppose if you wanted to look up each person’s nose…”

Krieger did not sound amused. “I was thinking you might be able to find the gene responsible for that.”

“Oh, possibly, although they themselves may already know. Ponter implied that they long ago undertook the equivalent of our Human Genome Project. But, sure, I suppose I could search for a diagnostic marker.”

“Can you do it? How fast can you do it?”

“Take it easy,” said Mary. “We only have DNA from four prehistoric Neanderthals and one contemporary one. I’d really rather have a much larger sample base.”