by Larry Niven
“They’ve got names.”
“That’s what I decided. GILA MONSTER, ELEPHANT, OSTRICH,” she read. “You give Horace a name so you won’t mix him up with Gilbert. But nobody would get HORSE mixed up with ELEPHANT. There’s only one of each. Poor beasties.” She stopped before the cage marked OSTRICH. “Is this your prize? I’ve been meaning to come see him.”
The bird shifted its feet in indecision; it cocked its head to consider the couple on the other side of the glass. It seemed surprised at Svetz’s return.
“He looks just like a newly hatched chick,” she said. “Except for the legs and feet, of course. They seem to have developed to support the extra mass.”
Svetz was edgy with the need to be in two places at once. His own suggestion had sparked Zeera’s project. He ought to be at the Center. Yet—the ostrich had been his first failure.
He asked, “Does it look neotenous?”
“Neotenous? Of course. Neoteny is a common method of evolution. We have neotenous traits ourselves, you know. Bare skin, where all the other primates are covered with hair. When our ancestors started chasing their meat across the plains, they needed a better cooling system than most primates need. So they kept one aspect of immaturity, the bare skin. Probably the big head is another one.
“The axolotl is the classic example of neoteny—”
“Excuse me?”
“You know what a salamander was, don’t you? It had gills and fins while immature. As an adult it grew lungs and shed the gills and lived on land. The axolotl was a viable offshoot that never lost the gills and fins. A gene shift, typical of neoteny.”
“I never heard of either of them, axolotls or salamanders.”
“They needed open streams and ponds to live, Svetz.”
Svetz nodded. If they needed open water, then both species must be over a thousand years extinct.
“The problem is that we don’t know when your bird lost its ability to fly. Some random neotenous development may have occurred far in the past, so that the bird’s wings never developed. Then it may have evolved its present size to compensate.”
“Oh. Then the ancestor—”
“May have been no bigger than a turkey. Shall we go in and find out?”
* * *
The glass irised open to admit them. Svetz stepped into the cage, felt the tug of the pressure curtain flowing over and around him. The ostrich backed warily away.
The vet opened a pouch on her floating platform, withdrew a stunner, and used it. The ostrich squawked in outrage and collapsed. No muss, no fuss.
The vet strode toward her patient—and stopped suddenly in the middle of the cage. She sniffed, sniffed again in horror. “Have I lost my sense of smell?”
Svetz produced two items like cellophane bags, handed her one. “Put this on.”
“Why?”
“You might suffocate if you don’t.” He donned the other himself, by pulling it over his head, then pressing the rim against the skin of his neck. It stuck. When he finished he had a hermetic seal.
“This air is deadly,” he explained. “It’s the air of the Earth’s past, reconstituted. Think of it as coming from fifteen hundred years ago. There’s no civilization. Nothing’s been burned yet. That’s why you can’t smell anything but ostrich.
“Out there—Well, you don’t really need sulfur dioxide and carbon monoxide and nitric oxides to stay alive. You do need carbon dioxide. There’s a nerve complex in the lymph glands under your left armpit, and it triggers the breathing reflex. It’s activated by a certain concentration of CO2 in the blood.”
She had finished donning her filter helmet. “I take it the concentration is too low in here.”
“Right. You’d forget to breathe. You’re used to air that’s four percent carbon dioxide. In here it’s barely a tenth of that.
“The bird can breathe this bland stuff. In fact, it’d die without it. What we’ve put into the air in the past fifteen hundred years, we’ve had fifteen hundred years to adapt to. The ostrich hasn’t.”
“I’ll keep that in mind,” she said shortly; so that Svetz wondered if he’d been lecturing someone who knew more than he did. She knelt beside the sleeping ostrich, and the platform floated lower for her convenience.
Svetz watched her as she ministered to the ostrich, taking tissue samples, testing blood pressure and heartbeat in reaction to small doses of hormones and drugs.
In a general way he knew what she was doing. There were techniques for reversing the most recent mutations in an animal’s genetic makeup. One did not always get what one expected. Still—there was a Homo habilis several cages down, who had been in the Circle of Advisors until he called the Secretary-General a tyrannical fugghead.
While she was identifying the neotenous developments, she would also be trying to guess what she would have when they were eliminated. Then there were matters of metabolism. If Svetz was right, the bird’s mass would increase rapidly. It must be fed intravenously, and even more rapidly.
In general—but the details of what she was doing were mysterious and dull.
Svetz found himself studying her filter helmet. Full inflation had rendered it almost invisible. A golden rim of it showed by diffraction against the yellow-brown sky.
Did Space really want to take over the Institute for Temporal Research? Then that golden halo was support for their claim. It was a semipermeable membrane. It would selectively pass gasses in both directions in such a way as to make an almost breathable atmosphere breathable.
It had been taken unchanged from a Space warehouse.
Other ITR equipment had come from the space industries. Flight sticks. Anaesthetic needle guns. The low-mass antigravity unit in the new extension cage.
But their basic argument was more subtle.
Once the ocean teemed with life, Svetz thought. Now the continental shelf is as dead as the Moon: nothing but bubble cities. Once this whole continent was all forest and living desert and fresh water. We cut down the trees and shot the animals and poisoned the rivers and irrigated the deserts so that even the desert life died; and now there’s nothing left but the food yeast and us.
We’ve forgotten so much about the past that we can’t separate legend from fact. We’ve wiped out most of the forms of life on Earth in the last fifteen hundred years, and changed the composition of the air to the extent that we’d be afraid to change it back.
I fear the unknown beasts of the past. I cannot breathe the air. I do not know the edible plants. I could not kill the animals for food. I do not know which would kill me.
The Earth’s past is as alien to me as another planet.
Let Space have it!
* * *
The Palace Veterinarian was busy jabbing the pointed ends of color-coded tubing into various portions of the bird’s anatomy. The tubes led back to machinery on the floating platform.
Svetz’s pocket phone rang. He flipped it open.
“There’s trouble,” said Ra Chen’s image. “Zeera’s cage was on its way home. She must have pulled the go-home lever right after she called for the big extension cage.”
“She left before the big cage could get there?”
Ra Chen nodded grimly. “Whatever happened must have happened fast. If she called for the big cage, then she had the automobile. A moment later she aborted the mission. Svetz, I’m worried.”
“I’d hate to leave now, sir.” Svetz turned to look at the ostrich. In that moment all of the bird’s feathers fell out, leaving it plump and naked.
That decided him. “I can’t leave now, sir. We’ll have a full-grown roc here in another ten minutes.”
“What? Good! But how?”
“The ostrich was a neotenous offshoot of the roc. We’ve produced a throwback.”
“Good! Stick with it, Svetz. We’ll handle it here.” Ra Chen switched off.
The Palace Veterinarian said, “You shouldn’t make promises you can’t keep.”
Svetz’s heart leapt. “Trouble?”
/> “No. It’s going beautifully so far.”
“All the feathers fell out. Is that good?”
“Don’t worry about it. See for yourself: already there’s a coat of down. Your ostrich is reverting to chickhood,” she said cheerfully. “Its ancestor’s chickhood. If the ancestor really was no bigger than a turkey before it lost the ability to fly, it’ll be even smaller as a chick.”
“What’ll happen then?”
“It’ll drown in its own fat.”
“We should have taken a clone.”
“Too late. Look at it now: look at the legs. They aren’t nearly as overdeveloped.”
The bird was a big ball of pale yellow down. Its frame had shrunk, but its legs had shrunk much more. Standing, it would have been no more than four feet tall. The extra mass had turned to fat, so that the ostrich was nearly spherical; it bulged like a poolside toy, lying on its inflated side in a pool of feathers.
“Now it really looks like a chick,” said Svetz.
“It does, Svetz. In fact, it is. That was a big chick. The adult is going to be tremendous.” The Palace Veterinarian jumped to her feet. “Svetz, we’ve got to hurry. Is there a basic dole yeast source in this cage?”
“Sure. Why?”
“He’ll starve at the rate he’s growing, unless … Just show me, Svetz.”
The animals of the Zoo ate dole yeast, like everyone else, but with special additives for each animal. A brain tap could induce the animal to imagine it was eating whatever it was used to eating when the time probe had picked it up.
Svetz showed her the yeast tap. She hooked the pipeline to one of the machines on her floating platform; she made adaptations, added another machine.…
The bird grew visibly. Its fat layer shrank, deflated. Its legs and wings stretched outward. The beak began to take a distinctive hooked form, sharp and wicked.
Svetz began to feel panic. Beneath its downy feathers the bird was little more than taut skin stretched over long bones.
The yeast was now feeding directly into two tanks on the floating platform, and from there into the colored tubes. Somehow the Palace Veterinarian was converting the yeast directly into sugar-plasma.
“It’s working now,” she said. “I wasn’t sure it would. He’ll be all right now, if the growth cycle slows down in time.” She smiled up at him. “You were right all along. The ostrich was a neotenous roc.”
At that moment the light changed.
* * *
Svetz wasn’t sure what had disturbed him. But he looked up—and the sky was baby blue from the horizon to the zenith.
“What is it?” The woman beside him was bemused rather than frightened. “I never saw a color like that in my life!”
“I have.”
“What is it?”
“Don’t worry about it. But keep your filter helmet on, especially if you have to leave the cage. Can you remember that?”
“Of course.” Her eyes narrowed. “You know something about this, Svetz. It’s something to do with time, isn’t it?”
“I think so.” Svetz used the key beam then, to avoid further questions. The glass peeled back to let him out.
* * *
He turned for a last look through the glass.
The Palace Veterinarian looked frightened. She must have guessed too much for her own comfort. But she turned away to care for her patient.
The ostrich lay on its side, its eyes open now. It was tremendous, and still scrawny despite the volume of the intravenous feed. Its feathers were changing color. The bird would be black and green.
It was half as big as the elephant next door … whose air of gray wisdom was giving way to uneasiness as he watched the proceedings.
It looked nothing like an ostrich.
* * *
The sky was baby blue, the blue of the deep past, crossed with fluffy clouds of clean and shining white. Blue from the horizon to the zenith, without a trace of the additives that ought to be there.
Unconscious men and women lay everywhere. Svetz dared not stop to help. What he had to do was more important.
He slowed to a walk as he neared the Center. There was pain like a knife blade inserted between his partly healed ribs.
ITR crewmen had fallen in the walkway around the Center, presumably after staggering outside. And there was the Secretary-General’s automobile sitting quietly in front. Behind it, flat on his back, was Ra Chen.
What did he think he was doing there?
Svetz heard the purr of the motor as he approached. So that was it. Ra Chen must have hoped that the exhaust would revive him. Damn clever; and it should have worked. Why hadn’t it?
Svetz looked into the polished metal guts of the motor as he passed. The motor had changed … somehow. What ran it now? Steam? Electricity? A flywheel? In any event, the exhaust pipe Ra Chen had been searching for was no longer there.
Ra Chen was alive, his pulse rapid and frantic. But he wasn’t breathing. Or … yes, he was. He was breathing perhaps twice a minute as carbon dioxide built up enough to activate the reflex.
Svetz went on into the Center.
More than a dozen men and women had collapsed across lighted control panels. Three more figures sprawled in an aisle. The Secretary-General lay in angular disorder, smiling foolishly up at the ceiling. His guards wore troubled sleeping expressions and held drawn guns.
The small extension cage had not returned.
Svetz looked into the empty gap in the time machine, and felt terror. What could he accomplish without Zeera to tell him what had gone wrong?
From 50 Ante Atomic to the present was a thirty minute trip. Ra Chen’s call to the Zoo must have come less than thirty minutes ago. Weird, how an emergency could telescope time.
Unless that was a side effect of the paradox. Unless the paradox had chopped away Zeera’s extension cage and left her stranded in the past, or cast off into an alternate world line, or …
There had never been a temporal paradox.
Math was no help. The mathematics of time travel was riddled with singularities.
Last year somebody had tried to do a topological analysis of the path of an extension cage. He had proved not only that time travel was impossible, but that you couldn’t travel faster than light either. Ra Chen had leaked the news to Space on the off chance that their hyperdrive ships would stop working.
What to do? Start putting filter helmets on everyone? Great, but the helmets weren’t kept at the Center; he’d have to go across town. Did he dare leave the Center?
Svetz forced himself to sit down.
* * *
Minutes later, he snapped alert at the pop of displaced air. The small extension cage had returned. Zeera was crawling out of the circular doorway.
“Get back in there,” Svetz ordered. “Quick!”
“I don’t take orders from you, Svetz.” She brushed past him and looked about her. “The automobile’s gone. Where’s Ra Chen?” Zeera’s face was blank with shock and exhaustion. Her voice was a monotone, ragged at the edges.
Svetz took her arm. “Zeera, we’ve—”
She jerked away. “We’ve got to do something. The automobile’s gone. Didn’t you hear me?”
“Did you hear me? Get back in the extension cage!”
“But we’ve got to decide what to do. Why can’t I smell anything?” She sniffed at air that was scentless, empty, dead. She looked about her in bewilderment, realizing for the first time just how strange everything was.
Then the eyes rolled up in her head, and Svetz stepped forward to catch her.
* * *
He studied her sleeping face across the diameter of the extension cage. It was very different from her waking face. Softer, more vulnerable. And prettier. Zeera had quite a pretty face.
“You should relax more often,” he said.
His ribs throbbed where the ostrich had kicked him. The pain seemed to beat like a heart.
Zeera opened her eyes. She asked, “Why are we in here?”
; “The extension cage has its own air system,” said Svetz. “You can’t breathe the outside air.”
“Why not?”
“You tell me.”
Her eyes went wide. “The automobile! It’s gone!”
“Why?”
“I don’t know. Svetz, I swear I did everything right. But when I turned on the duplicator the automobile disappeared!”
“That.… doesn’t sound at all good.” Svetz strove to keep his voice level. “What did you—”
“I did it just the way they taught me! I hooked the glow-painted end to the frame, set the dials for an estimated mass plus a margin of error, read the dials off—”
“You must have hooked up the wrong end somehow. Wait a minute. Were you using the infrared flash?”
“Of course. It was dead of night.”
“And you’d taken the pills so you’d be able to see infrared.”
“Do you always think that slowly, Svetz?” Then her eyes changed. “I was seeing infrared. Of course. I hooked up the hot end.”
“The duplicator end. That would duplicate empty space where there was an automobile. You’d get emptiness at both ends.”
“Stupid,” Zeera said bitterly. “Stupid.”
She hooked her arms under her knees and relaxed against the curved side of the extension cage. Presently she said, “Henry Ford sold that automobile for two hundred dollars, according to the book. Later he had trouble getting financed.”
“How much is two hundred dollars?”
“I think it depends on the year. Enough to ruin a man, apparently, if you take it away at the right time. Then someone else used assembly lines to make automobiles. And he must have liked steam or electricity.”
“Steam, I’d guess. Steam cars came first.”
“Why would that affect the air? We can breathe what comes out of an automobile exhaust pipe, but we don’t need it to live. Except CO2. A steam automobile would burn fuel, wouldn’t it?”
“I wondered about that too,” said Svetz. “It took me a while, but I got it. Some of what comes out of an exhaust pipe never goes away. It just stays in the air, like a curtain between us and the sun. It’s been there for a thousand years, cutting off half our sunlight. And we made it didn’t happen.”