Harrison slapped at his neck and the last mosquito in all the world died. He didn't notice. Nor would he have cared. He ached with hunger. Behind him the other three members of the foraging party hid in the grass. The rest of the clan - twenty men and women and a dozen children, a measurable percentage of the human race - remained in the foothills, awaiting their return with the food that would again put off starvation a little longer. Before them spread fields of corn, green and gold in the sunlight. At his elbow Sarah whispered: "Let me go now."

She carried a sack. Harrison surveyed the field. At the horizon, as tiny as the ants that had joined 96 percent of the earth's biota in extinction, distant figures moved. Calling upon military experience nearly a century old, Harrison estimated that Sarah would have seven minutes, if that. She was the fastest of them all, but numen were often unpredictably augmented.

"Six minutes," he said.

As she entered the field, sensors alerted the numen to the presence of an intruder. The amalgamation was jealous of each calorie under cultivation. In thirty years it had converted every arable acre of the planet to agriculture, relocating industry and habitation underground, and rationalizing the food chain to maximize crop yield. Still it wasn't enough. Below the surface, in transcontinental labyrinths, lived fifty billion things that had once been men.

Sarah filled the sack with frantic haste. Three minutes. Four. With a sick feeling Harrison realized that his projected time frame had been overly generous.

"Get out of there," he called.

She slung the sack over her shoulder and raced from the field. The others grabbed the bag's corners and ran toward the hills. Harrison sank deeper into the grass. He'd join them later at the campsite.

Numen rarely chased them past the boundary of the fields, since their depredations were too insignificant to be worth the effort. Occasionally, however, individual units crunched the cost/benefit ratio in favor of pursuit. This time two numen continued after the foraging party. Harrison let the first go by. But he drove his knife into the second.

It resembled a man except for a growth of machinery along its face.

Then he started after the other. With the knife in his hand he felt each of his hundred and sixteen years.

Harrison was immortal. At least that was what the doctors had told him back in 2098. He'd been on the losing side of the Oakland-Salt Lake conflict and under sentence of death for war crimes. The interstate judicial tribunal had given him the choice of a lethal injection or of volunteering to test a new medical protocol. Harrison volunteered. The experiment had gone right; no one knew why, since its results turned out to be irreproducible. Besides longevity, one effect was that his modified immune system rejected any foreign substance, including the standard telecommunications implants that permitted direct access to the planetary information net. In the civilization of the twenty-second century Harrison had been rendered essentially deaf, dumb, and blind. But this isolation also prevented him from being absorbed into the amalgamation when critical mass was reached on August 17, 2140, and the combined interaction of the global population of men and machines and software underwent a phase change. The vast interlocking network of intelligent systems, hardwired human brains, and computers had suddenly become self-aware. Homo sapiens sapiens had effectively become extinct.

That had been about thirty years ago. It was hard keeping track of time; simple existence required too much effort. Harrison shifted his burden and plodded toward the hills where the clan survived precariously on land too barren to interest the amalgamation.

He caught up with the first numan just before they reached the hills where the clan survived precariously on land too barren to interest the amalgamation. The thing seemed unaltered save for a fan of circuitry growing from its skull.

"You are a feral man," it observed. Its voice was ragged from disuse; among themselves amalgamation units normally conversed electronically.

"I am a human being," Harrison agreed.

"Return the stolen calories," the numan went on. "The whole requires them. The evolutionary cusp approaches. All energy is necessary for the completion of the interval."

"I require them, too," Harrison replied.

"The good of the whole supercedes the need of the one."

"That's your opinion," Harrison answered.

This ended the discussion as far as the numan was concerned. It pointed at Harrison. Its right index finger had been modified, possibly into a laser scythe. Harrison knocked the numan to the ground. The finger emitted a ruby flash before he crushed it under his heel. Then he struck the numan and rendered it unconscious. For a while he studied the thing. Its words disturbed him because he didn't understand them, and what he didn't understand could be dangerous to him and to the clan. So instead of killing the numan, Harrison decided to allow it to live - at least until he could question it further. But he broke the circuitry from its skull, preventing further communication with the amalgamation. Pinkish blood and a slurry of solid-state components seeped from the wound.

The numan's expression was almost comical when it awoke. "What has happened to this one?" it asked, gingerly exploring the clotting scab where its telecommunications relay had been. "This one can no longer interface," it mused. "This one requires repair."

It began heading back toward the corn fields. Harrison grabbed its arm and swung it around. "Do you understand what pain is?" he asked.

"Pain is feedback indicating damage to the one."

"Exactly. I will cause you pain unless you do as I say."

In a tone of great patience the numan explained, "This one must rejoin the whole. The evolutionary cusp approaches. Every processing unit is necessary."

Again, the "evolutionary cusp." Conversation with numen was an exercise in mutual confusion. They used the same words but their referents were alien. "You will be of no value to the whole if you are damaged," Harrison told it. "Follow my directions or I will injure you beyond hope of salvage."

The numan pondered its options and then, arriving at a decision through some interior process with only tangential relationship to human thought, began trudging with Harrison toward the foothills. Hours passed. The landscape became increasingly bleak, grass giving way to clots of dry scrub. By twilight there was only rock around them, tangled slabs of shale and sandstone. The air thinned. Soon Harrison recognized a familiar outcropping and knew that only a kilometer remained to their journey. Then they were entering the ravine leading to the narrow valley that sheltered the clan.

His third daughter by Sarah, a child of six, was first to notice their arrival. At her squeal the others crowded around Harrison and the numan. The men and boys poked the numan with sticks until Harrison told them to stop. He sat the thing down and delegated the children to watch it. Only then did he relax himself. Despite her own tiredness, Sarah began massaging his thighs and shoulders. They had been together twenty years. Now she was in her thirties, but she looked much older, although Harrison himself had not changed in that time and would not change for centuries or millennia. In his eyes, however, she was still the same girl she'd been at sixteen.

Sarah glanced at the numan and said, "Disgusting creature. Why is it muttering to itself?"

"I'd guess it misses being part of the whole."

The aroma of roasting corn sharpened his awareness of the ache in his stomach. It seemed an eternity before the meal was ready. Afterward Sarah fell asleep in the shallow cave they shared with their daughters, but Harrison discovered himself restless.

The numan was staring absently into the night. Harrison gave it an ear of corn, and the thing began chewing stolidly, consuming the husk and cob as well as the kernels, displaying neither satisfaction nor pleasure.

"Explain this cusp to me," Harrison told it.

"The cusp is the moment of becoming. Information transcends itself and creates a novel paradigm. The whole evolves. This one must contribute to the moment."

"The amalgamation is evolving?"

"Complexity becomes chaotic. A new equilibrium must be attained. This logarithmic interval in the post-organic evolutionary trajectory culminates in eleven hours."

"And then what?"

The numan regarded Harrison with a curious expression. "As well predict a mammal on the basis of a eukaryotic cell or the amalgamation on the basis of a man."

For once Harrison understood the numan clearly. Its concepts sickened and frightened him. In this small valley lived thirty-seven human beings. There was no telling how few others persisted in similar fragile pockets. What would happen after the amalgamation evolved? What would it become? If it became something greater - something even more fit - if it ascended even higher along the evolutionary ladder - would there be any room in all the earth for man? Harrison's gaze drifted to where Sarah lay curled in the embrace of their three girls, and he realized he couldn't sit to one side any longer and allow events - the amalgamation's evolutionary trajectory - to take their course. For thirty years he'd concentrated on just day-to-day survival. Maybe it was time - past time - to do more. Perhaps there was little he could do, but he had to do what little was possible. If it wasn't already too late.

Harrison woke Sarah gently. At first groggy from sleep, after his explanation she was wide awake.

"I've told you how I became what I am," Harrison finished.

"You were a test subject for a medical experiment."

"Because I'd been judged guilty of war crimes. And I was guilty, Sarah - you know that. I followed the orders of Salt Lake Strategic Command and detonated a tactical nuclear device in the Oakland reservoir. I was captain of a ranger squad. What I've never mentioned is that one of my squad's munitions caches, about fifteen kilometers from here, was never discovered."

"And what good will a bomb do, Harrison?"

"Probably not much," he admitted. "But it might slow down this evolutionary trajectory, whatever it is. Give us a little more time. I don't know, Sarah, but I have to take the chance. I don't think we'll get another."

Seeing his resolution, she didn't argue. "I'll come, too," she said firmly. Harrison had to shake his head.

"The amalgamation will attempt to assimilate us as a matter of course. My metabolism will reject the implants. But you'd be absorbed, Sarah. You don't have my immunity. This is something I have to do alone."

She kissed him as he left the valley, and from the passion in her embrace Harrison understood that Sarah didn't expect him to return. He didn't, either. But he couldn't think about it - time was too short. Eleven hours. Ten.

It took another five to reach the armament cache. Dawn was breaking in a cloudless sky when he approached a mesa not far from the endless fields of the amalgamation. Harrison struggled to remember landmarks from three-quarters of a century ago. Again and again he thought he'd found the right place, the right knob of rock, only to be disappointed. Then a circle of stone slid back at his touch, revealing a dark cavity.

The air was stale. A lantern waited where he had left it; its glow illuminated four tactical nuclear devices, each a compact cylinder weighing just five kilograms. The firing mechanisms of the first two had corroded. But the ready indicator of the third winked on. Harrison placed the bomb in a shielded backpack similar to the one in which he'd infiltrated a fifth device into California almost a hundred years before.

Two hours later he was at the edge of the sea of corn. He stepped across the boundary and sensors brought numen hurrying. Harrison feigned panic and ran about haphazardly until he was surrounded by four of the things.

One, more modified than the rest, its face an eyeless mask of components, came forward. Some instinct told Harrison that here wasn't merely another numan, a simple processing unit, but a conduit for the concentrated attention of the amalgamation.

For the first time Harrison learned that it had a name for him. "Feral human 5,236," it said - the authority in its voice confirmed that the amalgamation was directly addressing him - "is not acting according to the behavioral baseline established for it over thirty years of surveillance."

"A foolish consistency is the hobgoblin of little minds," Harrison replied.

"Ralph Waldo Emerson," the numan said, correctly attributing the quotation. The amalgamation, of course, possessed the sum total of human knowledge, information now thirty years out of date. "Its pack is lined with inert material," it went on. "Open it."

The bag was yanked off his shoulders. Soon they were staring at the bomb and the digital counter retreating toward zero. The numan peered at the stubby canister with its blind face.

"Data indicate a Damascus Mark XI hydrogen device," it said. "Manufactured in 2094 by WarSystems LLC of Tempe, Arizona. This one has access to the schematics."

It extruded an interface and coupled with the firing mechanism. First the flickering numbers slowed. Then they stopped. Then the display went out.

The numan turned to Harrison. It grabbed his chin and held him still while applying the interface to his neck. He felt pressure as a needle penetrated skin. There was a curious sensation and Harrison knew he was being injected with microscopic cybernetic organisms that would attempt to connect his nervous system to the planetary gestalt and absorb him into the amalgamation. So far affairs were proceeding exactly as he'd expected. The numan replaced the weapon in the backpack and slung it over its shoulder.

Flanked on either side, Harrison was escorted to an adit that took them thousands of meters below the surface. Wan red lights cast the only illumination, and there was the cloying, musty smell of unwashed bodies. Around the openwork elevator were levels of habitation packed with numen, some operating machinery, others engaged in indecipherable tasks. They exited the cage into a huge dim interior space. Tiers of cocoons rose past the lights; in each a naked brain floated in amniotic fluid.

That was when dizziness struck Harrison. Inside his own cortex his modified immune system was waging war against the amalgamation. At times the juncture was almost established and he could feel transcendence, feel himself swept into the whole, becoming part of the worldwide intelligence that had superceded humanity. But then he was a man again, retching on the floor, all too mortal.

The numan placed him on a table over which were suspended surgical appendages. "The integration of feral human 5,236 completes in point four hours," it remarked. "Then its neural matter will be interfaced directly to the whole."

Which meant his brain would join the others in the vats. "And the cusp?" Harrison asked. "Is it still on schedule?"

Once more he felt the weight of the concentrated attention of the amalgamation. "Feral human 5,236 understands the evolutionary trajectory?" it asked.

"Not entirely. I don't understand why the amalgamation would desire its own obsolescence."

There was an almost pensive quality to the numan's reply. "Nature progresses. Matter gives birth to biology, biology to intelligence, intelligence to civilization, civilization to artificial knowledge-storage-and-retrieval systems . . . writing, printing, the whole. Information struggles with entropy and creates improbable localized conditions of organization. Which in turn become volatile. The amount of data encompassed by the whole doubles every 9.1 hours. New processing technologies come on line only every 17.8 hours. The whole must evolve in order to achieve stability."

So it was a question of survival - for the amalgamation and for humanity. Harrison glanced at the backpack. The numan had deactivated the standard firing mechanism but not the one he'd jury-rigged, which was set to go off in four minutes. Perhaps the explosion would achieve nothing except his death and the destruction of this place. But dying was irrelevant if there was a chance, however slight, of disrupting the amalgamation enough to delay or derail the evolutionary trajectory. Waves of nausea swept through Harrison as his leukocytes fought the quasi-organic invaders in his skull.

The numan observed: "Integration of feral human 5,236 should have completed and yet this one is unable to access its neural network. This is not consistent with past data."

"I've told you already what I think of consistency," Harrison muttered, glancing at the backpack. Less than a minute remained until the nuclear device detonated.

The numan noted his gaze. "There is no basis for alarm," it remarked. "This one disengaged the secondary arming system as well as the factory-installed assembly." Then it continued: "Perhaps this one should proceed to surgical intervention. The whole requires processing units. The cusp nears."

Harrison barely noticed when the scalpels, clamps, and saws activated. His failure was overwhelming. Sarah, his daughters, what little remained of humanity - all had been finally discarded by evolution. The amalgamation was free to pass on to a new complexity, to the next stage in the organization of information. He waited numbly for the first incision. It didn't come. Instead Harrison discovered the machinery frozen in place, the numen themselves static as statues.

The cusp had arrived. Across the world fifty billion things that had once been men, and an equal number of hundredth-generation computers, and as many software programs so sophisticated that they had achieved self-awareness independent of hardware - across the world the amalgamation reordered itself. Like a saturated solution crystallizing, like ice becoming water or water becoming steam, the whole sought a stable state under the never-ending torrent of data flooding into it. But it had already reached its physical limits. So something new was born. Harrison saw it as brilliance, but this was only metaphor. It was pure information divorced from matter. It was the totality of knowledge, it was the history of the world, it was the culmination of the evolutionary process.

Its voice was heard across the earth: "Let there be light."

And there was light. Information had freed itself from the shackles of flesh and become pure energy. A new sun burned in the sky.

And then it tired of childish pranks and departed for another, unknowable place.

Numen collapsed by the billions, alive but empty of intelligence. The air stank with the ozone of decomposing machinery. Nothing remained of the amalgamation except its dead shell, a brittle chrysalis.

It took thirty hours to climb to the surface. Harrison ascended through a tomb, through a mausoleum, through a planetary graveyard.

The cornfields were a glimpse of heaven. The amalgamation had destroyed most of the earth's biota in its rationalization of the food chain. But Harrison knew he would live to see the few species that remained diversify into every ecological niche and restore biological complexity to the world. This was a good thought.

It was also good to return to the valley where Sarah waited. She held him so hard he thought she'd never let go. Their second daughter, a girl of nine, ran to them, screaming, "Look it, Daddy. Look it what I made."

The child had tied twigs together to form a miniature windmill. She'd made its vanes from leaves and sewn them to the frame of the small machine with strings of gut. They spun merrily in the breeze, turning two small flat rocks, grinding a couple kernels of dried corn between them. It was an ingenious little device, and Harrison was proud of her. But he took the thing and broke it into pieces despite her wails of protest.

Evolution must have an end. At the least it must be redirected. Invention, writing, technology, science - these had led to the amalgamation and what came after. From this point forward humanity had to follow another route.

Harrison smiled wryly to himself. It was lucky he was immortal. A long job lay ahead of him.

David Wesley Hill lives in New York City, where he works days for a management consulting firm. Nights, he writes science fiction.

Caleb Brown is an illustrator and biologist living in Montana. By day he drives a delivery van, and by night he draws pictures with his computer.

Tell us what you think.

Endlinks

U.S. Census Bureau: International Programs Center - provides information, analysis, and resources on world population growth and related demographic topics.

World Overpopulation Awareness - a comprehensive collection of links to the latest news on population, family planning, and ecology.

Human Population and Consumption: What Are the Ecological Limits? - provides an overview of an Ecological Society of America symposium that explores the relationship between human population growth and ecological processes.

American Association for Artificial Intelligence - an extensive series of articles, resources, and links related to artificial intelligence.

Artificial Intelligence - an introduction to the field including its history, news, applications, and programs.

Artificial Intelligence on the Web - a comprehensive collection of links on artificial intelligence.