Evolution (92 page)

But NEAR had survived this far, among the last of all of mankind’s artifacts. If Eros had kept up its eccentric dance around the sun, perhaps NEAR could have survived longer yet. But it was not going to get that chance.

The asteroid’s passage through the atmosphere would be mercifully swift. The fragile probe, returning to the planet where it had been made, would flash to vapor only fractions of a second before the great body with which it had long ago rendezvoused was itself destroyed.

Earth’s evolutionary laboratories had been stirred many times by monstrous interventions from without. Now, here was another stirring. And over the bright scene on which Remembrance gazed, a curtain would soon be drawn.

Remembrance herself would survive, as would the children she would bear in the future. Once again the great work would begin: Once again the processes of variation and selection would sculpt the descendants of the survivors to fill shattered ecological systems.

But life was not infinitely adaptable.

On Remembrance’s Earth, among the new species there were many novelties. And yet they were all variations on ancient themes. All the new animals were built on the ancient tetrapod body plan, inherited from the first wheezing fish to have crawled out of the mud. And as creatures with backbones, they were all part of a single phylum— a great empire of life.

The first great triumph of multicellular life had been the so-called Cambrian explosion, some five hundred million years before the time of mankind. In a burst of genetic innovation, as many as a
hundred
phyla had been created: each phylum a significant group of species representing a major design of body plans. All backboned creatures were part of the phylum of chordates. The arthropods, the most populous of the phyla, included creatures like insects, centipedes, millipedes, spiders, and crabs. And so on. Thirty phyla had survived life’s first great shaking down.

Since then species had risen and fallen, and life had suffered major disasters and recoveries over and over again. But not one new phylum had emerged,
not one,
not even after the Pangaean extinction event, the greatest emptying of all. Even by the time of that ancient event, life’s capability for innovation was much constrained.

The stuff of life was plastic, the mindless processes of variation and selection inventive. But not infinitely so. And with time, less.

It was a question of the DNA. As time had worn away, the molecular software that controlled the development of creatures had itself evolved, becoming tighter, more robust, more controlled. It was as if each genome had been redrafted over and over, each time junk and defects were combed out, each time the coherence of the whole was improved— but each time the possibility for major change was reduced. Extraordinarily ancient, made conservative by the inward-looking complexity of the genomes themselves, life was no longer capable of a great innovation. Even DNA had grown old.

This epochal failure to innovate was an opportunity lost. And life could not take many more hammer blows.

The light in the sky was strange. But, Remembrance’s instinctive calculus quickly computed, it was no threat. In this she was wrong. Purga, who had watched the Devil’s Tail similarly slide silently overhead, might have told her that.

Before the sun had touched the horizon she at last reached her forest in the lee of the volcanic hills, her target for many days. Remembrance peered up at the tall trees before her, the canopy that strained up toward the sky. She thought she saw slim shapes climbing there, and perhaps those dull clots of darkness were nests.

They were not her people. But they were people, and perhaps they would be like her.

She pulled herself off the ground and clambered upward into the comforting green of the canopy.

Something fluttered past her head. It was a flying fish, coming from the sea. As she watched, it sailed into the forest canopy, flapping its fin-wings earnestly, and settled clumsily onto a nest, air wheezing into primitive lungs.

Montana, Central New Pangaea. Circa 500 million years after present.

Ultimate dug listlessly in the dirt, hoping to find a scorpion or beetle. She was a mound of orange-colored fur on the rust-tinged ground.

This was a flat, dry plain of crimson red rock and sand. It was as if the land had been scraped bare by some vast blade, and the bedrock wind-burnished to a copper sheen. Once there had been mountains to the west, purple-gray cones bringing relief to eyes wearied by flatness. But long ago the wind had torn all the mountains down, leaving great fans of scattered rocks over the plains, rocks that had themselves eroded to dust, leaving no trace.

Half a billion years after the death of the last true human, a new supercontinent had assembled itself. Dominated by desert, as red as the ancient heart of Australia, it was like a vast shield fixed to the blue face of the Earth. On this New Pangaea, there were no barriers, no lakes or mountain ranges. Nowadays it didn’t matter where you went, from pole to equator, from east to west. Everywhere was the same. And there was dust everywhere. Even the air was full of red dust, suspended there by the habitual sandstorms, making the sky a butterscotch-colored dome. It was more like Mars than Earth.

But the sun was a ferocious disk, pumping out heat and light, much brighter than in the past. Any human observer would have cowered from that great fire in the sky.

Under that tremendous glare the heat lay heavy on the land, by day and by night. There was no sound save for the wind and the scratching of the few living things, no sense that things had ever been different on this red planet. The land
felt
empty, a huge place of resonant silence, a stage from which the actors had departed.

As it happened, far beneath the dust where Ultimate dug— buried under half a billion years of deposits, under the salt and the sandstone of New Pangaea— was the place that had been known as Montana. Ultimate was not far above Hell Creek, where the bones of Joan Useb’s mother had at last joined those of dinosaurs and archaic mammals in the strata she had searched so assiduously.

Ultimate had no way of knowing her peculiar place in history, still less of understanding. But she was among the last of her kind.

Ultimate went home. Home was a pit carved in the harder rock. It offered some shelter from the wind. This was where Ultimate and her kind eked out their lives.

The pit looked artificial. Its floor was smooth, its terraced walls steep. The pit was in fact a quarry, made half a billion years earlier by human beings, dug deep into the bedrock. Even after all this time, even as mountains had come and gone, the quarry had survived almost intact, a mute memorial to the workings of man.

Trees grew on the floor of the pit, standing stately and alone, like sentinels, with their satellite termite colonies towering all around. They were stubby, ugly trees with perennial needlelike leaves, defiant of time. Little else lived here save the people, and other symbiotes of the trees, and many, many tiny creatures that toiled in the dust.

As Ultimate clambered down the pit’s walls, the wind changed and began to blow from the west, from the direction of the inland ocean. Gradually the humidity rose. At last, over the ruined mountains to the west, heavy black clouds began to gather.

Ultimate peered into the western sky. It had never rained here, in Ultimate’s lifetime. Most clouds coming from the distant ocean dumped their rainfall long before they reached a place like this, deep in the supercontinent’s interior. It took a mighty storm indeed to breach those immense defenses of arid plain, a once-in-a-lifetime monster. But that was what was approaching now. You could feel it in the air, feel that something was wrong.

The people hurried back to their Tree, and clambered into its welcoming branches. Hurried, yes— but still they moved with a languid slowness, as if they were swimming through the air’s dense heat.

At ten years old, Ultimate looked something like a small monkey. She was long-limbed, with a narrow torso, narrow shoulders: Even now, in these distant descendants of mankind, the basic body plan of the primates persisted. Her slim body was coated in thick fur, bright red, red as the sand. She had a small head with a large brow and a mobile, expressive face— a very human face, in fact. Small flaps of skin, rather like eyelids, could cover her ears, nose, anus, vagina to trap precious moisture. Her brow was swollen, almost as if her kind had re-evolved the big forebrains of the human age, but behind that brow there was only spongy bone, a great system of sinuses that worked as a refrigeration system to keep her brain cool.

And, though she was fully grown, her body was childlike. Ultimate was functionally female— people still gave birth— but there were no males any more, and gender was meaningless. She had no breasts, not even vestigial nipples. Nowadays there was no need for mother’s milk, just as there was no need for the elaborate superstructure of a large brain. The Tree took care of all of that for you.

And she was not bipedal. That was obvious as she made her way back to the Tree: her arms and legs were made for swinging and climbing, her feet for grasping, not walking upright. That particular locomotive experiment had been thoroughly buried long ago. Compared to her ancestors, she was slow-moving, lethargic, like all her kind.

At the Tree, Ultimate looked for her daughter.

The infant’s leafy cocoon nestled in the crook of a low branch. Threads of orange hair littered over her swollen brow, the little girl was safely enfolded in soft white down. As the Tree’s sap passed along the pale thread of the belly-root that wormed into her stomach, the child stirred and murmured, her tiny thumb clamped firmly in her mouth, dreaming vegetable dreams.

Something was wrong. Ultimate was not capable of much in the way of analysis, but her instinct was unmistakable. She prodded at the tangled red fur on the child’s little belly, and smoothed out the fluffy cottonlike lining of the cocoon. The little girl mewled, turning blindly in her sleep. Nothing Ultimate did made that feeling of wrongness go away. Uncertain, she patted the walls of the cocoon back into place.

The wind rose, like a great breath.

Ultimate clambered higher into the Tree’s welcoming branches. Hastily she pulled her own cocoon into place around her body, sealing up the leaves. The leaves were thick and tough, like plates of leathery armor. The others were doing the same, people huddling on the branches, so that it looked as if the Tree were suddenly sprouting huge black fruits.

The clouds streamed overhead, blotting out the intense heat of a too hot sun. Ultimate stared. Curiosity wasn’t much use now, when there was so little difference in the world across great stretches of time and space. But today
was
different. She had never felt air as moist and heavy and oppressive as this, never seen black clouds that boiled and bubbled like that.

And in the last moment before the storm hit, she glimpsed something new.

Settled on the timeworn plain, it was a sphere. It was twice as tall as she was. It was not blue like the evening sky, nor rust red like the ground, nor the color of sand and dirt like most of the creatures in the world. Instead, it was a shimmering mixture of purple and black, the colors of the night.

On this day of strangeness, here was something extraordinary. She gaped, unable to comprehend. But she sensed that this new thing was not of her world. In that she was right.

But now lightning cracked, and she buried her face in the green, mewling. The leaves closed around her, sealing themselves up seamlessly. In the warm darkness the air grew moist and comforting. But when the belly-root came probing for the valvelike orifice on her stomach, just below her navel, she pushed it away. She was here for shelter; she had nothing to give the Tree today.

And then the storm hit.

Wind and dust came out of the west like a red wall. Dried plants were shattered. Even the scattered, stately Trees were shaken, branches ripped away. People and other symbiotes were wrenched from their cocoons, utterly terrified.

The first few raindrops, landing like bullets, heralded an immense downpour. The rain was so heavy it even began to erode the rock-hard surfaces of the ancient termite mounds. There was nothing to absorb the water, no grass to consolidate the loose soil. Within minutes water was running down every dried-out gully and streambed. A great muddy wave came cascading into the quarry. The water seethed around the roots of the trees, turbulent, tinged red by mud.

But the rain dissipated as quickly as it had begun. The clouds cleared, racing deeper into the heart of the supercontinent. The flood quickly subsided, sinking into the parched sand.

There hadn’t been such a storm since Ultimate’s mother had first opened her eyes. Nothing in Ultimate’s experience had prepared her for such a catastrophic downpour. But the Tree, in its slow vegetable way, understood.

Even as Ultimate cowered, shocked, in her cocoon, she felt the leathery skin pulse around her. She longed to stay here in the moist dark rather than face whatever lay beyond these enclosing walls. But she was made to feel uneasy, restless. The Tree wanted her to leave, to go to work.