Evolution

For a million years the sphere had studied the distribution of the replicators through the Galaxy. It wasn’t easy, for the great disk had rotated twice since the origin of its kind, and the stars had swum about, smearing the robot colonists across the sky. Great mathematical models had been built to reverse that great turning, to restore the stars as they once must have been, to map back the replicators’ half-forgotten expansion.

And at last the sphere had converged on this system, this world — amid a handful of others — as the putative origin. It had found a world of organic chemistry and creatures interesting in their way. But it was a dying world, overheated by its sun, the life-forms restricted to the fringes of a desert continent. There was no sign of organized intelligence.

And yet, here and there, the ancient rocks of the supercontinent had been marked deliberately, it seemed to the sphere, with cuts and gouges and great pits. Once there had been mind here, perhaps. But if so it was vanished from these wretched, crawling creatures.

The sphere represented a new order of life. And yet it was like a child, wistfully seeking its lost father. The last traces of the Martian robots’ original blueprint, assembled by long-dead NASA engineers in computer laboratories in California and New England and much modified since, had been lost. It was somehow appropriate that this greatest, and strangest, of all of mankind’s legacies should have been created entirely accidentally — and that those created should have been abandoned to their fate.

There was nothing more to be learned here. With an equivalent of a sigh, the sphere leapt to the stars. The small world dwindled behind it.

Ultimate huddled in the dirt until the scavenging siblings had finished feeding. Then she stumbled away, clutching her baby, not even noticing that the sphere had vanished.

III

Ultimate kept heading west, away from the borametz quarry.

At night she wedged herself with her infant into crevices between rocks, trying to emulate the comforting enclosure of the Tree’s cocoon. She ate whatever she could find — half-desiccated toads and frogs buried in the mud, lizards, scorpions, the flesh and roots of cacti. She fed the child a chewed-up pulp of meat and vegetable matter. But the child spat out the coarse stuff. She was still missing her belly-root, and she mewled and complained.

Ultimate walked, and walked and walked.

She had no strategy in mind save to keep moving, to keep her infant out of the chemical clutches of the Tree, and to wait to see what turned up. If her thinking had been sophisticated enough she might have hoped to find more people, somewhere she could stay, maybe even a community that lived independently of the Trees.

It would have been a futile hope, for there were no more such communities anywhere on Earth. She didn’t know it, but she had nowhere to go.

The land began to rise slowly. Ultimate found herself walking on coarse sand and gravel fans.

After half a day of this she came to a place of low, smooth-shouldered hills. She could see how these eroded stumps went marching off to the horizon, to north and south, for kilometer after kilometer, all the way to the dust-laden horizon and beyond. She was walking through the remnant of a once-great mountain chain, thrown up by the ancient stitching together of the continents. But the dust-laden winds of New Pangaea had long since worn down the mountains to these meaningless stumps.

When she looked back she could see her own footprints, accompanied by the scraping of knuckles, marked by the messy places where she had stopped to feed or make waste or sleep. They were the only trail through these silent hills.

It took her two days to cross the mountains.

After that the land began to descend again.

On the plain, a little more vegetation grew. There were spiky trees with gnarled branches and clumps of needlelike leaves, like bristlecone pines. Around their roots sheltered a few leaping mice — hardy rodent survivors, ferocious conservers of water — and many, many lizards and insects. She chased tiny things like geckos and iguanas, and munched their flesh. But on this looser ground Ultimate had to be cautious, watching for rat-mouths embedded in the ground, and for the quivering, invisible mass of an ambush hunter.

As the land descended further, the view to the west opened up. She saw a great plain. Beyond a kind of coastal fringe, the land was white, white as bone, a sheet that ran all the way to a knife-sharp, geometrically flat horizon. A thin wind moaned in her face. On its breath, she could already taste the salt. Nothing moved, as far as she could see.

She had come to a fragment of the dying inland ocean. There was still water out there — it took a long, long time to dry out a sea — but it was a narrowing strip of water so saline it was all but lifeless, and it was framed by this great white rim of exposed salt flats, a sheet that extended to her horizon.