With a tentative fingertip she stroked the sphere’s surface. It was neither warm nor cold. It was
The burnt-metal smell was in fact the result of exposure to hard vacuum: a legacy of space.
Their foraging done, one by one the people returned to the Tree, climbed into its branches, and folded themselves securely inside its leaves.
Ultimate pulled leathery leaves around her body. The belly-root snaked out quickly, probing for the valve on her stomach, and nestled into her like a reattached umbilical. As her salt-laden fluids began to circulate into the Tree, so Ultimate was rewarded by a soothing sense of security, of peace, of lightness. This mood was induced by chemicals leaked into her body as she exchanged blood for Tree sap, but it was no less comforting for that. This was her immediate reward for feeding the Tree, just as her longer-term reward was life itself. The Tree did not take without giving. Posthuman and Tree were neither of them parasites on the other. This was a true symbiosis.
But there was something wrong. Ultimate felt uneasy, wordlessly disturbed.
Even though the warm sap filled her head with green sleepiness, she kept thinking of how the child had been lying in her cocoon, her thumb in her mouth, the belly-root curled before her.
The sap pulsed harder into her gut, and soporific chemicals washed through her. This drastic injection meant the Tree wanted her to stay here, where she was, safe in her cocoon. But still that nagging sense of wrongness pulled at her.
She pulled the belly-root out of her stomach, and pushed hard with her shoulder and legs. The cocoon popped open, and she tumbled to the ground.
Briefly she was overwhelmed by light and warmth. Though the day was still bright the sun was low. Inside the cocoon, time swam at a different pace from the world outside — a pace chosen by the Tree. But the ground was hard and dust-strewn. Save for a few raindrop stipples, it was as if the storm had never been.
Nobody was around. All the cocoons were closed — all but one. Cactus was gazing down at her, her small head protruding from her own half-sealed cocoon. With a look of playfulness, Cactus pushed her way out of her enclosing leaves and tumbled easily to the ground beside Ultimate.
Ultimate’s sense of anxiety was still growing.
She hurried around the base of the Tree to find her baby’s cocoon in the crook of the low branch. But it was sealed tight, and would not yield when she tried to open it. As if this were a game, Cactus joined her. The two of them dug their fingers into the seams between the sealed-up leaves, straining and pushing and grunting.
Once it would have occurred to a person to use a tool to open this pod. Not anymore. Toolmaking was gone, all the artifacts of man had long since rotted away save for a few pithecine nodules buried in lost strata. And Ultimate and Cactus weren’t even very good at solving unusual problems, for in their flat world they encountered few novelties.
At last, however, the cocoon opened with a pop.
Here was Ultimate’s baby, still swaddled in the white cottonlike material of the cocoon’s interior. But, Ultimate saw immediately, the cottony stuff had grown thicker. It had closed around the baby’s face, and tendrils of it were pushing into her mouth, nose, eyes, and ears.
Cactus flinched, an expression of revulsion on her face.
Both of them knew what this meant. They had seen it before. The Tree was killing Ultimate’s baby.
A new Pangaea.
A hundred million years after Remembrance had gone to her unmarked grave, the Americas had begun to slide east once more. As the Atlantic closed, so Africa drifted north of the equator, in the process pushing Eurasia further north still. Meanwhile Antarctica sailed north to collide with Australia, and that new assemblage began to push into east Eurasia. So a new supercontinent had been born. Africa was the central plain of the new assemblage, with the Americas pressing to the west, Eurasia to the north, Australia and Antarctica to the east and south. In the interior, far from the mediating effect of oceans, severe conditions took hold — ferociously hot and arid summers, killingly cold winters.
All barriers to movement had been eliminated. There was a brutal free-for-all as plants and animals migrated in all directions. It was a chilling parallel to the great global mixing that humans had forced during their few thousand years of dominance of the planet — and, just as it had been before, a world united was a world reduced. There had been a rapid pulse of extinctions.
And as time wore away, things got worse.
The new supercontinent immediately began to age. The great tectonic collisions had thrown up new mountains, and as they eroded, their debris enriched the plains with chemical nutrients like phosphorus. But now there were no new mountain-building events, no new uplift. The last mountains wore away. Rainwater and groundwater, percolating through the soil, leached out the last nutrients — and when they were gone there was nothing to replace them.
New red sandstones were laid down, rust red, red as the lifeless Martian deserts had been — the signature of lifelessness, of erosion and wind, heat and cold. The supercontinent became a great crimson plain spanning thousands of kilometers and marked only by the worn stumps of the last mountains.
Meanwhile the reduction in sea levels exposed shallow continental shelves. As they dried out they quickly began to weather, drawing oxygen out of the air. On land many animals simply suffocated to death. And in the oceans, as the pole-to-equator temperature gradient flattened out, the circulation of the ocean slowed. The waters stagnated.
On land, in the sea, species fell away like leaves from an autumn tree.
In a desiccating world the familiar games of competition, of predator and prey, were not so effective anymore. The world didn’t have the energy to sustain great complex food webs and pyramids.
Instead, life had fallen back on much more ancient strategies.
Sharing was as old as life itself. Even the cells of Ultimate’s body were the result of mergers of more primitive forms. The most ancient bacteria had been simple creatures, living off the sulfur and heat of hellish early Earth. For them the emergence of cyanobacteria — the first photosynthesizers, which used sunlight to turn carbon dioxide into carbohydrates and oxygen — was a disaster, for reactive oxygen was a lethal poison.
The survivors won by cooperating. A sulfur eater merged with another primitive form, a free-living swimmer. Later an oxygen-breathing bacterium was incorporated into the mix. The three- part entity — swimmer, sulfur-lover, oxygen breather — became capable of reproduction by cell division and could engulf food particles. In a fourth absorption some of the growing complexes engulfed bright green photosynthetic bacteria. The result was swimming green algae, the ancestors of all plant cells. And so on.
Throughout the evolution of life there had been more sharing, even of genetic material. Human beings themselves — and their descendants, including Ultimate — were like colonies of cooperative beings, from the helpful bacteria in their guts which processed foods, to the mitochondria absorbed eons ago that powered their very cells.
So it was now. Joan Useb’s intuition, long ago, had been right: One way or another, the future for mankind had been cooperation, with one another and the creatures around them. But she could never have foreseen this, the final expression of that cooperation.
The Tree, a remote descendant of the borametz of Remembrance’s time, had taken the principle of cooperation and sharing to its extremes. Now the Tree could not survive without the termites and other insects that brought nutrients to its deep roots, and the furry, bright-eyed mammals who brought it water, food, and salt, and planted its seeds. Even its leaves, strictly speaking, belonged to another plant that lived on its surface and fed on its sap.
But likewise the symbiotes, including the posthumans, could not have survived without the succor of the Tree. Its tough leaves sheltered them from predators, from the harsh heat of the climate, even from the once-in-a-century rainstorms. Sap was delivered through the belly-roots, just as the Tree took back its nutrients by the same conduits: infants were not breast-fed but were swaddled by the Tree, nurtured by these vegetable umbilicals. The sap, drawing on the deepest groundwater, sustained them through the mightiest supercontinental droughts — and, laden with beneficent chemicals, the sap healed their injuries and illnesses.
The Tree was even involved in human reproduction.
There was still sex — but only homosexual sex, for there was only one gender now. Sex served only for social bonding, pleasure, comfort. People didn’t need sex for breeding anymore, not even for the mixing of genetic material. The Tree did it all. It took body fluid from one 'parent' in its sap and, circulating it through its mighty bulk, mixed it and delivered it to another.
People still gave birth, though. Ultimate herself had given birth to the infant that now lay in its leafy cradle. That heritage, the bond between mother and child, had proved too central to give up. But you no longer fed your child, by breast or otherwise. All you had to give your child was attention, and love. You no longer raised it. The Tree did all that, with the organic mechanisms in its leafy cocoons.
Of course there was still selection, of a sort. Only those individuals who worked well with the Tree and with each other were enfolded and allowed to contribute to the circulating stream of germ material. The ill, the weak, the deformed, were expelled with vegetable pitilessness.
Such a close convergence of the biologies of plant and animal might have seemed unlikely. But given enough time, adaptation and selection could turn a wheezing, four-finned lungfish into a dinosaur, or a human or a horse or an elephant or a bat — and even back into a whale, a fishlike creature, once again. By comparison hooking up people and trees with an umbilical connection was a trivial piece of re-engineering.
In the myths of vanished humanity there had been a kind of foreshadowing of this new arrangement. The Middle Ages’ legends of the Lamb of Tartary had spoken of the Borametz, a tree whose fruit was supposed to contain tiny lambs. All of mankind’s legends were forgotten now, but the tale of the Borametz, with its twining of animal and plant, found strange echoes in these latter days.
But there were costs, as always. Their complex symbiosis with the Tree had imposed a kind of stasis on the postpeople. Over time the bodies of Ultimate and her kind had specialized for the heat and aridity, and had simplified and become more efficient. Once the crucial linking was made, Tree and people became so well adapted to each other that it was no longer possible for either of them to change quickly.
Since the snaking umbilicals had started to worm their way into posthuman bellies, since people had first huddled in the protective enclosure of borametz leaves, two hundred million years had worn away unmarked.
But even now, even after all this time, the symbiotic ties were weak compared to more ancient forces.
In its slow vegetable way, the Tree had concluded that for now the people could not afford another baby. Ultimate’s infant was being reabsorbed, her substance returning to the Tree.
It was an ancient calculation: in hard times it paid to sacrifice the vulnerable young, and to keep alive mature individuals who might breed again in an upturn.
But the infant was almost old enough to feed herself. Just a little longer and she would have survived to independence. And
It was a primordial calculus, an ancient story told over and over again, in Purga’s time, in Juna’s, for uncounted grandmothers lost and unimaginable in the dark. But for Ultimate, here at the end of time, the dilemma hurt as much as if it had just been minted in the fires of hell.
It took heartbeats to resolve. But in the end the tie of mother to child defeated the bonds between symbiotes. She dug her hands into the cottony stuff and dragged her baby from the cocoon. She pulled the belly-root from the infant’s gut, and bits of white fiber from her mouth and nose. The child opened her mouth with a popping sound, and turned her head this way and that.
Cactus watched, astonished. Ultimate stood there panting, her mouth open.
Now what? Standing there holding the baby — in defiance of the Tree that had given her life — Ultimate was out on her own, beyond instinct or experience. But the Tree had tried to kill her baby. She had had no choice.
She took a step away from the Tree. Then another step. And another.
Until she was running, running past the place where she had dug the salt — the sphere was gone now, faded from her memory — and she kept running, her baby clutched in her arms, until
