Evolution

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 this was Ultimate’s baby: the first she had had, perhaps the only one she would ever be permitted to have. Ancient drives warred. It was a failure of adaptation, this battling of one instinct against another.

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 she came to the walls of the quarry, up which she scrambled in a flash.

She looked back into the great pit, its floor studded with the lowering, silent forms of the borametz trees. And here came Cactus, running after her with a defiant grin.

II

The land was bare. There were a few stubby trees, and shrubs with bark like rock and leaves like needles, and cacti, small and hard as pebbles and equipped with long toxin-laden spines. Protecting their water, these plants were little balls of aggression, and Ultimate and Cactus knew better than to tackle such risky fare until it was essential to do so.

You had to watch where you put your feet and hands.

There were pits in the desert’s crimson floor. They were bright red, a little like flowers, barely visible against the red soil, but with knots of darkness at their centers. Foolish lizards and amphibians, and even the occasional mammal, would tumble unwarily into these waiting traps — and they would not emerge, for these pits were mouths.

These deadly maws belonged to creatures that lived in narrow burrows under the ground. Hairless, eyeless, their legs reduced to scrabbling finlike stubs with sand-digging claws, they were rodents, among the last remnants of the great lineages that had once ruled the planet.

This time of openness and lack of cover did not favor large predators, and the survivors had been forced to find new strategies. The frantic activity and sociability of their ancestors long abandoned, these burrowing rat-mouths spent their lives in holes in the ground, waiting for something to fall into their mouths. Shielded from the excesses of the climate, moving from their burrows only when driven to mate, the rat-mouths had slow metabolisms and very small brains. They made few demands of life, and in their way were content.

But for creatures as smart as Ultimate and Cactus, the rat-mouths weren’t hard to avoid. Side by side, the companions moved on.

The companions came to a little gully. It was nearly choked: the rainstorm had filled it with pebbles and stones. But there was still a trickle of silty runoff water. Ultimate and Cactus crouched down, Ultimate shielding her baby, and they pushed their faces into the water, sucking at it gratefully.