The mole folk’s underground way of life had started as a response to the aridity of this place — that and the usual ferocious predation. Even the rats couldn’t get you if you burrowed in the ground.

Of course there had been prices to be paid. People had shrunk, generation by generation, the better to fit into the growing complexes of burrows. And over time bodies had been shaped by the restrictions of tunnel life: useless eyes were lost, nails became digging claws, body hair evaporated save for vibrissae, whiskers, which sprouted from lengthening muzzles, the better to help them feel their way in the dark.

The aridity had also promoted cooperation.

The mole folk lived off roots and tubers, riches buried in the ground. But in the dryness the tubers grew large and widely spaced. It was better for the plants that way, because big tubers did not desiccate so easily. A solo mole person, however, burrowing away at random, was likely to starve long before stumbling across the scattered bounty. But if you were prepared to share what you found, then having many colony members digging in all directions brought a more likely chance of success for the group as a whole.

All posthumans were social, like their ancestors, but they specialized in the way they had developed that sociality. These mole folk had taken sociality about as far as you could go. They came to live like social insects, like ants or bees or termites. Or perhaps they were like naked mole rats, the peculiar hive-dwelling rodents that had once infested Somalia, Kenya, and Ethiopia, now long extinct.

This was a hive. There was no conscious mind at work here in the hive. But then consciousness wasn’t necessary. The hive’s global organization emerged from the sum of the interactions of its members.

Most of the inhabitants of the colony were female, but only a few of those females were fertile. These “queens” had produced the infants Remembrance had stumbled upon in the birthing chamber. The rest of the females were sterile — indeed they never entered puberty — and their lives were devoted to the care not of their own children, but of those of their sisters and cousins.

For the genes it made sense, of course. Otherwise it would not have happened. The colony was one vast family, bound together by inbreeding. By ensuring the preservation of the colony, you could ensure that your genetic legacy was transmitted to the future, even if not directly through your own offspring. In fact, if you were sterile, that was the only way you could pass on your genes.

More sacrifices. As the bodies of these colony people had shriveled, so had their brains. You didn’t need a brain. The hive would take care of you — rather as the mouse-raptors took care of the elephant folk they farmed. There were better things to be done with your body’s energy than fuel an unnecessary brain.

And, with time, the mole folk were even giving up that most precious of all mammalian inheritances: hot-bloodedness itself. As they rarely ventured out of their burrows, the mole folk did not need such expensive metabolic machinery — and a cold-blooded scout cost less food than a hot-blooded one. It was done without sentiment. With time, the colony folk would grow smaller yet, smaller than any hot-blooded mammal’s design could maintain. In another few million years these mole folk would swarm like tiny lizards, competing with the reptiles and amphibians who had always inhabited the microecology.

So the mole folk scuttled through their spit-walled corridors, their whiskers twitching, fearful and ignorant. But in their dreams their residual eyes, covered by flesh, would flicker and dart as they dreamed strange dreams of open plains, and running, running.

She lost track of time. Suspended in the suffocating heat of the chamber, she slept, ate roots and tubers, sucked water from the tree roots. The mole folk left her alone. She was in there for days, not thinking, with no impulse to act save to eat, piss, shit, sleep.

At last, though, something disturbed her. She woke, looked up drowsily.

In the dim, diffuse light, she saw that mole folk were clambering into the chamber, and out again through a narrow passageway in the roof. They moved in a jostling column, the flaccid skin on their pale bodies crumpling as they pressed against each other, their whiskers twitching, clawed hands scrabbling.

Though the mouse-raptor and other dangers lingered at the back of her mind, Remembrance found herself longing for openness — for a glimpse of day, for fresh air, for green.

She waited until the mole folk had passed. Then she clambered over the low heapings of roots and pushed her way into the narrow breach in the roof.

It was a kind of chimney that led up toward a crack of purple-black sky. The sight of the sky drove her on, and she wedged her body ever more tightly into the narrow, irregular chimney, scrabbling at the dirt with her hands and feet, knees and elbows, forcing her chest and hips through gaps that seemed far too small for them.

At last her head broke above ground level. She took in great gulps of fresh air and immediately felt invigorated. But the air was cold. The twisted forms of the borametz trees occluded a star-laden sky. It was night, the most natural time for the mole folk to venture to the surface. She forced her arms out of the hole, got her hands onto the surface, and with a tree-climber’s strength she pushed herself upward, prizing her body out of the chimney like a cork from a bottle.

The mole folk were everywhere, running on hind legs and knuckles, snuffling, shuffling, and squirming. But their movement was orderly. They moved in great columns that wound through the termite heaps and ant nests, to and from the borametz trees. They were picking off the nuts that grew in clusters at the roots of the trees, nuts that were sometimes as large as their heads. But they did not seem to be trying to break them open, to get at their flesh. They weren’t even taking them into their underground stores. In fact, she saw now, they were actually bringing nuts up from the underground chambers.

They were taking the nuts, one at a time, out to the fringe of the borametz grove. There workers dug into the dirt, scattering the thin grass to make little pits into which the nuts were dropped and buried.

Each borametz was the center of a symbiotic community of insects and animals.

Symbioses between plants and other organisms were very ancient: The flowering plants and the social insects had actually evolved in tandem, one serving the needs of the other. And it was the social insects, the ants and termites, who had been the first to be co-opted by the new tree species’ reproductive strategies.

Every symbiosis was a kind of bargain. Attendants, insect or mammal, would remove the borametz trees’ seeds from their root bases, but they would not devour them. They would store them. And when conditions were right they would transport them to a place suitable for planting, usually at the fringe of an existing grove, where there would be little competition with established trees or grasses. And so the grove would grow. In return for their labors the attendants were rewarded with water: water brought up even in the most arid areas from deep water tables by the borametz’s exceptionally deep-growing roots.

It had not been hard for the mole folk, with their cooperative society and still-agile primate hands and brains, to learn how to emulate the termites and the ants and begin to tend the borametz trees themselves. Indeed with their greater sizes, they were able to move larger weights than the insects, and the development of new borametz species with large seed cases had resulted.

For the borametz it was a question of efficiency. The borametz had to expend much less energy on each successful seedling than its competitors. And so it was a reproductive strategy that enabled the borametz to flourish where other tree species could not. Little by little, as their attendants carried their seeds from their orchards into the meadows, the borametz species were moving out into the grasslands. At last, more than fifty million years after the triumph of the grasses, the trees were finding a way to fight back.