As Remembrance lingered, a young male hissed at her. He had a bizarre white patch of fur on his backside, almost like a rabbit’s. She knew what he was thinking: He suspected she might be after the patch of bark he was working with his mother and siblings. People’s minds were not what their ancestors’ had been, but Remembrance was still capable of working out the beliefs and intentions of others.

But White-patch’s troop had been weakened today. Since the last time Remembrance had seen them, their elder son had gone. He might have left to seek some other colony, suspended somewhere in the forest’s green depths. Or, of course, he might be dead. The family members themselves showed they were still aware of the lost one’s absence in the way they looked over their shoulders at nobody, or left a space for a big male who never came. But soon their memories would heal over, and the brother would vanish into the unremembering mists of the past, as lost as had been all the children of man since the construction of the last tombstone.

Remembrance herself would never learn what had become of the other son. This was not an age of information. Nobody told anybody else anything anymore. All she knew for sure was what she saw for herself.

For Remembrance, though, this was an opportunity. She could probably fight this weakened group for a place on their tree. But her poor sleep had left her feeling brittle, restless. It was a mood that had plagued her since the loss of her child. The child’s death had been more than a year ago, but so sharp was the pain, so vivid was it still in her kaleidoscopic, unstructured mind, that it might have been yesterday. Like all her kind, Remembrance was a creature not of purposeful planning but of impulse. And today her impulse was not to fight these squabbling folk for the privilege of a place on their crowded branch, to peel back a bit of bark in search of grubs.

She turned away and began to make her way through the tangled levels of trees.

As she swung, clambered, and leapt her way from branch to branch, she began to feel better. The stiffness quickly worked out of her muscles, and it was as if she were coming fully awake. She even forgot, briefly, the loss of her child. She was still young; her kind often lived beyond twenty-five or even thirty years. And, long after a remote ancestor had crawled, baffled, out of a sewer into the greening daylight, her body was well adapted to her way of life, if not yet the deepest chapels of her mind.

So, as she worked in a blur of speed through the trees, she felt a kind of joy. Why not? Much had been lost, but that made no difference to Remembrance. Her brief moment in the light was here, now, and was to be cherished. As she soared through the dense twilight of the forest layers, her lips drew back from her teeth, and she laughed out loud. It was a reflex the children of man had never lost — even though, across Earth’s healing face, thirty million summers had flickered and gone.

Remembrance’s tropical forest was part of a great belt wrapped around the waist of the planet, a belt broken only by oceans and mountains. The forests were luxuriant — although they had taken thousands of years after the cessation of man’s ferocious logging to attain something like their former richness.

The reassembled world, engulfed by forest, had left little room for the descendants of mankind. And so Remembrance’s ancestors had left the ground and taken once more to the green womb of the canopies. There had already been primates here: monkeys whose ancestors had evaded the starving humans in the final days, survivors of the great extinction event. At first the posthumans were clumsier than the monkeys. But they were still smart, relatively — and they were desperate. Soon they completed the extinction that their forefathers had begun.

After that they had begun to proliferate. But the pressures that had driven them off the ground continued to pursue them.

Remembrance knew nothing of this. And yet she carried within her a molecular memory, a continuing unbroken line of genetic inheritance that stretched back to the vanished folk who had carved the mighty roadway out of the rock — and back, back far beyond them, to still more distant times when creatures not unlike Remembrance had clambered in trees not unlike this one.

She stopped at a branch laden with fat red fruit. She sat squat on the branch and began to feed briskly, shelling the fruit and sucking down the soft contents, letting the drained husks fall into the darkness below. But as she ate she kept her back to the trunk, her gaze darted fearfully around the shadows, and her motions were fast, furtive.

Despite her watchfulness, she was startled when the first chunk of rind hit her on the back of the head.

Cowering against the trunk, she looked up. Now she saw that the branches above her were heavy with what looked like fruit: fat, dark, pendulous. But those “fruit” were sprouting arms and legs and heads and glittering eyes, and clever hands that hurled rinds and bits of bark and twig down at her. They had probably lain in wait as she approached, and then just as silently converged on her position. They even threw lumps of warm shit.

And now the chattering began. It was a screaming, meaningless jabber that filled her head, disorienting her — as was its purpose. She huddled in the crook of the branch, her hands clapped over her ears.

The Chattering Folk were cousins of Remembrance’s kind. They used to be humans too. But the Chatterers lived differently. They were cooperative hunters. All of them, from barely weaned young upward, would work with a cold, instinctive discipline to bring down any prey, or battle any predator. The strategy worked: Remembrance had seen more than one of her kind fall before this treetop army.

Despite their different ways of living, up to a couple of million years ago the two kinds of people could still have crossbred, though their offspring would have been infertile. By now that was impossible. It had been a speciation, one of many. To the Chattering Folk, Remembrance was not kin, nothing but a potential threat — or perhaps, a meal.

She was cut off. There seemed to be a Chatterer on every branch. She could never get past them and reach the sanctuary of another tree. She had only one way off this bare trunk: across the ground itself.

She didn’t hesitate. Skittering down the trunk — letting herself fall for long distances, trusting on her reflexes to grab at branches and slow her descent — she escaped toward the deeper gloom of the forest floor.

At first the Chatterers followed her, and their bits of fruit and shit hailed around her, splattering against the bark. She heard them spread out through the tree from which they had ousted her, chattering and screaming their useless triumph.

At last she slid off the trunk. She intended to make for another great tree trunk a couple of hundred meters away, which might be far enough away from the Chatterers to give her a safe passage back to the canopy.

She stepped forward, her eyes wide and alert, walking upright.

Remembrance had narrow hips and long legs, relics of the bipedal days of ground-dwelling savannah apes. She was more upright than any chimp had ever been, more upright than Capo’s folk. But even upright, her legs remained slightly bent, her neck sloped forward. Her shoulders were narrow, her arms long and strong, and her feet were long and equipped with opposable toes — all good equipment for climbing, clinging, leaping. Arboreal life had reshaped her kind: Selection had reached back to ancient designs, much modified, their templates never abandoned.

She wasn’t comfortable here on the ground. When she looked up she saw layers of foliage, trees competing for the energy of the sun, cutting out all but the most diffuse light. It was like looking up at another world, a three-dimensional city.