The song’s meaning was simple: This is who we are! If you are not kin, stay away, for we are many and strong! If you are kin, come home, come home! But the song’s richness went beyond its utilitarian value. Much of it was random, bubbling, like scat singing. But at its best it was a spontaneous vocal symphony, running on for long minutes, with passages of extraordinary harmonic purity that entranced Noth.

He lifted his muzzle to the sky and called.

Noth was a kind of primate that would be called notharctus, of a class called adapid, descended from the plesiadapids of the early millennia after the comet. He looked much like a small lemur. He had a high conical chest, long and powerful legs, and comparatively short arms with black, grasping hands. His face was small with a pronounced muzzle, an inquisitive nose, and pricked-up ears. And he was equipped with a long, powerful tail, laden with fat, his winter hibernation store. He was a little more than one year old.

Noth’s brain was considerably larger than Plesi’s or Purga’s, and his engagement with the world was correspondingly richer. There was more in Noth’s life than the urgencies of sex and food and pain; there was room for something like joy. And it was a joy he expressed in his song. His mother and father quickly joined in. Even Noth’s infant sisters contributed as best they could, adding their tiny mewling voices to the adults’ cries.

It was noon, and the sun was the highest it would travel today, but it was still low in the sky. Shafts of low green-filtered light slanted through the trees, illuminating the dense, warm mist that rose from the steaming mulch on the floor, and the tree trunks sent shadows striping over the forest floor.

This was Ellesmere, the northernmost part of North America. The summer sun never set, but merely completed circles in the sky, suspended above the horizon, as the broad leaves of the conifer trees drank in the light. This was a place where the shadows were always long, even in high summer. The forest, circling the Earth’s pole, had the air of a vast sylvan cathedral, as if the leaves were fragments of stained glass.

And everywhere the adapids’ voices echoed.

Emboldened, the adapids began to clamber down the branches toward the ground.

Noth was primarily a fruit eater. But he came upon a fat jewel beetle. Its beautiful carapace, metallic blue green, crunched when he bit into it. As he moved he followed the scent marks of his own kind: I came this way. This way is safe… I saw danger here. Teeth! Teeth!… I am of this troop. Kin, come this way. Others, stay away… I am female. Follow this to find me… That last message gave Noth an uncomfortable tightness in his groin. He had scent glands on his wrists and in his armpits. Now he wiped his wrists through his armpits and then drew his forearms across the trunk, using bony spurs on his wrists to embed the scent, and to cut a distinctive curving scar in the bark. The female patch was old; the brief mating season was long over. But instinct prompted him to cover the patch with his own multimedia signature so that no other male would be alerted by it.

Even now, even fourteen million years after the comet, Noth’s body still bore marks of his kind’s long nocturnal ancestry, like the glands for scent marking. His toes were tipped, but not with nails, like a monkey’s, but with grooming claws, like a lemur’s. His watchful eyes were huge, and like Purga he had whiskers to help him feel his way forward. He retained a powerful sense of hearing and smell; he had mobile radar-dish ears. But Noth’s eyes, while wide and capable of good night vision, did not share the dark-loving creatures’ ultimate adaptation, a tapetum, a yellow reflective layer in the eye. His nose, while sensitive, was dry. His upper lip was furry and mobile, making his face more expressive than those of earlier adapid species. His teeth were monkeylike, lacking the tooth comb — a special tooth used for grooming — of his ancestors.

Like every species in the long evolutionary line that led from Purga to the unimaginable future, Noth’s was a species in transition, ladened with the relics of the past, glowing with the promise of the future.

But his body and mind were healthy and vigorous, perfectly adapted to his world. And today he was as happy as it was possible for him to be.

In the canopy above, Noth’s mother was taking care of her infants.

She thought of her two remaining daughters as something like Left and Right, for one preferred the milk of the row of nipples on her left side, and the other — smaller, more easily bullied — had to make do with the right. The notharctus usually produced large litters — and mothers had multiple sets of nipples to support such broods. Noth’s mother had in fact borne quadruplets. But one of the infants had been taken by a bird; another, runtish, had quickly caught an infection and died. Their mother had soon forgotten them.

Now she picked up Right and pushed her against the trunk of the tree, where the infant clung. Parked like this, her brownish fur blending into the background of the tree bark, Right would remain here until her mother returned to feed her. She was able to stay immobile for long hours.

It was a form of protection. The notharctus were deep enough in the forest to be safe from any diving bird of prey, but the pup was vulnerable to the local ground-based predators, especially the miacoids. Ugly animals the size of ferrets, sometime burrow-raiders who scavenged opportunistically from the kills of other predators, the miacoids were an unprepossessing bunch, but nonetheless were the ancestors of the mighty cats and wolves and bears of later times. And they could climb trees.

Now the attentive mother moved along the branch, seeking a comparable place of safety to leave Left. But the stronger child was happy where she was, clinging to her mother’s belly fur. After gentle pushing, her mother gave up. Laden with her daughter’s warm weight, she worked her way down a ladder of branches toward the ground.

On all fours, Noth walked across a thick mulch of leaves.

The trees here were deciduous, every autumn dropping their broad, veined leaves to cover the ground with a thick layer of decaying vegetation. Much of the mat on which Noth walked was made up of last autumn’s leaves, frozen by the winter’s hard cold before they could rot; now the leaves were mulching quickly, and small flies buzzed irritatingly through the misty air. But there were also butterflies, their gaudy wings making splashes of flitting color against the drab ground cover.

Noth moved slowly, seeking food, wary of danger. He wasn’t alone here.

Two fat taeniodonts grubbed their way across the ground, their faces buried in the rotting leaves. They looked like heavy-jawed wombats, and they used their powerful forelimbs to dig into the dirt, seeking roots and tubers. They were followed by an infant, a clumsy bundle pushing at her parents’ legs, struggling through the thick layer of leaves. A paleanodont scuffed for ants and beetles with its long anteater’s snout. And here was a solitary barylambda, a clumsy creature like a ground sloth with powerfully muscled legs and a stubby pointed tail. This creature, scuffling gloomily in the dirt, was the size of a Great Dane — but some of its cousins, in more open country, grew to the size of bison, among the largest animals of their day.

In one corner of the clearing Noth made out the slow movement of a primate, in fact another kind of adapid. But it was quite unlike Noth himself. Like the loris of later times, this slow, ground-loving creature looked more like a lazy bear cub than any primate. It moved slowly across the mush of leaves, making barely a sound, its nose snuffling the ground. This adapid generally stuck to the deeper forest where its slowness was not as disadvantageous as it would be on more open ground. Here, its slow and silent movements made it almost invisible to predators — and to the insect prey it sniffed out acutely.