Evolution

He had tried to keep them both feeding, to fatten up their tails with the winter storage that would see them through the long months of hibernation to come. That was just as his innate programming instructed. But they weren’t eating enough. Isolated from the support of the troop, he was having to spend much too much of his time watching for predators.

He could have gone back. Like all his species — the mobile males more than the sedentary females — he kept track of his position by dead reckoning, integrating time, space, and the angle of the slanting sunlight. It was an ability that helped him find scattered sources of food and water. If he needed to Noth could find his way back "home," to the stand of trees that had been the center of his troop’s range. But he never heard the distinctive warbling song of his troop; his rudimentary decision-making machinery pressed him to keep searching for a troop that would accept him and his sister.

Meanwhile, though the sun still circled endlessly above the horizon, much of the daylight was tinged with the red of sunset, and here on the forest floor brown spores clung to the fern fronds. Autumn was coming. And then there would be winter. They were underfed, and time was running out.

Right became distressed, as she so often did. She dropped the pea pods and folded over on herself, rocking, keening softly, her hands over her small face. Noth took her in his arms and carried her to the crook of a branch, where he began to groom her. He worked carefully through the sparse fur on her back, neck, head, and belly, removing dirt, bits of leaf, and dried feces, untangling knots, picking out parasites that were attempting to feast on her young skin.

Right quickly calmed. The grooming’s mixture of pleasure, attention, and mild pain flooded her system with endorphins, her body’s natural opiates. Before she grew much older she would be addicted, literally, to this pleasurable scratching — as her brother already was. Noth badly missed the strong, nipping caress of adult fingers on his back.

But Noth was worried about her, on deep levels he could not understand.

Right’s bewildering grief served a purpose. It was a signal to her that she had suffered a loss, that there was a hole in her world that she must fix. And though Noth was not capable of true empathy — if you didn’t really understand that other people had minds and thoughts and feelings like yours, you couldn’t possibly be empathetic — still the signs of grief in his sister triggered a kind of protectiveness in him. He wanted to put the world right for his sister: The instinct to help the orphaned went very deep.

But in the end obsessive grief was maladaptive. If Right was unable to recover, in the end there would be nothing he could do for her. He would have to abandon her, and then she would surely die.

As day followed day, the sun, at the lowest point of its arc in the sky, began to slip beneath the southern horizon. At first the brief nights were like twilight, and on clear nights purple-red curtains of light climbed into the tall sky. But quickly the sun’s excursions into invisibility became longer, and there were increasing intervals when stars shone in a deepening blue. Soon true darkness would return to the polar forest.

The weather quickly became colder and drier. Rainfall was scarce now, and on some days the warmth of the sun barely seemed to penetrate the lingering mist. Already many of the birds of the forest canopy had departed, skein after skein of them flitting over the sky to the warmer lands to the south, watched by uncomprehending primate eyes.

Noth became exhausted, ragged, and his dreams were full of flashing teeth and biting claws, visions of his scrap of a sister taken by gigantic mouths.

Now their biggest problem was thirst. It had been so long since the last rain that the treetops were becoming parched. And already the trees were starting to shed; the last leaves were withered and brown. Soon Noth was reduced to licking the bark each morning for the cold dew.

At length, driven by their thirst, the siblings went in search of ground water. Near the closest large lake they scurried down a tree trunk, eyes wide.

Approaching the water, the primates crept past a pair of what looked like miniature deer. The size of small dogs with long, trailing tails, these fast, solitary runners, browsing on leaves and fallen fruit, were ancestors of the mighty artiodactyl family, which would one day include pigs, sheep, cattle, reindeer, antelope, giraffes, and camels. Right disturbed a frog, which hopped away, croaking in protest. She cowered back, eyes wide at its strangeness. Soon they saw more amphibians, frogs and toads and salamanders. Birds crowded the bushes, raising shrill cries that filled the dank air.

Noth was uneasy. The shore was too crowded: Noth and Right were not the only thirsty creatures in this shivering jungle.