As the children plodded on, their hunger gnawed.

They crossed a low rocky ridge. In its lee a stand of spruce had grown — dwarfed. The trees were no taller than Jahna was, but in the rock’s shelter they were at least able to lift up from the ground.

Suddenly Jahna grabbed Millo and unceremoniously dumped him to the ground. Their bodies concealed, they poked their heads over the ridge.

On a frozen pond beyond the ridge walked a small flock of ptarmigan. The birds were pecking at the ice, plunging their beaks into cracks and leads. They were brilliant white against the ice’s steely blue gray. These early-arriving birds were invisible against the snow, but they would stand out brightly against the greens and browns of the later spring.

“Come on,” she said. They turned and slithered down the ridge, back to the little stand of spruce.

Jahna selected a fine, supple young tree. With a stone ax from her pocket, she quickly felled it, a hand’s breadth above the snow, and she lopped away its crown, leaving a length of trunk nearly as tall as she was. Now, with Millo’s help, she made a notch in the trunk and drove in a wedge. The trunk split easily, leaving her with a thin, springy strip. She began to scrape it quickly. Meanwhile Millo peeled the bark off the rest of the trunk. He split it up into fibers and quickly wove it together into a length of string. The bow was so unfinished it had bits of string dangling where they had been hastily tied. Not perfect, she thought, but it would serve its purpose.

She turned hastily to splitting arrows off the remnants of the trunk. There was no fire to harden the arrows, of course — and, more seriously, no feathers to serve as flights. So she improvised; she took bits of peeled-off bark and jammed them in slits in her arrows.

They worked as fast as they could. But the sun had slid a little further down the sky by the time she was done.

She poked her head and shoulders above the ridge once more, wielding her bow. The birds were still there. She took aim, pulling back the bowstring.

The first arrow went so wide it didn’t even disturb the birds. The second served only to startle them, and the birds took off, shrieking in protest, their shining wings rattling. She loosed off her last shot — a much more difficult attempt at a moving target — but one of the birds crumpled and fell out of the sky.

Whooping, brother and sister clambered over the ridge and ran down to the frozen pond. The bird lay sprawled on the ice, a splash of blood on its ragged feathers. The children knew better than to rush on to the ice. Millo found a length of spruce branch. They lay flat on their bellies on the firm land at the edge of the ice and used the branch to bring the bird to the shore.

In death the bird looked ugly, ungainly. But Jahna cupped its small head in her hands. She took a bit of snow, let it melt into her palm, and trickled the water into the bird’s unmoving beak: a final drink. “Thank you,” she said. It was important to pay this kind of respect to animals and plants alike. The world was bountiful — but only so long as you did not trouble it too much.

When the little ceremony was done, Jahna quickly plucked the bird, slit open its belly, and flensed it. She folded up the skin and put it in her pocket: she would make better arrows tomorrow, with the feathers the ptarmigan had given her.

They ate the meat raw, the blood trickling down their cheeks and making crimson spots in the snow beneath them. It was a moment of triumph. But Jahna’s satisfaction at the kill did not last long. The light was fading, and the air was growing colder.

They would die without shelter.

Her bow on her back, the last of the bird’s meat in her mouth, Jahna led Millo a little way inland. Soon they came to an open, snow-covered plain. Toward the center of the meadow, the snow came almost up to her knees.

Good enough.

She shaped blocks out of the snow around her. It was hard work; she had nothing to use but her hands and stone blades, and the upper layers of snow were soft and crumbled easily. But deeper down the snow was compressed and satisfyingly hard.

She began to pile the blocks in a tight ring around herself. Millo joined in with a will. Soon they were building a circular wall of snow blocks around an increasingly deep pit. With care they turned their spiraling lines of blocks inward, until they had made a neat dome shape. Jahna punched a tunnel into the wall through which they could come and go, and Millo smoothed over the dome’s surface, inside and out.

The snow house was small, rough and ready, but it would do.

The light was fading fast now, and the first wolves’ calls were already echoing. Hurriedly they dug themselves into their snow house.

We are more secure than last night, Jahna thought as they huddled together for warmth. But tomorrow we must find more food.

And we must build a fire.

The hunters returned from the sea. They dispersed among their families, bearing the food they had brought. There were no expressions of gratitude. These people had no words for please or thank you; among these hunter-gatherer folk there were no social inequalities that would have required such niceties. The food was simply shared out, according to need.

Of Jahna and Millo there was much quiet talk.

Mesni, mother of Millo and Jahna, visibly strove for self-control. She went about the tasks of the day, caring for her infant, gutting the fish and preparing the rest of the ocean harvest Rood had brought home. But sometimes she would put down her knife or her bowls and give way to open despair. She even wept.

She became insane with grief: that was how it seemed to Rood. The people prized themselves for their equanimity and control. To show visible anger or despair was to behave like a small child who knew no better.

As for Rood, he withdrew into himself. He stalked around the village, and out into the country, in his shame and sorrow struggling to keep his face expressionless. There was nothing he could do for Mesni. He knew she must adjust to her loss, must regain her own inner sense of calm and control.

But the loss was indeed terrible for the little community. There weren’t that many of them to begin with. This little village of around twenty people consisted essentially of three large families. They were part of a more extended clan, who every spring would gather at the bank of a great river to the south of here for a great celebratory festival of trade, partner seeking, and storytelling. But, though they came from far away, there were never more than about a thousand at these gatherings: The tundra could support no higher a density of people than that.

In later times, archaeologists would find artifacts left behind by people like Rood’s and wonder if some of them signified fertility magic. They did not. Fertility was never a problem for Rood’s folk. Quite the opposite: The problem was controlling their numbers. The people knew they must not overstretch the carrying capacity of the land that sustained them — and that they must stay mobile, in case of flood or fire or freeze or drought.

So they took care over the number of children they raised. They spaced their births by three or four years. There were a number of means to achieve this. Mesni had breast-fed both Jahna and Millo to advanced ages to suppress her fertility. Simple abstinence, or nonpenetrative sex, would do the trick. And, just as it always had, death stalked the very young. Disease, accident, and even predators could be relied upon to take away a good fraction of the weak.

If necessary — though Rood was grateful he had not gone through this himself — if a healthy child arrived for whom there really was no room, death could be given a helping hand.