But now, Mother saw, it was right that they should couple. Ant-eater would have been wrong; Sapling was right. Because Sapling understood. She stood over them until Sapling’s hand had moved to the girl’s small breast.

A full month after Ox’s death, the people were woken by a wild, high-pitched keening. It was Mother. Bewildered, most of them already terrified of this disturbing woman in their midst, they came running to see what new strangeness was going to befall them.

Mother was kneeling beside the sapling trunk that had borne the skull of her child. But now the skull lay on the ground, broken into pieces. Mother pawed at the fragments, wailing as if the child had died a second time.

Eyes and Sapling hung back, unsure what Mother wanted them to do.

Mother, cradling the pathetic, broken bits of skull in her left hand, glared around at the people. Then her right hand shot forward, pointing. “You!”

People flinched. Heads turned, following her line. Mother was pointing at Honey.

“Here! Walk, walk here!”

The sagging jowls under Honey’s chin shook with terror. She tried to pull back, but those around her stopped her. At last Sapling stepped forward, grabbed the girl by the wrist, and dragged her to Mother.

Mother threw the bits of skull in her face. “You! You throw stone. You smash boy.”

“No, no. I—”

Mother’s voice was hard. “You stop rain.”

Honey squealed, as terrified as if it might be true, and urine dribbled down her thighs.

This time, Mother didn’t even have to perform the kill herself.

It did not start to rain that day. Or the next. Or the next after that. But on the third day after Honey’s sacrifice thunder pealed across a dry sky. The people cowered, an ancient reflex that dated back to the days when Purga had huddled in her burrow. But then the rain came at last, pouring out of the sky as if it had burst.

The people ran, laughing. They lay on their backs, mouths open to the water falling from the sky, or they rolled and threw mud at each other. Children wrestled, infants wailed. And there was a great round of coupling, an instinctive, lusty response to the end of the drought, this new beginning of life.

Mother sat beside her blood-soaked pallet and watched this, smiling.

As always she was thinking on many levels simultaneously.

Her sacrifice of Honey had once again been politically astute. Honey had not been a calculating opponent, but she was a focus of dissent; with her gone it would be easier for Mother to consolidate her power. At the same time the sacrifice had clearly been necessary. The sky and earth were appeased; mankind’s first gods had relented, and let their children live.

But on still another level of calculation Mother knew that the storm would have come whatever she did. If the rain had not followed her sacrifice of Honey, she would have been prepared to continue, working through the people one by one — pushing her spear even into Eyes’s heart if she had to.

She knew all these things simultaneously; she believed many contradictory things at once. That was the essence of her genius. She smiled, the water running down her face.

Sapling walked slowly along the grassy river bank. He wore a simple skin wrap, and carried nothing more than a spear tied over his back and a net bag containing a few bone tools and artwork — no stone tools; if they were needed, it was easier to knap them on the spot than carry them.

In his thirties now — fifteen years after the deaths of Ox and Honey and the installation of Mother as the troop’s de facto leader — Sapling had filled out, his face harder, his hair thinning and streaked with gray. But his body was as whiplash thin as ever. It wasn’t possible to hide the tattoos that covered his arms and face, but he had been careful to rub dirt and mud over his skin to subdue their effect. Over the years the tattoos had proved alarming to strangers, and the barrier of mistrust was high enough anyhow.

He looked like a hunter, out exploring at random far from his troop, perhaps seeking to trade. But he was not alone; others watched every step, hidden in the foliage of the riverbank. His appearance was an elaborate lie. And his exploration was anything but random. He was scouting.

He was spotted first by a child, a chubby little girl playing with worn pebbles at the water’s edge. Aged maybe five, she was naked save for a string of beads around her neck. She looked up, startled. He smiled at her, eyes wide and empty. She screamed and bolted down the riverbank, as he had expected her to do. He walked slowly after her.

The signs of settlement were soon apparent. The muddy ground underfoot was pocked with footprints, and he saw fishing nets strung across the river. After following a tight curve in the river’s flow he came into view of the settlement itself. From a cluster of huts, roughly conical, threads of smoke curled up into the afternoon sky.

This was no temporary camp, he saw immediately. The huts had been built on sturdy logs driven deep into the ground. These river folk had been here for a while, and they evidently intended to stay.

A glance at the river showed why. Not far along the bank, the vegetation on both sides of the water had been trampled down, and he could see the glimmer of stones on the riverbed. This was a ford, where the migrating herds could cross the water. All the people had to do was wait here for the animals to come to them. And, indeed, he saw a great pile of bones, what looked like antelope, ox, even elephant, stacked up behind the huts.

But he was puzzled by the huts themselves. Their walls were solid, save for a break at each cone’s apex to allow the smoke out, and there was no way for light to get in. Who would live in such darkness?

Two adults came running toward him — both women, he saw. They carried unremarkable wooden spears and stone axes, and wore straightforward skin wraps, much like his own. Their faces were daubed with crude but fierce-looking ocher designs, and they both had bits of bone pushed through their noses. One of the women raised her spear toward his chest. “Fu, fu! Ne hai, ne, fu!…”

He recognized none of the words. But he could tell that this crude jabber was like the pidgin he had grown up speaking, with none of the richness that had been steadily developing among Mother’s people.

This was going to be easy.

He forced a smile. Then, moving slowly, he slid his bag from his shoulder and let it fall open. Watching the women, he produced a carved seashell. He put the shell on the ground before the women, and backed away, hands spread and empty. I am a stranger, yes. But I am no threat. I want to trade. And this is what I have. See how beautiful it is…

The women were disciplined. One kept her weapon aimed at his chest, while the other bent to inspect the shell.

The shell itself had last seen the sea a decade ago, and had since traveled hundreds of kilometers inland via tenuous, long-distance trading chains. And now it had been engraved with an exquisite elephant-head design by one of the people’s best artisans, a young girl with long, delicate fingers. When the woman recognized the elephant’s face, she gasped, childlike. She grabbed the shell and clutched it to her chest.

After that, the women beckoned Sapling to follow them toward the settlement. He walked easily, not looking back, confident his companions would remain concealed.

In the settlement of the river folk he created a stir. People glared as he passed, though they stared greedily at the carved shell. A couple of children, including the little girl who had first raised the alarm, tailed him, skipping, curious.

He was led into one of the huts. This was a typical living space, with an elaborate hearth, sleeping pallets, and food, tools, and skins stacked up. It looked as if ten or a dozen people lived here, including kids. But the family had cleared out, leaving only a couple of bearded men, at least as old as he was, and the women who had brought him here. The floor was well trampled and littered with the usual detritus of human occupation — bones, stone flakes from knapping, a few half-eaten roots and fruit.