They were robust folk, people like Pebble’s kind. But Pebble could see ocher markings scrawled on the skin of their faces, hands, and arms. Where Pebble’s own adornment was made up of vertical lines — bars and stripes and bands, all pointing to the sky — these people wore a kind of clumsy Crosshatch, sketched by thick fingers.

They were strangers. You could tell that by the markings. And strangers meant trouble. That was a law that worked as invariably as the rising of the sun, the waxing of the Moon.

Pebble waited until the newcomers had passed out of sight behind a stand of sparse acacia. Then, as silently as his slablike body would allow him, he began to run for home. The yam tubers he had dug up lay abandoned on the ground behind him — with his digging stick.

Pebble’s home was a kind of village, with four large huts set roughly around a clearing. And yet it was not a village, for his people lived not quite as any humans ever would.

Pebble stood, panting, in the central clearing. Nobody was around. Close to the door of one hut a fire smoldered. The trampled ground was scattered with bone, vegetable debris, tools, mattresses of leaves and grass, trays of bark, pegs, wedges, a broken spear, discarded bits of leather. The place was a mess.

The huts were crude and ugly, but serviceable. They had been built of thick saplings set in rough circles in holes in the ground. The gaps between the saplings were filled with rattan cane split into switches, and overlapping leaves, bunches of rushes, bark. The saplings were bent over together and their ends pushed over and under each other. It was a kind of weaving that Capo would have recognized, for five million years earlier he had made his treetop nests in much the same way: Every innovation of necessity was built on what had gone before.

The huts were old. The people had lived here for generations. The dirt beneath Pebble’s feet was thick with the bones of his ancestors. The people felt safe here. This was their place, their land.

But now, Pebble knew, all that might change.

He raised his head to the washed-out sky. “U-lu-lu-lu-lu! U-lu-lu-lu-lu!…” It was a cry of danger, of pain, the first cry any child learned after the feed-me yell.

Soon the people came running, from the huts, from the land beyond where they foraged and hunted. They gathered around Pebble in concern. There were twelve of them: three men, four women, three older children — including Pebble himself — and two infants in their mothers’ frightened grasp.

He tried to tell them what he had seen. He pointed back to where he had seen the strangers, and ran a few paces back and forth. “Others! Others, others, hunters!” He began an elaborate performance, gesticulating, posturing, puffing himself up to walk like powerful hunters, even miming to show how they would smash in the people’s heads with their mighty fists.

His audience were impatient. They turned away, as if eager to return to their foraging, or eating, or sleeping. But one man watched Pebble’s performance more carefully. He was a squat man even more powerfully built than most, and his face was distorted by a childhood accident that had smashed the cartilage in his great fleshy nose. This man, Flatnose, was Pebble’s father.

Pebble’s language was sparse. It was just a string of concrete words with no grammar, no syntax. And, a million years after Far, talking was still basically a social skill, in fact used mainly for gossip. To convey detail or complex information, you had to repeat, use endless circumlocution — and mime, gesture, perform. Besides, Pebble had to convince his audience. It was hard for the adults to accept what Pebble had to say. They couldn’t see the strangers for themselves. He might be lying or exaggerating: He was, after all, little more than a child. The only way they had to gauge his sincerity was by the passion and energy he put into his performance.

It was always this way. To get anyone to listen, you had to shout.

At last Pebble gave up, panting, and sat squat in the dirt. He had done his best.

Flatnose kneeled beside him. Flatnose believed his son: His performance had cost him too much to be lies. He rested his hand on his son’s head.

Reassured, Pebble touched his father’s arm. There he found a series of scars, long and straight, following the line of the forearm. These scratches were the marks of no animal. Flatnose had inflicted them on himself, with the sharp blade of a stone knife. When he was older, Pebble knew he would join in the same game, the same silent, grinning self-mutilation: It was part of what his father was, part of his strength, and Pebble found it reassuring now to stroke those scars.

One by one the other adults joined them.

Then, the moment of silent acceptance over, Flatnose got to his feet. There were no words now. Everybody knew what had to be done. The adults and the older children — Pebble and a girl a little younger than himself — started to move around the settlement, gathering weapons. There was no particular order to the settlement, and weapons and other tools lay where they had last been used, amid piles of food, debris, ash.

Despite the urgency the people moved sluggishly, as if even now reluctant to accept the truth.

Dust, Pebble’s mother, tried to soothe her squalling baby as she gathered up her gear. Her loose, prematurely grayed hair was, as always, full of dry, aromatic dust, an eccentric affectation. At twenty-five she was aging quickly, and she limped when she walked, the effect of an old hunting wound that had never healed right. Since then Dust had had to work twice as hard, and the cumulative effect showed in her stooped posture and careworn face. But her mind was clear and unusually imaginative. She was already thinking of the difficult times ahead. Watching her face, Pebble felt guilty at having brought this trouble down on her.

There was a soft sigh, a flash. Pebble turned.

In a dreamlike moment, he actually saw the wooden spear in flight. It was hewn from a fine piece of hardwood, thickest near the point and tapered back toward the other end, shaped to make it fly true.

Then it was as if time began to flow again.

The spear slammed into Flatnose’s back. He was thrown to the ground, the spear sticking straight out of his back. He shuddered once, and a burst of shit cascaded from his bowels, and a black-red pool spread under him, soaking into the dirt.

For a heartbeat Pebble couldn’t take this in — the thought that Flatnose had gone so suddenly — it was as if a mountain had suddenly vanished, a lake evaporated. But Pebble had seen plenty of death in his young life. And already he could smell the stink of shit and blood: meat smells, not person smells.

A stranger was standing between the huts, squat and powerful. He was wrapped in skins, and he held a thrusting spear. His face was daubed with crosshatched ocher marks. He was the one who had hurled the spear at Flatnose. And Pebble saw his own abandoned digging stick in the stranger’s hand. They had seen him at the yam stand. They had tracked his footsteps. Pebble had led them here.

Full of rage, fear, and guilt, he hurled himself forward.

But he went clattering to the ground. His mother had grabbed his waist. Lame or not she was still stronger than he was, and she glared at him, jabbering, “Stupid, stupid!” For an instant sanity returned to Pebble. Naked, unarmed, he would have been killed in an instant.

A man burst out of the heart of the settlement. He was naked and he carried his own thrusting spear. He was Pebble’s uncle, and he hurled himself at the killer of his brother. The stranger fended off the first blow, but his assailant closed in. The two of them fell to the dirt, wrestling, each trying to get in a decisive blow or thrust. Soon they had disappeared in a cloud of blood-spattered dust. They were two immensely muscled beings using all their mighty strength against each other. It was like a fight between two bears.