Evolution

Living like this was a challenge, though. Trading meant building up a new kind of map of the world. Other people were no longer just passive features of the landscape, like rocks and trees. Now a track had to be kept of who lived where, what they could offer, how friendly they were — and how honest. There was a ferocious pressure on the swamp people to get smarter, fast.

The design of their heads changed drastically. Their skulls enlarged to make room for bigger brains. And changing diets and lifestyles had a dramatic effect on their faces. No longer used to chew tough, uncooked food or to treat leather, their teeth became more feebly rooted. As chewing muscles withered, the upper tooth row shrank back. The lower jaw was left jutting, and the face tilted back, so that these hominids lost the last trace of their ancient apelike muzzles. The declining muzzle and ballooning foreheads provided new anchoring surfaces for the muscles of the face, and the old projecting browridges disappeared.

Meanwhile, as they got smarter, they didn’t need to be as strong. Their bodies shed much of the robustness of their immediate ancestors, and reverted to something like the graceful litheness of Far’s people.

Pebble’s first impression, that Harpoon had seemed childlike, was not accidental. With the proportions of their faces and their thinned bones these new people, compared to ancestral stock, were in some ways like children arrested in their growth. Once again, under ferocious selection pressure, the genes had reached for variations that could be implemented quickly: Adjusting the comparative growth rates of skeletal features was comparatively easy.

All of these changes had been essentially complete within a few millennia. After this process Harpoon, anatomically, was all but identical to a human of Joan Useb’s time, even in her skull and the gross features of her brain. And it had been trading, a new way of dealing with other people, that had made them what they were.

But even Harpoon was not yet human.

There was a little more invention, a little more organization in her life. Her kind built hearths, for instance. But her tool kit was scarcely more advanced than that of Pebble and his ancestors. Her language was the same unstructured babbling. Much of the way she lived her life, like her sexuality, had been inherited with little change from the kinds of people who had gone before. There were still rigid barriers in her mind, a lack of connections in the neural wiring of her brain. A true human of Joan Useb’s age, stranded in this age of her ancestors, would quickly have been driven crazy by the sameness, the routine, and ritual, the lack of art and language — the boring, drab poverty of life.

And, human form or not, these folk had not been dramatically successful. Though they had spread across Africa from their origins in that southeastern swamp, their lifestyle remained marginal. It was difficult to trade if there was nobody like you to trade with. Even now the new nomads’ survival was chancy, and most extant groups, around the continent, would not survive.

The children of Harpoon were destined to pass through this bottleneck, but their genes would always bear the imprint of that narrow passage. In the future, the swarming billions who would spring from this unpromising seed would be virtually identical, genetically; every human would be a cousin.

Pebble’s relationship with Harpoon came to a head during a hunt.

One day, Pebble found himself in a blind, upwind of a herd of giant horse who cropped the long grass peacefully. The blind was just a lean-to frame of saplings, loosely woven together and covered with palm fronds and grass. Here Pebble huddled, his thrusting-spear at his side, peering out at the big, lame animal that was their target. And Harpoon was at his side. He was tense, adrenaline pumping, and the heat of the day and the sweat scent of the horse filled his head.

Suddenly he felt her fingers on his face.

He turned. Her skin seemed to glow in the green gloom. She traced the vertical ocher stripes he still wore. And then her fine fingers moved to his arm, the long-healed cuts he had inflicted there. Her every touch was startling, as if her fingers were made of ice or fire.

He ran his fingers down her arm. His fist enclosed her forearm easily, as if it were a bird’s leg. He felt he could snap the bone with a gesture. Suddenly it was just as it had been on the first day he had met her, on the beach. His mouth dried, his throat tightened.

He didn’t understand his lust: the lust that had never gone away. He thought of the clever tools she made, her long, easy stride across the ground, the food she had brought his people — and that harpoon, the exquisite harpoon point, unimaginable before he had seen it that first day. There was something in her his body wanted; the longing was unbearable.

He rolled on his back. In the rustling shade of the blind, she straddled him and smiled.

IV