She was no expert on botany, African or otherwise. It did seem to her there were a lot of fern-like trees and relatively few flowering plants, as if the flora here was more primitive than on Earth. A walk in the Jurassic, then.

As for the fauna, she glimpsed herds of antelope-like creatures: some of them were slim and agile, who would bolt as the Runners approached, but others were larger, clumsier, hairier, crossing the savannah in heavy-footed gangs. The animals kept their distance, and she was grateful for that. But again they didn’t strike her as being characteristically African: she saw no elephants, no zebra or giraffes. (But then, she told herself, there were barely any elephants left in Africa anyhow.)

It was clear there were predators everywhere. Once Emma heard the throaty, echoing roar of what had to be a lion. A couple of times she spotted cats slinking through brush at the fringe of forests: leopards, perhaps.

And once they came across a herd — no, a flock — of huge, vicious-looking carnivorous birds.

The flightless creatures moved in a tight group with an odd nervousness, pecking at the ground with those savagely curved beaks, and scratching at their feathers and cheeks with claws like scimitars. Their behaviour was very bird-like, but unnerving in creatures so huge.

The Runners took cover in a patch of forests for a full half-day, until the flock had passed.

The Runners called them “killing birds’. A wide-eyed Maxie called the birds “dinosaurs’.

And they did look like dinosaurs, Emma thought. Birds had evolved from dinosaurs, of course; here, maybe, following some ecological logic, birds had lost their flight, had forgotten how to sing, but they had rediscovered their power and their pomp, becoming lords of the landscape once more.

The Runners” gait wasn’t quite human. Their rib cages seemed high and somewhat conical, more like a chimp’s than a human’s, and their hips were very narrow, so that each Runner was a delicately balanced slim form with long striding legs.

Emma wondered what problems those narrow hips caused during childbirth. The heads of the Runners weren’t that much smaller than her own. But there were no midwives here, and no epidurals either. Maybe the women helped each other.

Certainly each of them clearly knew her own children — unlike the men, who seemed to regard the children as small, irritating competitors.

The women even seemed to use sex to bond. Sometimes in the night, two women would lie together, touching and stroking, sharing gentle pleasures that would last much longer than the short, somewhat brutal physical encounters they had with the men.

By comparison, the men had no real community at all, just a brutish ladder of competition: they bickered and snapped amongst themselves, endlessly working out their pecking order. At that, Emma thought, this bunch of guys had a lot of common with every human mostly-male preserve she had ever come across, up to and including the NASA Astronaut Office.

Stone was the boss man; he used his fists and feet and teeth and hand-axes to keep the other men in their place, and to win access to the women. But he, and the other men, did not seek to injure or kill his own kind. It was all just a dominance game.

And Stone was not running a harem here. With all that fist-fighting he won himself more rolls in the hay than the other men, but the others got plenty too; all they had to do was wait until Stone was asleep, or looking the other way, or was off hunting, or just otherwise engaged. Emma had no idea why this should be so. Maybe you just couldn’t run a harem in a highly mobile group like this; maybe you needed a place to hold your female quasi-prisoners, a fortress to defend your “property” from other men.

It was what these people lacked that struck Emma most strongly. They had no art, no music, no song. They didn’t even have language; their verbless jabber conveyed basic emotions — anger, fear, demands — but little information. They only “talked” anyhow in social encounters, mating or grooming or fighting, never when they were working, making tools or hunting or even eating. She thought their “talk” had more in common with the purring and yowling of cats than information-rich human conversation.

Certainly the Runners never discussed where they were going. It was clear, though, from the way they studied animal tracks, and fingered shrubs, and sniffed the wind, that they had a deep understanding of this land on which they lived, and knew how to find their way across it.

…Yes, but how did that knowledge get there, if not through talking, learning? Maybe a facility for tracking was hard-wired into their heads at birth, she speculated, as the ability to pick up language seemed to be born with human infants.

Whatever, it was a peculiar example of how the Runners could be as smart as any human in one domain — say, tracking — and yet be dumber than the smallest child in another — such as playing Maxie’s games of hide-and-seek and catch. It was as if their minds were chambered, some rooms fully stocked, some empty, all of the chambers walled off from each other.

When the Runners stopped for the night, they would scavenge for rocks and bits of wood and quickly make any tools they needed: hand-axes, spears. But they carried nothing with them except chunks of food. In the morning, when it was time to move on, they would just drop their hand-axes in the dirt and walk away, sometimes leaving the tools in the mounds of spill they had made during their creation.

Emma saw it made sense. It only took a quarter-hour or so to make a reasonable hand-axe, and the Runners were smart at finding the raw materials they needed; they presumably wouldn’t stop in a place that couldn’t provide them in that way. To invest fifteen minutes in making a new axe was a lot better than spending all day carrying a lethally sharp blade in your bare hands.

All this shaped their lifestyle, in a way she found oddly pleasing. The Runners had no possessions. If they wanted to move to some new place they just abandoned everything they had, like walking out of a house full of furniture leaving the doors unlocked. When they got to where they were going they would just make more of whatever they needed, and within half a day they were probably as well equipped as they had been before the move. There must be a deep satisfaction in this way of life, never weighed down by possessions and souvenirs and memories. A clean self-sufficiency.

But Sally was dismissive. “Lions don’t own anything either. Elephants don’t. Chimps don’t. Emma, these ape-men are animals, even if they are built like basketball players. The notion of possessing anything that doesn’t go straight in their mouths has no more meaning to them than it would to my pet cat.”

Emma shook her head, troubled. The truth, she suspected, was deeper than that.

Anyhow, people or animals, the Runners walked, and walked, and walked. They were black shadows that glided over bright red ground, hooting and calling to each other, nude walking machines.

Soon Emma’s socks were a ragged bloody mess, and where her boots didn’t fit quite right they chafed at her skin. A major part of each new day was the foot ritual, as Emma and Sally lanced blisters and stuffed their battered boots with leaves and grass. And if she rolled up her trousers wet sores, pink on black, speckled her shins; Sally suffered similarly. They took turns carrying Maxie, but they were laden down with their parachute silk bundles, and a lot of the time he just had to walk as best he could, clinging to their hands, wailing protests.

During the long days of walking, Emma found herself inevitably spending more time than she liked with Sally.

Emma and Sally didn’t much like each other. That was the blunt truth.

There was no reason why they should; they had after all been scooped at random from out of the sky, and just thrown together. At times, hungry or thirsty or frightened or bewildered, they would take it out on each other, bitching and arguing. But that would always pass. They were both smart enough to recognize how much they needed each other.