But that large body size and big brain came at a price. She had been born with her development incomplete, because that was the only way her head would have squeezed through her mother’s birth canal. She had been born premature. Unlike the apes and even the pithecines, walker infants could not forage for themselves until long after weaning: aside from their physical immaturity, the ability to exploit food sources like hunted meat, clams, and heavy-shelled nuts was not innate in the newborn, and so had to be learned. But at the same time the children of the walkers were being born into the predator hell of the savannah. So, while they were young, kids needed a lot of care.

These costly, dependent children made it difficult for the walker types to compete with the fast-breeding pithecines, with whom they often shared the same habitats. And that was why the walkers began to live longer.

Most pithecine females, like the apes before them, died not long after their fertility ended — indeed, few long outlived their last birth. Walker women, and men, began to live for years, even decades after their reproductive career was apparently over. These grandmothers and grandfathers began to play a crucial role in shaping walker society. They helped with the division of labor: They helped their daughters care for the children, they helped gather food, they were essential in passing on the complex information required by the walkers to survive.

All this had required a new efficiency in body design. Walker bodies were much better than pithecines’ at maintenance and longevity — all save their reproductive systems; a forty-year-old walker woman’s ovaries were as badly degenerated as would be the rest of her body at age eighty, if she lived that long.

Crucially, the grandmothers’ support meant their daughters could afford to have children more often. That was how the walkers outcompeted the pithecines and apes. Almost all walker children survived long after weaning. Almost all pithecine infants did not.

For the pithecines the emergence of this new form was a disaster. Walkers and pithecines were too close cousins to share the ecology easily. There were few direct conflicts between the types of people: Sometimes pithecines hunted walkers or walkers hunted pithecines, but they found each other too smart and dangerous a prey to be worth the trouble. But in ages to come the walkers — big-brained, flexible, mobile — would slowly drive their smaller-brained cousins to extinction.

Toolmaking and even consciousness were, ultimately, no guarantee of survival.

Of course it need not have happened. If not for the fluctuation of the climate, the chance isolation of Far’s ancestors, there might have been no mankind: nothing but pithecines, upright chimps screeching and making their crude tools and waging their petty wars for millions of years more, until the forests disappeared altogether, and they succumbed to extinction.

Life always had been chancy.

Far spent the night alone, cold, drifting through an uneasy sleep.

The next day, as she tried to join in the group’s activities, a woman, heavily pregnant, glared into her eyes, an ancient primate challenge. Was Far here to take food that might otherwise reach the belly of her unborn child?

Far felt more isolated than ever. She had no ties with anybody here. There was no reason why they should share their space, their resources with her. It wasn’t as if this place was brimming with riches. And now even Ax seemed to be rejecting her.

As the afternoon wore on she was the first to return, alone, to the hollow in the sandstone outcrop. She tucked herself into the peripheral corner she had come to think of as her own.

But she noticed some lumps of crimson rock scattered deeper at the back of the hollow. She picked them up, turning them over curiously. Their redness was bright in the daylight, and they were soft. They were lumps of ocher, the iron red of ferric oxide. Someone had been attracted by their color and, on impulse, brought them here.

She saw scrapes of red on scattered basalt rocks at the back of the hollow: red the same color as the ocher, red like blood. Experimentally she pushed the ocher over the rock, and was startled to see more bloody streaks smear over the rock surface.

For long minutes she played with the bits of ocher, not really thinking, her clever fingers working by themselves to add their own meaningless scribbles to the scrawls on the rock.

Then she heard the hollers of the people as they started to drift back to their temporary base. She dropped the bits of ocher where she had found them, and made for her corner.

But the palms of her hands were bright red: red like blood. For an instant she thought she had cut herself. But when she licked her palms she tasted salty rock, and the scraping of ocher came away.

Red like blood. A tentative connection formed in her mind, a chink of light shining between her compartments of thought.

She went back to the bits of ocher. Now she tried scraping them over the back of her hands, where she made a hatchery of lines, and on the healing pithecine cut on her shoulder, which she made bright red again.

And she marked herself between her legs — marking her skin red like blood, as if she were bleeding, as she had seen her mother bleed.

She went back to her corner and waited until the light faded. As the people tended and crooned to each other, she huddled over and tried to sleep.

Someone approached: warm, breathing softly. It was Ax. She could smell the dusty scent of rock chippings on his legs and belly. His eyes were pits of shadow in the fading light. The moment stretched. Then he touched her shoulder. His hand was heavy and warm, but she shivered. He leaned toward her and sniffed quietly, scenting her just as had Brow before she had become separated from her family.

She opened her legs, so he could see the “blood” in the fading light. She sat tense, watching him.

Her life hung on his acceptance; she knew that. Perhaps it was that basic desperation and longing, a longing for him to see her as a woman, which had driven her to come up with this peculiar deceit.

Unlike his forest-dwelling ancestors, Ax was a creature of sight, not smell; the message from his eyes overrode the warning of his nose. He leaned forward. He touched her shoulder, her throat, her breast. Then he sat beside her and his strong fingers began to comb through her tangled hair.

Slowly she relaxed.

Far stayed with Ax and his people for the rest of her life. But as long as she could, whenever she could — as she grew in wisdom and strength, as her children grew until they gave her grandchildren to protect and mold in turn — she ran, and ran, and ran.