But these axes were strange. Some of the axes were tiny, the size of butterflies, while some were huge. Some of them were broken, some smeared with blood. But when she tried to pick up one of the larger axes, its edge cut into her fingers; it had hardly been used, if at all.

Someone walked up to her. She cowered back.

It was Scar-face, the man who had taught the children how to knap rock. He was looking at Far with a kind of hungry intensity. He had one of the huge axes in his hands. It was impractically large, too large to use to butcher. Still gazing at her he turned it over in his hands, and tapped at it with a hammer-stone, tidying up an edge. Then he scraped it over his leg, and removed a swath of the fine black hair that grew there. All through this he watched Far's face and body, his half-covered eye gleaming.

She had absolutely no idea what he wanted- none, that is, until she saw the erection poking out of his tuft of pubic hair.

Ax had more or less finished the blade he was making: hand-sized, utilitarian, rough and ready, it was clearly a functional tool, manufactured in minutes. But when he saw what Scar-face was doing he threw down his ax angrily. He got up, scattering his spill of flakes, and punched the man's shoulder. "Away! Away!"

Scar-face snarled back, his erection subsiding. At last Ax grabbed the huge gaudy ax out of his hands, and threw it to the ground. Part of its beautiful edge sheared off. Scar-face looked at the ax, at Far, and, with a final glare at Ax, walked away.

Far sat where she was, her knees tucked against her chest, fearful and baffled.

Ax stared at her. Then he stalked up and down the dry stream again, surveying the stones. At last he came across a big malformed volcanic block, so heavy it took two hands to lift it. He sat down again, picked up a few hammer-stones, scattered more brush over his legs.

He started to slam at the rock, displaying all his strength. Flakes and sheets of it began to fall away. But very quickly, thanks to his skill and strength, a crude hand ax teardrop shape emerged. Now he started to use a succession of smaller stones to shape the two lenticular surfaces, and to finish the edge to a fine blade.

Where his first effort had come easily, borne out of a rock that had already had the rough shape of the final ax, this rock was much more difficult. He couldn't have picked a tougher challenge- and he had chosen it deliberately. And all through this he made sure Far was watching him.

The walking folk had already been making tools more or less like this for two hundred thousand years. Over such an immense span of time, the axes had become more than mere tools, more than functional.

To Ax, this feat of toolmaking was a kind of courtship. He was displaying his fitness as a mate to Far. By making the tool he was showing her in one clear demonstration the strength of his body, the precision of his working, the clarity of his mind, his ability to conceive and see through a design, his skill for locating raw materials, his coordination of hand and eye, his spatial skills, his understanding of the environment around him. All of these were traits he expected she would want to pass on to her offspring- and that was why such displays had acquired a logic of their own, divorced from the utility of the hand axes.

Driven by lust and longing, men and boys would make dozens of axes, over and over. They would labor for hours over a single ax, seeking perfect symmetry. They would make tiny axes the size of their thumbnails, or they would make huge unwieldy affairs that would have to be held in two hands like an open book. They would, as Ax had, seek out particularly difficult raw materials and go ahead and carve out axes anyhow. Sometimes they would even throw away their axes, deliberately, to show how rich they were in strength and skill.

It was even worth trying to cheat, as Scar-face had done. It didn't work very often- women quickly learned they had to see see the most impressive ax being made before them- but occasionally it paid off, and the liar got a chance to pass on his genes at very low cost. the most impressive ax being made before them- but occasionally it paid off, and the liar got a chance to pass on his genes at very low cost.

This mixing up of toolmaking with sexual courtship would have a profound effect on the future. As no male could afford not to make axes just as his forefathers had done, it was a recipe for stultifying conservatism. These people would make the same tool to the same plan, over and over, across several continents, despite several glacial cycles, for a million years. Even the different species species who followed them would continue with the same technology. It was a continuity and a consistency that no institution, no religion would ever match. Only sex had a strong enough hold on the human mind to have achieved such a vast freezing. who followed them would continue with the same technology. It was a continuity and a consistency that no institution, no religion would ever match. Only sex had a strong enough hold on the human mind to have achieved such a vast freezing.

When he worked on his tools, Ax had to think, to some extent, like a human. Unlike the pithecine stone-slammer who would take whatever shape and size of flake his cobble offered him, Ax had to have an image of the final artifact in his mind. He had to select the raw materials and hammer-stones to match that vision, and he had to work systematically toward his goal. But his mind was divided as no human's could be. Ax made his tools like a human, but he attracted mates like a peacock or a bower bird.

When Ax was done, he turned the tool he had made over and over in his hands, showing her its fine faces, its smoothly finished edge. It was magnificent, if impractical.

Far, brought up in a subtly different culture, had no clear idea of what he was doing- and she was just as baffled by Scar-face's attempt to cheat. But she did sense Ax's interest in her, and a warmth in her belly spread in response. And a more calculating corner of her mind was aware that if she mated with Ax, if she became pregnant, then she would become part of this group, and her future would be secured.

But she had never had sex, not with anybody. Longing, fearful, she sat there at the edge of the streambed, her legs still tucked against her chest. She didn't know how to respond.

At length he dropped the beautiful ax, among so many others. Baffled, casting backward glances at her, he walked away.

Speciation- the emergence of a new species- was a rare event.

One species did not morph smoothly into another. Rather, speciation relied on a group of animals being isolated from the larger population and put under pressure to survive. The isolation could be physical- say, if a group of elephants was cut off by a flood- or it could be behavioral, if, for instance, one group of hominids that had adopted a particular way of scavenging was shunned by another group that hadn't.

Variation was implicit in the genome of every species. It was as if every species, at any given moment, was contained in a field, fenced off by the habitable limits of its environment. Every viable variation would come into play, to fill up every available corner of the field. An isolated group was stuck in a fenced-off corner of the field. But perhaps a little of the outer fence came down, opening up a new and empty field, into which they began, slowly, to diffuse. More variation might be necessary to fill the newly available space- and if the necessary variation wasn't available in the genome, perhaps it could be generated by mutation.

In the end, those who reached the furthest corner of the new range might have gone a great distance, genetically, from those who had remained in the old field. If the distance became too great for the old and new kinds to crossbreed, a new species was born. Later, when the isolating barriers came down, the evolved kind might interact with the parent type- perhaps to supplant them.

Some three hundred thousand years earlier, in another part of Africa, a group of nondescript forest-fringe pithecines had found themselves cut off from their home range by a lava flow, cast out of their forest once and for all.

There were many challenges to be met. The old pithecine habits of forest-fringe hunting had been a start, something to build on. But out on the savannah the food supply was very different from that in the forest. Whereas the forest had provided a steady supply of fruit, the main savannah food was meat. Meat was high-quality nutrition, but it came in packages scattered sparsely over an arid, inhospitable landscape, packages you had to be smart to spot, get hold of, and use. And stranded out on the savannah, away from the trees' shelter, a new kind of body was needed to cope with the aridity and the heat, new kinds of behavior needed to extract the resources needed from the new environment- and to survive in predator hell.

Within a mere few dozen generations Far's ancestors had adapted drastically.

The ancient primate body plan had been rebuilt, stretched tall almost to human proportions. Far's body was much bulkier than that of the ancestral apes. She was twice as heavy as an adult gracile pithecine. That bulk was an adaptation for openness: a larger body was more efficient at storing water, a key advantage on a plain where there could be many hours' walking between water sources.

And her metabolism had become efficient at creating and storing subcutaneous fat, for fat was a key fuel reserve. Ten kilograms of fat would be sufficient to see her through forty days without food, enough to ride out all but the most severe seasonal fluctuations. The fat had fleshed out her body, giving her swollen breasts, buttocks, and thighs, a much more human human shape than the pithecines' chimplike slackness. But Far was not a round ball; instead she was tall and thin, so that her body was also an efficient radiator of waste heat, and when the sun beat down from above, comparatively little of her skin was directly exposed to its radiation. shape than the pithecines' chimplike slackness. But Far was not a round ball; instead she was tall and thin, so that her body was also an efficient radiator of waste heat, and when the sun beat down from above, comparatively little of her skin was directly exposed to its radiation.

More heat adaptations: Apart from her head, with its grooming patch of hair, her skin was all but bare. And she sweated, unlike Capo, unlike any other ape outside her species family, for bare, sweating skin was a better temperature regulator than hair for creatures destined to spend their lives in open tropical sunlight. Sweating was a paradox, for it meant Far lost water. So she had to be smart enough to find water sources to make up for that, and, unlike some of the true savannah creatures, her kind would always be tied to some extent to water courses and the coasts.

The most apelike characteristics of the pithecines- their grasping feet, long arms, and stooping gait- had soon been abandoned. Far's feet were best fit for running and walking, not climbing: her big toe was now a toe, not a thumb. But Far's rib cage was a little high, her shoulders a little narrow: even now her body still carried with it traces of its vanishing adaptation to the trees- as would modern humans', as would Joan Useb's.

Meanwhile her brain had grown to more than three times the mass of a pithecine's, the better to handle the puzzles of a difficult landscape and the intricacies of still more complex societies of large groups of savannah foragers. That big brain was very energy-hungry, but Far's diet was much richer than any pithecine's, with plenty of high-protein foods like meat and nuts, which in turn required greater intelligence to gather. Thus her smartness had been driven by a virtuous circle of development.

All these changes were drastic, and yet they had been achieved by an evolutionary strategy of remarkable economy. It had been heterochrony- different timing. different timing. Walker infants looked much as their more apelike ancestors had- as would human babies- with relatively large skulls, small faces and jaws. If you wanted to become Capo, you grew your jaw large and kept your brain relatively small. But Far's brain had grown large while her jaw had stayed small. Even the much larger size of her body had been achieved by stretching out growing phases: her body had something like the relative dimensions of a fetal Capo, inflated to adult size. Walker infants looked much as their more apelike ancestors had- as would human babies- with relatively large skulls, small faces and jaws. If you wanted to become Capo, you grew your jaw large and kept your brain relatively small. But Far's brain had grown large while her jaw had stayed small. Even the much larger size of her body had been achieved by stretching out growing phases: her body had something like the relative dimensions of a fetal Capo, inflated to adult size.

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. 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.

CHAPTER 10.

The Crowded Land Central Kenya, East Africa. Circa 127,000 years before present.

I.

Pebble had found a yam vine. He bent and inspected it.

He was eight years old, naked save for smears of ocher on his barrel chest and broad face. He pulled out a little grass from around the yam's base. This was a spot for yam, not grass, and it was best to keep it that way.

People had been here before to dig out these tubers. Perhaps he had even been here himself. At eight years old he had already covered every scrap of his people's range, and he thought he remembered this spot, here between these eroded bluffs of sandstone.

He took his digging stick. This was a heavy pole shoved through a hole crudely bored in a small boulder. Despite the tool's weight, he lifted it easily, and he used the mass of the boulder to ram the digger's point into the hard ground.

Pebble was a solid slab of muscle built over a tough, robust skeleton. If Far, his long-dead, distant grandmother, had looked like a long-distance runner, Pebble might have been a junior shot-putter. His face was large, massive-featured, dominated by a great ridge of bone over his brow. He had a mountainous nose and large sinuses that gave his face an oddly puffed-out look. His teeth were flat-topped pillars of enamel. His skull, which would become considerably larger than Far's, housed a large and complex brain- in fact comparable in size to a modern human's- but it sat much more directly behind his face than a human's brain would have.

When he had been born, wet from the womb, Pebble's body had been sleek and round, inspiring an odd image in his mother's mind, a pebble worn by a stream. Names for people still lay far in the future- with just twelve people in Pebble's group there was no need for names- but nevertheless this boy's mother would often look on a glistening rock in a stream, and remember her child as he had been as a baby in her arms.

Pebble, then.

In this age there were many kinds of robust folk like Pebble's spread through Europe and western Asia. Those who inhabited Europe would one day be called Neandertals. But just as in Far's time, most of these new kinds of people would never be discovered, let alone understood, classified, linked to a hominid family tree.

His were a strong people, though. Even at eight years old, Pebble performed work essential to his family's survival. He wasn't yet up to joining the adults on the hunts, but he could dig out yams with the best of them.

The wind picked up a little, bringing him the delicious scent of wood smoke, of home. He went at his work with a will.

Already his digging had broken up the earth. He plunged his hands into the dry ground and began exposing a fat tuber that looked as if it might go down a long way, perhaps as deep as two meters. He went back to his digging stick. Bits of dust and rock flew up, sticking to his sweat-covered legs. He knew what to do with yams. When he had the tuber he would cut off the edible flesh, but then replace the tuber's stem and top in the ground so that it would regrow. His digging aided the yam in more subtle ways, too. He was loosening and aerating the soil, further fostering regrowth.

His mother would be pleased if he brought home three or four fat tubers, ready to be thrown onto the fire. And yams were useful in a lot of other ways besides eating. You could use them to poison birds and fish. You could rub their juice into your head to kill the lice that crawled there... There was a crunching noise.

Startled, Pebble pulled back his digging stick. He leaned forward, shielding his eyes from the sun's brightness, trying to see what was down there in the hole. It could be some deep-burrowing insect. But he could see nothing but a scrap of rust brown, like a bit of sandstone. He reached down and, his clumsy fingers stretching, grabbed the scrap and pulled it to the surface. It was a ragged-edged dome, small enough to fit in the palm of his hand. When he held it up before his face two empty eye sockets peered back at him.

It was a skull. The head of a child.

That was no great horror. Children died all the time. This was a harsh place: There was little pity to spare for the weak and hapless.

But all the children who had died within Pebble's own short lifetime had been put in the ground close to the huts. Like all the dead, they were buried to keep the scavengers from harassing the living. Perhaps this child was long dead, then. Perhaps its people had buried it here before Pebble was born, where the yam clump grew now.

But the skull was oddly fine, light. Pebble weighed it in his hand. Its brow was a heavy lid of bone, from which a forehead sloped back almost horizontally. Pebble ran a hand over his own scalp and compared the slightly bulbous swelling of his forehead. There were tooth marks in the little cranium, he saw: precise puncture wounds inflicted by the teeth of a cat- but inflicted after the child was already dead, its body abandoned on the plain.

Pebble could not know that he was holding the remains of the Brat, brother of Far, who had lived and died not far from here. The Brat had succumbed to his infant vitaminosis and died while still a child, without issue. It would have been little comfort to the Brat if he could have known that one day, when his brief, forgotten life was already more than a million years gone, his small head would be cradled in the hand of a remote great-nephew.

And the Brat would have recognized little of this landscape, the place where he had once played.

The geological infrastructure of the Rift Valley- the plateau, the rocks, the volcanic mountains, the great sweep of the valley itself- had been left largely unchanged by time. But since Far's time this had become a sparse, dry place. Scattered stands of acacia, leadwood, and wild laurel had replaced the denser thickets and forest pockets of the past. Even the grasslands were subtly different, great swaths of them dominated by a handful of fire-resistant species. Meanwhile, the great animal communities of the past had imploded. There was not an elephant to be seen across this great dust bowl, not an antelope or giraffe. It was as if life had crashed here. The place was depleted. Far would have been startled by its impoverishment.

But the Brat's wretched remains had left their mark on the world: a scrap of moisture trapped in that buried, upturned skullcap had been enough to help establish the yam.

Incuriously Pebble closed his fist. The little skull was crushed to thin shards, and he let the dust fall back into the hole. He reached for his digging tool; there was still some root to be dug out.

That was when he glimpsed the strangers.

He crouched down behind a bluff, holding his breath.

They were hunters; he could see that immediately. They were following an old elephant track. Elephants walked to water, and where there was water, there would be many animals, including the medium-sized creatures like deer that people hunted by preference.

There were four of them, three men and a woman, all adults. As they walked the hunters' legs swung powerfully, with their torsos tipped a little forward. It was a gait built for strength, not elegance or speed: the hunters had none of the fleetness of Far. Thick beards hid the men's dark faces, and the woman had tied her long hair back with a bit of leather. Unlike Pebble this group wore clothes: just bits of hide, unsewn and tied around the body with strips of leather or plaited bark. Pebble could see the bite marks in the clothes. Leather was treated by chewing and stretching it with the teeth, and a major function of that big ridge of bone on Pebble's brow was to provide an anchor for the jaws that must do such mighty work.

And they carried weapons: narrow wooden throwing spears, and shorter, stubby thrusting spears, great logs of hardwood with slabs of stone stuck to the end with blobs of resin and leather ties. They were giants' weapons that a human would have had trouble lifting, let alone wielding in anger.

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.