She went naked save for a bolt of eland leather tied round her waist. She had a shaped stone in one hand, but carried nothing else. Her face was fully human, her brow smooth and upright, her chin sharp. But her mouth was pinched and her eyes were sunken, her gaze darting suspiciously.

The savannah around her was arid, dismal. The empty shadowless flatness stretched away, dissolving into a ghostly heat haze that obscured the encircling horizon, a flatness broken only by an occasional drought-resistant bush or the remains of an elephant-trampled copse. There wasn't even any dung to be seen, for the great herbivores passed rarely now, and the beetles had long done their tidy and efficient work.

Clutching the cactus stem, she moved on.

She reached the edge of the lake- or where its edge had been last year, or perhaps the year before that. Now the ground was dry, a patina of dark, heat-cracked mud so hard it didn't crumble when she put her weight on it. Here and there scrubby grass, yellow white, clung to life.

She cupped her hands over her eyes. The water was still there, but far from where she stood, just a remote shimmer. Even from here she could detect the dank stench of stagnation. On the lake's far side she glimpsed elephants, black shapes moving like clouds through the glassy heat haze, and animals rooting in the mud- warthogs, perhaps.

But on the lake's clogged surface she made out waterfowl, a flock roosting peacefully at the center of the water, safe from the hungry predators of the land.

Mother smiled. The birds were just where she wanted them. She turned and walked back from the lake's barren muddy aureole.

At thirty years old, Mother's body was as lithe and upright as it had been in her youth. But her belly bore marks from the birth of her single child, her son, and her breasts sagged. Her buttocks were full; this was an adaptation to the long periods of drought, to help her store water in fat. Her limbs showed stringy muscles, and her belly showed none of the malnutritional swelling affecting many of the folk. She was evidently effective at the business of life.

But she couldn't remember a time when she had been happy. Not even as a child, when she had been clumsy, slow to talk, slow to fit in. Not even when her son had been born, healthy and wailing.

She saw saw too much. too much.

This drought, for instance. The clouds had gone away, which enabled the sun to beat down all day, which dried the land and made the water vanish, which made the animals die, which made the people go hungry. So the people went hungry because of the clouds. What she couldn't figure out was what had made the clouds go away in the first place. Not yet.

This was what she had a talent for: seeing patterns and connections, networks of causes and effects that intrigued and baffled her. Her talent for spotting causal links brought her no comfort. It was more a kind of obsessive suspicion. But it did help her get through life sometimes- like today.

She came to a baobab tree, and studied its twisted branches. She knew what she wanted to make- a boomerang, a curved throwing weapon- and she inspected the branches and buttresses, looking for a place where the grain of the wood and its growth direction matched the weapon's final shape, as she could see it in her mind.

She found one slender branch that might work. With a brisk snap she broke it off close to where it joined with the tree. Then she sat down in the baobab's scrap of shade, took her stone tool, stripped off the bark, and began to carve the wood. She turned her stone blade over and over in her hand to bring favored edges into use. This tool- not quite an ax, or a knife, or a scraper- was her current favorite. Because any tool she couldn't make on the spot had to be carried, she had manufactured this one tool to do many jobs, and she had retouched it several times.

Soon she had produced a smoothly curved stick some thirty centimeters long, flat on one side and rounded on the other. She hefted the boomerang in her hand, assessed its balance and weight with a judgment born of long practice, and quickly scraped away a little excess.

Then she walked out of the baobab's shade and around the perimeter of the lake's muddy fringe. She found the place where she had stashed a net of plaited bark fiber a few days before. The net was undisturbed. She shook it clear of dust, and the beetles that gnawed its dry fibers.

She hung the net across two gaunt, conveniently placed baobabs so that it faced the lake. She had chosen this site, in fact, because of the baobabs.

Now she walked back around the lake, until she was sideways when compared to the position of her net. She took her throwing stick. Her tongue protruding, she hefted it, rehearsing the throw she would make. She would get only one shot at this, and she had to get it right.

Pain pulsed at her temples, distant, like thunder in remote mountains.

She lost her balance, and grimaced, annoyed at the distraction. The pain itself was trivial, but it was a precursor of what was to come. Her migraine was a relentless punishment she endured frequently, and there was nothing to be done about it- it had no cure, of course, not even a name. But she knew she had to get on with her task before the pain made it impossible. Otherwise she would go hungry today, and so would her son.

Ignoring the throbbing in her head, she set herself once more, hefted the stick, and hurled it with strength and precision. The whirling stick followed a sweet curving arc high into the air over the lake, its wooden blades whirling with a subtle whoosh.

The roosting waterfowl rustled and cawed irritably, and when the stick turned in the air and fell on them they panicked. With a clatter of ungainly wings the birds took to the air and fled from the lake- and the flock's low-flying outliers ran straight into Mother's net. Grinning, she ran back around the lake to claim her prize.

Connections. Mother threw the boomerang, which scared the birds, which flew into the net, because Mother had placed it there. As examples of Mother's causal-link thinking went, this had been elementary. Mother threw the boomerang, which scared the birds, which flew into the net, because Mother had placed it there. As examples of Mother's causal-link thinking went, this had been elementary.

But with every step she took her headache worsened, as if her brain were rattling in her capacious skull, and her brief pleasure at her success was crowded out, as it always was.

Mother's people lived in a camp close to a dry, eroded channel that ran into a gorge. Shelters had been set up among the rocky bluffs, just lean-tos, sheets of hide or woven rattan propped up on simple frames. There were no permanent huts here, unlike the structures in Pebble's long-vanished encampment. The land wasn't rich enough for that. This was the temporary home of nomadic hunter-gatherers, people forced to follow their food supply. The people had been here for a month.

The site had its advantages. There was a stream, the local rock was good for toolmaking, and there was a clump of forest nearby, a source of wood for fires, and bark, leaves, liana, and vines for cloth, netting, and other tools and artifacts. And the site was a good place to ambush animals that came wandering foolishly toward the gorge. But the produce of the area here had not been good. The camp was poor, the undernourished people listless. They would probably move on soon.

Mother stumbled home, three waterfowl slung on bits of leather rope over her shoulder. The pain in her head had grown sharp now, and every surface seemed overbright and tinged with strange colors. The ballooning of the human brain, in the millennia before the birth of Mother's distant ancestor Harpoon, had been spectacular. This hasty rewiring brought unexpected benefits- like Mother's pattern-making ability- but costs, like her plaguing migraine.

"Hey, hey! Spear danger spear!"

She looked around dimly.

Two of the younger men were staring at her. They wore wraparound hides tied in place with bits of sinew. They both held wooden spears, crudely finished, their tips hardened by charring. They had been hurling their spears at an ox hide they had draped over the branches of a tree. Mother, distracted by the pain and the strange lights, had almost blundered into their path.

She had to wait while the spear throwers completed their contest. Neither of the two young men was particularly skillful, and their hide wraps were shabby. Only one of their spears had pierced the hide to embed itself in the tree; the rest lay scattered in the dirt.

But one of the hunters was at least hurling his spears with more power, she saw. This boy held the spear unusually far back along its shaft, and used the length of his bony arms to get a little more leverage. Tall for his age, whip thin, she thought of him as a sapling, drawn up by the sunlight. When Sapling threw the spear, it hissed through the air, oscillating slightly. The spear's movement was intriguing. But as her eyes tracked it, her head hurt even more.

When the spear throwers were done she blundered on, seeking the dark of the hide she shared with her son.

Inside Mother's hut was a stocky woman of thirty-five. She had ragged, graying hair and a habitually pinched, sour face. This woman, Sour, was using a pestle to grind a piece of root. She glared at Mother, her expression as hostile as usual. "Food, food?"

Mother waved a hand vaguely, caring nothing about Sour. "Birds," she said.

Sour put down her pestle and root, and went outside to see the birds Mother had hung up.

Sour was Mother's aunt. She had become embittered when she had lost her second child to some unknown illness a couple of days after childbirth. She would probably steal the birds, giving Mother and Silent a fraction of what Mother had brought home. But Mother, her head full of pain, felt too weary to care.

She tried to focus on her son. He sat with his back to the slanting woven roof, his knees tucked up to his chest. A sickly boy of eight, short and bony, he was using one bit of twig to push another around the dirt floor. Mother sat beside him and ruffled his hair. He looked up at her with heavy, sleepy eyes. He spent a lot of his time like this- silent, withdrawn from the rest, waiting for her. He took after his father, a short, unsuccessful hunter who had lovelessly coupled with Mother just once- and in that one coupling had succeeded in impregnating her.

Her experience of sex had been sporadic and not very pleasurable. She had met no man strong enough, or kind enough, to withstand the intensity of her gaze, her obsessiveness, her quickness to anger, and her frequent pain-driven withdrawals into herself. It was her great misfortune that the man who finally made her pregnant had quickly moved on to another- and that he had soon fallen to the ax blow of a rival.

The child was Silent, for that was his defining characteristic. And likewise, since it sometimes seemed that she had no identity in the eyes of other people here- no identity for anybody except the boy- she was Mother. She had little to give him. But at least he was spared the swollen-belly hunger that was already afflicting some of the other little ones in this time of drought.

At length the boy lay on his side and curled up, thumb in his mouth. She lay down herself on her pallet of bundled-together straw. She knew better than to try to fight the pain.

She had always been isolated, even as a child. She could not throw herself into the games of chase and wrestling and chattering that the other youngsters had indulged in, or their adolescent sexual experiments. It was always as if the others knew how to behave, what to do, how to laugh and cry- how to fit in, fit in, a mystery she could never share. Her restless inventiveness in such a conservative culture- and her habit of trying to figure out a mystery she could never share. Her restless inventiveness in such a conservative culture- and her habit of trying to figure out why why things happened, things happened, how how they worked- didn't make her any more popular. they worked- didn't make her any more popular.

As time had gone on she had come to suspect that other people were talking about her when she wasn't there, that they were plotting against her- planning to make her unhappy in ways she couldn't even understand. None of which helped her get along with her fellows.

But she had her comforts.

The headache would not go away. But it was during the headaches that she saw the shapes. The simplest were stars- but they were not stars, for they flared, bright and evanescent, before fading away. She would try to turn her head to follow them, hoping to see where the next came from. But the stars would move with her eyes, drifting like reeds in a lake. Then would come more shapes: zigzags, spirals, lattices, nested curves, parallel lines. Even in the deepest darkness, even when the pain blinded her, she could see the shapes. And when the pain faded, the memory of the strange, brilliant shapes stayed with her.

But even as she willed her body to relax, she thought of long-armed Sapling and his spear throwing, and little Silent pushing his bits of twig back and forth, back and forth... Connections.

Sapling tried again.

A look of irritability on his face, he hooked the spear in the notch on the stick Mother had given him. Then, holding the stick in his right hand, he used his left hand to support the spear over his shoulder, point facing forward. He took a couple of hesitant steps forward, whipped his right arm forward- and the spear tipped up, its charred point gazing at the sky, before falling back to the dirt.

Sapling dropped the shaped stick and stamped on it. "Stupid, stupid!"

Mother, frustrated herself, slapped the back of his head. "Stupid! You!" Why couldn't he see what she wanted? She picked up the spear and the stick and thrust them into Sapling's hands, closing his fingers around the artifacts to make him try again.

She had been working at this all morning.

After that ferocious migraine Mother had woken with a new vision in her head, a peculiar melange of Silent's indirect stick poking and Sapling's long, leverage-rich throwing arm. Ignoring her son, she had rushed to the clump of woods nearby.

Soon she had made what she wanted. It was a short, massy stick with a notch cut into one end. When she put the spear in the notch and tried to thrust the spear forward- yes, it was as she had thought; the stick was like an extension of her arm, making it longer even than Sapling's, and the notch was like a finger that grasped her spear.

There were very few people on the planet who could have thought this way, drawing an analogy between a stick and a hand, a natural object and a part of the body. But Mother could.

As always, when she had latched on to some project like this, she had become completely immersed in it, resenting the time she spent away from it to eat, drink, sleep, gather food- even to be with her son.

In her more lucid moments she was aware of her neglect of Silent. But Sour, her aunt, was around to take care of him. That was what aging female relatives were for, to share the burden of child rearing. Deep down, though, Mother was suspicious of Sour. Something had indeed soured inside her when she lost her second child; even though she had a daughter of her own, she took an interest in Silent that wasn't healthy. But Mother had no time to think about that, not while the spear throwing obsessed her.

She kept trying with Sapling, over and over, as the sun arced over the sky and the young man grew restive, hot, thirsty, his day's chores not even started. But every time he failed.

At length Mother started to see what the problem was. It wasn't a question of clumsy technique. Sapling didn't understand the principle of what she was trying to show him: that it was not his hand hand that would do the throwing, but the that would do the throwing, but the stick. stick. And until he got that, he could never get the spear-thrower to work. And until he got that, he could never get the spear-thrower to work.

There were rigid compartment walls in Sapling's mind, almost as rigid as in Pebble's, his remote grandfather's. He was supremely intelligent socially; in his maneuverings, coalition-building, wooings and betrayals, he could rival Machiavelli. But he didn't apply that intelligence to other activities, like toolmaking. It was as if a different mind were switched on at such times, a mind no more advanced than Far's.

But it wasn't quite quite like that for Mother- and that was the source of her strangeness, and her genius. like that for Mother- and that was the source of her strangeness, and her genius.

She took the thrower from him, set the spear in its notch, and made as if to throw. "Hand, throw, no," she said. Now she mimed the stick pushing the spear. "Stick, throw. Yes, yes. Stick. Throw. Spear. Stick throw spear. Stick throw spear..."

Stick throw spear. It wasn't much of a sentence. But it had a rudimentary structure- subject, verb, object- and the honor of being one of the first sentences spoken in any human language, anywhere in the world. It wasn't much of a sentence. But it had a rudimentary structure- subject, verb, object- and the honor of being one of the first sentences spoken in any human language, anywhere in the world.

As she repeated her message over and over, it gradually sank in.

Sapling grinned and grabbed the spear and thrower from her. "Stick throw spear! Stick throw spear!" Quickly he fitted the spear into its notch, reached back, set the spear over his shoulder- and hurled with all his might.

It was a lousy throw, that first time. The spear ended up skidding in the dirt far short of the palm she had identified as a nominal target. But he had gotten the idea. Excited, jabbering, he ran after the spear. With an obsession that briefly matched Mother's own he tried over and over.

She had come up with this idea thanks to her peculiar ability to think about the throwing stick in more than one way. It was a tool, yes- but it was also like her fingers in the way it held the spear- and was even like a person in that it could do do things, it could throw the spear for you. If you were capable of thinking of an object from more than one point of view, you could imagine it doing all sorts of things. For Mother, consciousness was becoming more than just a tool for lying. things, it could throw the spear for you. If you were capable of thinking of an object from more than one point of view, you could imagine it doing all sorts of things. For Mother, consciousness was becoming more than just a tool for lying.

Sapling probably would never have come up with this insight by himself. But once she had gotten through to him he had grasped the concept quickly; after all his mind wasn't so much different from hers. As Sapling hauled the throwing stick forward, the great force it applied to the spear made it bend: the spear, flexing, actually seemed to leap away, like a gazelle escaping a trap. Mother's mind spun with satisfaction and speculation.

"Sick." The flat, ugly word cut through her euphoria. Sour, her aunt, was standing outside the shelter they shared. She pointed inside. The flat, ugly word cut through her euphoria. Sour, her aunt, was standing outside the shelter they shared. She pointed inside.

Mother ran across the trampled dirt to the shelter. As soon as she stepped inside she could smell the harsh stink of vomit. Silent was doubled over, clutching his distended belly. He was shivering, his face sleek with sweat, and his skin was pale. Vomit and shit lay smeared around him.

Standing in the bright light outside the shelter, Sour was grinning, her face hard.

It took Silent a month to die.

It nearly destroyed Mother.

Her instinctive understanding of causality betrayed her. In this ultimate emergency, nothing worked. nothing worked. There were some illnesses you could treat. If you took a broken limb, pulled it back into shape and bound it up, very often it would set as good as before. If you rubbed dock leaves on insect bites, the poison could be drawn. But there was nothing she could do for this strange wasting away for which there wasn't even a There were some illnesses you could treat. If you took a broken limb, pulled it back into shape and bound it up, very often it would set as good as before. If you rubbed dock leaves on insect bites, the poison could be drawn. But there was nothing she could do for this strange wasting away for which there wasn't even a word. word.

She brought him things he had loved- a tangled chunk of wood, bright bits of pyrite, even a strange spiral stone. In fact it was a fossilized ammonite, three hundred million years old. But he would just finger the toys, his eyes sliding, or he would ignore them completely.

There came a day when he didn't stir from his pallet. She cradled him and crooned wordlessly, as she had when he was an infant. But his head lolled. She tried to cram food into his mouth, but his lips were blue, his mouth cold. cold. She even pressed those cold lips to her breast, but she had no milk. She even pressed those cold lips to her breast, but she had no milk.

At last the others came.

She fought them, convinced that if she only tried a little longer, wanted it a little more, then he would grin, reach for his bits of fool's gold, and get up and run into the light. But she had let herself grow weak during his illness, and they took him away easily.

The men dug a pit in the ground, outside the encampment. The boy's stiffening body was bundled inside, and the debris from the pit was hastily kicked back in, leaving a discolored patch of dirt.

It was functional- but it was a ceremony, of sorts. People had been sticking bodies in the ground for three hundred thousand years. Once it had been an essential way of disposing of waste: When you could expect to grow old and die in the same place you were born, you had to keep it clean. But now people were nomadic. Mother's folk would be gone from here soon. They could have just dumped the boy's body and let the scavengers take it, the dogs and birds and insects; what difference would it have made? And yet they still buried, as they always had. It had come to seem the right thing to do.

But no words were spoken, no marker was left, and the others dispersed quickly. Death was as absolute as it had always been, deep back down the lineages of hominids and primates: death was a termination, an end of existence, and those who had gone were as meaningless as evaporated dew, their very identities lost after a generation.

But it wasn't that way for Mother. No, not at all.

In the days that followed that brutal ending and efficient burial, she returned again and again to the patch of ground that held her son's bones. Even when the upturned ground began to fade in color, and the grass began to spread over it, still she remembered exactly where that hole's ragged edges had been, and could imagine how he must be lying, there deep in the earth.

There was no reason reason for him to have gone. That was what plagued her. If she had seen him fall, or drown, or be trampled by the herds, then she could have seen for him to have gone. That was what plagued her. If she had seen him fall, or drown, or be trampled by the herds, then she could have seen why why he died, and perhaps could have accepted it. Of course she had seen disease afflict many members of the tribe. She had watched many people die of causes no one could name, let alone treat. But that only made things worse: If someone had to die, why Silent? And if blind chance had killed him- if someone so close could be taken so arbitrarily- then it could happen to he died, and perhaps could have accepted it. Of course she had seen disease afflict many members of the tribe. She had watched many people die of causes no one could name, let alone treat. But that only made things worse: If someone had to die, why Silent? And if blind chance had killed him- if someone so close could be taken so arbitrarily- then it could happen to her, her, at any time, anywhere. at any time, anywhere.

It couldn't be accepted. Everything had a cause. And so there must be a cause of Silent's death. there must be a cause of Silent's death.

Alone, obsessing, she retreated into herself.

II.

Soon after the time of Pebble and Harpoon had come an interglacial, an interval of temperate climes between the long, icebound millennia. The bloated ice caps had melted, and the seas had risen, flooding the lowlands and deforming the coastlines. But, twelve thousand years after Pebble's death, this latest great summer drew to a close. A savage cooling cut in. The ice began to advance once more. As the ice sucked the humidity out of the air, it was as if the planet were drawing in a great, dry breath. Forests shrank, grasslands spread, and desertification intensified once more.

The Sahara, cupped in its mighty Himalayan rain shadow, was not yet a desert. Wide, shallow lakes lay across its interior- lakes, in the Sahara. These bodies of water waxed and waned, and sometimes dried out completely. But at their greatest extents they were full of fish, crocodile, and hippos. Around the waters gathered ostriches, zebra, rhinos, elephants, giraffes, buffalo, and various antelope- and animals that modern eyes would not have thought so characteristically African, like oxen, Barbary sheep, goats, and asses.

Where there was water, where there was game, there were people. This was the environment that cradled Mother's people. But it was a marginal place, the skim of life shallow. People had to work hard to survive.

And people were still scattered remarkably thin.

No humans had yet moved out of Africa. In Europe and across Asia, there were only the heavy-browed robusts and, in places, the older forms, the skinny walkers. America and Australia were still empty altogether.

Even in Africa people were thin on the ground. The more mobile, trade-based way of life that had been born with Harpoon and her kind had not been a uniform blessing. Ever since the move out of the forests, hominids had been vulnerable to trypanosomes- the parasites that caused sleeping sickness- carried by the clouds of tsetse flies that followed the savannah's ungulate herds. Now such diseases were spreading. The people's trading networks had proven very effective at exchanging goods, cultural innovations, and genes- but also at transmitting pathogens.

And, culturally, things weren't happening.

Pebble would have recognized almost everything in Mother's camp. People still split stone flakes off prepared cores, and still wrapped hide around their bodies, tied in place with bits of sinew or leather. Even their language was still a formless jabber of concrete words for things, feelings, actions, useless for transmitting complex information.

Across seventy thousand years seventy thousand years these people- humans with as modern a body plan, even as modern a brain, as any twenty-first-century citizen- had scarcely made a single innovation in their technology or techniques. It had been a time of stupefying passivity, stunning stasis. After all this time, people were just another tool-using animal in the ecology, like beavers or bowerbirds, still little more than glorified chimps. And, bit by bit, they were losing their battle to survive. these people- humans with as modern a body plan, even as modern a brain, as any twenty-first-century citizen- had scarcely made a single innovation in their technology or techniques. It had been a time of stupefying passivity, stunning stasis. After all this time, people were just another tool-using animal in the ecology, like beavers or bowerbirds, still little more than glorified chimps. And, bit by bit, they were losing their battle to survive.

Something was missing.