Evolution Read online

  Perhaps her chest was a little high, a little conical; perhaps in the proportion of her long limbs she might have looked unusual. But her body was within the boundaries of human variation; she might have looked like a denizen of a desert country, like the Dinka of the Sudan, or the Turkana, or the Masai, who would one day walk the land she now crossed.

  She looked human. Her head was different, though. Above her eyes ran a broad ridge of bone, which led back to a long, back-sloping forehead. From there, the bone ran with almost no rise to the back of her skull. The shape of her head was masked by her thick mass of hair, but it would have been impossible to mistake its flatness, the smallness of her cranium.

  She had the body of a human, the skull of an ape. But her eyes were clear, sharp, curious. Nine years old, suffused with the joy of her body in this brief moment of life and light and freedom, she was as happy as it was possible for her to be. To human eyes, she would have been beautiful.

  Her people were hominids — closer to humans than chimps or gorillas — and were related to the species one day tentatively labeled Homo ergaster and Homo erectus. But all across the Old World there were many, many variants, many subspecies based on the same overall body plan. They were a successful and diverse kind, and there would never be enough bones and bits of skull to tell their whole story.

  Something darted out at her feet. She pulled up, startled, panting. It was a cane rat, a rodent; disturbed from its slow foraging it scuttled away, indignant.

  And she heard a cry. “Far! Far!”

  She looked back. Her people, a remote blur, had gathered on the rocky outcrop where they intended to stay for the night. One of them — her mother or grandmother — had clambered to the rock’s highest point, and was calling to her through cupped hands. “Far!” It was a cry no ape could have made, not even Capo. This was a word.

  The sun had begun to slide away from the zenith, and already the shadow at her feet had lengthened. Soon the animals would begin to stir; she would no longer be safe, no longer be shielded by the noon world’s somnolence.

  Alone, far from her people, she felt a delicious frisson of fear. Every day, every chance she got, she ran too far; and every day she had to be called back. She did not have a name. No hominid had yet given herself a name. But if she had, it would have been Far.

  She turned back toward the rock and began to run again, at her steady, ground-devouring pace.

  There were twenty-four people in the band.

  Most of the adults were dispersed over the landscape near the eroded sandstone bluff. They moved like slim shadows across the dusty ground, seeking out nuts and small game, silent, intent, expert. Mothers had taken their youngest children along, clamped to their backs or scuttling at their feet.

  Far’s mother was working through a small stand of acacia trees that had been comprehensively destroyed by the passage of a herd of deinotheres. These ancient elephant types had used their downward-pointing tusks and stubby trunks to leave the trees broken and splintered, the ground churned up, and the roots hauled out. People weren’t the only foragers here: warthogs and bushpigs grunted and squealed as they pushed their ugly faces into the churned-up earth. The destruction was recent. Far could see giant beetles at work burying fresh deinothere dung, and aardvarks and honey badgers rooting in the ground, seeking the beetles’ larvae.

  Such a place made for good foraging. A good strategy for finding food in an unfamiliar land was to seek out the leftovers of other animals, especially destructive types like elephants and pigs. In the smashed-up stand of trees, Far’s mother would find food that would have otherwise been hidden or inaccessible. Among the broken trunks there were even ready-made levers, struts, and digging sticks to prize out roots from the ground, broken branches to shake to get at fruit, and slivers of palm to dig out pith.

  Far’s mother was a serene, elegant woman, tall even for her kind; she might have been called Calm. She walked with her two children, the sleeping baby cradled over one shoulder, and a son. The boy was half Far’s age but already nearly as tall as she was, a skinny youth Far thought of as the Brat: irritating, clever, and much too successful at competing for their mother’s attention and generosity.

  Calm’s own mother, Far’s grandmother, was at her side. In her mid-forties now, the grandmother was too stiff to be of much help digging for food. But she assisted her daughter by keeping an eye on the youngest child. No human would have been surprised to see old people in this group; it would have looked very natural. But no previous types of primates had grown old; few had survived much past their fertile years. Why should their bodies continue to keep them alive when they could not contribute further to the gene pool? But now it was different; among Far’s kind, old people had a role.

  Panting, dusty, Far climbed the rock. It was just an outcrop a hundred meters across bearing nothing but strands of tough grass and a few insects and lizards. But for the people it was a temporary home base, an island of comparative sanctuary in this open savannah, this sea of danger. On the outcrop itself a couple of men were repairing wooden spears. They worked absently, eyes roving, as if their hands were working by themselves. Some of the older children played, rehearsing for the adulthood to come. They wrestled, chased, mock-stalked each other. Two six-year-olds were engaged in clumsy foreplay, fingering each other’s nipples and bellies.

  Far was neither an adult nor a child, and in this small band there was nobody close to her age. So she kept away from the rest and walked to the summit of the eroded sandstone lump. She found a bit of antelope jaw, deposited here by some scavenger, now scraped clean by hungry mouths and the patient work of insects. She cracked the bone into fragments on the rock, and used a sharp edge to scrape the sweat and dirt from her legs and belly.

  From this vantage, the landscape was laid out, presenting a complex panorama. This was an immense valley. Huge geological anguish showed in a panorama of domes, lava flows, tiltings, and craters. To the east — and, beyond the horizon, in the west — the land had been uplifted, forming a plateau some three thousand meters high at its maximum, laden with fertile volcanic soil. The great plateau came to an end in a precipitate wall that plunged down into the valley.

  This was the Rift Valley: a fracture between two separating tectonic plates. It ran for three thousand kilometers from the Red Sea and Ethiopia in the north down through Kenya, Uganda, Tanzania, and Malawi, terminating in Mozambique to the south. For twenty million years geological activity along the length of this great wound had created volcanoes, built highlands, and collapsed lowlands into valleys that channeled the waters into some of the continent’s largest lakes. The land itself had been remolded, laid down as layer upon layer of volcanic ash, interspersed with broad beds of shale and mudstone. On the volcanic hills grew humid forests, and a complex mosaic of vegetation, from woodland to savannah to scrub, filled the floor. It was a crowded, jumbled, varied place.

  And it was full of animals.

  As the sun continued to roll down the sky, so the creatures of the savannah became more active: the hippos wallowing in the marshes, the herds of stately elephant types washing serenely across the grasslands. There were many species of elephant, in fact, subtly differing in the shape of their backs, skulls, trunks. They trumpeted shrilly to each other, sailing like dusky ships through the sea of dust they kicked up. As well as these large herbivores there were many other species directly dependent on the grass: hares, porcupines, and cane rats, rooting pigs. Predators upon the grass eaters — and themselves prey for still more dangerous animals — included jackals, hyenas, and mongooses.

  The animals of the savannah would have looked startlingly familiar to human eyes, for they had already become finely adapted to savannah conditions. But the richness and variety of the life here would have astounded an observer used to the Africa of human times. This was the richest region on Earth in terms of the number of mammalian species, their diversity and abundance, and this was one of its most prolific periods. In this crowded, complicated pla
ce, plains creatures like antelopes and elephants lived close to forest dwellers like pigs and bats. The Rift provided a rich, sprawling landscape that presented opportunities for adaptation for many species of animals, like elephants, pigs, antelopes — and people. This, indeed, was the crucible from which Far’s kind had emerged.

  But they had not stayed here.

  After Capo’s time, liberated from the last ancestral ties to the forest, Far’s people had become a wandering species. They had walked out of Africa: The first hominid footsteps had already been planted all along the southern coasts of the Asian landmass. Far’s grandmothers, though, had unwittingly completed a great circuit to north, east, and south, over many generations returning here, to the place their kind had originated.

  Sitting on her outcrop, Far surveyed the landscape with a professional, calculating eye. In their wanderings, the people mostly followed water courses. They had come to this place from the north, and she could see the streambed they had followed, a silver snake that slashed through the grass and scrub. Along the riverbank the land was silty, watered, and dense with nutrients, and a vigorous mix of trees, thicket, and grassland grew there, marked by pillars of termite mounds. To the east the ground rose, becoming dry and barren, and to the west the forest grew thicker, making an impassable belt. But if she looked south she could see possibilities for tomorrow, a great corridor of savannah with the mixture of grass, scrub, and forest patches that her people preferred.

  Far was still young, still learning about the world and how best to use it. But she had a deep, systematic understanding of her environment. She was already capable of assessing an unfamiliar landscape like this and picking out sources of food, water, and danger, even spying out routes for onward migration.

  It was a necessary skill. Committed to the open, Far’s kind had been pushed by a harsh winnowing to develop a new kind of awareness of nature. They had been forced to understand the habits of game, the distribution of plants, the changes of seasons, the meanings of tracks — to solve the endless puzzles of the complex, unforgiving savannah. By comparison, her remote ancestor Capo, who had lived and died thousands of kilometers northwest of this place, had learned the features of his generous forest world by rote: Unable to read the land, to figure out new patterns, he had been endlessly baffled by the unfamiliar.

  Now the adults and their infants were coming back to the rock, carrying food. They were naked, and they carried only what they could cram into their hands and cradle in their arms. Most of them came back with mouths still full and chewing. The people ate as fast as they could, helping themselves, feeding only close family members, not averse to stealing when they thought they could get away with it. And they ate silently save for belches, grunts of pleasure or disgust when a bit of rotten food turned up — and an occasional word. “Mine!” “Nut,” “Break,” “Hurt, hurt, hurt…”

  They were simple nouns and verbs, possessives and challenges, one-word sentences with no structure, no grammar. But nevertheless it was a language, the words labels that referred to definite things — a system far advanced over the jabbering of Capo’s time, and that of any other animal.

  Here came Far’s brother, the Brat. He was carrying the limp corpse of some small animal, maybe a hare. And her mother, Calm, had an armful of roots, fruit, and palm pith.

  Far was suddenly hungry. She hurried forward, mewling, her hands held out and her mouth open.

  Calm hissed at her, theatrically holding her armful of food away from her daughter. “Mine! Mine!” It was a rebuke, and it was backed up by glares from the grandmother. Far was getting too old now to be fed like an infant. She should have come to help her mother rather than waste her energy running purposelessly about the landscape. Why, here was her brother, the Brat, who had been hard at work and had even returned with his own scrap of meat. All of that was conveyed in a word.

  Life was not as it had been in Capo’s time. Nowadays the adults tried to coach the youngsters. The world had become too complex for children to be given the time to reinvent all the technology and techniques of survival from scratch; they had to be taught how to survive. And one of the roles of elders like Far’s grandmother was to drive such wisdom home.

  But Far held her hands out again, making piteous animal mewls. Just once more. Just for today. I’ll help tomorrow.

  “Graah!” Calm, as Far had known she would, dumped the food on the rock. She had gathered nuts, tsin beans, cowpeas, and asparagus bean tubers. She handed Far a fat tuber; Far bit into this quickly.

  The Brat sat close to his mother. He was still too young to sit with the men, who were pawing through their own pile of food. The Brat had pulled apart his hare by main force, twisting off the limbs and head, and was using a chip of rock to lay open the chest. But as he performed this miniature butchery his gestures were tense, shivery.

  None of his family knew it, but he was already gravely ill, through hypervitaminosis. A few days before one of the men had given him a few scraps of hyena liver, brought down in a brief battle over the remains of an antelope. Like that of most carnivorous predators, the liver had been full of vitamin A, and that subtle poisoning would soon become visible in the boy’s body.

  In a month he would be dead. In twelve, forgotten, even by his mother.

  But for now Calm cuffed him, reasonably gently, and grabbed some of his hare away from him, making him share with his sister.

  Since Capo’s time the world had continued to cool and dry.

  North of the equator, a great belt of taiga stretched right around the world, through North America and Asia, a forest of nothing but evergreen trees. And in the far north tundra had formed for the first time in three hundred million years. For the animals, the living offered by the taiga was meager compared to the old mixed deciduous and coniferous temperate forests. Similarly, the great grasslands continued to expand — grass was less thirsty than trees — but grass made arid plains, able to support only a much-reduced assemblage of animal species compared to the vanishing forests. As the slow desiccation continued, there were extinctions again.

  But if the quality was diminished, the quantity of life was tremendous, astonishing.

  The need to ride out periods of seasonal food shortages, and the need for guts able to process coarse diets all year round, favored the development of large herbivores. Giant mammals, a new “megafauna” on a scale not seen since the death of the dinosaurs, spread across the planet. Ancestral mammoths had already spread across northern Eurasia and, crossing the land bridges periodically exposed by the falling ocean levels, walked into North America. For now, living in equable climes, they were hairless and ate foliage rather than grass. They looked like typical elephants, but they had the high crowns and curling tusks of their woolly descendants.

  Meanwhile there were giant camels in North America, and in Asia and Africa wandered the huge, mooselike sivatheres. A type of large rhino called an elasmotherium roamed across northern Eurasia. For a rhino it had long legs and a horn that could grow to two meters in length: It looked like a muscular unicorn.

  And along with these huge packages of meat came new, specialized predators. The cats, freshly evolved, had perfected the technology of killing. They had side teeth like shears that could slice through skin, rip it aside, and get inside a body, where their incisors could nibble at the flesh. The saber-tooths were the acme. The saber-tooths would grow to twice the size of the lions of human times, becoming vast muscular predators built like bears, with short stocky limbs. They were built for power, not speed, and were ambush hunters, with mouths that could open hugely wide to crush prey. But all cats made even the dogs look like generalists by comparison; cats were perhaps the ultimate land predators.

  But then, some half million years before Far’s birth, a new and dramatic worsening of the climate began. For the world’s creatures, the rules changed again.

  There was a call from the plain. “Look, look! Me, look, me!” People stood up, gathering to see.

  A man was appro
aching. He was tall, more heavily muscled than the rest, with a powerful, abnormally prominent browridge. This man, Brow, was dominant right now, the boss man in the tight, competitive world of the males. And he had a dead animal draped across his shoulder, a young eland.

  The eight other adult men in the band began dutifully to whoop and yell, and they ran down the rocky slope. They slapped Brow on the back, stroked the eland respectfully, and ran and capered, kicking up a spectacular cloud of dust that hung, glowing, in the light of the descending sun. Together they hauled the eland up the slope and hurled it to the ground. The older children ran to see the eland, and began competing for its meat. The Brat was amongst them, but he was weaker even than others younger than himself, and he was easily pushed aside. Far could see a snapped-off wooden spear buried in the animal’s chest. That was how Brow had killed his prey, probably after an ambush, and perhaps he had left the spear in there to show how he had achieved this feat.

  Brow, meanwhile, had sprouted an impressive erection. The women, including Calm, Far’s mother, made subtle signs of availability — a crooked hand here, thighs smoothly parting there.

  Far, neither woman nor child, hung back from the rest. She nibbled on a root and waited as events unfolded.