Evolution

by Stephen Baxter

  Solo lunged at the Emperor, ramming his scarred muzzle into his belly.

  The Emperor was knocked flat on his back on the branch, winded, and might have fallen from the tree if his quick-working primate hands had not scrabbled at the bark. He was as much shocked by the sudden physical assault as hurt. Save for cuffs and slaps by food-monopolizing females, and occasional inadvertent blows from other males, nobody had ever deliberately hurt him in his life.

  But it was not over.

  With a bound, almost graceful for a creature his size, Solo jumped on the Emperor. He sat on the older male’s chest, compressing the Emperor’s fragile ribs. The Emperor screamed. He chuffed and panted, and he beat at Solo’s back. If he had used all his strength he might yet have driven the other off. But to injure another went against his instincts, and his punches were weak, his blows ineffective.

  He had missed his chance.

  Solo bent forward and pushed his muzzle into the Emperor’s crotch. He teased aside fur that was stiff with semen and the vaginal fluids of several females. With a brisk, practiced lunge, he bit into the Emperor’s scrotal sac, severing one testicle.

  The Emperor howled, thrashing. Blood gushed, mingling with the mating fluids on his fur.

  Solo climbed easily away. With a single firm motion of his foot, he pushed the Emperor off the branch. The older male’s body went crashing through the foliage beneath, plummeting toward the ground. Then Solo spat out the bloody testicle, letting it fall into the green below.

  Solo advanced on Right, Noth’s sister, one of the youngest of the females. He fingered his rapidly swelling penis, preparing to take her.

  But now here was Noth, young, eager, horny, plummeting out of the air to land at Solo’s feet. Solo turned like a tank turret to face this new challenger.

  Noth hadn’t known Solo was here. But he remembered him.

  Noth was a creature of the here and now. He had no real conception of yesterday or tomorrow, and his memory was not arranged in an orderly narrative; it was more like a corridor of vivid images, rendered in sight and scent. But the powerful stink of Solo brought images flooding back, shards and glimpses of that dreadful day in another part of the forest, his mother’s despairing howl as she fell into the pit of teeth.

  Conflicting impulses surged through him. He should display, stink-fight — or else he should show his submission to this powerful creature, just as Rival had submitted to him.

  But Solo didn’t fit. He didn’t obey any of the unwritten rules that governed the notharctus’ fragile society. He had just mutilated the troop’s dominant male. Solo would surely not be satisfied with a symbolic victory. Solo, huge, still, meant to injure him, if not kill him.

  And here was Right, Noth’s only kin, cowering in the foliage at Solo’s feet. Here were the females with whom he had lived for half a year, and whose swelling pudenda had filled him with anticipatory lust for days, weeks — and here was this monster, Solo, who had destroyed everything he had grown up with.

  He stood upright and howled.

  Solo, startled, hesitated.

  Noth’s wrists and crotch itched with musk. He performed a frantic, one-second display, an accelerated demonstration of his power and youth. Then, blindly, not understanding what he was doing, he lowered his head and barged at Solo’s midriff. With a gasping hoot, Solo was knocked backward, finishing on his back in a clump of foliage.

  If he had followed up, Noth could have capitalized on his surprise attack. But he had never fought a physical fight in his life. And Solo, with the instincts of an experienced fighter, twisted and slammed his knee against Noth’s temple. Noth went down face first and instinctively scrabbled for a hold. An immense mass crashed into his back, crushing him against the bark. And now Noth felt Solo’s incisors sink into the soft flesh of his neck. He screamed at the sharp pain. He twisted and thrashed. He could not shake off Solo — but the vigor of his movements tipped them both off the narrow branch.

  Hooting, with Solo’s teeth ripping at his flesh, Noth found himself plummeting through layers of foliage and twigs.

  They crashed to the ground, their fall scarcely cushioned by the rotting leaf cover. But Solo was shaken free, his clenched jaw giving one last rip at Noth’s shoulder. Solo made his own display of aggression. He roared, an ugly, unstructured noise. He stood upright and hammered his small fists into the detritus at his feet; bits of leaf flew everywhere, surrounding him in a loose, sunlit cloud.

  It was a battle of two small creatures. But much larger animals, watching timidly, backed away from Solo’s ferocity.

  It was a one-sided contest. Solo advanced on Noth, stalking out of the settling leaf fragments. Noth watched, not even displaying, as if hypnotized. He looked down in horror at his shoulder, where a flap of skin hung loose and blood soaked into his fur.

  But now a burly mass came flying at Solo. It was the Emperor. Even as the blood continued to gush from his ragged scrotum, the big notharctus slammed feetfirst into Solo’s back, knocking him flat, facedown in the debris.

  This time Noth did not hesitate. He threw himself at Solo and began to pummel his back and shoulders with feet, hands, and muzzle. The Emperor joined in — and so did more of the males, until Solo was immersed beneath a blanket of hooting, jostling, inexperienced assailants. Any one of them Solo would have defeated — but not all of them together. Under the rain of inexpertly aimed blows, it was impossible even for him to rise.

  At last he burrowed like a taeniodont through the forest floor detritus, out from under the clamoring pack. By the time the ragged army had noticed he was gone, that their punches and kicks were either landing in the dirt or on each other, Solo was limping away.

  Aching, battered, Noth clambered back into the tree. When he got there he found the females grooming each other calmly, picking bits of dried semen out of their crotch hair, as if the combat beneath had never taken place. The Emperor was sitting quietly with the female Biggest. His flow of blood had stilled — but his copulatory campaign was suspended forever.

  And here was Rival, vigorously covering Right. Noth saw his sister’s face buried in her own chest hair, low squeaks of pleasure emanating from her throat. Noth felt an oddly warm glow. He was not driven by jealousy of other males over his sister — even of this male whom he had bested, and who had apparently recovered very quickly. A deeper biochemical part of him recognized that with his sister pregnant, the line would go on: the shining unbroken molecular thread that stretched from Purga, through this moment lit by the low polar sun, on into unimaginable futures.

  He heard a remote lowing. It was the call of a moeritherium, the matriarch of a migrant herd, walking slowly up from the south. With the return of the herds, summer had truly come again. And from all over the forest came a high keening: It was the song of the notharctus, a song of loneliness and wonder.

  In just a few years Noth’s life would be over. Soon his kind would be gone too, their descendants transmuted into new forms; and soon, as Earth cooled from this midsummer peak, even the polar forest would shrivel and die. But for now — bloodied, panting, his fur covered with leaf mold — this was Noth’s moment, his day in the light.

  The huge female Big approached him. He trilled gently. With a glance into his eyes, she turned her back and presented to him. Noth entered her quickly, and his world dissolved into unthinking pleasure.

  CHAPTER 6

  The Crossing

  Congo River, West Africa. Circa 32 million years before present.

  I

  Here, close to its final oceanic destination, the mighty river pushed sluggishly between walls of lush, moist forest. There were many meanders and oxbow lakes, which, cut off from the flow, had turned into stagnant marshes and ponds. It was as if the river were exhausted, its long journey done — but this river was draining the heart of a continent.

  And this late summer there had been much rain. The river was high, and it spilled over onto land where the water table was already near the surface. The dense, muddy wat
er contained fragments of eroded rock, mud, and living things. There were even rafts of tangled branches and bits of vegetation drifting like unruly schooners down the river’s tremendous length, relics that had already traveled thousands of kilometers from their point of origin.

  High above the water, in the forest’s cacophonous upper story, the anthros were making their daily destructive procession.

  They were like monkeys. Running along branches, using their powerful arms to swing from tree to tree, they stripped off fruit, ripped open palm fronds, and tore away great swaths of bark to get at insects. Crowds of females moved and worked together, occasionally stopping for a moment’s grooming. There were mothers with infants clinging to their backs and bellies, supported by clusters of aunts. Males, larger, wider-ranging, made loose alliances that merged and fragmented constantly as they competed for food, status, and access to the females.

  More than thirty anthros worked here. They were clever, efficient foragers, and where they passed, they laid waste. It was a joyful, clamoring racket of feeding, cooperating, and challenging.

  Temporarily alone, Roamer was swinging from one thick branch to the next. Though she was high above the ground, she had no fear of falling; she was in her element here, her body and mind exquisitely adapted for the conditions of this tangled forest canopy.

  Bordering the sea, to the west, there were dense mangrove swamps. But here, inland, the ancient forest was rich and diverse, full of tall trees with flaring buttresses: papaws, cashews, fan palms. Most of the trees were fruit bearing and rich in resin and oils. It was a comfortable, rich place to live. But it was a relic of a world that was vanishing, for a great cooling had gripped the Earth since Noth’s time, and the once global and beneficent forests had shrunk back to scraps and fragments.

  Roamer found a palm nut. She settled on a branch to inspect it. A caterpillar, fat and green, crawled over its surface. She licked off the caterpillar and chewed it slowly.

  The troop moved noisily through the canopy around her. Alone or not, she knew exactly where everybody else was. In the long years since Noth’s time the primates had become still more intensely social: To the anthros, other anthros had become more interesting than mere things — the most interesting objects in the world. Roamer was as aware of the rest of her troop as if they were a series of Chinese lanterns stuck in the foliage, diminishing the rest of the world to a dull, mute grayness.

  Roamer belonged to no species that would ever be labeled by humans. She looked something like a capuchin, the organ-grinder monkey that would one day roam the forests of South America, and was about that size. She weighed a couple of kilograms, and she was covered in dense black fur topped by white shoulders, neck, and face; she looked like she was wearing a nun’s wimple. Her arms and legs were lithe and symmetrical, much more so than Noth’s: It was a body plan typical of the inhabitant of an open forest canopy. Her nose was flat, her nostrils small and protruding sideways, more like the monkeys of a later South America than those of Africa.

  She looked like a monkey, but she was no monkey. Remote descendants of Noth’s adapids, her kind was a type of primate called anthropoid — ancestral to both monkeys and apes, for that great schism in the family of primates had yet to occur.

  Nearly twenty million years after the death of Noth, the grooming claws of notharctus feet had been replaced on Roamer’s body by nails. Her eyes were smaller than Noth’s, capable of a wide, three-dimensional field of view past her shorter muzzle, and each of her eyes was supported by a solid cup of bone; Noth’s had been protected by a mere ring of bone, and his vision could even be disturbed by his own cheek muscles when chewing. And Roamer had lost many of Noth’s ancestral relics of the times of night foraging. Her reliance on smell had diminished, to be replaced by a greater dependence on sight.

  From Right’s grandchildren had sprung a great diffusing army. They had migrated down through the Old World to inhabit the dense tropical forests of Asia, and here in Africa. And as they had migrated, so they had flourished, diversified, and changed. But the line of Old World anthropoids would not continue through Roamer. Roamer could not know that she would never see her mother again — and her fate was to be far more strange than anything that had befallen her immediate ancestors.

  The whiteness of Roamer’s fur made her face seem sketchy, unformed, and oddly wistful. But she had a youthful prettiness. In fact, she was three years old, still a year short of her menarche. A juvenile female independent of spirit, not yet fully absorbed into the troop’s hierarchies and alliances, she retained something of the solitary instincts of more distant ancestors. She liked to keep herself to herself. Besides, the group wasn’t a particularly happy bunch right now.

  The last few years had been times of plenty, and the troop’s numbers had expanded. There had been a baby boom, of which Roamer was a part. But growth brought problems. There was too much competition for food, for one thing. Every day there were squabbles.

  And then there was the grooming. In a small group there was time to groom everybody. It all helped to maintain relationships and cement alliances. When a group got too big, there just wasn’t the time to do that. So cliques were forming, subgroups fragmenting out whose members groomed each other exclusively, ignoring the rest. Already some of the cliques were traveling separately during the day, although they would still come together to sleep.

  Eventually all of this would become too intense. The grooming cliques would fission off, and the group would split up. But the new, smaller groups each had to be large enough to offer protection against predators — the main purpose of these daytime bands in the first place — so it would be a long time yet, perhaps even years, before any fission was permanent. It happened all the time, an inevitable consequence of the growing sizes of primate communities. But it meant there was a lot of squabbling to be done.

  So Roamer was happy to get away from all the bickering for a while.

  The bug thoroughly masticated, Roamer inspected her palm nut. She knew that the kernel was delicious to eat, but her hands and teeth were not strong enough to break open the shell. So she began to pound the shell against the branch.

  She became aware of two bright eyes watching her, and a slim, rust-colored body clinging to a branch. She was not alarmed. This was a crowder, a type of primate closely related to Roamer’s kind but smaller, more slender — and a lot less smart. Beyond its slim form Roamer made out many more of its kind, clinging to the branches of this tree and the next, arrayed through the forest’s green-lit world. The crowder was not competing for Roamer’s nut, and was certainly not threatening her; all the little primate wanted was Roamer’s leavings.

  Roamer was mostly a fruit eater. But the crowders, like their common adapid ancestors, relied heavily on the caterpillars and grubs they snatched from the branches, and they had sharp, narrow teeth to process their insect prey. They lived in great crowded mobile colonies of fifty or more. This gave them a defense against predators and other primates. Even a troop of anthros would have had trouble driving off one of these agile, coordinated mobs.

  But Roamer was a lot smarter than any crowder.

  It would be tens of millions of years before any primate used anything that could be called a true tool. Much of Roamer’s intelligence was of a specialized kind, designed to enable her to cope with the fast-shifting intricacies of her social life. But Roamer was clever at understanding the natural environment around her and manipulating it to get what she wanted. Smashing a nut against a tree trunk was hardly advanced engineering, but it required her to plan one or two steps ahead, a precursor of much greater inventiveness in ages to come. And such nut smashing was a cognitive leap beyond the grasp of any crowder, which was why the crowders were hanging around now.

  Roamer heard a rustling far below. She clung to her branch, peering down into the green gloom.

  She could see the litter of the forest floor, and a shadowy shape moving through the trees with a rustle of feathers, tentative pecks at the ground. It
was a flightless bird, something like a cassowary. And when she tracked back the way the bird had come to the middle of the clearing, Roamer made out a rounded, polished gleam.

  Eggs. There were ten of them, nestling in the bird’s crude nest, each of them a reservoir of yolk as big as Roamer’s head. In the stillness of noon, with her mate away, the bird had left her nest briefly unguarded, taking the chance that no harm would come to it while she briefly assuaged her hunger. She was unfortunate that Roamer’s sharp eyes had detected the nest so quickly.

  Roamer hesitated for a heartbeat. If she went after the eggs she would be taking a risk. Her nut cracking had already delayed her long enough for the troop to move away, and it would be bad to get lost. And the bird itself was a menace. A stalking monster, it was one of the last representatives of a twenty-million-year dynasty. After the comet, around the world, the land mammals had at first remained small, crammed into the dense forests — but some birds had grown large, and flightless monsters like this had briefly contested the role of top predator. Released from the weight limitations of flight they had become heavily built, muscular, and monstrously powerful, with beaks that could snap a backbone. But they had been out of time: When the mammalian herbivores grew large, so did mammal carnivores, and the birds could not compete.

  The eggs were there, right below Roamer. She could take them easily.

  If she had been older, more integrated into the group, her decision might have been different. But as it was she slid down the tree’s rough bark toward the ground, her small mouth already moist with anticipation. It was this moment of decision that caused a great divergence in her own life — and the destiny of the greater family of primates in the future.

  She had dropped the remains of her nut kernel. Behind her the little crowder, its patient wait over, fell on the sweet fragments. But in an instant more of its fellows came swarming over the branch to steal its prize.