Evolution

by Stephen Baxter

  Capo had been born in the basin that lay between the coast of Africa, to the south, and Spain, to the north. In fact, he was not very far from the place where a clever dinosaur called Listener, long ago, had stood at the shore of Pangaea and gazed out on the mighty Tethys Sea. Now he had climbed out of the basin to reach Africa proper. But if Listener had seen the birth of the Tethys, Capo was witnessing something like its death. As the ocean levels dropped, this last fragment of the Tethys had become dammed at Gibraltar. Landlocked, the great ocean had evaporated — until at last it emptied, leaving behind a great valley in places five kilometers deep, littered with salt pans.

  But as the climate oscillated, the sea level rose again, and Atlantic waters broke through the Gibraltar barrier. Now, the ocean was refilling. But Capo had nothing to fear of giant waves cascading from the west, for even a thousand Niagaras could not refill an ocean overnight. The Gibraltar waters suffused the great basin more gradually, creating great rivers. The old seafloor turned slowly into sodden marshland, where the vegetation slowly died, before the waters rose so high they covered over the ground altogether.

  But after each refilling the global ocean levels would drop again, and once again the Mediterranean would evaporate. This would happen as many as fifteen times over the million years bracketing Capo’s brief life. The Mediterranean would be left with a complex seabed geology, with layers of silt sandwiching salt pans laid down in the successive dryings.

  But this trapped ocean’s dryings were having a profound effect on the area Capo lived in — and on Capo’s kind. Before the great dryings, the Sahara region had been densely forested and well watered, and home to many species of apes. But with the climatic pump of the dryings, and in the lengthening rain shadow cast by the more remote Himalayas, the Sahara was becoming increasingly arid. The old forests were breaking up. And with them the communities of apes were splintering, each fragmentary population embarking on its own journey to a new evolutionary destiny — or extinction.

  But the great rumbling, the blurred vision of Gibraltar, was too remote to have any meaning for Capo. He turned away, and stumbled down onto the plain.

  At last Capo moved off bare rock on to vegetation. He relished the green softness of the grass under his knuckles as he loped forward. As the others tumbled after him they rolled and sprawled, pulling up the long grass around them, relishing the delicious contrast with the hard lifeless rock.

  But they weren’t home yet. A stretch of a few hundred meters of open savannah, studded with thorn bushes, separated them from the nearest forest clump — and the plain was not unoccupied.

  A group of hyenas worked at a fallen carcass. Bulky, round, it might have been an infant gomphothere, perhaps felled by a chasma. The hyenas snapped and growled at each other as they worked at the scavenged meat, their heads buried in the creature’s stomach, their sleek bodies writhing industriously.

  As Capo cowered in the grass, Frond and Finger came up alongside him. They hooted softly, and gave Capo’s backside a perfunctory groom, picking out bits of dust and rock. The younger males were cursorily acknowledging his authority. But Capo could tell they were impatient. Weary, thirsty, hungry, thoroughly spooked by the trek across the openness, they, like the rest of the troop, longed to reach the shelter and provision of the trees. And that was corroding Capo’s hold on them. The tension between the three males was powerful, toxic.

  But it was a confrontation conducted in near silence, as the three of them kept their presence concealed from the hyenas.

  While Capo still hesitated, it was Frond who made the move. He took one, two tentative shuffles forward. He received a hefty clout on the back of his head from Capo for his defiance. But Frond just bared his teeth, and moved out of reach.

  The tall grass stems waved languorously at Frond’s passing, as if he were swimming through a sea of vegetation. And now Frond got up on to his hind legs, poking his head, shoulders, and upper torso out of the grass so he could see better. He was a slim shadow, upright, like a sapling.

  The hyenas were still intent on their baby elephant. Frond ducked back into the grass and continued on his way.

  At last he reached the nearest stand of trees. Capo, with a mixture of resentment and relief, saw him climb up a tall palm tree, his legs and arms working in synchrony, like components of a smoothly oiled machine. When Frond had reached the top of the palm he hooted softly, calling the others. Then he began plucking nuts from the palm and throwing them down to the ground.

  One by one, led by Finger and the senior female, Leaf, the apes scurried through the grass toward the forest pocket.

  They were not troubled by the hyenas, though many of the scavengers scented the vulnerable apes. They were fortunate that in the bloody calculations of the hyenas’ small minds, the lure of the immediately available meat outweighed the attraction of attacking these dusty, ragged-looking primates.

  Capo tried to make the best of it. He slapped and punched the other males as they loped along, as if the whole thing had been his idea, as if he were directing them in their short migration. The males submitted to his blows, but he sensed a tension about them, a subtle lack of deference that made him uneasy.

  On entering the forest, the apes fanned out.

  Capo pushed through a bank of slim young trees to find a marshy lake: flat green-blue water surrounded by the comforting green and brown of forest. He hurried down to the water’s edge, pushed his muzzle into the cool liquid, and began to drink.

  As the apes reached the water, some of them waded into it, walking upright until they were waist deep. They used their fingers to strain blue-green algae from the water and gobbled it down: a way of feeding that was another little gift of bipedalism. Several youngsters dove headlong into the water and started scraping the accumulated dust out of their fur; they made a terrific hooting and splashing. A flock of birds had been drifting in peace at the heart of the lake, but now they took fright, and clattered thunderously into the sky.

  But some of the younger males had gathered together at the water’s edge, Frond and Finger among them. Frond had found a cobble that might serve as a hammer-stone; he was toying with it experimentally. And every now and then the males cast sly glances toward Capo. Their body language was redolent of conspiracy.

  Capo pursed his lips and blew a soft raspberry.

  He was very smart at working through social problems. He knew what the younger males were thinking. He had brought them to safety, but that wasn’t good enough: his performance as they had crossed that last grassy barrier had not convinced anyone. To restore his authority he was going to have to do some impressive displaying. He could rip down some branches and start stalking around the water’s edge, for instance; the foliage, the water, and the light would make for a powerful show. And then there would be hard battles to be won.

  But perhaps now wasn’t the time.

  He watched mothers gently bathing their infants, younger males wrestling almost politely as their limbs and skin recovered from the heat and aridity of the salt pan. Later. Let them get over the trek, before business as usual was resumed.

  And besides, truth be told, he didn’t feel up to a great new war right now. His limbs ached, his skin was sore and covered in scrapes and lesions, and his gut, used to a continual flow of food and water, rumbled at the stop-start treatment it had endured. He was tired. He rubbed his eyes and yawned, allowing himself an explosive belch. Time enough later for the hard work of life, of being Capo. For now he needed to rest.

  With that excuse lodged in his mind, he turned away from the water and loped into the forest.

  He quickly found a kapok tree filled with large ripe fruits. The kapok, though, was armed with long sharp thorns to defend its fruit. So he tore two smooth branches from the tree and placed one under each foot, gripping the branches with his toes. Then, clinging to the branches with his feet, he climbed the tree, marching over the thorns as if they didn’t exist. The action of climbing made his limbs glow with the accustomed p
leasure, their ancient design fulfilled; if he never took another step on the ground in his life he would have been content.

  When he had reached a patch dense with fruit, he pulled off another branch and set it down over the thorns. Sitting on his impromptu saddle, he began to feed.

  From here he could see that this forest clump had grown up around an oxbow lake, cast off by a river that wound its way back into the deeper country to the south, across this rich, vegetated Sahara. In the future this great Nile-like artery would be dislodged by tectonic shifting from its present course, and would curl around to the south, no longer crossing the Sahara. Eventually it would outflow into the Bight of Benin in western Africa, and humans would know it as the Niger: Even rivers were molded by time, as the land rose and fell, as the mountains grew and shrank away like dreams.

  But for now this river was a great green corridor into the interior of the country. The troop could work that way, following the forest, penetrating deeper, moving away from the coast.

  A piercing hoot echoed through the forest. It was a cry with only one meaning: Danger is here. Capo spat out a mouthful of fruit and scrambled down to the ground.

  Before he got to the lake he knew what the problem was. He could smell them. And as he looked more carefully he could see the signs of their passing: bits of fruit skin, dumped even under this kapok, what looked like nests high in the taller trees.

  Others.

  They came swarming out of the trees and the undergrowth. There were many of them, bewilderingly many — fifty, sixty — more than Capo’s troop had ever numbered. Their males came toward the water’s edge. They were all displaying ferociously, fur bristling, drumming on roots and branches and hurling themselves through the low branches of the trees.

  After all they had endured to get here, this patch of forest was not empty. Capo’s heart sank, heavy with a sense of failure.

  But Capo’s troop was responding. Weak as they were, fur too damp to bristle effectively, nevertheless the males and even a couple of the older females were displaying as best they could. Capo threw himself forward to the front row of his troop and immediately began his own display, summoning up all his long experience to create as spectacular and intimidating a show as possible.

  The two troops lined up; two walls of shrieking, posturing apes faced each other. They were the same species, and they looked indistinguishable, one from the other. But they could smell the differences between them: on the one hand the subtle, familiar savor of kin, and on the other the sharper stink of strangers. There was true xenophobic hatred in these displays, an authenticity in the threat they conveyed. Here was the other side of these clever animals’ social bonds: If you were locked into a group, then everybody else became your enemy, just because they weren’t you.

  But Capo was scared. He quickly realized that these others were showing no signs of backing down. Indeed, their displays were becoming more ferocious, and those big lead males were steadily advancing on his troop.

  Capo knew how it would go. It would not be an all-out war. The strongest would go first, the males and senior females; the infants would probably provide some sweet flesh for the bellies of these strangers. One by one. It would be a slow, bloody killing, but it would continue until it was complete. Such systematic slaughter was a horror new to the world, a horror only these apes, of all the Earth’s animals, were smart enough to conceive of and see through.

  They couldn’t stay here, Capo knew. Maybe they could go on, resume the trek across the plain; maybe Capo could yet lead his troop somewhere empty, somewhere safe.

  But in his deepest gut he intuitively knew the truth. In this world of shrinking forests, the surviving animals had already crammed themselves into all the remaining islands of the old vegetation. And that was why the others would fight so hard to exclude them. There were already too many of them for this dwindling patch — and they had nowhere else to go either.

  There was nowhere safe to go, but no choice but to leave.

  With much foot scuffing and branch waving, he began the subtle dance that indicated he wanted to lead his troop away from this place — back to the edge of the forest, back to the savannah. One or two of the females responded. Intimidated by these ferocious others, realizing how hopeless their situation was, Leaf and the others gathered up their infants and prepared to follow. Even Frond, one of the defiant young males, turned in confusion.

  But Finger would not accept it.

  He had been slamming a hammer-stone against an exposed root, adding its powerful noise to his display. Now, with a sudden, terrifying surge, he turned away from the others and launched a ferocious assault on Capo. He slammed into Capo’s back, knocking him flat, and he pounded his leader’s head with his fists. Then he rolled away and threw himself with equal vigor at the largest of the others’ males. Suddenly the noise, already high, became cacophonous, and the air filled with the stink of blood and panic shit.

  Capo rolled on to his back and sat up, his neck aching. The other males subtly moved away, even as they hooted and yelled.

  Finger was not faring well. He had managed to pin the big male to the ground. But now more of the others were throwing themselves into the melee. Soon they had hold of Finger. They hauled him away from his opponent, holding his limbs and head as if he were a hunted monkey; already blood streamed from bite-inflicted gashes in his skin. And then they threw him to the ground. But his cries soon became gurgles, drowned in blood, and Capo heard the grisly rip of flesh, the cracking of bone, the snapping of ligaments.

  But Finger’s attack had had a profound effect. If anyone was going to attack these others, it should have been Capo. Capo knew he had already lost. He would be lucky to survive the day: If these others did not kill him, then his own former subordinates would.

  Capo, though shamed and beaten, resumed his calling dance, trying to get his troop to come away. There was nothing else he could do.

  They didn’t all respond, even now. Some of them, spitting fear and defiance, dispersed into the forest to seek their own destinies. He would never see them again.

  The young female Howl glanced at her troop with wide, fearful eyes — and then made directly for the others. She would suffer a beating at the hands of the females, but maybe she would be attractive enough to the other males to be allowed to live, especially if she managed to become pregnant quickly through the hard matings she would have to endure.

  Those who remained with Capo at last began moving, back toward the fringe of the forest — but only when Frond echoed Capo’s dance.

  Capo understood, of course. They were following Frond, not him.

  They came back to the fringe of the forest. They were not pursued, not for now. They picked at leaves and scraps of fruit, dismayed, uncertain.

  Capo was depressed to be back where he had started. He could even see the corpse of that infant gomphothere, still lying on the ground. He clambered into a tree away from the others, and built an impromptu nest.

  Now that Finger was dead, he wasn’t sure who would emerge as his main challenger. Frond, perhaps? It was possible Capo could continue to maintain a powerful position by forming an alliance with one male against the other. He might no longer be the boss of bosses, but like a kingmaker his backing would be crucial, and he would continue to enjoy many of the privileges that came with power, notably mating privileges. Maybe he could even work his way back to the top that way. His subtle mind thought further, considering shifting alliances, treacheries…

  His thoughts dissolved. He felt overwhelmed by the journey he had made, the crashing disappointment that had waited at the end of it. Nothing seemed to matter anymore, not even the intricate political games that had won him so much in the past.

  The others seemed to sense his mood. They avoided him, not coming to groom, not even looking at him. His gruesome defeat had been postponed by the death of Finger, but its sad process was still under way. Capo’s day was done, his life nearly over. All his swagger was gone.

  Bu
t now Leaf came to him. She clambered into his nest alongside him, and, gently, began to groom him, as she had when they were both young and the world was bright and rich and full of possibility.

  Frond wasn’t interested in Capo, one way or the other. He had something else on his mind.

  He knuckle-walked a few paces out into the sunlit green. There he got to his hind legs once more. As always he was unsteady on his feet. But the elevation of his head gave him a platform from which to view the land, check on any predators or other dangers around.

  Frond ducked back into the grass, and made his way cautiously to the gomphothere corpse. As he approached, carrion birds screeched their protest but flapped away. The scavengers had done their work well: The body looked as if it had exploded, with limbs and ribs lying scattered on the ground, bloody bone gleaming, and an eyeless, fleshless head peering back at him accusingly, spadelike tusks lying broken and gnawed. He rooted through the scraps of skin and bits of hyena-chewed flesh, but there was little to be had; the scavenging machinery of the savannah had worked thoroughly to consume the proboscidean’s flesh. The hyenas had even destroyed the soft ribs. But he found a thigh bone, long, thick, terminating at either end in huge, bulging lumps. It was unbroken. He tapped it experimentally against another bone; it sounded hollow.

  He found a cobble in the dirt, the right size to fit into his fist. He raised the cobble and smashed it into the bone. The bone split, and rich, delicious marrow began to leak out. It was a resource that had been beyond the reach of the dogs and carrion birds, beyond their teeth and beaks. But now it was not beyond Frond. He raised the bone and began to suck down the marrow greedily.

  The others who had driven Capo and his troop out of the forest would stay there, clinging to what they had. Such groups would eventually give rise to the chimpanzees, who would differ little from this ancestral stock. They would survive, even prosper: As the desert spread and the forests retreated to their last redoubts around the equator, the great rivers would provide corridors for the chimps to use to migrate into Africa’s interior.