Five million years ago, in the western arm of the Great Rift Valley in Africa, the chimp that walked like a man was perfecting his stride. Australopithecus afarensis was forced to forage on the dangerous open ground because the forest had diminished and there was too much competition for the resources of the trees. To do this, he had to lift his upper body up and balance on his hind legs. The supposedly simple act of walking habitually on two feet—bipedalism—entailed a complicated series of bodily adjustments. The spine had to reverse part of its curve so that the head could be right above the feet, the pelvis had to be reshaped to support a torso that would otherwise sag, the feet had to straighten out the big toes and develop arches for shock absorption, and the knees had to lock so that prolonged walking would not wear then out. None of this developed quickly; probably at least a million years were required. But for the purpose of this story, it is assumed that the knees happened in a single mutation applying to the younger generation of a small roving band. Thus for the first time these folk were able to travel comfortably on two feet, and extend their range considerably.
But was bipedalism necessary? Why didn’t mankind simply range out four-footed, as the baboons did? Why undertake the formidable complications of a change unique among mammals? This may at one time have been a close call. But Australopithecus, having descended from the trees with his head set vertically, had the ability to go either way, and there was one compelling reason that two feet were better than four. It would have been better for the baboons, too, had they been able to do it.
At this stage speech would have been extremely limited, with an assortment of sounds perhaps emulating the animals they represented, and a few key connecting words. But the expressions of chimpanzees in the wild are more varied and useful than some may credit, and the brain of Australopithecus was slightly larger than that of the chimp. So probably his vocabulary was larger and more effective than the chimp’s, though not by much.
* * *
Sam ranged out across the eerie barrens. HE was the eldest juvenile male of the band; soon he would be adult. But the adult members would not take him seriously until he proved himself. So he had to survive alone for long enough to prove his capability, and locate a good source of food; then he would be allowed to help protect the band and to mate with all its grown females except his mother. Mothers were funny about that: they would accept attention from any male of any age except the one they knew best. So now he braved the unfamiliar region, hoping there was something there. Part of the challenge was nerve; it took courage to go out alone, and courage was one of the differences between adults and juveniles, among the males, at least. He was nervous, but refused to turn back until he found something.
The sun was hot, very hot. Normally the band folk found shelter in the middle of the day, grooming each other’s pelts, copulating, or merely snoozing. But Sam didn’t dare relax while alone, because there was no one to watch out for him. A leopard could attack. Of course a predator could attack anyway, especially since Sam was alone, but was less likely to bother an alert person. So he forged on despite the discomfort. The heat made him tired, and he staggered, but wouldn’t quit. He had to prove he was adult. Had to keep going, no matter what.
He followed the known path to its end, then cast about for some animal trial. Sam was not the band’s smartest member, but he had a good eye for paths, and that had always helped him get around. People paths were easy to follow, and not just because they were close and familiar; the smell of people feet was on them. Animal paths varied; they could be discontinuous, or pass under brambles, or enter dangerous caves. But they were close and familiar; the smell of people feet was on them. Animal paths varied; they could be discontinuous, or pass under brambles, or enter dangerous caves. But they were better than nothing, because any path led somewhere, and it was more useful to go somewhere than nowhere. Some times they led to water that wasn’t otherwise easy to find. So he continued along the animal paths, going wherever the animals went. Until at last the ground became too dry and hard to show any path clearly, leaving him uncertain. The only path was now the trail of scuff marks his feet left in the dirt behind him. But of course that path led in the wrong direction.
The sun beat down on his fur, making it burningly hot. It was midday, and the heat blurred his vision. He thought he saw pools ahead, but knew from experience that it wasn’t so. There was no water out here on a dry day like this. The thought made him thirsty, but still he refused to turn back in defeat. He was determined to find something, anything, and be an adult. So he plowed on through the blur, trying to ignore the heat and his thirst.
He felt tired, then oddly light. His feet moved slowly, but hardly seemed to touch the ground. It was as if they were detached from him, moving of their own accord, carrying him along like some separate burden. His head seemed to want to float from his shoulders. How long had he been walking? He didn’t know, but it felt like days. Everything was somehow different. But he just kept going.
Something strange happened. The sun seemed to expand, becoming enormous. It bathed him in its fierce light, making him dizzy. A dreadful foreboding came, and then a horrible fear. Something terrible was happening:
The fiery fringe of the sun passed beyond him, enclosing him within its territory. Great vague shapes loomed within it, threatening him, glaring with eyes of flame and licking with tongues of smoke. Doom! Doom! they cried, saying the sound of warning, of terror, of grief. Sam wanted to turn about, to flee, but would not, though he knew it meant destruction. Anyway, he had no path to follow, so would only get lost if he fled.
Then he was falling, falling, for a long time, the barren plain tilting around him. He felt the shock of landing, but it was far away. He was down, and had to get up, but some-how he could not. Something awful was going to happen if he didn’t flee, but his body would not move.
Why hadn’t he fled back along his own path, while still on his feet? Because he had been unable to admit defeat. Now he had suffered that defeat anyway.
A long time passed. Then he discovered that the sun was down, and the cool of evening was coming. He had to return home—and he had failed to find anything.
Sam got up. He was logy, and his head hurt, but he seemed merely bruised, not injured. He brushed off his fur hand started back, dejected, following his own spoor until he could pick up a suitable animal trial. He had failed to find food. He was not yet an adult.
He moved slowly back the way he had come, quiet because he lacked the vigor to be noisy. The land darkened around him. Then he heard something, and paused, looking.
Two warthogs were stirring in the bush. One grunted and snuffled at the other, its projecting teeth-tusks gleaming in the twilight. Sam looked warily around for a rock or stick he could use to try to beat the boar off, as there was no nearby tree to climb. But eh hog ignored him. It scrambled up, putting its forelegs on the back of the other, who was squealing in seeming protest, and pulled in close. Oh—they were mating. No threat there, as long as he didn’t try to interfere.
Mating. Which was what Sam wouldn’t get to do, having been unsuccessful on his mission. Dispirited, he walked on. He found increasingly clear paths, which he could follow even in the darkness. So he would make it safely back, for what little that was worth.
When he reached the camp, his sister Flo was the first to spy him. She was almost as old as he, and would soon have to leave the bank and find another band, so she could mate and have a baby of her own. It would be sad to see her go, for she was his closest companion and friend, but it was the way it was.
Flo ran to him, and hugged him. Her fur was sleek and fine. “Find?” she asked, making the general purpose query sound.
“Doom,” he said, repeating the horror of the sun, and shivering, thought it was not yet cool.
Now the other young folk clustered around, eager to know how he had done. They did not understand doom, because he had returned safely. “Find! Find!” they chorused.
So he tried to tell them what else he had seen, making the grunt and squeal of the mating warthogs. They laughed, “Sam grunt ugh!” The implication was that Sam wanted to mate with an ugly warthog.
But Flo did not laugh. Her face showed concern. She knew that he had sought experience and status. She knew he had failed. She hugged him again, trying to cheer him, but it was no good. Maybe the children were right. Maybe it was a curse on him, to suffer disaster and humiliation.
Flo tried once more. She brought him a fruit to eat. This was unusual, because normally sharing occurred only when a female mated with a male and took food. The two of them when a female gave her young child food. The two of them would never mate, because they were band siblings, thought neither was really a child. Oh, they could mate, as some other siblings did, but were not inclined; they were too close. He accepted the fruit, because he was hungry after his day without eating. Then he went to his favored tree and climbed into it to sleep. Maybe in the morning his shame of failure would hurt less fiercely, in the manner a cut toe eased as it healed.
Two days later the group of elder children was foraging in a deep valley when a storm threatened. The tended to forage together, because all of them were in that awkward stage between weaning and maturity, too old to be cared for by the adult, and too young to be adults themselves. Sam hated still being a child, but until he went out alone again and found significant good food for the band, he would not be accepted as adult. He couldn’t to that yet, because of the overwhelming feeling of doom his first attempt had left him with. He seemed to be cursed, but he couldn’t understand how or why.
They started to return to the safety of their camp, but the storm rushed in too swiftly. The clouds swelled and hurled down their rain in a sudden deluge. The drops were cold despite the heat of the air. They blasted the children and the rocks, thickening into a torrent. The water sluiced through the narrow left cleft leading from the safe upper valley to the richer lower valley, making it into a turbulent river. The group had to retreat from it, bowing their heads before the onslaught; they could not pass that water.
Sam, staring at it, felt again the horror of his vision. “Doom,” he said. The sky itself was chasing him, trying to hurt him. Now he was with the others, and it was attacking them all.
Flo heard him, despite the angry roar of the wind. She understood his sentiment. “Flee,” she said, saying the word for running away from danger.
Sam, hesitated, because that meant leaving the known path. It was always dangerous to leave the path when distant from the most familiar grounds, for only the path knew the way home. Yet that path was clearly impassable; no hope there. So, reluctantly, he hopped.
Soon the group was walking away from the cleft, deeper into the valley, though this was not a comfortable direction. There were animal paths that all of them could trace, but they led in the wrong direction. The great wide plain beyond was dangerous, especially at night, and they all feared it. Sam himself had been lucky to return from his venture onto it; there had been others who never came back. But it was not yet night, though the storm made it seem as dark; they would be able to return once it passed and the water drained.
There was a loud cracking noise and a great flash of light behind them. They all paused and turned to look. The storm was smiting the cleft!
Dirty water surged around their feet, as if it, too, was trying to escape. Then it thinned, spreading out. The storm passed, leaving bands of vapor rising into the sky,
They reversed course, walking back up the valley. But as they approached the cleft, they paused, staring with confusion and consternation. The cleft was gone! It had become a tumble of stone below a sleep cliff. There was no way they could climb up that sheer ridge.
“Doom,” Sam muttered. His vision had been true.
Flo was more practical. “Around,” she said, speaking a more difficult concept. When there was something in the way, people went around it. They would go around the mountain, and get home another way. Sam agreed, because he had no alternative to offer.
They started out, walking swiftly, the two of them in the lead, the lesser children following. First they had to get all the way out of the valley, because its rocky ledges were impassable throughout. That turned out to be a longer distance than it looked, because as the valley widened and the sides curved away, more cam into view. Fortunately there were good animal paths here, making rapid walking feasible.
Three of the children were trailing. Sam saw that they were the bent-knee ones. Most of them walked with straight knees, but some didn’t. They never had. It didn’t make much difference around the home camp, where there were always things to hold to and couldn’t keep up.
Flo saw him looking, and glanced back herself. Then she looked forward. He knew what she was thinking: they had a long way to go, to get around the mountain, and if they didn’t go fast enough, they could be caught out here by night. Then the leopards would come, and the big snakes, and other things they feared without knowing.
So they didn’t dare go slow. The bent-knees would simply have to follow at whatever pace they could, tracking the spoor of the others. Maybe they wouldn’t be too far behind when the way home was found. When night came.
When Sam next looked back, he didn’t see the three laggards. That made him feel uneasy, but he didn’t know what else to do but keep moving on. He could tell that Flo was similarly disturbed.
At last the valley opened out into the frighteningly broad plain of the unknown. No one foraged alone this far out, because it was too far from their safe retreat. Now they had to.
It was hot out here, with no shade. The sun was near the top of the sky, with no clouds. Sam was wet with sweat, and he saw it matting the fur of the others. His sense of doom returned; the others. His sense of in the open.
There were bushes here, rich with ripe berries, and Sam recognized several good tuber plants. Excellent foraging! But could they pause to eat? He looked at Flo, and she looked at the sky, then shrugged. She glanced back again: maybe if they remained here a while, the three lost children would catch up.
They ate the berries, which were rich and juicy. Not only did this feed them, it allowed them to rest, and to cool. Had they known how good the foraging was out here, they might have braved it before.
Flo kept looking back the way they had come. She was hoping the bent-knee children would catch up. But there was no sign of them. They had probably returned to the head of the valley. Maybe they would find a way past the new rubble and cliff. It was better to think that, than to think of what else might happen to them.
Soon, somewhat restored, they resumed walking, this time not quite as fast, because of the awful heat. The animal paths were good, and this helped. The mountain curved on around, allowing them to head toward another great valley. There were trees at its end, and it looked passable. In fact, they discovered a people path leading there. Encouraged, they walked along it. Only to encounter hostile folk.
As they approached the trees, several bent-legged people came out led by a scowling man and a rather interesting woman. At first Sam thought the others were coming out to welcome them, but when they got close the man made gestures of striking with his fist and biting. Perplexed, Sam halted, and so did the others with him. What was the matter?
“Who?” he called, saying the recognition word.
“Bub,” the man said, frowning. He gestured to the woman. “Sis.” She smiled, but not nicely. Had she been a new member of the home band, it would have been nice to breed with her, but she evidently had no interest in doing it with strangers. Despite his fatigue, Sam regretted that.
“Sam,” Sam said. He indicated Flo. “Flo.” He indicated the four smaller children. “Us.” It was a formidable introduction, but he managed it.
Bub pointed toward the plain. “Go!”
Sam tried to explain. “Far,” he said, indicating the valley beyond them. That meant that they intended to go beyond the territory of this band, to reach their own band.
“Go!” Bub repeated. He bent down to pick up a rock.
Sam recognized the challenge. He would have fought, had he been grown. Had he not been hot and tired. Had there not been too many adults before him, and only children behind him. But as it was, he had to retreat.
He turned, and the children turned with him, weary but knowing they had no choice. Outsiders could not enter the territory of a hostile band without getting beaten or killed. So they started to walk away.
All except Flo. “Bad,” she said, for a moment standing up to Bub, letting him know her sentiment.
Then something unexpected happened. Bub looked closely at Flo, sniffing, then grabbed her. She screeched in protest, thinking he was attaching her. He was, but not in the way she supposed. He wrapped his arms around her body, hauled hr up, and threw her down on the ground. This was easy for him to do, because he was twice her size, being a grown male.
Sam leaped to Flo’s defense, but another bent-knee male caught him and held him, pinning his arms to his sides. The male might not be able to stride as well as Sam on the plain, but he had more strength in his body than Sam did, and Sam was helpless. The children didn’t dare even voice a protest. They could only watch what Bub was doing with Flo.
Bub dropped to the ground, holding Flo there. He hauled his body on top of hers. She screeched again and struck at him, but her small arms hardly affected his strong body. She lifted her head, snapping at him. Then he closed one fist and struck her in the face, stunning her. She stopped screeching and lay still, her arms and legs relaxing. He hauled his pelvis in close to hers and jammed in between her spread legs.
Suddenly Sam recognized what Bub was doing. He was mating with her. Not in the manner of a male of the home band, sharing joy with a grown female of the band, but as an act of aggression against a foreign female. He had smelled her dawning maturity and done it.
It was quickly over. Bub got up, leaving Flo lying on the ground, her limbs twitching. She turned her head from side to side, and groaned. She didn’t know exactly what had happened.
The one holding Sam let go. The others were holding stones they were ready to throw. Sam went to Flo and put out one hand. “Go,” he said, afraid that worse was coming.
She groaned, recovering her senses. There was blood on her nose, dribbling down the side of her face. Her eyes were wild. “Hurt,” she said.
“Go,” he repeated urgently. They had to get away from here, before the members of the hostile band fell on them and killed them all. Sometimes it happened, when band members got too far separated from their home band.
Flo evidently realized the danger. She took his hand, and he hauled her up. She took an unsteady step, and he grabbed her shoulder, stabilizing her. They walked away from the hostile band, and the children scurried along with them, frightened.
A stone landed near them. Sam broke into a run, hauling Flo along, and the children ran too. Soon they were out of range, because the bent-knees did not pursue them.
They slowed, finding a good path, resuming their striding, which was the best way to travel any distance. Sam looked back, but the hostile band members were gone. They had simply driven off intruders, as bands tended to do. Had Flo been older, they might have taken her captive, so that all the men could mate with her, beating hr until she stopped objecting. Females often didn’t seem as interested in mating as males were, so had to be encouraged. Sam had seen it happen, when his band had intercepted a grown female of a neighboring and who had stayed too far from her own folk. After every male was satisfied, they had let her go, and thought no more of it. It was her won fault for straying; no one had had any sympathy for her. If a strayed female remained after the first round of mating, and the males liked her, she would be allowed to join the band as a member. Then she wouldn’t be beaten unless she refused to mate with a male who wanted to. That was how it was.
But this time it was different. Flow was young, and she was his friend. She had not really strayed or left her band; she had been cut off from it by Sam’s bad fortune. She definitely had not sought to mate yet. He wished this hadn’t happened to her. He wished he could kill Bub. But all he could do was flee.
“Doom,” Flo said, trying to wipe the blood from her face. Her nose was swollen and she looked awful.
“Doom,” he echoed, realizing that she thought this was part of the curse he had seen. Maybe it was. So it was his fault. Everything bad was happening since that vision in the sun.
They went on, their pace slowing, because the path was fading, the children were tired, and so was Flo, weakened by the attack on her. The sun was no longer beating down as hotly; it was hidden by a cloud. That helped, but not a lot.
They rounded another swell of the mountain, and entered another valley. But soon the band of this valley spied them, and charged out, screaming threats. They quickly reversed and walked back into the plain. The bent-knees pursued them.
This was trouble. Was every valley going to be like this? If so, they would never get home! They were already very hot and tired.
Worse, the sun came out again, heating their fur. Sam remembered what had happened when he kept walking into the sun. The sun would eat them all.
But one thing about the bent-knees was that they had even more trouble in the sun. Sam didn’t know why, but it was the case. So he did something desperate. He found a new path and led the way not around to the next valley, where there might be more enemies, but directly into the breadth of the hot plain.
Flo and the children did not question him. They just plodded on, trusting him to lead them somewhere.
When the hostile band saw where the group was going, it turned back. The heat and fatigue were just too much.
Sam looked ahead—and saw something new. There was an outcropping of rock across the plain. Maybe that would do for a camp. So he chose another path and headed for it, striding more slowly now that there was no pursuit. The slower speed was better for all of them; they youth and straight-legged and had no trouble despite their youth and tiredness. This was good, because the rocks were far away.
But when they finally approached the rocks, something came out from them. There were several hunched shapes, moving swiftly. Sam couldn’t tell what they were. Should he turn back? If they were people, they might throw rocks or mate with Flo again. If they were animals, they might try to eat the whole group.
He paused, considering. The day was now late; they would not be able to return to the mountain before nightfall, even if they had the strength. So it was better to go on to the rocks and see what was there, hoping it wasn’t too bad.
He moved on, and the others were with him, crowding closer because they heard the shapes ahead. They were afraid, and so was he.
Then there was a gust of wind, bringing a scent: baboon. This was a baboon lair.
Ordinarily people did not tangle with baboons. The beasts were strong and fast, and could be vicious. But they weren’t as smart as people. Sometimes they could be bluffed.
He had seen bandsmen drive off baboons by throwing stones and making a lot of noise. It could work here, if there weren’t too many baboons.
“Rocks,” he said, casting about until he found a good one to pick up.
The children were uncertain, but did as he said. When all of them had stones in each hand, he led the charge. He lifted his arms and screamed. “Yah-yah-yah-yah!” He ran right toward the rocks.
Baboons were dangerous! Flo hesitated, and so did the children, but they were afraid to be left behind. So in a moment they joined in, screaming in a chorus and waving their arms.
The baboons looked at the charging group, and ran the opposite way. There turned out to be only four of them. This must be a mere fragment of their band, temporarily isolated from it; otherwise this charge would never have worked. When one showed signs of turning back, Sam hurled one of his stones at it. The stone missed, but did spook the creature, and it hurried on after the others. Soon they were gone.
Sam’s knees felt weak. It had worked! They had bluffed out the animals. Maybe the baboons had thought that any creatures who screamed and charged like that had to have many more of their own kind behind them. Maybe baboons couldn’t count. Regardless, it was a great relief.
The outcropping turned out not to be large, but it did offer a raised section shielded by surrounding boulders. It would be hard for the predators of the night to attack. Sam carried the heaviest stones he could manage, to shore up the retreat, and made a den under the overhang of the largest rock section. It wasn’t as good as home, but it would do.
Night was coming. They found good berries all around the outcropping, because no people had foraged there recently, so they were able to eat well before darkness closed. There was a stream not too far distant, so they were able to slake their thirst. Then they entered the den and huddled together for sleep. The children did not seem to be too concerned; they trusted Sam to protect them. They were very tired, and sank rapidly into slumber.
Flo tried to sleep, too beside him, but she was groaning softly. Her bashed nose was probably hurting. Sam reached out to stroke her hair, and she settled down. Grooming always made a person feel better. But who was there to comfort Sam?
* * *
The key is heat. The African savanna was hot, and creatures that moved around too much in the heat of the day risked heatstroke. Antelopes have special networks of veins and heat exchangers associated with the nose to cool the blood for the brain; baboons, like cats and dogs, pant, and have enlarged muzzles that facilitate this. But mankind’s ancestors had neither device; their noses were too recessed and puny to make panting worthwhile. They had to find another way. That way was bipedalism. Creatures who became vertical presented less than half as much surface area to the blazing sun as those who remained horizontal, and that made a significant difference in heat absorption. So it paid to become bipedal, if they went out into the burning plain at noon. Not just occasionally being on two feet, but constantly, while moving as well as while standing still. Because the beat of the deadly sun was steady. Since this was where chimpanzees were not foraging, because of that heat, it was richer harvesting of bipedal Australopithecus. Food was the great incentive; a species that might otherwise have been squeezed to oblivion was able to survive, here on the fringe of the Garden of Eden.
But it was dangerous on the plain, especially at night. So it was necessary to have a safe retreat for sleeping, and forage only by day, in the heat of the sun that restricted quadrupedal predators more than bipeds. It is unknown where Australopithecus slept, but it surely was not on the dangerous plain or by treacherous river. Probably it was in caves or on ledges that were difficult for predators to reach. This was a problem, because the best foraging seems to have been on the open plain, far from the mountains where there were safe places to sleep. How could early hominids have both safety and food?
The answer seems to be that they became commuters. Each morning they left their rocky dens and strode across the terrain to suitable places to eat. Each evening they returned to the dens. Since the two regions might be many miles apart, efficient traveling was essential. Hence the importance of paths—and knees. Bending knees were like constant running, fatiguing to the legs and wastefully expending energy at slow speeds. Lockable knees enabled mankind to stride longer while generating less muscle heat. That made commuting in the heat of the day feasible. It wasn’t necessary to seek the shade of isolated trees during the worst heat. Mankind, like mad dogs, could walk in the noonday sun. Thus mankind colonized what other apes could not: the open noon savanna. That greatly extended his foraging range, and was a key survival advantage. It wasn’t that he preferred the heat, it was that he could handle it slightly better than rival creatures could, so it paid him to do so.
But becoming bipedal was only the beginning. This turned out to be an extremely significant change, setting Australopithecus on the course that was to lead to modern man, it ways the following chapters will explore. The one most relevant to heat adaptation is the loss of body fur. Though standing vertical cut down the heat from the noon sun, it was as first a marginal advantage; other creatures did have brain-cooling systems. But it enabled mankind to shed that fur, because the bulk of the body was no longer exposed to the sun’s rays during the worst of the day. The relatively bare skin (hair remains on it, just much shorter and thinner) was a more efficient surface for sweat to affect, and mankind developed the most effective cooling system among mammals. Why was this necessary, when bipedalism and lockable knees had already enabled him to survive nicely? Because mankind was later to develop an organ that generated extra heat, and demanded extra cooling, lest it suffer: the giant brain. It probably couldn’t have happened on four feet.
Copyright © 1997 by Piers Anthony Jacob