Children of the Comet

by Donald Moffitt

  Another hand went up. “You mean the Trees were already there when they arrived?”

  “We’re getting ahead of ourselves, but yes. They’d had six billion years to evolve. Don’t forget, Torris’s forebears had only a four-hundred-thousand-year headstart on us—a mere drop in the bucket of time.”

  He gave them time to digest that, then said, “I don’t know how many generations it took for them to forget the star-hopping civilization they came from—it could have been fifty or a hundred thousand years—but eventually they hit bottom. They were the equivalent of the naked apes that we once were when early Homo sapiens and Homo neanderthalensis went their separate ways with the aid of the simple tools that were available to both of them in their common environment—chipped stone, wooden clubs, and so forth. The Neanderthals didn’t make it, but Homo sapiens did. They became modern Homo sapiens—or Homo sapiens sapiens, as we paleoanthropologists like to say. Wise, wise apes. And at some point—about thirty thousand years before agriculture became a way of life and the first cities arose in Egypt and Mesopotamia—something quite wonderful happened.”

  Nina grinned at her grandfather. “Guess what he’s going to say next.”

  Before Joorn could respond, someone in the front row impatiently yelled, “What?”

  “Grandfathers,” Andrew said with a broad smile. “Grandfathers happened.” He regained his professorial tone. “That’s the only way I can put it.”

  He moved the cursor on the easel, and a procession of fossil skulls appeared, each with its own bar graph. A header helpfully proclaimed O-Y RATIO.

  “Teeth are the reason we know this,” Andrew said. “In the early twenty-first century, a pair of paleoanthropologists had the bright idea of doing a statistical analysis of large numbers of fossil teeth. There were plenty of teeth—enamel is harder than bone. It was possible to tell from the wear of the teeth displayed how old the individual was at death.”

  He paused for emphasis. “In other words, given an existence that was short, nasty, and brutish, had any of these individuals lived long enough to become a grandparent? And applying statistical methods that hadn’t been used up until that time, it was possible to discover the O-Y ratio for any given population.”

  There was an uneasy stirring in the audience, and Andrew anticipated the next question. “O-Y simply refers to the relative numbers of old and young individuals of breeding age—old being someone of thirty or more. And they discovered the remarkable fact that the O-Y ratio multiplied abruptly and dramatically about thirty thousand years before the onset of civilization. That was the turning point. We begin to see the sudden appearance of conceptual thought. Cave paintings. Ornamental necklaces, some of them quite elaborate. A new, more thoughtful method of chipping the flint weapons that had remained unchanged for hundreds of thousands of years, as far back as the pre-sapiens hominids. Tools changed from crude hand axes to quite sophisticated stone knives with long, thin blades. Man changed from a hunter-gatherer into a farmer. Of course there were cultural overlaps. In ancient Sumeria, well into the Bronze Age, there were peasants who were still using those Neolithic tools.”

  The impish look reappeared on his face, and he said, “So we can thank grandfathers for civilization.” Catching the look that Nina gave him, he added, “And grandmothers. They’d lived long enough to pass on what they’d learned. How to weave a better basket. How to make a sharper knife or improve your range with a throwing stick. How to paint shells to make prettier necklaces. In a word, traditions. The sense that there is a past.”

  He became utterly serious. “We believe that Torris’s people were at this point when we found them. Certainly our survey found plenty of grandfathers. And grandmothers too—excuse me, Nina. They’ve had traditions for an unknown number of generations. Torris fell afoul of at least one of them.”

  He lifted his head and locked eyes with his audience. “We also believe that Torris’s people are at this turning point now and have been since their O-Y ratio began to change. And we think we can help speed things up.”

  The fellow in the first row, whom Joorn now recognized as a classmate of Andrew’s, raised his hand. Joorn believed that Andrew was not above using him as a plant to keep things moving.

  “This is all very interesting, Andrew, but what a lot of us would like to know is where did this full-blown ecology based on the Bernal trees come from?” he asked. “How is it that Torris’s shipwrecked antecedents found a ready-made environment able to support them after they’d finished cannibalizing their ship and sunk into savagery?”

  “I think I’d better let Jen answer that,” Andrew said. “Jen is our expert on evolutionary theory.”

  He made way for a lanky young woman with straggling ash-blond hair. Nina nudged Joorn. “Jen’s new to the team, but she knows more than some of them.”

  The young woman began briskly rearranging Andrew’s visuals. The hominid skulls, the teeth, and the Stone Age tools flashed by and disappeared. When the blur of images slowed down and stopped, there was only a picture of a tree growing out of a comet left on the screen. The tree was ten or twenty times taller than the comet’s diameter, like a small potato sprouting a stalk bigger than itself. It looked very much like Torris’s Tree seen from a distance.

  “This is an artist’s conception of a Bernal tree,” Jen began. “It was drawn in the early twentieth century, before there was space travel or genetic engineering—at a time when most scientists thought that space travel would forever be impossible and before the very concept of genetic engineering even existed.

  “Bernal’s tree was derided by most scientists at the time, but in the years that followed, it was championed by a few visionary thinkers, notably the evolutionary biologist J.B.S. Haldane and the physicist Freeman Dyson. Here’s what Dyson had to say about Bernal’s dream.”

  The tree was replaced by the close-up of a face, presumably that of the physicist. Jen read from the text of an old book that was also displayed on the screen.

  “‘How high can a tree on a comet grow? The answer is surprising. On any celestial body whose diameter is of the order of ten miles or less, the force of gravity is so weak that a tree can grow infinitely high. Ordinary wood is strong enough to lift its own weight to an arbitrary distance from the center of gravity. This means that from a comet of ten-mile diameter, trees can grow out for hundreds of miles, collecting the energy of sunlight from an area thousands of times as large as the area of the comet itself.’

  “‘Countless millions of comets are out there, amply supplied with water, carbon, and nitrogen—the basic constituents of living cells. They lack only two essential requirements for human settlement, namely warmth and air. And now biological engineering will come to our rescue. We shall learn how to grow trees on comets.’”

  She paused to let that sink in. A low murmuring had begun in the audience. Jen let it grow, then said, “And evidently the human race did just that. The process had already begun when Time’s Beginning left Earth in pursuit of a quasar. Captain Gant and his contemporaries can remember the early stages personally. We already had forests on the moon. Now the lumber industry proposed moving to the relatively nearby comets of the Kuiper Belt—the Oort cloud still seemed impractically far away then. The trees could be bigger—big enough to make wooden spaceships and habitats. We don’t know what happened in the next six billion years after our departure. The Others came and, evidently, went. Humanity—whatever was left of it in our little corner of the galaxy—undoubtedly became extinct too. But the trees flourished and spread—to the Oort cloud and beyond.”

  Nina could no longer contain herself. She stood up, shaking off Joorn’s restraining hand, and said, “Tell them about the animals, Jen.”

  Jen smiled. “Ah yes, Nina, those wonderful animals. And the saprophytic plants that the herbivores feed on while waiting to be fed on themselves by the larger carnivores, like man.”

  She wiped the
easel clean, and the images were replaced by footage out of the old Earth archives. The scenes were familiar to Joorn, if to few others in the audience. One of them, under the title LUMBERJACKS IN SPACE, showed crews of spacesuited workers guiding gigantic self-propelled chain saws that were delimbing boughs that themselves were thicker than a California redwood, against the background of an immense trunk whose size could hardly be imagined. Another sequence, titled FARMERS IN THE SKY, showed shirtsleeved and overalled men in what seemed to be some sort of dimly-lit cavern driving a herd of perfectly ordinary-looking dairy cows toward a milking shed, while a narrator burbled: “Hungry men have to eat, and these fellows are there to feed them.” That clip dissolved into a scene that obviously had been filmed some time in the future, showing the same cavern with a lot of new construction. The milking line had been replaced by a warren of livestock pens. The placid Jerseys of the previous scene had been superseded by animals that still looked like cattle but had short, stubby legs and grotesquely enlarged briskets. The header this time was GRAZING PRIVILEGES.

  “Gengineering was working its marvels on life forms other than the poplar tree,” Jen said. “There was still some distance to go. These must have been an early effort. An animal that could graze—live off the land, so to speak—instead of depending on a hay crop, either brought from Earth or grown locally. It could live in vacuum for an hour at a time, holding its breath like a whale or a dolphin. It had nictitating membranes to protect its eyes and nostrils. Its limbs were atrophied, adapted for microgravity so that it couldn’t inadvertently kick itself into space. Some of them must have been left behind when mankind vanished, and the fittest survived.”

  Nina leaned over to confide in her grandfather. “Jen didn’t want to say so here, but some of the genes they used when they gengineered the animals that evolved into meatbeasts came from cetaceans. Whales once had legs, you know, and they lost them when they went back to the sea. Jonah became very upset. That’s why he didn’t want to come to the briefing.”

  “Can’t say I blame him,” Joorn said. “How would you like Australopithecus afarensis stew for supper?”

  She poked him. “You’re awful.”

  The inquisitive fellow in the front row spoke out again. “What about some of the other wildlife, Jen? Where on Earth would something like a flutterbeast or a web spinner come from?”

  Jen spoke directly to him. “You know very well, Jason. You helped collect some of the specimens that went to the molecular biology lab. They were hitchhikers. Or, I should say, they were derived from the species that were the original hitchhikers six billion years ago. They had a long time to evolve. Longer than life itself had existed on Earth by the time mammals and reptiles and even flowering plants arrived.”

  She turned to the audience at large. “What do I mean by hitchhikers? Unwelcome passengers have been around ever since human commerce was invented. Rats and mice in grain shipments. Insect stowaways in just about anything. Barnacles attached to the bottoms of ships. Snakes, spiders, even bats trapped in some cranny before they could return to their roosts at daylight.”

  She gave a nod to Nina before continuing. “We have Nina to thank for noticing a distant resemblance to bats when the first flutterbeast was observed on our arrival in the Oort cloud. It was an amazing feat of intuition for a little girl at a distance of two astronomical units, when there was nothing to go on but an indistinct image whose fluttering movement could only be inferred from a blurred speck.”

  “I wasn’t a little girl then,” Nina whispered indignantly to Joorn. “I was almost grown up. You were there, Granddaddy. You remember.”

  Joorn patted her knee. He was busy studying the display easel, where a series of visualizations by the study group’s artist traced the presumed evolution of a house bat to the fearsome creature that had pursued Torris.

  “By the time man departed,” Jen went on, “bats had established a foothold in the caverns that housed the original lumber camps. Man had thoughtfully provided air and warmth for them, and there were plenty of moths and mosquitoes for them to hunt. We’ve still got moths aboard Time’s Beginning, though we got rid of the mosquitoes before we settled Rebirth. We can only conjecture about the first steps that led to flutterbeasts. Perhaps when man disappeared, the caverns took millennia to lose their air—after all, there are still air-filled caves on Torris’s comet, thanks to a little help from the inhabitants. Perhaps it was a gradual process of adaptation that took millions of years. When the moths grew scarce, there were plenty of insects outside, though they couldn’t fly in vacuum. But neither could the bats. They adapted to new ways of hunting. Their wings became appendages modified to help them move through the branches. The claws became useful for clutching small animals. Sonar was no longer useful in vacuum, so the ears, with their large surfaces, became infrared detectors for hunting by body heat—the tree snakes had an easier time adjusting. And as time went on, the flutterbeasts became bigger, as the dinosaurs did, to take advantage of the economics of hunting large animals like meatbeasts. After all, T. rex’s predecessors began as something the size of a chicken. When man arrived some billennia later in the form of Torris’s ancestors, he became an additional source of snacks.”

  Jason couldn’t resist being a smart aleck. “From chicken thou came, and to chicken thou shalt return,” he said.

  Jen made a face and forged doggedly ahead. “Spiders were another story. They had quite a headstart. In the first place, there were more of them. There are about thirty thousand different species, each with its own specialty. Most of them are too small to notice, but they’re all around us—just ask anybody in the ship-cleaning department how many webs the cleaning bots sweep up in the course of a week. Some of them were—are—aquatic, like the fisher spider, which can stay underwater for an hour or more to hunt its prey, thanks to tiny hairs that trap air. Other species prefer to spin silken diving bells for themselves. They had a leisurely time of it over the millennia learning to live in vacuum. And, like flutterbeasts, they learned the advantages of growing bigger, including less surface area in proportion to total mass, which improved heat conservation. Some caught their prey in webs. Some, like the wolf spiders, hunted their prey or lassoed it by throwing a thread. We see the same two types among the web beasts. And yes, we got enough tissue samples thanks to the help of the Tree people to confirm the spider heritage of the web beasts.

  “We have our work cut out for us to classify all the plant and animal species we’ve found here. We set out, six billennia ago, to seed another galaxy with terrestrial life. And while we were gone, our own galaxy was doing it for us here, in a way we never imagined. Perhaps it would be fitting for me to close with the prophetic words of Freeman Dyson himself.”

  She clicked the audiovisuals to sound only, and a sonorous voice filled the auditorium. Whether it was the voice of Dyson or some actor back in the vanished twentieth century reading his words was impossible to know.

  “We shall bring to the comets not only trees but a great variety of flora and fauna to create for ourselves an environment as beautiful as ever existed on Earth. Perhaps we shall teach our plants to make seeds that will sail across the ocean of space to propagate life upon comets still unvisited by man. Perhaps we shall start a wave of life that will spread from comet to comet without end until we have achieved the greening of the galaxy. That may be an end or a beginning, as Bernal said. …”

  Torris had never been to a cocktail party. He took a cautious sip of his martini and wrinkled his nose. “Is it a religious custom?” he asked. “You people gather together and drink dizzy juice to celebrate a leave-taking?”

  Chu laughed. “It’s called a going-away party. We gather together and have a drink to celebrate almost anything.”

  “I think it’s a fine custom,” Ning said. “Now that we are working with our priests to change things, it’s a custom we should adopt. As soon as your friends from beyond the stars teach us to squeeze
juice that tastes like this from Tree sap.”

  She held up her glass for another look at its contents. She was drinking Chablis with a splash of soda, a more judicious selection thanks to Irina’s intervention. Irina had gotten to the bar too late to prevent Chu from ordering a martini for Torris.

  “Why do you have to go at all?” Torris asked Chu.

  “We’ll be back for another look at you to see how you’re doing,” Chu said. “But we’ve done all we can for now. Now we have to proceed to the inner system to see what the red star has done to Earth, the planet we all came from when the Universe was young.”

  “I do not understand,” Torris said. “Inner system. Planet. Universe. Why inner? All I know is that the Stepsister is very far away.”

  “It is,” Chu said, taking another sip of his own martini. “We have a long way to go before we even get to the outer planets, whatever’s left of them.”

  “And you say that the Stepsister swallowed this planet Earth long ago and that it melted?”

  “That’s what we think.” Chu knew that Torris was thinking of Earth as a ball of ice, somewhat larger than his own comet.

  “And yet you say you want to walk on this Earth.”

  “That’s right. A nice walk in the sun.” Chu was enjoying himself.

  “But if Earth is inside the Stepsister, how is such a thing even possible?”

  “Your friend Nina ran the figures. And she’s convinced her father and her grandfather that it might be possible.”

  “Nina? That little girl? Is she a numberer then?”

  “Among other things.”