“You’re just hoping we don’t travel very far so when I die you don’t have so long to carry the corpse.”

  “I thought my father told you—if you actually die, I’m supposed to call for help and observe your decomposition process.”

  “That’s right. You only carry me if I’m breathing.”

  “Or do you want me to start now? Hoist you onto my shoulders so you can’t discover another whole family of plants every fifty meters?”

  “For a respectful, obedient young man, you can be very sarcastic.”

  “I was only slightly sarcastic. I can do better if you want.”

  “This is good. I’ve been so busy arguing with you, we’ve gone this far without my noticing anything.”

  “Except the dogs have found something.”

  It turned out to be a small family of the horned reptile that seemed to fill the bunny rabbit niche—a big-toothed leaf-eater that hopped, and would only fight if cornered. The horns did not seem to Sel to be weapons—too blunt—and when he imagined a mating ritual in which these creatures leapt into the air to butt their heads together, he could not see how it could help but scramble their brains, since their skulls were so light.

  “Probably for a display of health,” said Sel.

  “The antlers?”

  “Horns,” said Sel.

  “I think they’re shed and then regrown. Don’t these animals look like skin-shedders?”

  “No.”

  “I’ll look for a shed skin somewhere.”

  “You’ll have a long look.”

  “Why, because they eat the skins?”

  “Because they don’t shed.”

  “How can you be sure?”

  “I’m not sure,” said Sel. “But this is not a Formic import, it’s a native species, and we haven’t seen any skin shedding from natives.”

  So the conversation went as they traveled—but they did cover the ground. They took pictures, yes. And now and then, when it was something really new, they stopped and took samples. But always they walked. Sel might be old and need to lean on his walking stick now and then, but he could still keep up a steady pace. Po was likely to move ahead of him more often than not, but it was Po who groaned when Sel said it was time to move on after a brief rest.

  “I don’t know why you have that stick,” said Po.

  “To lean on when I rest.”

  “But you have to carry it the whole time you’re walking.”

  “It’s not that heavy.”

  “It looks heavy.”

  “It’s from the balsa tree—well, the one I call ‘balsa,’ since the wood is so light.”

  Po tried it. Only about a pound, though it was thick and gnarled and widened out at the top like a pitcher. “I’d still get tired of carrying it.”

  “Only because you put more weight in your backpack than I did.”

  Po didn’t bother arguing the point.

  “The first human voyagers to the moon and the planets had an easy time of it,” said Po, as they crested a high ridge. “Nothing but empty space between them and their destination. No temptation to stop and explore.”

  “Like the first sea voyagers. Going from land to land, ignoring the sea because they had no tools that would let them explore to any depth.”

  “We’re the conquistadores,” said Po. “Only we killed them all before we ever set foot on land.”

  “Is that a difference or a similarity? Smallpox and other diseases raced ahead of the conquistadores.”

  “If only we could have talked to them,” said Po. “I read about the conquistadores—we Mayans have good reason to try to understand them. Columbus wrote that the natives he found ‘had no language,’ merely because they didn’t understand any of the languages his interpreters knew.”

  “But the Formics had no language at all.”

  “Or so we think.”

  “No communication devices in their ships. Nothing to transmit voice or images. Because there was no need of them. Exchange of memory. Direct transfer of the senses. Whatever their mechanism was, it was better than language, but worse, because they had no way to talk to us.”

  “So who were the mutes?” asked Po. “Us, or them?”

  “Both of us mutes,” said Sel, “and all of us deaf.”

  “What I wouldn’t give to have just one of them alive.”

  “But there couldn’t be just one,” said Sel. “They hived. They needed a hundreds, perhaps thousands to reach the critical mass to achieve intelligence.”

  “Or not,” said Po. “It could also be that only the queen was sentient. Why else would they all have died when the queens died?”

  “Unless the queen was the nexus, the center of a neural network.”

  “As I said, I wish we had one alive, so we could know something instead of guessing from a few desiccated corpses.”

  “We have more of them preserved than any of the other worlds. Here, there are so few scavengers that can eat them, the corpses lasted long enough for us to get to the planet’s surface and freeze some of them. We actually got to study structure.”

  “But no queens.”

  “The sorrow of my life,” said Sel.

  “Really? That’s your greatest regret?”

  Sel fell silent.

  “Sorry,” said Po.

  “It’s all right. I was just considering your question. My greatest regret. What a question. How can I regret leaving everything behind on Earth, when I left it in order to help save it? And coming here allowed me to do things that other scientists could only dream of. I have been able to name more than five thousand species already and come up with a rudimentary classification system for an entire native biota. More than on any of the other Formic worlds.”

  “Why?”

  “Because they stripped those and then established only a limited subset of their own flora and fauna. This is the only world where most of the species evolved here. The only place that’s messy. The Formics brought fewer than a thousand species to their colonies. And their home world, which might have had vastly more diversity, is gone.”

  “So you don’t regret coming here?”

  “Of course I do,” said Sel. “And I also am glad to be here. I regret being an old wreck of a man. I’m glad I’m not dead. It seems to me that all my regrets are balanced by something I’m glad of. On average, then, I have no regrets at all. But I’m also not a bit happy. Perfect balance. On average, I don’t actually exist.”

  “Father says that if you get absurd results, you’re not a scientist, you’re a philosopher.”

  “But my results are not absurd.”

  “You do exist. I can see you and hear you.”

  “Genetically speaking, Po, I do not exist. I am off the web of life.”

  “So you choose to measure by the only standard that allows your life to be meaningless?”

  Sel laughed. “You are your mother’s son.”

  “Not father’s?”

  “Both, of course. But it’s your mother who won’t put up with any bullshit.”

  “Speaking of which, I can hardly wait to see a bull.”

  By the time they had been a fortnight gone, with almost two hundred kilometers behind them, they had talked about every conceivable subject at least twice, and finally walked along in companionable silence most of the time, except when the exigencies of their journey forced them to speak.

  “Don’t grab that vine, it’s not secure.”

  “I wonder if that bright-colored froglike thing is venomous?”

  “I doubt it, considering that it’s a rock.”

  “Oh. It was so vivid I thought—”

  “A good guess. And you’re not a geologist, so how could you be expected to recognize a rock?”

  At two hundred clicks, though, it was time to stop. They had rationed carefully, but their food was half gone. They pitched a more permanent camp by a clear water source, chose a safe spot and dug a latrine, and pitched the tent with the stakes deeper and the ground more padded under the floor of it. They would be here for a week.

  A week, because that’s about how long they expected to be able to live on the meat of the two dogs they slaughtered that afternoon.

  Sel was sorry that only two of the dogs were smart enough to extrapolate that their human masters were no longer reliable companions. Those two left—they had to drive the other pair away with stones.

  By now, like everyone else in the colony, both Sel and Po knew how to preserve meat by smoking it; they cooked only a little of the meat fresh, but kept the fire going to smoke the rest as it hung from the bending limbs of a fernlike tree . . . or treelike fern.

  They marked out a rough circle on the satellite map they carried with them and each morning they set out in a different direction to see what they might find. Now they collected samples in earnest, and took photographs that they bounced to the orbiting transport ship for storage on the big computers there. It was nothing but a big satellite now, its electronics running on a tiny amount of the fuel and its databases constantly being transmitted to Earth automatically by ansible. The pictures, the test results, those were secure—they would not be lost, no matter what happened to Sel and Po. The samples, though, were by far the most valuable items. Once they brought them back, they could be studied at great length using far more sophisticated equipment. The new equipment from the colony ship.

  At night, Sel lay awake for long hours, thinking of what they had seen, classifying it in his mind, trying to make sense of the biology of this world.

  But when he woke up, he could not remember having had any great insights the night before, and certainly had none by morning light. No great breakthroughs; just a continuation of the work he had already done.

  I should have gone north, into the jungles.

  But jungles are far more dangerous to explore. I’m an old man. Jungles could kill me. This temperate zone, colder than the colony because it’s a little closer to the poles and higher in elevation, is also safer for an old man who needs open country to hike through and nothing unusually dangerous to snag or snap at him.

  On the fifth day, they crossed a path.

  There was no mistaking it. It was not a road, certainly not, but that was no surprise, the Formics had built few roads. What they made were paths, and those inadvertent, the natural result of thousands of feet treading the same route.

  Those feet had trodden here, though it was forty years before. Trodden so long and often that after all these years, and overgrown as it was, the naked eye could trace the path of it through the pebbly soil of a narrow alluvial valley.

  There was no question now of pursuing any more flora and fauna. The Formics had found something of value here, and archaeology took precedence, at least for a few hours, over xenobiology.

  The path wound upward into the hills, but not terribly far before it led to a number of cave entrances.

  “These aren’t caves,” said Po.

  “Oh?”

  “They’re tunnels. These are too new, and the land hasn’t shaped itself around them the way that it does with real caves. These were dug as doorways. All the same height, do you see?”

  “That damnably inconvenient height that makes it such a pain for humans to go inside.”

  “It’s not our purpose here, sir,” said Po. “We’ve found the spot. Let’s call for others to explore the tunnels. We’re here for the living, not the dead.”

  “I have to know what they were doing here. Certainly not farming—there’s no trace of their crops gone wild here. No orchards. No middens, either—this wasn’t a great settlement. And yet there was so much traffic, along that single path.”

  “Mining?” asked Po.

  “Can you think of any other purpose? There’s something in those tunnels that the Formics thought was worth the trouble of digging out. In large quantities. For a long time.”

  “Not such large quantities,” said Po.

  “No?” said Sel.

  “It’s like steel-making back on Earth. Even though the purpose was smelting iron to make steel, and they mined coal only to fire their smelters and foundries, they didn’t carry the coal to the iron, they carried the iron to the coal—because it took far more coal than iron to make steel.”

  “You must have gotten very good marks in geography.”

  “I never saw Earth,” said Po. “Neither did my parents—all born here. But Earth is still my home.”

  “So you’re saying that whatever they took out of these tunnels, it wasn’t in such large quantities that it was worth building a city here.”

  “They put their cities where the food was, or the fuel. Whatever they got here, they took little enough of it that it was more economical to carry it to their cities, instead of building a city here to process it.”

  “You may grow up to amount to something, Po.”

  “I’m already grown up, sir,” said Po. “And I already amount to something. Just not enough to get any girl to marry me.”

  “And knowing the principles of Earth’s economic history will attract a mate?”

  “As surely as that bunny-toad’s antlers, sir.”

  “Horns,” said Sel.

  “So we’re going in?”

  Sel mounted one of the little oil lamps into the flared top of his walking stick.

  “And here I thought that opening at the top of your stick was decoration,” said Po.

  “It was decorative,” said Sel. “It was also the way the tree grew out of the ground.”

  Sel rolled up his blankets and put half the remaining food into his pack, along with their testing equipment.

  “Are you planning to spend the night down there?”

  “What if we find something wonderful, and then have to climb back out of the tunnels before we get a chance to explore?”

  Dutifully, Po packed up. “I don’t think we’ll need the tent in there.”

  “I doubt there’ll be much rain.”

  “Caves can be drippy.”

  “We’ll pick a dry spot.”

  “What can live in there? It’s not a natural cave, I don’t think we’ll find fish.”

  “There are birds and other creatures that like the dark. Or that find it safer and warmer indoors.”

  At the entrance, Po sighed. “If only the tunnels were higher.”

  “It’s not my fault you grew so tall.” Sel lit the lamp, fueled by the oils of fruit Sel had found in the wild. They grew it in orchards now, and pressed and filtered it in three harvests a year, though except for the oil the fruit was good for nothing except fertilizer. It was good to have clean-burning fuel for light, instead of wiring every building with electricity, especially in the outlying colonies. It was one of Sel’s favorite discoveries—particularly since there was no sign the Formics had ever discovered its usefulness. Of course, the Formics were at home in the dark. Sel could imagine them scuttling along in these tunnels, content with smell and hearing to guide them.

  Humans had evolved from creatures that took refuge in trees, not caves, thought Sel, and though humans had used caves many times in the past, they were always suspicious of them. Deep dark places were at once attractive and terrifying. There was no chance the Formics would have allowed any large predators to remain at large on this planet, particularly in caves, since the Formics themselves were tunnel makers and cave dwellers.

  If only the Formic home world had not been obliterated in the war. What we could have learned, tracing an alien evolution that led to intelligence!

  Then again, if Ender Wiggin had not blown the whole thing up, we would have lost the war. Then we wouldn’t have even this world to study. Evolution here did not lead to intelligence—or if it did, the Formics already wiped it out, along with any traces the original sentient natives might have left behind.

  Sel bent over and squat-walked into the tunnel. But it was hard to keep going that way—his back was too old. He couldn’t even lean on his stick, because it was too tall for the space, and he had to drag it along, keeping it as close to vertical as possible so the oil didn’t spill out of the canister that was holding it.

  After a while he simply could not continue in that position. Sel sat down and so did Po.

  “This is not working,” said Sel.

  “My back hurts,” said Po.

  “A little dynamite would be useful.”

  “As if you’d ever use it,” said Po.

  “I didn’t say it would be morally defensible,” said Sel. “Just convenient.” Sel handed his stick, with the lamp atop it, to Po. “You’re young. You’ll recover from this. I’ve got to try a new position.”

  Sel tried to crawl but instantly gave up on that—it hurt his knees too much to rest them directly on the rocky floor. He finally settled for sitting, leaning his arms forward, putting weight on them, and then scrabbling his legs and hips after him. It was slow going.

  Po also tried crawling and soon gave up on it. But because he was holding the stick with the light, he was forced to return to walking bent over, knees in a squat. The boy would end up crippled, probably, but Sel would never have to hear his father and mother complain about it, because Sel himself would never get out of this tunnel alive.

  And then, suddenly, the light went dim. For a moment Sel thought it had gone out, but no—Po had stood up and lifted the stick to a vertical position, so that the tunnel where Sel was creeping along was now in shadow.

  It didn’t matter. Sel could see the chamber ahead. It was a natural cavern, with stalactites and stalagmites forming columns that supported the ceiling.

  But they weren’t the normal straight-up-and-down columns that normally formed, when lime-laden water dripped straight down, leaving sediment behind. These columns twisted crazily. Writhed, really.

  “Not natural deposits,” said Po.

  “No. These were made. But the twisting doesn’t seem designed, either.”

  “Fractal randomness?” asked Po.

  “I don’t think so,” said Sel. “Random, yes, but genuinely so, not fractal. Not mathematical.”

  “Like dog turds,” said Po.

  Sel stood looking at the columns. They did indeed have the kind of curling pattern that a long dog turd got as it was laid down from above. Solid yet flexible. Extrusions from above, only still connected to the ceiling.