The land here rose up into peaks as sharp as torn tin. In the thick trees beyond, mist broke on gray smooth rocks. Even here, high up the slope of an imposing ridge, the Excursion Station was hemmed in by slimy, thick-barked trees standing in deep drifts of dead, dark leaves. With rotting logs half buried in the wet layers, the air swarmed so close it was like breathing damp opium.

 Dors stood, her drink finished. “Let’s go in, socialize.”

 He followed dutifully and right away knew it was a mistake. Most of the indoor stim-party crowd was dressed in rugged safari-style gear. They were ruddy folk, faces flushed with excitement, or perhaps just enhancers. Hari waved away the bubbleglass-bearing waiter; he disliked the way it sharpened his wits in uncontrolled ways. Still, he smiled and tried to make small talk.

 This turned out to be not merely small, but microscopic. Where are you from? Oh, Trantor—what’s it like? We’re from (fill in the planet)—have you ever heard of it? Of course he had not. Twenty-five million worlds…

 Most were Primitivists, drawn by the unique experience available here. It seemed to him that every third word in their conversation was natural or vital, delivered like a mantra.

 “What a relief, to be away from straight lines,” a thin man said.

 “Um, how so?” Hari said, trying to seem interested.

 “Well, of course straight lines don’t exist in nature. They have to be put there by humans.” He sighed. “I love to be free of straightness!”

 Hari instantly thought of pine needles; strata of metamorphic rock; the inside edge of a half-moon; spider-woven silk strands; the line along the top of a breaking ocean wave; crystal patterns; white quartz lines on granite slabs; the far horizon of a vast calm lake; the legs of birds; spikes of cactus; the arrow dive of a raptor; trunks of young, fast-growing trees; wisps of high windblown clouds; ice cracks; the two sides of the V of migrating birds; icicles.

 “Not so,” he said, but no more.

 His habit of laconic implication was trampled in the headlong talk, of course; the enhancers were taking hold. They all chattered on, excited by the prospect of immersing themselves in the lives of the creatures roaming the valleys below. He listened, not comment­ ing, intrigued. Some wanted to share the worldview of herd animals, others of hunters, some of birds. They spoke as though they were entering some athletic event, and that was not his view at all. Still, he stayed silent.

 He finally escaped with Dors, into the small park beside the Ex­ cursion Station, designed to make guests familiar with local condi­ tions before their immersion. Panucopia, as this world was called, apparently had little native life of large size. There were animals he had seen as a boy on Helicon, and whole kraals of domestic breeds. All had sprung from common stock, less than a hundred thousand years ago, on the legendary “Earth.”

 The unique asset of Panucopia was nowhere near, of course. He stopped and stared at the kraals and thought again about the Galaxy. His mind kept attacking what he thought of as the Great Problem, diving at it from many angles. He had learned to just stand aside and let it run. The psychohistorical equations needed deeper analysis, terms which accounted for the bedrock properties of humans as a species. As…

 Animals. Was there a clue here?

 Despite millennia of trying, humans had domesticated few creatures. To be domesticated, wild beasts had to have an entire suite of traits. Most had to be herd animals, with instinctive submis­ sion patterns which humans could co-opt. They had to be placid; herds that bolt at a strange sound and can’t tolerate intruders are hard to keep.

 Finally, they had to be willing to breed in captivity. Most humans didn’t want to court and copulate under the watchful gaze of others, and neither did most animals.

 So here there were sheep and goats and cows and llamas, slightly adapted to this world but otherwise unremarkable, just like myriad other Empire planets. The similarity implied that it had all been done at about the same time.

 Except for the pans. They were unique to Panucopia. Whoever had brought them here might have been trying a domestication experiment, but the records from 13,000 years before were lost. Why?

 A wirehound came sniffing, checking them out, muttering an unintelligible apology. “Interesting,” he remarked to Dors, “that Primitivists still want to be protected from the wild by the domest­ icated.”

 “Well, of course. This fellow is big.”

 “Not sentimental about the natural state? We were once just another type of large mammal on some mythical Earth.”

 “Mythical? I don’t work in that area of prehistory, but most his­ torians think there was such a place.”

 “Sure, but ‘earth’ just means ‘dirt’ in the oldest languages, cor­ rect?”

 “Well, we had to come from somewhere.” She thought a moment, then allowed slowly, “I think that natural state might be a pleasant place to visit, but…”

 “I want to try the pans.”

 “What? An immersion?” Her eyebrows lifted in mild alarm.

 “As long as we’re here, why not?”

 “I don’t…well, I’ll think about it.”

 “You can bail out at any time, they say.”

 She nodded, pursed her lips. “Um.”

 “We’ll feel at home—the way pans do.”

 “You believe everything you read in a brochure?”

 “I did some research. It’s a well-developed tech.”

 Her lips had a skeptical tilt. “Um.”

 He knew by now better than to press her. Let time do his work. The canine, quite large and alert, snuffled at his hand and slurred, “Goood naaaght, suuur.” He stroked it. In its eyes he saw a kinship, an instant rapport that he did not need to think about. For one who dwelled in his head so much, this was a welcome rub of reality.

 Significant evidence, he thought. We have a deep past together. Perhaps that was why he wanted to immerse in a pan. To go far back, beyond the vexing state of being human.

 2.

 “We’re certainly related, yes,” Expert Specialist Vaddo said. He was a big man, tanned and muscular and casually confident. He was a safari guide and immersion specialist, with a biology back­ ground. He did research using immersion techniques, but keeping the station going soaked up most of his time, he said.

 Hari looked skeptical. “You think pans were with us back on an Earth?”

 “Sure. Had to be.”

 “They could not have arisen from genetic tinkering with our own kind?”

 “Doubtful. Genetic inventory shows that they come from a small stable, probably a zoo set up here. Or else an accidental crash.”

 Dors asked, “Is there any chance this world could have been the original Earth?”

 Vaddo chuckled. “No fossil record, no ruins. Anyway, the local fauna and flora have a funny key-pattern in their genetic helix, a bit different from our DNA. Extra methyl group on the purine rings. We can live here, eat the food, but neither we nor the pans are native.”

 Vaddo made a good case. Pans certainly looked quasihuman. Ancient records referred to a classification, that was all: Pan troglodytes, whatever that meant in a long-lost tongue. They had hands with thumbs, the same number of teeth as humans, no tails.

 Vaddo waved a big hand at the landscape below the station. “They were dumped here along with plenty of other related species, on top of a biosphere that supported the usual grasses and trees, very little more.”

 “How long ago?” Dors asked.

 “Over thirteen thousand years, that’s for sure.”

 “Before Trantor’s consolidation. But other planets don’t have pans,” Dors persisted.

 Vaddo nodded. “I guess in the early Empire days nobody thought they were useful.”

 “Are they?” Hari asked.

 “Not that I can tell.” Vaddo shrugged. “We haven’t tried training them much, beyond research purposes. Remember, they’re sup­ posed to be kept wild. The original Emperor’s Boon stipulated that.”

 “Tell me about your research,” Hari said. In his experience, no scientist ever passed up a chance to sing his own song. He was right.

 They had taken human DNA and pan DNA—Vaddo said, waxing on enthusiastically—then unzipped the double helix strands in both. Linking one human strand with a pan strand made a hybrid.

 Where the strands complemented, the two then tightly bound in a partial, new double helix. Where they differed, bonding between the strands was weak, intermittent, with whole sections flapping free.

 Then they spun the watery solutions in a centrifuge, so the weak sections ripped apart. Closely linked DNA was 98.2 percent of the total. Pans were startlingly like humans. Less than two percent difference, about the same that separated men and women—yet they lived in forests and invented nothing.

 The typical difference between individual people’s DNA was a tenth of a percentage point, Vaddo said. Roughly, then, pans were twenty times more different from humans than particular people differed among themselves—genetically.

 But genes were like levers, supporting vast weights by pivoting about a small fulcrum.

 “So you think they came before us?” Dors was impressed. “On Earth?”

 Vaddo nodded vigorously. “They must have been related, but we don’t come from them. We parted company, genetically, six million years ago.”

 “And do they think like us?” Hari asked.

 “Best way to tell is an immersion,” Vaddo said. “Very best way.”

 He smiled invitingly and Hari wondered if Vaddo got a commis­ sion on immersions. His sales pitch was subtle, shaped for an aca-demic’s interest, but still a sales pitch.

 Vaddo had already made available to Hari the vast stores of data on pan movements, population dynamics, and behaviors. It was a rich source, millennia old. With some modeling, here might be fertile ground for a simple description of pans as protohumans, using a truncated version of psychohistory.

 “Describing the life history of a species mathematically is one thing,” Dors said. “But living in it…”

 “Come now,” Hari said. Even though he knew the entire Excur­ sion Station was geared to sell the guests safaris and immersions, he was intrigued. “I need a change, you said. Get out of stuffy old Trantor, you said.”

 Vaddo smiled warmly. “It’s completely safe.”

 Dors smiled at Hari tolerantly. Between people long-married there is a diplomacy of the eyes. “Oh, all right.”

 3.

 He spent mornings studying the pan data banks. The mathem­ atician in him pondered how to represent their dynamics with a trimmed-down psychohistory. The marble of fate rattling down a cracked slope. So many paths, variables…

 To get all this he had to kowtow to the station chief. A woman named Yakani, she seemed cordial, but displayed a large portrait of the Academic Potentate upon her office wall. Hari mentioned it and Yakani gushed on about “her mentor,” who had helped her run a primate studies center on a verdant planet some decades be­ fore.

 “She will bear watching,” Dors said.

 “You don’t think the Potentate would—”

 “The first assassination attempt—remember the tab? I learned

 from the Imperials that some technical aspects of it point to an academic laboratory.”

 Hari frowned. “Surely my own faction would not oppose—”

 “She is as ruthless as Lamurk, but more subtle.”

 “My, you are suspicious.”

 “I must be.”

 In the afternoons they took treks. Dors did not like the dust and heat and they saw few animals. “What self-respecting beast would want to be seen with these overdressed Primitivists?” she said.

 He liked the atmosphere of this world and relaxed into it, but his mind kept on working. He thought about this as he stood on the sweeping verandah, drinking pungent fruit juice as he watched a sunset. Dors stood beside him silently.

 Planets were energy funnels, he thought. At the bottom of their gravitational wells, plants captured barely a tenth of a percent of the sunlight that fell on a world’s surface. They built organic mo­ lecules with a star’s energy. In turn, plants were prey for animals, who could harvest roughly a tenth of the plant’s stored energy. Grazers were themselves prey to meat-eaters, who could use about a tenth of the flesh-stored energy. So, he estimated, only about one part in a hundred thousand of the lancing sunlight energy wound up in the predators.

 Wasteful! Yet nowhere in the whole Galaxy had a more efficient engine evolved. Why not?

 Predators were invariably more intelligent than their prey, and they sat atop a pyramid of very steep slopes. Omnivores had a similar balancing act. Out of that rugged landscape had come hu­ manity.