The Heart of the Comet

by David Brin

  It sticks to the cell wall, a simple capsule of protein, ready to inject its contents into the prostrate prey. Once inside, the viral RNA will take over the vast, complex chemical machinery of the cell, forcing it to forge hundreds, thousands of duplicates of the original virus, until, like an overstretched balloon, the ravaged cell bursts. The new viral horde spills forth, leaving only wreckage behind.

  There is the virus, stuck to the outer wall… poised to inject this tyrannical cargo into the prostrate prey…

  Prostrate, yes. But helpless?

  For a long time an argument raged among physicians, biologists, and philosophers. A small minority kept asking the same question over and over again.

  “Why does the cell let this catastrophe happen?”

  Biological heretics pointed out how difficult it was to seize and penetrate the intricate barriers of a cell wall. So much was involved, and it would seem so simple for a cell merely to refuse access.

  What about the fantastic number of steps needed to turn the machinery of the cell into a slave factory, forcing the ribosomes and mitochondria to perform tasks totally alien to their normal functions?

  “All the cell needs to do is interrupt any one of these steps, and the process is stopped, cold!” the unbelievers declared. “There must be a reason. Why does the cell allow itself to be such easy prey?”

  Classical biologists sniffed in disgust. Animals develop new ways to fight viruses all the time, they said. But viruses evolve methods around every obstacle. The balance is always struck across a knife edge of death.

  But the dissenters insisted, “Death is nothing but a side effect. Disease is not a war between species. More often, it is a case of failed negotiation.”

  “You’re losing me,” Carl told Saul.

  Saul drummed his fingers on the desktop and searched for the right words. “Hmmm. Let’s try an example. You know what mitochondria are, right?”

  Carl inclined his head and spoke in a hollow voice. “They’re organelles… internal parts of living cells. They regulate the basic energy economy… take electro-chemical potential from burning sugars and convert it into useful forms.”

  “Very good.” Saul nodded, impressed. Carl had, indeed, been studying over the long, hopeless years. No scholar, he had probably mastered the material by brute force. “And you know the widely held theory over where the mitochondria came from?”

  Carl closed his eyes. “I remember reading something about that. They resemble certain types of free-living bacteria, don’t they?”

  “Yes, that’s right.”

  “Some people think they were once independent creatures. But long ago one of their ancestors got trapped inside one of the first eukaryotes.”

  Saul nodded. “About a billon years ago… when our ancestors were only single cells, hunting around in the open sea.”

  “Yeah. They think one of our ancestors ate the ancestral mitochondria. Only, for some reason it didn’t digest it that time. It let the thing stay and work for it, instead.

  Carl looked up at Saul, seriously. “This is what you mean by symbiosis, isn’t it’? The early mitochondria provided more efficient energy conversion for the host cell. And in return, it never had to hunt for food again. The host cell.”

  “—Our ancestor.”

  “—took care of that from then on.”

  “And when one divided, so did the other, passing the arrangement down to each daughter cell. The partnership was inherited, generation by generation.” Saul nodded. “The same seems true of chloroplasts, the organelles in plant cells that do the actual work of photosynthesis. They’re kin to blue-green algae. And many other cellular components show signs they may have once been independent creatures, too.”

  “Yes. I do remember reading about that.” Carl seemed interested for the first time. Saul remembered some of the conversations they’d had back in the early days, before their differences had yawned like gulf between them. He wondered if Carl missed them s much as he did.

  Probably more. After all, I have Virginia.

  “The same holds for the entire organism, Carl. A normal human being has countless species of creatures living in him, depending on him as he depends on them. From gut bacteria that help us digest our food, to a special type of mite that lives only at the base of human eyelashes, scouring them, eating decayed matter and keeping them clean.”

  Saul spread his hands. “None of these symbiotic animals can live independently of man anymore. Nor can we very easily do without them. They’re almost as much parts of the colony organism called Homo sapiens as human DNA itself.”

  Carl blinked, as if trying to absorb this new leap. “It’s like a quantum field in physics, then. The boundaries of what I call ‘me’ are… are…”

  “Are amorphous. Nebulous. Difficult to define. You’ve got it! They’ve found that married couples share much the same suite of intestinal flora, for instance. Make love to a woman, and you exchange symbionts. In a sense, you become partly the same creature by sharing elements that grow and participate in each other.”

  Carl frowned. And Saul realized that he was skirting a touchy subject. He hurried on.

  “But here is my main point. Carl. Probably few, if any, of these symbionts simply settled into their niches without an initial struggle. Evolution doesn’t work that way… at least not usually.”

  “But—”

  “Every symbiont, from digestion helper to follicle cleaner, started out as an invader, once upon a time. Every synergism began in a disease.”

  “I don’t…” Carl frowned in concentration. “Wait. Wait a minute.” His brow was knitted with tight furrows. “You spoke of disease as negotiation between a host and an invading.”

  “— Visiting—”

  “— species. But… but even if that’s the case, this negotiation takes place over the bodies of uncounted dead of both sides!” Carl looked up, eyes flashing. “True, they may come to a modus vivendi someday, but that doesn’t help the individuals who die, often horribly, broken on the wheel of evolution.”

  Saul stared, unable to hide his surprise. In his most pensive moments, Carl Osborn seemed to have come upon a new facility with words. With tempering, an awkward youth had turned into something of a poet.

  “Well said.” Saul nodded. “And that’s exactly what we’re seeing here on Halley. Some die abruptly. Others fight the interlopers to a standstill. Some even profit a little from some side effect of their infestation.”

  Carl slapped the desktop with a loud report and swiveled to face Saul fully.

  “All very well and good, Saul. If— if— there were only one or two diseases, and if we had generations, with millions of people, in which to work all this out.”

  “But that’s not the case! Say you’re like that green-colored character up in Hydroponics Two.”

  “Old McCue? The one whose skin parasite seems to feed him nutrients made from sunlight?”

  “Yeah. Great stuff. But— to quote from your own report— the man’s mind has also been reduced to the level of a moron by a peptide byproduct of that very same fungoid parasite!”

  The younger man breathed heavily.

  “I’m glad you read my studies,” Saul answered.

  Carl snorted. “Besides Jeffers, and Virginia’s computer, you’re the only one who writes anything worth reading, anymore. I’m sure you’ll be more famous than ever, when you send your reports to Earth.”

  That made Saul wince. How had he managed to make Carl misunderstand him again? “It’s not like that.”

  “Oh? Then how is it, Mr. Great Man of Biology? Tell me! I’ve shown you 1 know plenty, for an amateur. Convince me! Tell me how the hell all these fancy theories about symbiosis are going to make one slice of difference to a tiny, overwhelmed colony, every member of which is a total, certain goner!”

  The pause lasted. Saul waited until the other man’s breathing had settled— until Carl had slipped back into the webbing on his side of the desk, glaring at him.


  “I already told you, but you weren’t listening,” he said softly. “There is one person on this planetoid who’s in no danger at all. Someone with attributes that make him safe in a totally new way.

  “That person is me, Carl.”

  For the first time, the full point of the conversation seemed to hit the spacer. He stood up.

  “You?”

  “Me.” Saul nodded. “My sneezing, my perpetual dripping are only surface features of that ‘negotiation process’ we spoke of. And it seams my immune system is a perfect diplomat. Except for the damage to my reproductive cells, my body has taken all comers almost without trouble. It accepts or rejects every new lifeform in short order, and each one soon finds its own niche.”

  There was another silence.

  “I am quite serious, Carl.”

  “But… how?”

  “How?” Saul shook his head. “I only know part of it, as yet. For one thing, I’ve inherited a rare enzyme that some have called N Complex. A dozen or so others on Halley have it too.”

  “And are they…”

  “More disease resistant? Seems so. But also, there’s something else, something in my blood that got there back when I worked with Simon Percell.”

  “Yes?” Carl’s voice was flat now, his expression guarded.

  “It’s called a reading unit. We only used the things for a couple of years, until we found better ways to strip and analyze DNA in vivo. Nearly forgot completely about the little things… until I saw them floating around down there, where they’d taken over my spermetic cells.”

  Saul shook his head. “Don’t know how they got into me, really. Must’ve stuck myself one day while doing a gene analysis. But however they got there, my body’s using them, somehow.

  “Now I think I know why I was so lucky, three decades ago, when I developed the new cyanutes. I didn’t really develop them. My body did.”

  The longest silence of them all followed this.

  At last Carl spoke.

  “I’ve also read psychology, Saul. You know, of course, that claims of invulnerability are symptoms of paranoia?”

  Saul shrugged. “I am, in almost every basic sense, completely healthy. Completely. The only one in the colony. You don’t believe me?”

  “Of course not! What do you take me for?”

  Saul held out his hand. “Take it,” he said casually. After a moment’s hesitation, Carl’s callused fingers wrapped around Saul’s, still soft from so long in the slots.

  Carl’s grim smile faded into intense concentration as Saul squeezed, talking on, casually.

  “Diseases, microgravity deconditioning, slot fatigue…they’ve pounded all of you down until a drugged Cub Scout could beat any of you with one hand tied.”

  Carl’s brow beaded. Obstinately, grunting, he tried to match Saul’s grip.

  ‘You know you can’t t knish the Nudge Launchers in time, even with all of Virginia’s mechs to help. You need people, and you don’t have ’em, Carl. Two hundred slotted for good, another hundred feeble as kittens—”

  He let go and Carl sagged back with a ragged sigh, his eyes wide.

  “I didn’t show you this to rub your nose in your weakness, Carl. I only want you to believe it when I say there may be a way. A way to give similar immunity to many, maybe even most of the members of this expedition.

  “Carl, we just may not be doomed, after all.”

  He said no more. There was no point in talking any longer. When the other man had questions, he would ask them. Let it have time to sink in, he thought.

  Right now, Carl’s face was like a statue’s. He stood up— rocky, unsteady— staring at Saul even as he backed away, shaking his head. With one hand he touched the doorplate, spilling phosphor light into the darkened room.

  From the hallway, Carl kept staring at him until the door had shut again, cutting off the view, but not the image.

  After a moment Saul looked up at the ceiling.

  Oh, I know you, Ado-shem, he thought at the bearded, fierce-eyed God of Abraham. Thismorning I opened your gift, tore off the wrapping paper, and looked inside. And just now I showed its frightening beauty to a man who was once a friend.

  It looks, at just, like a fine gift. Like the rock that flowed with water for the Hebrew children in the desert. But you and t know that inside the box is another box and another, and more ad infinitum.

  And I’m still no closer to an answer to the basic questions, am I!? Where did Halley-Life come from? Did comets seed the Earth, long ago? Or are we only the latest invaders of this little worldlet? How could all of this have happened in the first place?

  There was no reply, of course.

  He smiled upward, through half a mile of rocky ice, at the stars.

  Oh, yes. You will have your joke.

  CARL

  Carl and Virginia sat stiffly in nearby web-chairs. The G-wheel had broken down years ago and subtle side effects of constant low-gravity were showing. The lounge was deserted except for them, its vivid wall weather running unnoticed. A drowsy camel slowly bobbed along the brow of a distant sand dune.

  “What I mean is, do you think he’s got all his marbles?” Carl asked flatly.

  “Of course Saul is perfectly all right,” she answered indignantly, tension visible in her body language.

  I’ve got to remember, she really loves the jerk, Carl thought. Okay, be diplomatic. “I’m worried about his… health.”

  Virginia wasn’t having any of it. “You mean you think his discovery is a delusion.”

  “Well, it is extreme.” Carl threw his hands into the air and boomed out, “I, Saul Lintz, am a godlike immortal. Immune! Impervious! Kneel, mere mortals!”

  “That’s not his attitude.”

  “Well, let’s say he comes over as a quiet megalomaniac.”

  “He was describing a theory.”

  “With himself as prime evidence.”

  “Well, yes. Who else aboard has the N-constellation?”

  “Good question. You could check the DNA log for the corpsicles.”

  Virginia’s eyes shifted a fraction sideways for just an instant, but by now he could read her pretty well. “You already have, right?”

  She nodded, knitting her fingers together and staring into them. “There are three others.”

  “Good. Easy way to test his theory, right’? Unslot ’em and see if they catch a bug.”

  “Saul said the same thing when I told him yesterday.”

  “Hmmmm. I wonder why he didn’t mention that little fact to me.”

  “He’s been busy. I suppose he wants to think things through a little more before… experimenting.”

  “Or maybe— just maybe— he wants to do everything himself. Big Saul saves all.”

  Virginia flared. “You have no right to say that!”

  He held up his hands. “Okay, maybe so. Let’s say I’ve been dealing with a lot of crazies these years. I’ve gotten used to doubting everything.”

  She bit her lip. Containing her anger? Or keeping in the suspicion that maybe I’m right?

  “If Saul’s inoculations work,” she said in measured tones, “we will be able to save ourselves. The expedition will succeed. You must put your faith in him. You are going to okay his initial test treatments of volunteers, aren’t you?”

  Carl shrugged. “My authority is limited. The ‘tribes’ contribute their labor. I handle routine management and make up a maintenance roster. Cap’n Bligh I’m not. I don’t see where I could stop him from recruiting… volunteers.” He had almost said suckers.

  “Good. You’ll see, Carl. This is our hope.”

  Hope? He was tempted to tell Virginia about the side effect of Saul’s wondrous symbiosis— Saul’s sterility. But if Saul had already told her, it would make him look mean.

  Carl paused. Above her shoulder a caravan of scruffy tan camels plodded tirelessly across a vast sandy waste, heading for a green dab of palms halfway to the hard-edged horizon. Red-garbed traders swayed atop each, peerin
g directly toward Carl with unveiled suspicion. Their images wavered with the heat, making the ponderous caravan ripple like a dream. Psychologically effective, no doubt, but Carl’s feet still felt cold.

  “Something bothering you, Virginia?”

  “JonVon’s… sick.”

  “I’d heard. Is it— he— malfing?”

  “He’s an organic matrix, remember. Saul thinks he’s got some infestation of Halleyforms. I hope Saul can find a cure.”

  She started outlining the problem, the analogy between JonVon’s nonliving organics versus ordinary flesh and blood, and how JonVon could “catch a cold” in a more than metaphorical fashion. Carl listened, looking into her eyes for a long time. He still felt the old tug, that slow warm yearning that would come swelling up in him if he let it. Her pensive, expectant mouth, the regal cast to the high cheekbones…

  “Is JonVon immortal, same as Saul is supposed to be?” Carl asked.

  “Saul might make him so. If a cure is found. If Saul is right about himself…”

  “I still think it’s all baloney.”

  She said primly, “We must test those three from the slots immediately.”

  She seems so sure. Could Lintz be right?

  Virginia was too honest to let love blind her totally. She would have given some sign if she doubted Saul…

  “Okay, assuming a real miracle, we’ll need to activate more farm area. We’ll want to pull nearly everybody out of the slots. Maybe— who knows?—Saul can cure some of those with black borders.”

  “Even Commander Cruz?”

  The thought struck Carl hard. “Could be,” he said to cover his confusion. Reviving senior officers… I won’t be such a big cheese around here. But it would be great to work with the captain again, with somebody who really knew how to get things done…

  “It’ll be a hell of a rush, with only a few years to go to aphelion.”

  Virginia brightened. “We can do it. I know we can.”

  “Damn right.” And Carl forced a hopeful smile.