The exchange of messages recorded in Jupiter Five's Communications Center Day Log was enthusiastic and friendly.
Shapieron Good afternoon.
J5 Hi. How was the trip?
Shap. Excellent. How has the weather been?
J5 Pretty much the same as ever. How were the engines?
Shap. Never better. Did you save our rooms?
J5 Same ones as before. You wanna go on down?
Shap. Thanks. We know the way.
Within five hours of the Shapieron touching down at Ganymede Main Base, familiar eight-foot-tall figures were clumping up and down the corridors at Pithead once again.
Hunt's conversation with Danchekker had stimulated his curiosity about biological mechanisms for combating the effects of toxins and contaminants in the body, and he spent the next few days accessing the data banks of Jupiter Five to study up on the subject. Shilohin had mentioned that terrestrial life had evolved from early marine species that hadn't developed a secondary circulation system because they hadn't needed one; the warmer environment of Earth had imposed less strenuous demands for oxygen with the result that load-sharing had not been necessary. But it was this same mechanism that had later enabled the emerging Minervan land dwellers to adapt to a C02 -rich atmosphere. The terrestrial animals imported to Minerva had obviously possessed no similar mechanism, and yet they had adapted readily enough to their new home. Hunt was curious to find out how they did it.
His researches failed, however, to throw up anything startling. Each world had evolved its own family of life, and the two systems of fundamental chemistry on which the two families were based were not the same. Minervan chemistry was rather delicate, as Danchekker had deduced long ago from his study of the preserved Minervan fish discovered in the ruins of a wrecked Lunarian base; land animals inheriting such chemistry would be inherently sensitive to certain toxins, including carbon dioxide, and would require an extra line of defense to give them a reasonable tolerance if atmospheric conditions were extreme--hence the adaptation of the secondary system in the earliest land dwellers. Terrestrial chemistry was more rugged and flexible and could survive a far wider range of changes, even without any assistance. And that was really all there was to it.
One afternoon, Hunt found himself sitting in front of the view-screen in one of the computer console rooms at Pithead at the end of another unsuccessful attempt to uncover a new slant on the subject. Having nobody else to talk to, he activated his channel into the Ganymean computer network and discussed the problem with ZORAC. The machine listened solemnly without offering much in the way of comment while Hunt spoke. Afterward it had one comment. "I really don't see much to add, Vic. You seem to have got it pretty wrapped up."
"There's nothing you can think of that I might have left out?" Hunt queried. It seemed a funny question for a scientist to put to a machine, but Hunt had come to know well ZORAC's uncanny ability to spot a missing detail or a small flaw in what appeared to be a watertight line of reasoning.
"No. The evidence adds up to what you've already concluded: Minervan life needed the help of a secondary system to adapt and terrestrial life didn't. That is an observed fact, not a deduction. Therefore there's not a lot I can say."
"No, I guess not," Hunt conceded with a sigh. He flipped a switch to cut off the terminal, lit a cigarette and slumped back in a chair. "It wasn't really that important, I suppose," he commented absently after a while. "I was just curious to see if the differences in biochemistry between our life forms and Minervan ones pointed to anything significant. Looks as if they don't."
"What were you hoping to find?" ZORAC asked. Hunt shrugged automatically.
"Oh, I don't know. . . something that might shed light on the kinds of things we've been asking . . . what happened to all the Minervan land dwellers, what was it that they couldn't survive that the animals from Earth could--we know it wasn't the CO2 concentration now. . . . Things like that."
"Anything unusual, in fact," ZORAC suggested.
"Mmm. . . guess so."
A few seconds passed before ZORAC spoke again. Hunt had the uncanny impression that the machine was turning the proposition over in its mind. Then it said in a matter-of-fact voice:
"Maybe you've been asking the wrong question."
It took a moment for the implication to sink in. Then Hunt snatched the cigarette from his lips and sat forward in his chair with a start.
"What d'you mean?" he asked. "What's wrong with the question?"
"You're asking why Minervan life and terrestrial life were different and succeeding only in proving that the answer is,'because they were.' It's undeniably true, but singularly ineffective in telling you anything new. It's like asking,'Why does salt dissolve in water when sand doesn't?' and coming up with the answer,'because salt's soluble and sand isn't.' Very true, but it doesn't tell you much. That's what you're doing."
"You mean I've simply been working around a circular argument?" Hunt said, but even as he spoke he could see it was true.
"An elaborate one, but when you analyze the logic of it--yes," ZORAC confirmed.
Hunt nodded to himself and flicked his cigarette to the ashtray.
"Okay. What question should I be asking?"
"Forget about Minervan life and terrestrial life for a moment, and just concentrate on the terrestrial," ZORAC replied. "Now ask why Man is so different from any other species."
"I thought we knew all that," Hunt said. "Bigger brains, opposable thumbs, high-quality vision all in one species together--all the tools you need to stimulate curiosity and learning. What's new?"
"I know what the differences are," ZORAC stated. "My question was why are they?"
Hunt rubbed his chin with his knuckle for a while as he reflected on the question. "Do you think that's significant?"
"Very."
"Okay. I'll buy it. Why is Man so different from any other species?"
"I don't know."
"Great!" Hunt exhaled a long stream of smoke with a sigh. "And how exactly is that supposed to tell us more than my answers did?"
"It doesn't," ZORAC conceded. "But it's a question that needs answering. If you're looking for something unusual, that's a good place to start. There's something very unusual about Man."
"Oh, how come?"
"Because by rights Man shouldn't exist. It shouldn't have been possible for him to evolve. Man simply can't happen, but he did. That seems very unusual to me."
Hunt shook his head, puzzled. The machine was speaking in riddles.
"I don't understand. Why shouldn't Man have happened?"
"I have computed the interaction matrix functions that describe the responses of neuron trigger potentials in the nervous systems of higher terrestrial vertebrates. Some of the reaction coefficients are highly dependent on the concentrations and distributions of certain microchemical agencies. Coherent response patterns in key areas of the cerebral cortex could not stabilize with the levels that are usual in all species except Man."
Pause.
"ZORAC, what are you talking about?"
"I'm not making sense?"
"To put it mildly--no."
"Okay." ZORAC paused for a second as if getting its thoughts organized. "Are you familiar with Kaufmann and Randall's recent work at the University of Utrecht, Holland? It is fully recorded in Jupiter Five's data bank."
"Yes, I did come across some references to it," Hunt replied. "Refresh my memory on it."
"Kaufmann and Randall conducted extensive research on the way in which terrestrial vertebrates protect themselves against toxic agents and harmful microorganisms that enter their systems," ZORAC said. "The details vary somewhat from species to species, but essentially the basic mechanism is the same--presumably handed down and modified from common remote ancestral forms."
"Ah yes, I remember," Hunt said. "A kind of natural self-immunization process, wasn't it?"
He was referring to the discovery by the scientists at Utrecht that the animals of Earth manufactured a w
hole mixture of contaminants and toxins on a small scale, which were injected into the bloodstream in quantities just high enough to stimulate the production of specific antitoxins. The "blueprint" for manufacturing these antitoxins was thus permanently impressed into the body's chemical system in such a way that production would multiply prodigiously in the event of the body being invaded on a dangerous scale.
"Correct," ZORAC answered. "It explains why animals are far less bothered by unwholesome environments, polluted diets and so on than Man is."
"Because Man is different; he doesn't work that way--right?"
"Right."
"Which brings us back to your question."
"Right."
Hunt regarded the blank screen of the console for a while, frowning to himself in an effort to follow what the machine was getting at. Whatever it was, it failed to register.
"I still don't see where it gets us," Hunt said at last. "Man's different because he's different. It's just as much a pointless question as before."
"Not quite," ZORAC said. "The point is that it shouldn't have been possible for Man to become different. That's what's interesting."
"How come? I'm not with you."
"Permit me to show you some equations that I have solved," ZORAC suggested.
"Go ahead."
"If you key in a channel-activate command I'll put them on the large screen via the UNSA comnet."
Hunt obliged by tapping a quick sequence of characters into the keyboard in front of him. A second later the screen above kaleidoscoped into a blaze of colors which immediately stabilized into a mass of densely packaged mathematical expressions. Hunt stared at the display for a few seconds and then shook his head.
"What's it all supposed to be?" he asked.
ZORAC was happy to explain. "Those expressions describe quantitatively certain aspects of behavior of the generalized central nervous system of the terrestrial vertebrate. Specifically they define how the basic nervous system will respond to the presence of given concentrations and mixes of various chemical agents in the bloodstream. The coefficients indicated in red are modifiers that would be fixed for a given species, but the dominant factors are the general ones shown in green."
"So?"
"It reveals a fundamental drawback in the method that was adopted by terrestrial animals to protect themselves from their chemical environment. The drawback is that the substances introduced into the bloodstream by the self-immunization process will interfere with the functions of the nervous system. In particular, they will inhibit the development of higher brain functions."
Suddenly Hunt realized what ZORAC was driving at. Before he could voice his thoughts, however, the machine went on.
"In particular, intelligence shouldn't be capable of emerging at all. Larger and more complex brains demand a greater supply of blood; a greater supply of blood carries more contaminants and concentrates them in the brain cells; contaminated brain cells can't coordinate sufficiently to exhibit higher levels of activity, that is, intelligence.
"In other words, intelligence should never have been able to evolve from the terrestrial line of vertebrate evolution. All the figures there say that terrestrial life should have gotten itself truly stuck up a dead end."
Hunt gazed for a long time at the symbols frozen on the screen while he pondered the meaning of all this. The ancient architecture evolved by the remote ancestors of the vertebrates hundreds of millions of years before had met a short-term need but failed to anticipate the longer-term consequences. But Man, somewhere along his evolutionary line, had abandoned the self-immunization mechanism. In doing this he had increased his vulnerability to his surroundings, but at the same time he had opened up the way to evolving the superior intelligence that would, in time, more than make up for the initial disadvantage.
The intriguing question of course was: How and when had Man done it? The theory offered by the Utrecht researchers was: during the forced exodus of his ancestors to Minerva, during the period that lasted from twenty-five million to fifty thousand years ago. Twenty-five million years before, many species of ordinary terrestrial life had been shipped there; nearly that long later, only one had come back--one that had been very far from ordinary. Homo sapiens , in the shape of the Lunarians, had returned--the most ferocious adversary that the survival arena of either world had ever witnessed. He had dominated Minerva while contemporaneous anthropoids on Earth groped around in the dim twilight zone on the fringes of self-awareness, and then, having destroyed that world, had returned to Earth to claim his place of origin, completely and ruthlessly extinguishing his remote cousins in the process.
Danchekker had reasoned that a violent mutation had taken place along the line of human descent isolated on Minerva. This latest piece of information pointed out the area in which the mutation had occurred; it didn't attempt to explain why it had happened. But then, mutations are random events; there was nothing to suggest that there had been any specific cause to look for.
The evident fact of the emergence of Ganymean intelligence fitted in nicely with this body of theory too. The architecture of Minervan land dwellers had isolated the system that carried the toxins from the system that carried blood. Thus, when larger brains became in order, the way was clear to evolve a brain that could draw more blood without more toxins--the density of one network simply increased while that of the other didn't. Higher brain functions could develop without hindrance. The intelligence of the Ganymeans was the natural and logical outcome of Minervan evolution. Terrestrial evolution, however, pointed to no such natural and logical outcome; Man had somehow cheated the system.
"Well," Hunt declared finally. "It's interesting, sure. But what makes you say it shouldn't have happened? Mutations are random events. The change came about as a mutation that took place on Minerva, somewhere along the line that led to the Lunarians and from there to Man. It looks straightforward. What's wrong with that?"
"I thought you'd say that," ZORAC commented, somehow managing to give the impression of sounding quite pleased with itself. "That's the obvious first reaction."
"So--what's wrong with it?"
"It couldn't work. What you're saying is that somewhere early on in the primate line on Minerva, a mutation must have occurred that deactivated the self-immunization system."
"Yes," Hunt agreed.
"But there's a problem in that," ZORAC advised him. "You see, I have performed extensive computations on further data available from J5--data that describe the genetic coding contained in vertebrate chromosomes. In all species, the coding that controls the development of the self-immunization process in the growing embryo contains the coding that enables the animal specifically to absorb excess carbon dioxide. In other words, if you deactivated the self-immunization mechanism, you'd also lose the ability to tolerate a C02 -rich environment. . . ."
"And Minerva was becoming CO2 -rich," Hunt supplied, seeing the point.
"Exactly. If a mutation of the kind you're suggesting occurred, then the species in which it had occurred could not have survived on Minerva. Hence, the ancestors of the Lunarians could not have mutated like that. If they did, they'd have died out. The Lunarians would never have existed and you wouldn't exist."
"But I do," Hunt pointed out needlessly, but with a certain sense of satisfaction.
"I know, and you shouldn't, and that's my question," ZORAC concluded.
Hunt stubbed out his cigarette and lapsed into thought again. "What about the funny enzyme that Chris Danchekker is always talking about? He found it in all the preserved Oligocene animals in the ship here, didn't he? There were traces of a variant of it in Charlie too. D'you reckon that could have something to do with it? Maybe something in the environment on Minerva reacted in some complicated way and got around the problem and the enzyme appeared somehow in the process. That would explain why today's terrestrial animals haven't got it; the ancestors they're descended from never went there. Perhaps that's why modern Man doesn't have it either--he's been back on E
arth for a long time now and away from the environment that stimulated it. How about that?"
"Impossible to confirm," ZORAC pronounced. "Inadequate data available on the enzyme at present. Very speculative. Also, there's another point it doesn't explain."
"Oh, what?"
"The radioactive decay residues. Why should the enzymes found in the Oligocene animals appear to have been formed from radioisotopes while the ones found in Charlie didn't?"
"I don't know," Hunt admitted. "That doesn't make sense. Anyhow, I'm not a biologist. I'll talk about all this to Chris later." Then he changed the subject. "ZORAC--about all those equations you computed."
"Yes?"
"Why did you compute them? I mean. . . do you just do things like that spontaneously. . . on your own initiative?"
"No. Shilohin and some of the other Ganymean scientists asked me to."
"Any idea why?"
"Routine. The computations were relevant to certain researches that they are conducting."
"What kind of researches?" Hunt asked.
"On the things we have been discussing. The question that I suggested a few minutes ago was not something that I originated myself; it was a question that they have been asking. They are very interested in the whole subject. They're curious to find out how Man came to exist at all when all available data says he shouldn't and all their models predicted that he would destroy himself if he did."
Hunt was intrigued to learn that the Ganymeans were studying his kind with such intensity, especially since they appeared to have progressed so much further in their deductions than the UNSA team had. He was surprised also that ZORAC would so readily divulge something that could be considered sensitive information.
"I'm amazed that there aren't any restrictions on you talking about things like that," he said.
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