Читать книгу Asgard's Conquerors - Brian Stableford - Страница 11

CHAPTER EIGHT

I was keen to have a discussion with the Tetron bioscientist, 673-Nisreen, but this proved difficult, partly because I was kept so busy, partly because the Tetron hardly ever left his cabin, and partly because Valdavia seemed to want all communication with the Tetron channeled through him.

Eventually, though, I did manage to speak to Nisreen long enough to arrange an assignation of sorts in his cabin. He seemed as pleased as I was to have the meeting set up, and I gathered that he would have issued an invitation himself had he not been as worried as Valdavia was about the necessity of observing protocol.

I let him ask me the first few questions, as if I were briefing him about Asgard. He’d never been there, and everything he knew about it was from memory chips that were long out of date.

I gave him a selective account of my adventures before moving on to what they implied.

“The people who thought there were no more than half a dozen levels always had a strong case,” I observed, “because the technology we were digging out of the top levels wouldn’t have been capable of erecting much more than that. The romantics who wanted Asgard to be an artifact from top to bottom had to credit its builders with technological powers far beyond anything known in the galactic community. We still can’t say, of course, whether there’s an ordinary planet inside the shells, but even if there is, we now know that the levels constitute a feat of engineering beyond anything your people or mine could contemplate. Imagine how long it must have taken to put that thing together!”

“It would seem to have been a remarkable achievement,” he opined, in typical Tetron fashion.

“And it begins to look,” I continued, “that it might be much older than many investigators thought. That might have interesting bearings on the question of the origin of the galactic races. I understand that your own researches also have some relevance to that?”

“It would be premature to draw conclusions,” he said. I didn’t intend to let him get away with that. I’d told him my side of the story. Now I wanted his.

“I was told on Goodfellow that DNA-based life has been found in the outer system of Earth’s star—micro-organisms deep-frozen for billions of years,” I said, broaching the matter as forthrightly as I dared, without running the risk of offending him. “The Tetrax must have had a chance to study thousands of life-bearing solar systems. How many are like ours in this respect?”

“Nearly all of them,” he said, lightly. “I know of one or two anomalous cases, but we have concentrated our researches on stars of the same solar type, whose planetary systems are roughly similar.”

“That seems to indicate that life didn’t evolve in any one of them—in fact, that there’s no way of knowing where DNA first came from.”

“We certainly have no basis for speculations about the ultimate origin of life,” admitted the Tetron.

“My ancestors always supposed that life evolved on Earth,” I said, carefully angling for more information. “Even when we came out into space and found the other humanoid races, we clung to that idea, and invented theories of convergent evolution to save it.”

“Our scientists never supposed that to be the case,” he informed me, with a touch of that lofty superiority that the Tetrax love to display. The best way get them to tell you something is to play up to that vanity.

“How did they work that out?” I asked, trying to sound suitably awed.

“A simple matter of the elementary mathematics of probability. The basic chemical apparatus of life is very complex. It is not only DNA itself, but all the enzymes associated with it, and the various types of RNA involved in transcription of the genetic code. It was easy to work out the probability of such a system arising by the random accretion of molecules. When we compared that probability to the area of our planet and the length of time since its origin, it was perfectly obvious that the chance of life originating there—or on any other planet—was absurdly small.

“It was obvious to us that the chemistry of life is so complicated that its evolution by chance would require vast areas of space and incredible spans of time. Our best estimate is that, given the size of our universe, the length of time for which we expect it to endure, and the kind of life-history we expect it to follow, the odds against life evolving at all were about ten to one against. It would appear that we owe our existence to a remarkable stroke of luck.”

I didn’t ask him to explain the mathematics of this remarkable calculation, but I took it with a pinch of salt. The trouble with the calculus of probability is that you can easily get silly answers if there are factors operating which you don’t know about. Ludicrous improbabilities are ten a penny in scientific research.

“Does that explain why the life-systems of the homeworlds of all the galactic races are so very similar?” I asked.

“Not in itself,” he told me. “If your world and mine had simply received the same elementary biochemical system, in the form of bacteria and virus-like entities, natural selection might have built very different systems. The fact that the pattern is repeated so closely, to the point where the insects of Tetra are very similar in their range to the insects of Earth—and so on for all the other major groups—implies that each of our worlds was seeded more than once. We think that new genetic material drifts from the outer to the inner regions of solar systems more-or-less constantly, and that this provides a major source of variations upon which natural selection can work; but we also think that seedings of more complicated genetic packages have occurred two or three times in recent galactic history—within the last billion years, that is.”

“So you think that the humanoid gene-complex was actually dumped on the inhabited worlds we know—by godlike aliens using the whole galactic arm as a kind of garden?”

Tetrax can’t frown, but I could tell that he thought I was going way over the top, and he clearly didn’t want such implications read into his argument. “We could not isolate the humanoid gene-complex as such,” he said. “At present, our best theory is that the last seeding may have been done at the time when, in Earthly terms, the dinosaurs died out. That radical break in the evolutionary story is something which recurs on many worlds, but there is no reason to suppose that alien intelligences were responsible for the seeding.”

“But you are saying that the mammalian gene-complex came from outer space, not from the DNA that already existed on Earth or Tetra?”

“That seems to be the case,” he confirmed. He looked at me carefully for a minute or two, perhaps wondering how much I would be able to understand. I got the feeling that we were now getting close to his own hobby-horse. “Do you know what is meant by the phrase ‘quiet DNA’?” he asked.

“No,” I replied. I began to suspect that we mightn’t get much further. Pan-galactic parole is a language designed to be easy to use. It isn’t geared up for complicated scientific discourse, and my limited mastery of it might soon come up against its limitations.

“Your gene-mappers, like ours of a few centuries ago, have now succeeded in locating on mammalian chromosomes—including human chromosomes—the genes that produce all the proteins making up your bodies.”

He paused, and I said: “Okay—I understand that.”

“Those genes,” he said, “account for somewhere between five and ten percent of the DNA in your cells. The rest is ‘quiet DNA’.”

“What you mean,” I said, in order to demonstrate my intelligence, “is that nobody knows what it does.”

“Quite so. Our scientists thought for some time that it must be made up of genes to control other genes. You see, there is more to building an organism than a mere chemical factory. An egg-cell, as it develops into a whole organism, must not only produce the proteins it needs, but must organize them into a particular structure. For many years our biotechnologists have tried to discover how it is that an egg is programmed to develop into a particular kind of organism. We had always assumed that the answer lay in the quiet DNA. We have failed to solve the problem. Your own biotechnologists are just beginning to be frustrated by that barrier to progress. We have found many practical applications for our biotechnology, and have been able to accomplish many things in spite of our incomplete understanding, but we must reluctantly acknowledge that one of the basic features of the chemistry of reproduction is still a complete mystery.

“What we have discovered, however, is that the quiet DNA of many—perhaps all—lower mammals includes genes which are expressed only in higher forms.”

I was having a little difficulty in following this, and had to pause for thought, but I suddenly saw what he was getting at. “You mean,” I said, “that virtually all the genes coding for the bodies of humanoids were already in mammals when they first appeared on Earth—or Tetra—and that the subsequent evolution of the mammals has been partly a matter of that quiet DNA waking up.”

He looked a little surprised.

“That’s correct, Star-Captain Rousseau,” he said. “In my view, at least, that is a distinct possibility—although it remains as yet unproven. The evolution of mammalian forms is, we think, partly pre-programmed. The program has to be adapted by natural selection to fit local circumstances, but in essence, the evolution of intelligent humanoid life-forms on all the worlds of the galactic community was inevitable from the moment the mammalian gene-complex appeared there. The subsequent millions of years of evolution can be seen as a kind of unfolding of potential already contained in the DNA-complex.”

I found that a pretty startling thought. 673-Nisreen was still watching me, and I realized that there was something else. Having impressed him with my intelligence, I was now expected to see the next step in the argument. It took me about a minute.

“And the story isn’t over!” I said, getting excited. “Ninety percent of human DNA—and Tetron DNA—is still quiet. We have no idea what other possibilities are still locked up in our cells!”

“Indeed we have not,” he replied. “Nor do we know what trigger might be necessary to bring it out. Our scientists thought, when they first invented biotechnology, that we had become masters of our own evolution. It is possible that the assumption was premature.”

“So the garden isn’t in full flower,” I murmured. “We might be just the first humble shoots, peeping up through the spring soil. We haven’t the faintest idea what it is that we’re scheduled to become....or why.”

“I must repeat my objection to your assumption that the galactic arm has been deliberately seeded for some particular purpose,” said 673-Nisreen. “Your image of godlike alien gardeners, while picturesque, has no evidence to support it. It remains conceivable that some entirely natural process was responsible for the spreading of this genetic material through local space.”

“Oh sure,” I said. “It was probably a fleet of flying pigs on their annual vacation.” He didn’t get the joke. There isn’t a word in parole for pigs, and even if there had been, it would have been taking coincidence to ridiculous lengths if the Tetrax had used the phrase “pigs might fly” as an expression of absurd improbability.

Humans came out of their own solar system to find superior aliens already there, in the shape of the Tetrax. It was easy for me to jump to the conclusion that there might be even more superior ones waiting in the wings. The Tetrax had strong ideological reasons for not jumping to any such conclusion. We humans had been anthropocentric in readily assuming that life might have evolved on Earth, making us the product of a special Creation—even though the Tetrax knew better, they had their own anthropocentric, or tetrocentric, tendencies.

“If there are answers to these questions,” I said, to cover up for my momentary impoliteness, “I think we might find them inside Asgard. There, I think, there are some very good biotechnologists.”

“I think that you might be right,” said 673-Nisreen. “And if the evolutionary future of your species and mine is yet to unfold from our quiet DNA, then it might well be that in the lower levels of Asgard we might find that potential already displayed.”

He didn’t seem to find this an overwhelmingly depressing thought, perhaps because his scientific curiosity was sufficient to outweigh his anxieties as a member of a politically ambitious species. I was willing to bet that some of his compatriots couldn’t contemplate the possibility with similar serenity.

When I left him, I had already begun to toy with scenarios in which Asgard could be made to play some crucial role in my hypothetical galactic gardening business.

Maybe Asgard was the gardener’s shed. Maybe it was a seed-bank.

Or maybe it was the combine harvester.

It didn’t take long for me to get round to looking at the question from the dark and nasty underside.

Suppose, I told myself, that the galaxy is a garden, and that deep in the heart of Asgard are its gardeners. But just suppose, for a moment, that we aren’t the crop that’s being raised. Suppose we’re only the weeds! And even if we aren’t, what can we possibly expect to happen when we come a-calling on the creatures we hope we might become?

I asked myself what might happen if a legion of Neanderthal men suddenly turned up on the Earth’s surface, expecting to be invited to the party.

It seemed a slightly ominous question even then, although I couldn’t imagine at the time how soon it would assume a much more peculiar relevance, and what an awful answer might be implied by the example with which I was to be confronted.