Asgard's Conquerors (13 page)

"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 that 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 which produce all the proteins which make 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 organise 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, though, 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 which code 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 programme has to be adapted by natural selection to fit local circumstances,
but in essence, the evolution of intelligent hu- manoid 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 realised 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 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, 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, though 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.

9