[ Pobierz całość w formacie PDF ]

"It's a something that should be followed up," she answered.
Nostreny smiled. "You still like that idea, don't you?"
Lorili had long learned that trying to hide anything would be futile. The
clear, gray eyes, ever-mobile behind his metal-rimmed spectacles, seemed to
see into heads and read brain patterns. "Yes, " she admitted. "The Terrans
seemed to combine a fascinating combination of conflicting qualities. Having a
better idea of how close we are to them might tell us things about ourselves."
"But I thought we went through all that with Iwon. The time scale on Venus has
been too short to have gotten from some primordial ancestor to us and the
other quadribasics by any mechanism of the kind the Terrans postulated even
with your environmentally cued mutations to speed things up. And even if you
did somehow telescope the process into Venus's life span, you've still got the
morphological similarities to explain. Skeletally it's practically impossible
to tell the difference between us and Terrans.
And so far, the soft-tissue specimens from Luna are telling us the same
thing." Nostreny spread his hands.
"Two independent sequences, both resulting in virtually identical
end-products? . . . It's too much to accept as a coincidence, surely."
"That's what I wanted to talk about," Lorili said. "Maybe the cued mutation
idea in the form I've been stating it might be too weak. I think there's a
stronger form that could explain it. These latest Terran finds could be our
chance to test it. But it would need a full bio-lab investigation."
Nostreny, grinned and shook his head. You just don't give up, do you?"
"Maybe it comes from studying Terrans. As I said, it's important to me."
"A stronger form of the theory."
"Yes. It occurred to me when I was thinking about undifferentiated cells in a
growing embryo"
Nostreny interlaced his fingers and sat back in his chair. "Okay, go on. let's
hear it."
"Their plasticity is an astounding example of how sensitive biological systems
are to environmental cues. Any one can become bone, muscle, nerve, or any
other kind of tissue. The potential to be all of them is inherent in the
common genetic program that they all carry. The cues merely determine which
parts of the program are switched on." She knew she was hardly telling
Nostreny anything that he wasn't aware of. It was more to set her direction.
Page 83
ABC Amber Palm Converter, http://www.processtext.com/abcpalm.html
"Okay," he agreed, opening his fingers briefly.
"Mightn't the same principle operate at a higher level? We still only know a
tiny fraction of what genomes do. Perhaps the reason they're so huge is that
they carry the potential to become anything over a far wider range than has
been supposed."
Nostreny inclined himself forward, evidently taking the point. "You mean more
than just the potential to differentiate into different kinds of cell?"
"Yes, exactly. The potential to be totally different organisms. Not just to
produce different beak shapes and body sizes. But all of it already in there,
contained in a common program. So the forms they come to actualize and express
could be determined not by the kind of selection that the Terrans talked
about, but by selective activation of already existing genetic potential."
Nostreny nodded that he was following. Lorili warmed to her theme. "On that
basis, the first life to appear on a hot, recently formed planet would be of a
primitive form not because it represents an early stage of evolving
information, but because it's appropriate in terms of what a primitive
environment can support. A young planetary surface cues the appearance of
microbes because nothing else could live there. Microbes initiate processes
that transform the environment. The transformed environment provides new cues
that switch the genetic programs to producing new types of organism. And there
you have it."
Nostreny looked intrigued, to be sure. But that was just his way. It didn't
meant that he bought it. His willingness to consider new things on their merit
was one of the things that made him easy to work with. It mirrored Lorili's
own inclinations. "So as soon as the conditions are right, you can have [ Pobierz całość w formacie PDF ]