Authors: Brian Stableford
“Why not?” Matthew asked, wondering whether the “mavericks” in question included Bernal Delgado.
“Because they’re excessively impressed by the fact that this world is a billion years older than Earth. They’re not convinced that evolution happened here at a much slower rate. They wonder whether there might have been an advanced civilization here at one time: one as advanced as Earth’s. If so, they argue, it too might have developed artificial coding systems for biotechnological and nanotechnological purposes. Personally, I find it impossible to believe that any such civilization wouldn’t have left more obvious relics.”
“After a billion years?” Matthew countered.
“A sophisticated inorganic technology ought to have left
some
identifiable traces,” Lityansky insisted. “There’s no evidence of any such traces on the surface. Anyhow, the situation
now
is that Ararat’s second coding molecule is associated with a whole new sideline of organic chemistry, which collaborates with the one that’s a close analogue of Earthly organic chemistry. Given that fundamental collaboration, maybe it isn’t so surprising that we also find biochemical collaborations of a much more adventurous kind.
“With the aid of hindsight, perhaps it isn’t so unusual that all the metazoan cells in the Ararat ecosphere have two differently based genomes. After all, you and I and all our animal cousins have two genomes too, although the nuclear genome and the mitochondrial genome are both DNA-based. Collaboration between genomes is obviously possible, given the Earthly example, so it’s not such a huge stretch of the imagination to wonder whether it might somehow be necessary, or at least very advantageous, to the production of authentically complex organisms. It’s hard to believe that it’s mere coincidence that the only other place in the galaxy where we’ve found evidence of humanoid organisms—albeit, perhaps, unsuccessful humanoid organisms—built them on a double-genome basis.”
Matthew had been studying the molecular models carefully, hoping for some insight into their potential, but it was no more possible to deduce the organisms he’d studied with Vince Solari from the formulas on the screen than it was to deduce a housefly and a human being from the formula of DNA. It took him a few seconds to realize that the bearded man had paused again, this time in order to invite a response.
“
Collaboration
was an emotionally loaded word where I come from,” Matthew observed, cautiously. “It didn’t sit too well within the theory of evolution by natural selection. It’s not a word that Bernal Delgado was wary of using, but he wasn’t the hardest-centered Darwinian in the selection box.”
“Were you?” Lityansky asked. The way his lips had pursed when Matthew mentioned Bernal Delgado’s name told Matthew that Bernal was indeed one of the disapproved mavericks—almost certainly their loudest spokesman.
“No,” Matthew admitted, “but whenever Bernal and I got together, I was prepared to play devil’s advocate.”
“You can call it assimilation if you’d prefer that way of looking at it,” Lityansky offered, as if he were making a generous concession. “Lichens are the only obvious Earthly example of that kind of cross-category fusion, but there are a lot more here. On Ararat, the distinction between plants and animals is unclear. Lots of animals, of many different families, possess chloroplast-analogues.”
“One could argue that
all
Earthly plants and
all
Earthly animals are the products of cross-category fusions,” Matthew pointed out. “Chloroplasts and mitochondria probably started out as independent organisms that became resident in other kinds of cells.”
“However the association between nuclear and mitochrondrial DNA arose,” Lityansky said, doggedly, “it’s there and it’s productive. It produced a selective advantage that enabled organisms with it to out-compete organisms without it. Something similar must have happened here. The metazoans with two genomes won out over any metazoans that tried to get by with one, whether the one was two-dimensional or three-dimensional.”
Lityansky dismissed the various images of the new world’s coding molecules from the screen, and brought up a new set of images. At first, Matthew couldn’t make head nor tail of them, but then he realized that they were electron microscope images of cell-clusters, including some cells that were in the process of division and some clusters where neighboring cells appeared to be undergoing some kind of fusion or exchange of nuclear material.
“Can you see what’s happening here?” Lityansky asked.
Matthew couldn’t, but he wasn’t prepared to look stupid. He felt obliged to make a tentative guess.
“Reproduction,” he said. “Shuffling the genetic pack. The local equivalent of meiosis. But there’s a twist. There’s something odd about reproductive processes on this world. I never saw any young in the archive photographs, nor any obvious secondary sexual characteristics.”
It was close enough to wring a grudging flicker of respect from Lityansky. “That’s the heart of the matter,” he conceded. “I believe that biotechnologists had already begun to explore techniques of artificial chimerization by the time you left Earth?”
“Mosaic organisms had been produced by embryo fusion long before then,” Matthew said. “It was never more than a gimmick in my day, used to produce experimental interspecies hybrids and children for same-sex couples. But it’s different here, right? Chimerization is routine—and the mavericks who reckon that the genomic duplex might be a relic of ancient biotech also wonder whether the local chimeras might be echoes of a glorious past. On the other hand, patterns of chimerization must have been built into metazoan evolution when the first local slime-molds started experimenting with communal living and cellular division of labor. From there, they were handed down to the entire range of metazoans, conserved in every new burst of adaptive radiation.” His guesses were growing more elaborate now, as he picked up cues from Lityansky’s body language that told him that he was on the right track. “At any rate,” he concluded, “that’s why the big animals don’t seem to go in for sex, even though convergent evolution has made them in the same image as their Earthly counterparts in other respects. So how
does
reproduction work here?”
Lityansky frowned, partly because his prepared script had been subverted and partly because he was now aware that he had underestimated his pupil. Like Milyukov, the genomicist had seen tapes of Matthew’s TV performances, and like Milyukov, he had formed an unjustly modest estimate of Matthew’s intelligence.
“As you can see,” he said, although he probably knew well enough how opaque the electron micrographs were to anyone unfamiliar with their context, “the local organisms do manifest a physiological process analogous to sexual reproduction. Individual cells do exchange genetic information—but it’s not meiosis because it doesn’t produce gametes. The exchanges are between different somatic components of chimerical mosaics.”
It took Matthew a few seconds to get his head around that. Put very crudely, what Lityansky was saying was that different bits of local organisms had sex with other bits of the same organism, which had a different genetic makeup, but that whole organisms didn’t have sex with one another. Sex on Ararat/Tyre wasn’t a matter of individuals at all; it was strictly a cell-on-cell business within chimerical individuals.
If he’d been talking to a man like Bernal Delgado, Matthew would have called it mind-boggling, but Andrei Lityansky didn’t seem to be the kind of man whose mind went in for that kind of thing.
“We’ve observed this in a wide range of primitive plants and animals,” Lityansky added, while Matthew was catching up. “We assume the same thing goes on in higher plants and animals, but that’s only speculation at present.”
“Why?” Matthew asked, genuinely surprised.
“Why
what
?” Lityansky retorted.
“Why is it only speculation? Why haven’t you found out?”
“The live specimens brought up into orbit had to be accommodated to the constraints of our biocontainment facilities,” Lityansky told him.
In other words, Matthew thought, Lityansky had never seen an alien creature he couldn’t fit on to a microscope slide.
“The work we’ve done on
Hope
,” Lityansky continued, “has consisted of fundamental biochemical, genomic, and proteonomic analyses. The biologists at Base One have had more opportunity to observe more complex organisms in the wild, but their lab work has had to be devoted almost entirely to the practical problems of adapting Earthly crops and animals to live in native environments.”
“That’s ridiculous!” Matthew said. “Are you telling me that you’ve been confronted for
three years
with a world whose higher plants and animals don’t appear to have any sex organs or to produce any young, but that you haven’t made any significant attempt to find out how they
do
reproduce?”
“What I’m telling you,” Lityansky said, frostily, “is that we’ve had too few people working on far too many problems to have made as much progress as we would have liked, or as much progress as we
need
. We had no idea, when we began, how strange the physiology of the most primitive organisms would turn out to be, but we have taken the view that if we can unravel the mysteries of the simpler entities first, we will then stand a far better chance of understanding the mysteries of the more complex.”
“So how do the simple entities reproduce themselves?” Matthew wanted to know.
“Some by simple fragmentation, others by sporulation.”
“Just like a lot of simple entities on Earth,” Matthew pointed out. “Not much help there in figuring out how the monkeys and the weasels do it. What’s the favorite hypothesis?”
“I don’t have a
favorite hypothesis
,” the bearded man told him. “That’s not the way I work.”
“So what’s the favorite hypothesis of the people who
do
have favorite hypotheses? What was Bernal Delgado’s favorite hypothesis?”
Lityansky pursed his lips. “Professor Delgado had become fond of speculating about
gradual chimerical renewal
,” he admitted. He seemed reluctant to dignify the phrase with elaboration, let alone explanation, but it only took Matthew a moment to connect the term to its most celebrated referent.
“Gradual chimerical renewal is a fancy name for the Miller Effect,” he said. “That’s not reproduction. That’s a kind of emortality.”
“Gradual chimerical renewal is a general concept, one of whose specific instances is the so-called Miller Effect,” Lityansky said, using pedantry to avoid simple agreement.
“I get it,” Matthew said. “It doesn’t remove the need for an account of reproduction, but it
might
explain why rates of reproduction are so slow that it’s almost impossible to observe immature individuals.”
“It’s pure speculation,” Lityansky pointed out, “and it’s
very
difficult to put any such hypothesis to the test. There’s no way to establish how long any individual is potentially capable of living if you can only observe it for a limited period of time. May I return to matters of which I
do
have some reliable knowledge?”
“I’m sorry I interrupted,” Matthew said, hoping that he didn’t sound too insincere.
“We
have
been able to study the various ways in which the simpler chimeras are compounded,” Lityansky went on, “and the ways in which certain individuals seem to hybridize types that would have been considered on Earth to be different species. Earth wasn’t entirely devoid of natural chimeras, of course. Mules and zeehorses, tigons and ligers were the most obvious—all compounds of closely related species, and they were unable to reproduce themselves because they were almost invariably sterile. There were, however, others far less obvious. In species where multiple embryos were simultaneously implanted, producing litters of fraternal twins, two embryos would occasionally fuse into a single individual. If the result was a
fetus in fetu
it usually aborted spontaneously, but in rare instances it resulted in a mosaic individual: a single-species chimera not unlike one of those produced by artifice for same-sex couples. The phenomenon was not unknown even in humans, although very rare.
“After it became possible in the late twentieth century to identify such same-sex chimeras by DNA analysis, some studies did suggest that animals of that kind could manifest a kind of hybrid vigor, because the fact that their individual tissues included two complete sets of chromosomes instead of one made them less vulnerable to genetic deficiency diseases. That was irrelevant from the viewpoint of natural selection, because each individual sperm or egg produced by a mosaic individual could only be a product of one set of genes …”
“But if the mosaic identity had been heritable,” Matthew put in, “then Earthly mosaics might have had sufficient selective advantages over single-genome individuals to have become the norm!”
Lityansky had grown used to Matthew’s interruptions by now, and accepted this one with better grace. “Perhaps. Here, where sexual exchanges occur between the cells of chimerical individuals rather than between the whole individuals, and where primitive reproduction is a matter of fragmentation and sporulation, the fundamental situation is very different. We can only speculate as to what happened in the earliest phases of evolution on Ararat, but the situation
now
is that sexual exchanges between chimerically associated genomes produce new types of somatic cells, some of which are then shed, or encapsulated as spores, which may then meet and fuse with the similar products of other individuals, eventually growing into new chimerical wholes. The vast majority of those we’ve so far catalogued are equivalent to Earthly same-species chimeras, but some are more ambitious combinations, of a kind manifest on Earth only in the lichens—”
“Hold on,” Matthew said, as he was struck by a sudden inspiration. “I’m not sure that’s true.”
“
What
’s not true?” Lityansky snapped back.
“That the only ambitious chimeras on Earth are lichens. What about insects?”