“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 someidentifiable traces,” Lityansky insisted. “There’s no evidence of any such traces on the surface. Anyhow, the situation nowis 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.
“ Collaborationwas 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 allEarthly plants and allEarthly 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 doesreproduction 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.”