“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 yearswith 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 doreproduce?”

“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 dohave 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 mightexplain 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 verydifficult 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 dohave some reliable knowledge?”

“I’m sorry I interrupted,” Matthew said, hoping that he didn’t sound too insincere.

“We havebeen 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 fetuit 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 nowis 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?”

Lityansky was mystified. “What about insects?” he countered.

“Well, what’s an insect but a serial chimera? The imago is only a maggot’s way of making more maggots, so they’re exactly like lichens in being strapped into a specific straitjacket by the limitations of sexual reproduction, but what an insect has, in essence, is a genome that codes for two quite different physical forms.”

“I don’t think it helps to introduce the notion of serial chimeras,” Lityansky complained. “The whole point about the situation here is that the vast majority of organisms on Ararat are made up of simultaneouschimerical combinations of cell types.”

Matthew didn’t want to be slapped down so easily. “When Solari and I were trawling through the data banks yesterday,” he said, “arthropod analogues seemed conspicuous by their absence. Assuming that the insects and their kin didn’t just slip into the cracks of our admittedly slapdash search, mightn’t that have something to do with the prevalence of un-serial chimeras?”

Lityansky wasn’t impressed. “It’s true that Ararat’s ecosphere has a dramatic dearth of exoskeletal organisms,” he admitted. “We think it’s because the local DNA-analogue has a blind spot where chitin and its structural analogues are concerned. We think that the principal reason for the apparent depletion of the vertebrate-analogues by comparison with Earth is due to the same blind spot. The local organisms aren’t good at producing hard bone. Their endoskeletons are more like cartilage, which means that the bigger animals need more complicated articulations to produce similar leverage. The organisms you saw in those photographs aren’t as similar to their Earthly analogues as they appear at first glance. Each individual might almost be regarded as a fusion of several disparate individuals, routinely combining as many as eight different genomic cell types. In some cases, only half of those cell types are sufficiently similar that they’d be reckoned as same-species in Earthly terms. We’ve hardly begun to extrapolate the possibilities opened up by that fundamental difference.”