Dark Ararat - Brian Stableford [51]
“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