Dark Ararat - Brian Stableford [100]
“Have you been able to do much work on the higher animals?” Matthew asked. “Lityansky didn’t seem to have looked at anything as complicated as the slug, let alone the mammal-analogues.”
“When I first came here,” Tang said, “I was excited by the possibility that we might be able to go straight to the top, as it were, by recovering some genetic material from the city-builders, but the quest has so far proved frustrating. We know that there are monkey-analogues further downstream, which are presumably the nearest relatives of the humanoids so far observed, but our attempts to trap mammal-analogues in and around the ruins have been just as frustrating as our attempts to discover humanoid remains. The river expedition was, of course, intended to compensate for those disappointments. I assume that it still is. One of my fallback projects—fortunately, as it has turned out—was to investigate the class of creatures that includes the one that incapacitated poor Maryanne. My initial interest had nothing do do with the fact that all the species in the group are poisonous, but the work Maryanne and I have done on the toxins has proved very useful. You’ve presumably been informed that the genomics of organisms like this one seem unusually complex even if one sets aside the matter of the second coding molecule. The genomic potential of the DNA-analogue seems to be far more elaborate than its representation in quotidian proteomics.”
Matthew had little difficulty in cutting through Tang’s excessively pedantic choice of terminology, which inevitably tempted him to an opposite extreme. “You mean that it has more genes than it seems to be using at any one time,” Matthew chipped in. “In other words, the orthodox exon-bank has all kinds of tricks up its sleeve—just the sort of thing that a serial chimera would need.”
Tang didn’t take offence at the crudity of Matthew’s presentation. Indeed, he recognized its propriety with a smile. “That’s one possible interpretation,” he agreed. “But let’s not forget the example of the humble frog.”
Matthew nodded to signify that he took the biochemist’s point. Earthly genomic analyses had shown that the relationship between genomic complexity and physical complexity wasn’t a simple one. In spite of their metamorphic capability, frogs were fairly low down on the complexity scale, but they had very bulky genomes because they maintained several parallel sets of genes for performing such seemingly simple tasks as determining the conditions in which their eggs could hatch. On the other hand, that same flexibility extended to patterns of development in early embryos—which was exactly the kind of versatility that might be an interesting consequence of the relative complexity of Tyrian genomes. “Have you made any progress figuring out what the presently unexpressed genes might be for?” he wanted to know.
“Yesterday, I would have had to say no,” Tang said. “Today …” He paused in order to wave a languid hand at his prize specimen before picking up the story. “It’s not just bigger than the other specimens I’ve seen. The mass-surface area considerations that affect growth and form are universal. It hasn’t got legs, so it doesn’t suffer from the supportive problems that affect so many Earthly animals, but the tentacles pose a similar problem. The muscular strength needed to move them increases geometrically in proportion to their length. That could be accomplished straightforwardly by adding muscular bulk, but it isn’t. The structural materials framing the muscle are different. Either a different set of genes has come into play, or the exons are teaming up according to a different pattern. Ike will suspect the latter, of course, but he’s primed to look for gene-nesting explanations. He and I will have to get together to see if we can fit the proteomics to the genomics.”
“That might help to explain why the local invertebrates don’t use a chitin-analogue