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last night i read michael crichton's prey. actually, that's not true - i started reading it, quickly became bored/annoyed, skipped through to the action scenes and then skimmed backwards to try and piece together the technical justifications for the plot. so what follows may be completely wrong...

the plot revolves around a nanotech lab that has leaked machines into the environment. these machines "evolve" into deadly, intelligent, killing systems. the writing is fine (it's not noticeably bad, like some science fiction, for example) and a fair amount of science is cited in the footnotes and text. i suspect much of this citation is a device to make the story feel more real, although there's a preachy introduction that suggests crichton believes he is making a serious point about the dangers of nanotech.

i don't doubt the dangers of nanotech - i describe the details above because they sit uncomfortably with the way evolution is used in the text. with the qualifications above about my not having read the whole novel, evolution is treated as if it is some universal process that will improve the design of everything without question. the treatment of intelligence is also suspect, although less central to the plot.

one reference is used to justify the rapid evolution of the nanotech. it describes how cholera can spread in different ways - if water sanitation is bad then a virulent strain spreads quickly because it causes sever diarrhea, otherwise a more mild strain is selected which kills people more slowly, and is passed on by contact with the living. that's a nice example (although it may raise the philosophical question of whether it is really evolution if both strains already exist - perhaps they didn't; you'd have to read the paper). however, for the process to work, the virulent cholera must die when there is good sanitation. if diarrhea were good at spreading the disease even with good santitation, then there would be no change in how the disease spreads.

evolution, then, is not just survival of the fittest, but also extinction of the less fit. nothing i could find in this novel described how, for example, more stupid nanotech were being killed. and if nothing was killing the stupid 'bots, why would there be selection for intelligence?

that is one problem with the treatment of evolution. another is the absence of a process for influencing the development of offspring.

if, somehow, there is a source of selection pressure - something that does kill the more stupid machines - then what makes the next generation smarter too? in animals, gene inheritance provides the key - the intelligence is inherited. more precisely a range of intelligences exist because of (random) genetic mutation. adults with genes that make them more intelligent are more likely to survive and have children with the same (intelligence enhancing) genes.

the nanobots in this story, however, are created on a microscopic assembly line. they are buily by "assemblers", which are themselves nanotech (i think - presumably slightly less so?). there are no children. the situation isn't that different to hoping that car crashes will somehow stop less safe car designs from being produced - there's nothing to stop the factory from producing unsafe cars, even if they crash withint a few minutes of leaving the production line.

without those two critical components, it is hard to see how the nanotech can evolve. without evolution you get a much less exciting novel (which may explain these errors - crichton may have chosen to sacrifice accuracy for art). the more likely outcome of misguided nanotech is the stupid destructiveness of "grey goo".

(one possible escape route is the evolution of ideas - memes - which uses selection through intelligence rather than death. whether this is justified depends on the treatment of intelligence in the swarm of machines - something that is barely touched on in the text. i found only a conversation in which "memory" switches to "intelligence" without any intervening logic and various invocations of the vague idea of "emergence". if only it were that easy.)