I'm sort of a Bear fan myself. Something tied into evolution but a little more far fetched is
Blood Music. White blood cells are given intelligence and madness ensues.
For the physicists on this site, you might also like Bear's
Eon and the sequel
Infinity (I think thats the right sequel anyway). Has to do with alternate universes and the warping of space time, something I see talked about quite often around here. There is a conservative faction in the story who call themselves Naderites, after the great Ralph Nader of all things. Got a chuckle out of that one.