Post is an unfortunate affix that has found itself stuck to the front of a variety of words in the last few years: postindustrial, postsexual, posmodem and so on. So post-human' has to be tried on, after which maybe the whole trend can safely become, so to speak, posthumous, or can be retired like the imitation humans, the androids, in Bladerunner, the first story I shall mention. After a look at Philip K. Dick's black,…