bradhicks in this post links the rise of a particular type of horror plot, characterised by surviving by abandoning increasing number of your friends to their fates, with the horror of late capitalism (he says Reaganomics, I'd say Thatcherism, same diff). He argues, convincingly that the excellent horror 'novel' World War Z takes the argument a step further.Meanwhile John Barnes (not the footballer/dancer) has written an essay on 'why SF is finished as a genre'. Now, I don't agree with his conclusion, but I think he's really onto something about what brings a genre into being and sustains it as a creative force.
A genre is forced into existence by a vacuum in the art of a society, which is failing to give expression to some important aspect of that society.
At some time, just prior to the formation of the genre, there is some sort of hole in the culture, some subject the culture can't think about well, or reconcile itself to. It might be rhythm and exuberant sexuality (as with rock'n'roll). It might be the plain feelings of ordinary people, unmediated by formal analysis and classical references (as with the early Romantic poets). It doesn't matter what it is nearly as much as it matters that somewhere, there's something culturally important that the culture doesn't have a way to talk about.
A few artists produce works with a shared set of tropes that plug that hole, perhaps not completely satisfactorily. The people who feel that hole most acutely are drawn to the new solution, and they pull others with them... and as more people find that this stuff is good, and that it has something to do with what interests them, the audience grows.
I think this is bang on.
The Marxist in me would say it's when that silent need is empowered by economic strength - the increased spending power of the young or the middle classes in the two cases he gives - that the genre is able to come into existence.
Needless to say I think fanfiction and fan video are two such genres (or one genre perhaps) empowered by the access of women to the media of creation and dissemination. Heh - the means of production.
