Is There a Meme Propagation?

The correct to source type is, uh, at least intending to be static. And what will happen is that it will evolve to suit it. It's still under fitness pressures and the fitness pressures that it is under are do more people propagate it and do they propagate it the same way? So if you've got one chain letter that says forward this to 10 of your friends and you've got another chain letter that say forward this to ten of your friends or you will be visited by the unlucky spirit of doom. If the second one causes more people to forward it, well, that's going to be the version that gets forward.