For me memes can work like genes when there is good enough copying. This restricts them to simple mechanical and expressive functions.

The mechanisms are getting to be well understood, mirror neurons and young comparatively unwired (neotenous!) brains as recipients.

My monthly Victoria Horner Link.

Memes restricted to simple mechanical and expressive tasks can lay down a huge substrate of behaviours that may well facilitate more complex cultural idea acquisition.

The meme idea itself, however, evaporates with much more "idea" sophistication due mainly to the very high error rate in the copying mechanism and the lack of a robust container. Thats not to say that copying doesn't go on. It clearly does. But the clarity of the process recedes much as it would in the transition from cell wrapped DNA packets to RNA World soup.