I just found out that the Bradshaw Foundation, which specializes in rock art, has a podcast. Some audio, some video. Here's the link:
Just watching the video on the Bushmen (called San here - I think that's the name some of the Bantu-speaking people give them not one they use themselves, but anyway ...) They mention David Lewis-Williams who showed, pretty inarguably, I think, that there's a connection between rock art and altered states of consciousness:
Here's the main Bradshaw Foundation website:
The flash animation of "the peopling of the world" in the "Journey of Mankind" section, based on Stephen Oppenheimer's genetic research and a lot of archaeology and climatology is really good.