Among the most popular posts on Green Comet is the Cave Art series, parts One, Two and Three. They make a nice summary of the state of the discipline for anyone with a casual interest. A good way to get a sense of what is out there in the way of cave paintings and rock art in general. On Scienceblogs I found a post by Greg Laden that goes into it in more depth, with emphasis on when and where our human ancestors began to produce it. From his post, How are art and human evolution related:
“Art is almost certainly important and has a place on (the) list of things to consider when wondering about the evolution of our species.” – Greg Laden
Laden does a good job of exploring the subject and makes useful suggestions for further thought and exploration. If you enjoyed the Cave Art series, I recommend furthering your education with his blog post.