Cave Painting to Graffiti: Covered in One Blog Post

"Tracing the Roots of Modern Street-Art and Graffiti"
WebUrbanist (April 22, 2009)

"Since before the Italians had the word 'Graffiti,' and in fact, before there were any Italians, people have been leaving their marks on walls. These people weren’t viewed as criminals, nor were they likely seen as artists, but they could be hailed as forebears of modern journalism. Before there was recorded history, there were recorded events, and recorded moments. As culture has evolved over the millenia, so has art, and what we leave behind tells a story for those who follow...."
Cave Painting to Graffiti
This is a pretty good (and extremely quick) look at the last several thousand years of humanity's wall art. The text is informative and the photos (I think) well chosen.

On the other hand, the writer has a very definite point of view. Nothing wrong with that: but it's something to keep in mind while reading the post.

"...It wasn't until the dawn of the Age of Reason that art finally began to manifest the highest of human culture...." I have a high regard for logic and reason, and I think that the Euro-American culture of the last five centuries has contributed to the world's storehouse of knowledge and art. But I'm not Eurocentric enough to claim that the Age of Reason led to "the highest of human culture."

Still, it's a good read.