Cave drawings or cave paintings are drawings found from pre-historic
times on the walls and ceilings of caves. One theory is that they were
a way of transmitting information; another is that they had spiritual
or ceremonial meaning and were part of religious or hunting mythology.
In primitive tribes life was hard and work was constant - nobody had
time to sit and draw on a cave wall for nothing. You'd have to find
the time, get a light source, and mix the colors from natural
ingredients. It wasn't done just for fun - it almost certainly had
something to do with hunting magic.http://teachers.net/gazette/JUN09/
newlin/

Were ancient cave painters "pre-historic taggers"? Are graffiti
artists today "Urban Cave Painters" or are they just immature teens
from overly strict families with a repressed need to draw on walls?
Some claim that graffiti is good art which, if properly appreciated
and used correctly, can have some benefit.

The above is from artist and online drawing tool creator Tim Newlin's
latest article, worthy of reading and sharing.
http://teachers.net/gazette/JUN09/newlin/