"Louisville artist Matt Gatton started thinking of primitive people hunkering inside caves and arrived at a radical, quite possibly revolutionary and insistently plausible theory of the origin of representational art.
It struck Gatton, a St. Francis High School art teacher, that the question of how Paleolithic people got the notion to create representational art could be answered by their living conditions. Holes in the animal hides that covered their dwellings could have projected images from outside -- a phenomenon of physics we now call camera obscura. The people could then have traced the images onto their cave walls."
Camera Obscura and Paleolithic Drawings