Art begins in prehistory, which is merely the history of humankind before recorded history. This is the time of the hypothesized cavemen. One of the reasons historians have theorized about cavemen is the presence of so much ancient art within caves like Lascaux, France and Alta Mira, Spain (just to name a couple). It is clear that caves were prevalently used as shelters during this time, although the existence of actual "cavemen" (the only half-developed ape-like Homo sapiens which evolutionists frequently fantasize about) is quite a stretch, to put it mildly, as is most, if not all, of the doctrines of the Theory of Evolution. But you all know this already.
Prehistory is divided into two epochs: Paleolithic and Neolithic. The first of these two is further divided into three phases: Lower, Middle, and Upper Paleolithic (upper being the most recent, and lower being the oldest—it is so named based on the depth from which archaeologists have unearthed the findings). Paleolithic and Neolithic history is often sometimes nicknamed the Stone Age due to the frequent usage of stone for tools, weapons, shelters, etc., and lithos in fact means "stone." Scientists estimate the Paleolithic period around 30,000 to 10,000B.C. Obviously there is not too much known about this period of history, but we can gain clues from artifacts and pictographs that have remained preserved. In my opinion, this would have to be post-Flood, as it is unlikely this art could have remained so well preserved during such an apocalyptic, worldwide catastrophe.
Pictographs are paintings on rocks; and petroglyphs are carvings. Again, this is believed to be before any written language had developed, so no words or symbols of any sort of language can be found on these cave walls—only images. I believe language had to have existed then, according to the Bible, since Genesis describes Adam conversing with God first and then Eve, and Cain and Abel speaking to each other; but this does not necessarily mean that written language existed. So, shall we say that it is not beyond possibility that the first written or inscribed intelligible symbols were images? I think that would be pretty cool.
While petroglyphs were carved onto the surface of the cave wall using sharpened tools, pictographs were made with paint. The paint was made from minerals suspended in water, and it was applied to rock surfaces by either brush or blow tubes. We know this because oftentimes the artists' tools were found left at the site. These drawings and drawing tools are generally located in the furthest ends of the caves, where the effects of weather could not destroy them. It also says a lot about how these people may have valued this art; it was not just carelessly placed at an entranceway, but rather deep inside the earth, hidden like buried treasure.