Petroglyphs- Rock Art, Ancient Graffiti or Something Sacred?

We have had the pleasure of seeing lots and lots of petroglyphs on this south west journey we are on. These ancient artwork symbols adorn rocks for hundreds of miles, and many of them are 700 or more years old. Some of the best were at Saguaro National Park. We also went to Petroglyph National Monument, and those were nice too, but honestly, the place didn't have the magic. That's probably because there is now a subdivision of big look alike houses that comes practically right up to the chain link fence around the monument. When we climbed the hill trail, and looked out beyond the petroglyphs, what we saw was suburbia encroaching on a large scale.
At Saguaro, we looked out and saw nothing but desert and mountains and cacti, and you could just imagine the people who were once there. It was much more conducive to contemplating the messages that these ancient people might have been sending than a housing tract. I am glad that they did at least fence in Petroglyph National Monument, and that they are preserving it, but still, we all wished they could have sprung for a little more land around it. I guess budgets affect everything.

In any case, Boy Child had lots of questions on the meanings of these drawings. Were they just art or were they messages? Were they ancient graffiti artists? Why do we see the same images in so many places? Do they have a sacred meaning? Will anthropologists someday in the future be mystified by the graffiti of today when they uncover crumbling bridges and walls in cities of our time? We all got a kick out of that idea.

Boy Child also spent some time making petroglyphs of his own (not in the National Park or anywhere near the ancient ones of course, just at our campsite and on random rocks.)

No one really has an answer to his questions, but in any case, these ancient drawings were pretty cool to look at and ponder the what and why they are still there.