How did this:
Answer: very faint artwork "enhanced" by people with chalk trying to see what they want to see instead of what's there. Check out the story and look at more photos to see how people can deceive themselves into believing weird things...
Personally, I think the newly distinguished figures are much more interesting. What is that snake thing, anyway? And is that a guy using a dog to round up a goat? What stories are being told here?