Archaeologists and historians are very proud of and fascinated by the wonderful cave paintings early man made of animals, hunting scenes, etc. They're not so proud, apparently, that early man painted pornographic scenes of orgies on some cave walls as well. I heard one scientist say they were "disappointed" in our early ancestors for painting such things.
But if they think they're disappointed, imagine how the likely cave-adolescent artist's parents felt when they first saw those paintings. The caveman father probably said: "Mother disappointed you paint sex scene on wall. Why you do? You no go on hunt. You stay in cave and think about what you do to disappoint mother!" And then he probably just painted more.
