I was fortunate in 2013 to visit cave painting sites in SW France and NE Spain. It is a moving experience to see images made tens of thousands of years ago, es

I was fortunate in 2013 to visit cave painting sites in SW France and NE Spain. It is a moving experience to see images made tens of thousands of years ago, especially the "negative hand" pictures made by holding a hand up to a wall and blowing pigment across it, leaving a hand-shaped hole in the stain on the wall. One cave had dozens, from adults and children, in one spot. The Nat'l Geo article doesn't mention a glyph that is common in the caves: the "tectiform", which looks a bit like a sign for a picnic shelter in a state park. It shows up in many caves and some people think that it may have been a tribal identifer.