Just watched a few documentaries about cave paintings. While I acknowledge the importance of discovery, I can't help but question one simple thing - why are there so few paintings in those caves? Paintings ranging from 40K to 20K years old, placed a few feet apart. Does this mean the cave was occupied by countless generations of people, who all kept on painting? Shouldn't literally every inch of the wall surface be covered in paintings after that many years? Even if one person discovered how to paint say "negative hands", wouldn't that person paint hundreds of them all over the place, considering that painting must have been among the few available free time activities?