Ah! That's the 64 thousand dollar question! However, the other two articles, and when I have time to dig up more, should present some interesting tidbits. Think "sympathetic magic." Most interesting to me, is where the caves showed footprints, there were plenty in the living space as would be expected, but few footprints that led deep into the trance inducing sensory depriving recesses where the cave art was typically found.