I can believe humans are getting dumber, being a bit of a mong is no barrier to living to a ripe old age and passing on your mong genes nowadays.
I don't think a dumb cro-magnon would have been too successful in the longevity stakes..
You could be right there Rob...
Not dumber in the way we measure intelligence today - but perhaps less connected with our environment could explain a large part of it.
Religion has something to do with it too, just look at many of those who follow a religion, solid ivory from the eyebrows up!