Which Part of the Brain Controls Stupidity?

I was reading a book on brain plasticity the other day. It seemed to make a good deal of sense and not just because my own brain is so plastic it practically dribbles out my ears. Rather than "a place for everything and everything in its place" which was the traditional view of how the brain functions it would appear that our grey matter is highly flexible and, at least to a certain extent, capable of re engineering itself in response to damage or changing circumstances. I am awesomely impressed with how clever our brains are. Which makes me wonder; why are we so stupid? Why is it that the same brain that can reorganise itself in response to quite serious damage still can't stop us from falling for Nigerian bank scams? Perhaps slightly more topically, how did our brilliant, flexible brain ever think that sub prime mortgages were a good idea?

It really does seem that humans are a strange combination of genius and idiocy, not just collectively but within individuals as well. I am considered reasonably intelligent (by myself at any rate) but I can barely change a light bulb without killing myself. I have also recently been informed that I have been doing it wrong. This is one of those areas where it is convenient to believe in God. When faced with such a question the believer can wax lyrical about the infinite majesty of God's creation without stopping consider why some of this creation, no matter how infinitely majestic, is so bloody stupid.

Those of us who don't possess a belief system and are to lazy to go out and get one (I'm waiting for them to become available on eBay) are reduced to simply keeping score. So far we appear to be clever enough to get away with all of the stupid things we insist on doing, collectively if not individually. It will be interesting to see what happens if that changes. Although personally I recommend viewing the results from a different planet.