David Barash, a psychologist at U of Washington, poses the fundamental question posed by Intelligent Design theories: if the universe is so well-designed, why are human bodies such a mess? We have bad backs, weak knees, prostates that have older men leaning against a wall for half an hour trying to take a leak, and birth canals routed through skeletal structures barely (and often not even barely) wide enough to fit a baby through. In his words:

…these and other incongruities testify to the contingent, unplanned, entirely natural nature of natural selection. We are profoundly imperfect, cobbled together rather then designed. And in these imperfections reside some of the best arguments for our equally profound natural-ness.