The story of how a popular breed of dog became the most demonized and supposedly the most dangerous of dogs -- and what role humans have played in the transformation. When Bronwen Dickey brought her new dog home, she saw no traces of the infamous viciousness in her affectionate, timid pit bull. Which made her wonder: How had the breed -- beloved by Teddy Roosevelt, Helen Keller, and Hollywood's "Little Rascals" -- come to be known as a brutal fighter?...