Morbid Fascination

Last night, I stayed up past midnight reading the end of a book called "The Usual Rules." It's the story of a 13 year old girl whose mother worked in the Twin Towers and never came home after September 11. It was a wretched, heart-rending story that wasn't even all that well written, but I couldn't put it down as I got to the end. Then, this morning, I was listening to a traffic update on the radio, and they were talking about the backup due to onlookers was worse than the backup in the actual lanes effected by the wreck. And, finally, as I drove to work, the d.j.'s I was listening to made an analogy of something awful happening that they couldn't turn away from and likened it to a train wreck. What is this morbid fascination we have with all things wretched? Why can't we just put the book down, turn the channel, or keep driving when we come across something terrible? Just curious.