Pit Bulls have been genetically bred to attack. This was done by ghetto culture.
I pay a little attention to bears, and something that I have read about black bears versus Grizzlys, that is disturbing, is that black bears are more likely to stay with the attack once it starts, and finish you off.
Harrison Forbes, author of the book Dog Talk told The Globe:
Pit bulls are very strong dogs. They were bred initially to hunt large animals. And for more than 200 years after that, they were bred to be fighters. You can breed certain things out of dogs, too. But that does not happen after just one or two generations. It will take a while, during which time any change will be attributable to responsible dog ownership.
It was also done further back before ghetto culture.