I read a book by Temple Grandin: Animals Make Us Human.
In it she notes that Pitbulls, once called Nanny Dogs, were bred to fight other animals, but not people. Over the last 10 years or so, owners have been selectively breeding for a wariness and readiness to attack people.
I don’t trust them.
Very few people are breeding them to be human-aggressive. The mere fact that out of 5 to 10 million pit bull-type dogs, an infinitesimally small percentage attack people. There are thousands of idiot owners that get them and encourage vicious behavior, only to be disappointed by their inherently trusting, friendly nature. It’s an interesting phenomenon occurring, that dogs being purposely bred for certain attributes simply aren’t being born with them. The dogs just don’t have that in their makeup, and the ones that are attacking seem to be doing so because of gross negligence and mistreatment on the owner’s part, as is noted in the above article, and on the CDC’s study.