The Term "Pit Bull" Is Not a Breed
Historically, "pit bull" was an informal and slang term that was used to describe any dog that was used for the cruel sport of bull-baiting - using dogs (of any breed) to seize tethered animals such as bulls within an enclosed area called a "pit" (thus the term "pit bull"). While many different breeds and mixes were used for this "sport", dogs that resemble today's bully breeds were commonly used and it was not a sport limited to today's "pitbull-type" breeds. In other words, "pit bull" was more of a term used to describe any dog that was used for bull-baiting and less of a term used to describe a specific breed or type of dog (technically, if a Husky had been used for baiting a bull in a "pit" it would have been considered a "pit bull" back then). Furthermore, baiting is not an inherent trait for any breed, it's an activity that must be taught and honed, no different than training a dog to sit or fetch.