From Wikipedia:
the dog will exhibit a smooth transition of response from cowed to angry, depending on how it is provoked. But higher stress levels correspond to moving to the region (a < 0). Then, if the dog starts cowed, it will remain cowed as it is irritated more and more, until it reaches the 'fold' point, when it will suddenly, discontinuously snap through to angry mode. Once in 'angry' mode, it will remain angry, even if the direct irritation parameter is considerably reduced.
Thank you. Unsure if this is true, but very interesting.
More:
Q: What is the history of the pit bull?
The blood sport of “bull baiting” began over 1,000 years ago in England (various sources dispute this date). What is undisputed is that by 1500, bull baiting had progressed to Britain’s national pastime. Bulldogs were reportedly first mentioned by name in 1631, referring to their function rather than a distinct dog breed. By 1800, and through further selective breeding, the bulldog developed into a compact muscular dog characterized by tremendous jaw strength.4
Due to public outrage, bull baiting was banned in England in 1835. Bulldog breeders and owners then moved to the sport of “ratting,” where a number of rats were placed into a pit and wagers were made on how many rats the dog could kill in a certain time period. To increase agility, quickness and prey-drive in the bulldog, ratters crossed the breed with terriers. Essentially, it was the sport of ratting that combined the bulldog and terrier into the modern day pit bull terrier.
On the heels of ratting, dogfighting developed. Pit bulls and dogfighting were exported to America as settlers made their way to the New World. In 1884, the American Kennel Club was formed but rejected pit bulls due to their use in dogfighting. In response, Chauncey Z. Bennett formed the United Kennel Club in 1898 to bring formal recognition to the pit bull breed. At that time, Bennett also drew up rules and regulations for dogfighting to bring “organization” to the blood sport.
https://www.dogsbite.org/dangerous-dogs-pit-bull-faq.php#dogfighting
True