Ask 10 people what makes a pit bull a pit bull, and you're apt to get as many different answers. (Or, simply, "I know pit when I see pit.") Take a peek under the pit bull umbrella, and you can find English bulldogs frolicking with bull terriers, American Staffordshire terriers and Bullmastiff-hound mixes.
There's plenty of regional variation, too, regarding what characteristics make a pit bull. Even canine experts have different definitions, as Christy Hoffman, a professor at Canisus College in Buffalo, N.Y., found firsthand. Hoffman was flipping through pictures of shelter dogs on her phone - "Here's a pit bull, here's a pit bull" - when her colleague Carri Westgarth, a scientist at the University of Liverpool, remarked that in the U.K., none of those pups would be considered pits.
Their scientific interest piqued, Hoffman, Westgarth and fellow researchers set out to determine the way animal shelter workers label certain dogs. The scientists found a significant regional difference between the U.S. and the U.K., with so-called Breed Specific Legislation, or BSL, playing a role. The U.K., as well as parts of the U.S., have laws that prohibit - or at least make it much harder to own - certain types of dogs. Under the U.K.'s 1991 Dangerous Dogs Act, for example, dogs with a set number of "pit bull type" physical characteristics are outlawed.