Studies show dogs in some areas are now showing signs of becoming more like a scavenger and less like a pack animal. This is due largely to the impact humans have on the species. Dogs are being left behind, mistreated, and abused. Humans tend to force a dog to understand them rather than the humans taking the time to learn how to speak dog. As a trainer I can tell you there is a great percentage of dogs that don't fit in the usual methods of dog training. Adversive techniques are causing problems and leading to the misdiagnosis of dogs. Rescues unknowingly are missing opportunities to help dogs merely because they misinterpret what they see. It is the dog psychology side of the equation that humans are failing.
Thus a change.
Remember that each dog is an individual, and must be treated as such. You'll come across dogs more often these days that don't fit into our categories, or whose language is different. Because the dog's language is developed through experience, human contact, training, and other variables, the results can be wide ranging.