Dogs are quadrupedal and built for speed. Their tails are relatively short, but very important in communication. The creature's jaws contain specialized teeth, with differentiated incisors, canines and molars enabling them to effectively process the meat of their kill. Through domestication, many different breeds of dogs have been created by humans in a process of selective breeding, varying greatly in size and appearance. Some breeds have extremely short tails and jaws, or a short and stubby build that greatly deviates from the original wild dogs, which were slender and strong runners.