Book excerpt: Mankind's relationship with the dog can be traced back for thousands of years. Indeed, the dog is probably our oldest non-human companion. Excavations of Middle Eastern fossils, believed to be at least 12,000 years old. Interestingly, for an animal that has been so important to us for so very long, there is uncertainty as to the exact way in which domestication of the dog occurred. We cannot even be absolutely sure of the evolutionary route by which the dog itself came about- although most experts are in agreement that the wolf is the most probable ancestor. This guide explores in more detail the most likely theories of dog evolution. It also explores some of the ways in which the dog may have begun to befriend humans.