I had heard that dogs may have been domesticated as a food animal at some point, which is a somewhat dark tale for the modern dog lover. This Independent article says new evidence tells a different story. First, Siberian wolves started sniffing around garbage in human settlements during the ice age. Then, they settled in. Although it might seem like humans would feel threatened by wolves in their midst, they may actually have helped defend the human settlements against other animals, including other wolves. (You can imagine there might have been a few misunderstandings early on where hungry wolves ate people and vice versa.) And then, because they are so smart, a specific pack of wolves would pass behaviors down from generation to generation, and in just a few generations you would have a population with distinct behavior and over time even a distinct appearance. At some point, humans did start training and breeding them to perform specific tasks, like pulling sleds.