Diffusion of Dogs
Research shows that ancient American dogs were more similar to dogs from the Old World than to the gray wolves found in North America. This implies that when nomadic hunter-gatherers migrated across the Bering Strait (the land) from Asia into North America, at least 12–14,000 years ago, they already had dogs with them. The diversity observed in the ancient American dogs indicates that multiple types of dogs were taken in to the New World. Before the voyage of Christopher Columbus in 1492, societies in the Americas were largely untouched by outside influences, and unlike the early societies on which Western culture is based, did not possess domesticated goats, sheep, cattle, pigs, or horses. Dogs were the only domestic animals present in the majority of Native American groups, the only animal allied with humans.
The summary of that research is that many thousands of years ago, somewhere in western Eurasia, humans domesticated grey wolves. The same thing happened far away in the east. At this time, there were two geographically separated groups of dogs, the Ancient Western and Ancient Eastern. Around the Bronze Age, some of the Ancient Eastern dogs migrated westward alongside their human partners, creating the deep split in the DNA tree. Today’s eastern dogs are the descendants of the Ancient Eastern ones. But today’s western dogs trace back to the Ancient Eastern migrants. Less than 10 percent comes from the Ancient Western dogs, which have since gone extinct. This means that different dogs all over the world are either descendants of the Ancient Eastern dogs or the dogs that migrated. Whichever the case, domestication of dogs diffused through relocation diffusion of people.