Our Oldest CompanionsHow did the dog become man's best friend? A celebrated anthropologist unearths the mysterious origins of the unique partnership that rewrote the history of both species. Dogs and humans have been inseparable for more than 40,000 years. The relationship has proved to be a pivotal development in our evolutionary history. The same is also true for our canine friends; our connection with them has had much to do with their essential nature and survival.