The story of how the canine brain developed is also a story of the minds of humankind at the time. If humans and wolves had not come to an understanding tens of thousands of years ago, the tameness and friendliness that separates Fido from his fanged cousins might not have developed. The changes that the canine brain has endured over the years has laid the groundwork for a bond that transcends other species. (The phrase man's best friend developed for a reason.) Humans have played a decisive role in the evolution of dogs, and these wolf descendants have worked their way into our hearts and been woven into the fabric of human society.