There’s a reason why dog are called “man’s best friend.” The good friendship that we have with dogs is thousands of years old and, as with most good friendship, was formed by mutual benefit. Dogs are of great value to people because they use their keen senses to detect threats and alert their owners by barking. You may find your dog’s yapping to be quite annoying, but under some circumstances it can be quite helpful. But people are of great value to dogs too. Dogs that live with people usually have easier access to food and a safer place to stay than they would on their own, and that truly is what friends are for.