The DNA of a dog is 99.9 percent the same as a gray wolf’s, but “half of that minuscule genetic difference is a sophisticated interface for interacting with humans”:
Notably, dogs become attached to people. Wolves – even when raised as cubs in a home – do not. This is true to an extraordinary extent. A dog put in a stressful situation will relax if a familiar human is there, but a familiar dog, even his mother, will make no difference. … Dogs have an ability to read and interpret human faces that is unique among all animals. Their first instinct when faced with a problem is to look to a human for guidance, something wolves do not do. Dogs will also communicate by looking at a human, then at a target object, then back again.
Wolves are not very vocal: they generally reserve howling and barking for long-distance communication with out-of-sight animals. Dogs bark far more frequently than wolves. They do it to communicate aggressiveness, fear, despair, playfulness, and happiness. But, in most cases, dogs do not bark to communicate with each other; they bark to communicate with us.