From the dawn of Man's Age to the present time,

we have forged a relationship with the dog

.Mondo wolfwolf pack

It is believed that Wolves and Prehistoric man somehow developed a relationship somewhere around 15,000 years ago. It is unknown which animal initiated the relationship, (wolf or man?) as we were both nothing more than animals at that time. But somehow the relationship was forged and man and wolf became more than tolerant of each others presence, they became working partners. We like to believe that man being a hunter gatherer at that time initiated the relationship, seeing a benefit in having a wolf as a companion, but this is purely speculation.

Being an intelligent species Man began to selectively breed the wolf to exhibit characteristics that man wanted. They bred for more "tame" animals that would transfer their wild pack instincts to including the family of man as his pack and relinquishing his leadership to man.

Wolves were bred for specific purposes such as guarding hearth and home, herding livestock, retrieving kills from the hunt, and more. Somewhere along the line man realized that the wolf was, in many ways, far more cunning than he was. In order to maintain the leadership role, he would have to breed for less intelligence and basically "lock his dogs in puppy hood".
As evidence to this, Adult Dogs play, Adult Wolves hunt but do not play. In a wolf pack it is only the puppies that play.
Over the generations, man has continued the selective breeding of dogs for various types, as a result we have the wide variety of sizes and breeds of dogs known today.
Here the world's tallest dog meets the world's smallest dog