Like human babies, wolf pups have big eyes and large heads, are playful and highly sociable. This nurturing behavior flooded us with gentling chemicals that assisted in developing our humanity and compassion for little things, and contributed to our domestication. Wild animals stay playful for a very short time after birth. One moment they are tumbling and silly, the next their fangs are bared and lunch becomes their focus. This is a result of chemicals in the brain which are solely for the flight or fight response.
Fear ensures alertness to seek safety from prey, and aggression and is necessary to grab dinner.
In time, what we call domestication of animals results. They never pass through the playful stage because the actual physical makeup of their brains is altered and wolves remained eternal children. They have been changed by breeding combinations and ever-deepening socialization. The result is Fido and Fifi. They are not only tamed but are domesticated and quite helpless to fend for themselves and are still willing to live alongside us whether it be a fifth avenue condo or the family farmyard.