... dogs are really neotenous wolves.  Man likes his 'best
   friend' to be playful and so he breeds more and more juvenile dogs.
   A fully grown domestic dog still leaps and bounds and plays with 
   his master like a young wolf cub.  But wolf cubs grow up and stop
   playing.  Young dogs grow up, too, but like man they remain infantile
   in their behaviour--they never stop playing.  This means that they
   will respond to man as if he is a parent.  The dog's owner becomes
   the dog's dominant father-figure, or mother-figure.  Being neotenous,
   the dog can mate and breed, but it still responds to parental 
   domination and obeys its master.  This makes it the perfect pet.
   To the dog, in other words, man is a god.

-- Desmond Morris, _Manwatching: A Field Guide to Human Behaviour_