The biological origin section doesn't mention it, but part of the reason the dog could make that big evolutionary leap so fast - and it works with foxes too, and probably other species - is a phenomenon called neoteny. Deferred maturation, basically - the dog has more puppy in it, than its wild relatives. You can see that in the physical features, behavior, etc. Suppress maturation a little, and you get a whole bunch of traits that help with domestication.
There's plenty of reason to think the same applies to humans, neoteny is part of our evolution.