I agree that the term "loyal" is what we appear to be seeing, based on human perceptions more than what the dog's motives are. I think because it's always been, from an evolutionary stand point, advantageous for dogs to stick around close to humans, they are just hard wired to hang close, some more than others.
I do think certain breeds tend to be more "stick-around-close" types, due to selective breeding. Shepherding, guarding and other types are very often, particularly this way and I think it's an individual thing too. Domestic dogs, by their very nature are going to tend, to some degree or another, to feel bonded and sociable to their human family.
I don't say that it is not caused by love. I do think dogs love us too, besides instinctively knowing that they'll thrive better when they bond to humans. But the term, "loyalty" suggests a deeper, much more complex connotation that humans are capable of deciphering. I don't think dogs have all the complex emotional associations that word denotes, going all around through their brains. Loyalty to me, infers that the possessor has a feeling or sense of duty or a moral obligation to allegence....a moral devotion. I know dogs love. And I know they are genetically programmed to depend on us to thrive. But, I think they love in a more simple way than the word, "loyal" suggests.
