Given the intelligence of parrots and ravens, judging intelligence by size and weight alone must be in early stages.

I spend time with a dog most days in and out of a dog park. She loves balls more than treats, and does a personaity 'flip' when there is a ball about. Meaning, she will get possessive and aggressive to other dogs when there is a ball in her mouth, as opposed to if we are walking her with no balls about, when she is 99% sweetheart.

She loves loves loves chasing the ball, and she makes an effort to throw the ball back, with a flip of her head, not so much to put English on the ball (though I would not put it past her) as to give the ball some linear velocity.

I think that most of us, and I don't think 'scientists' are exceptions, are still putting our prejudices into our experiments. I'm not at all convinced that dogs are less 'intelligent' than wolves. According to BBC Nova, dogs have learned to follow pointing fingers, and our ape cousins have not. Mind you, I can't get Nucknuck to follow my pointing finger to save her canine soul.