It Self Handicapping News Today

>> reporter: researcher mark beckoff who spent years analyzing dogs play, every nip, wag and bark in slow motion says theres more going on. he says hes discovered dogs share with us a sense of fairness and might even know right from wrong. >> you can say theyre just playing. but, boy, they are rapidly exchanging signals. >> reporter: watch as this great dane invites a dog half its size to play. this move is called a play bow. it means i want to be your friend. >> there is no doubt about it. okay...