This quote was from this article (in regards to an alpha role), has other info as well. It's up to the reader to decide their view on the subject manner. I agree with the quote.
"Closer observations of wolves over the last 40 years have shown that this infamous behavior is an act of submission, not dominance. A wolf voluntarily rolls on its back in a subordinate display. No contact is made, thus avoiding dangerous physical conflict"
http://4pawsu.com/dogpsychology.htm
I posted this article on another thread.