Steve -- perhaps you could look at the discussion at
http://babysafari.us/main-1_000003/ (Default Options) and expand on your comment which is posted there (at the end). A couple of references (and your last name) would be very helpful. My email address is snowwater3@netzero.com. Also your comments about why human babies are fat at
http://babysafari.us/main-1_000011/ would be very welcome. Many thanks. Frank Hodgson