I personally attribute nipple pulling to a baby's curiosity about his/her new
world and exploration with the mouth.  I noticed that my 5 month old goes
through "phases" during which she seems to be playing with the nipple just for
purposes of figuring out what it's all about.  I don't know if it does
anything to encourage milk flow, but I don't worry about it much.  It's not
causing any damage.

Early solids: I think this dilemma would solve itself if we were not bombarded
by baby food marketing in every magazine and on TV.

Nat'l Geographic article response:  Well said, Kathleen!  You go, girl!