Dr Karl Kruszelnicki (an Australian doctor and scientist) has written a
book called "Pigeon poo, the universe and car paint and other awesome
science moments" (HarperCollins 1996) with a chapter titled "Men's
nipples and breast-feeding". He mentions a herd of male goats that are
regularly milked and Dayak fruit bats from Malaysia (either sex can
lactate) and starving men lactating (their livers were unable to break
down their natural oestrogen). Finally there is a bit about the tribe of
men in Brazil: "According to missionaries of the 16th century, there was
a  tribe in Brazil in wihich the women had 'small and withered breasts
and whose children were brought up from birth by suckling males'." (M.
Howard, Victorian Grotesque, Jupiter Books, London 1977).
Lisa Amir
GP / IBCLC in Melbourne, Australia