Ask A Scientist© Biology Archive

Author:      damian
Text:        Why do Human males have nipples?
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It is probably easier for the body to produce nipples in men than 
to eliminate them.  Nipples in men have the same potential as nipples in 
women.  The difference is basically hormones, men can have nipples like women 
if they have certain hormonal problems (or takes certain medicines).
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Up-date: 3/8/2005
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I think that is basically correct.  Here is some background:  for the first
6-8 weeks of development, the fetus has the capacity to develop into either
a girl or a boy (or both).

If not influenced by hormones in the womb, the fetus will turn into a girl
and certain male characteristics will be lost.  If influenced by hormones in
the womb, the fetus will turn into a boy and certain female characteristics
will be lost.  Nipples are formed in an early stage and thus everyone
initially has them.

They are useful on adult females and so they are kept as a girl develops.
They apparently do no harm on adult males, and the body makes no effort to
get rid of them as a boy develops.   Males also have rudimentary breast
tissue, and also have milk ducts.

And don't think that nipples are limited to only two per person.  Sometimes
humans have several sets too!  (the extra ones are small).

B Erck
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