Another thought to add to the recent discussion of earlier age of
menstruation:  In a May 24, 1994 article, "Mother's Milk Found to Be Potent
Cocktail of Hormones," on page B5 of the N.Y. Times, Natalie Angier
reported on research conducted on breastmilk at the Weizmann Institute of
Science in Rehovoth, Israel.  This research was carried out by Dr. Yitzhak
Koch and colleages, and was reported in the Proceedings of the National
Academy of Sciences.  (Also on 5/24/94, but I have not read that article).
The articles suggest that gonadotropin-releasing hormone may be synthesized
in the breast of nursing rats (and human beings, too) and that "this
hormone influences the development of the newborn's sex organs, forstalling
their maturation until the offspring is ready for reproduction."  The
article goes on to cite other research studies in this area, and concludes,
"...the lack of breast milk theoretically could result in the premature
development of the ovaries, a state that can be dangerous.  Physicians know
that girls who mature sexually at a young age are at an increased risk of
infertility problems and breast and uterine cancer later on.  In developed
nations, the age of first menstruation has dropped significantly over the
last 75 years or so, a phenomenon that many experts have ascribed to the
West's high-calorie, high nutrient diet.  The new studies, however, suggest
that bottle-feeding might also contribute to the early onset of
menstruation..."

This is a long and complicated article, but very clear in pointing out how
complex and how wonderful human milk is, and how little we really know
about it.
Also, how very different it is from cows' milk.

Anne Altshuler, RN, MS, IBCLC and LLL Leader in Madison, WI