Male lactation
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The phenomenon of male lactation in humans has become more common in recent years due to the use of medications that stimulate a man's mammary glands. Though boys and men have nipples, many are unaware that they also have mammary glands. In ordinary circumstances, there is so little mammary tissue that it is unnoticeable; if the male breasts develop visibly, the condition is called gynecomastia. Though the mammary glands of human males cannot produce milk under natural conditions, with appropriate hormonal stimulus—mimicking that which human females produce naturally when they become pregnant and give birth—they can.[1] Newborn baby boys (and girls) can occasionally produce milk because of the intense hormones involved in their mother's pregnancy and the hours of childbirth; this is called witch's milk.
Male lactation was of some interest to Charles Darwin, who commented on it in The Descent of Man, and Selection in Relation to Sex (1871). Darwin noted that "It is well known that in the males of all mammals, including man, rudimentary mammae exist. These in several instances have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sexes is likewise shewn by their occasional sympathetic enlargement in both during an attack of the measles."[2] He later considered the nearly perfect function of male nipples in contrast to greatly reduced structures such as the vesicula prostatica, speculating that both sexes may have nursed young in early mammalian ancestors, and subsequently mammals evolved to inactivate them in males at an early age.[3]
The phenomenon of male lactation occurs in some other species, notably the Dayak fruit bat (Dyacopterus spadiceus), and the lactating males may assist in the nursing of their infants. In addition, male goats are known to lactate on occasion.[4]
[edit] In humans
Male lactation may be caused by hormonal treatments given to men suffering from prostate cancer. Female hormones are used to slow the production of cancerous prostate tissue, but the same hormones also stimulate the mammary glands. Male-to-female transsexuals may also produce milk owing to the hormones they take to reshape their bodies. It can occasionally be a side-effect of antipsychotic medication. Extreme stress combined with demanding physical activity and a shortage of food has also been known to cause male lactation. The phenomenon occurred in survivors of the liberated Nazi concentration camps after World War II.[1] Some American POWs returning from the Korean and Vietnam Wars also experienced male lactation. The phenomenon has also been observed in isolated cases in other parts of the world.[5]
In Why Is Sex Fun?, Jared Diamond reports of male and female cancer patients being treated with estrogen who proceeded to lactate when injected with prolactin, and suggests that mechanical stimulation of male breasts, by releasing prolactin, could result in lactation.[6]
Cases have been reported of men breast-feeding babies.[1]
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[edit] References
[edit] Notes
- ^ a b Jared Diamond (February 1995). "Father's milk - male mammals' potential for lactation". Discover. http://web.archive.org.nyud.net/web/20040909091015/http://www.findarticles.com/p/articles/mi_m1511/is_n2_v16/ai_16051177.
- ^ Descent of Man, Chapter I
- ^ Descent of Man, Chapter VI
- ^ Gómez MA, Garcés-Abadías B, Muñoz A, Vásquez F, Serrano J, Bernabé A (1999). "Structural and Ultrastructural Study of GH, PRL and SMT Cells in Male Goat by Immunocytochemical Methods". Cells Tissues Organs 165: 22–29. doi:.
- ^ Nikhil Swaminathan (2007-09-06). "Strange but True: Males Can Lactate". Scientific American. http://www.sciam.com/article.cfm?id=strange-but-true-males-can-lactate&sc=rss. Retrieved on 2008-05-27.
- ^ Jared Diamond (2006). Why is Sex Fun? The Evolution of Human Sexuality. New York: Basic Books. ISBN 0-465-03126-9.
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[edit] Sources
- Angier, Natalie; New York Times, February 24, 1994. Cr. J. Covey.
- Francis, Charles M., et al.; "Lactation in Male Fruit Bats," Nature, 367:691, 1994.
- Fackelmann, K.A.; Science News, 145:148, 1994.
- Anomalies and Curiosities of Medicine G.M. Gould and W.L. Pyle
