lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The proces ...
) from a male mammal's
mammary gland
A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in ...
Bismarck masked flying fox
The Bismarck masked flying fox (''Pteropus capistratus'') is a species of flying fox in the family Pteropodidae found in Papua New Guinea and named after the Bismarck Archipelago. It was once considered a subspecies of '' Pteropus temminckii'' be ...
. The term "male lactation" is not used in human medicine. It has been used in popular literature, such as Louise Erdrich's ''The Antelope Wife'', to describe the phenomenon of male
galactorrhea
Galactorrhea ( also spelled galactorrhoea) ( galacto- + -rrhea) or lactorrhea ( lacto- + -rrhea) is the spontaneous flow of milk from the breast, unassociated with childbirth or nursing.
Galactorrhea is reported to occur in 5–32% of women. M ...
, which is a human condition unrelated to childbirth or nursing. Newborn babies of both sexes can occasionally produce milk. This is called neonatal milk (also as "witch's milk") and not considered male lactation.
History
Male lactation was of some interest to
Alexander von Humboldt
Friedrich Wilhelm Heinrich Alexander von Humboldt (14 September 17696 May 1859) was a German polymath, geographer, naturalist, explorer, and proponent of Romantic philosophy and science. He was the younger brother of the Prussian minister ...
, who reports in ''Voyage aux régions équinoxiales du Nouveau Continent'' about a citizen of the Venezuelan village of Arenas (close to Cumana) who allegedly nurtured his son for three months when his wife was ill, as well as
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
, who commented on it in ''
The Descent of Man, and Selection in Relation to Sex
''The Descent of Man, and Selection in Relation to Sex'' is a book by English natural history, naturalist Charles Darwin, first published in 1871, which applies evolutionary theory to human evolution, and details his theory of sexual selection, ...
'' (1871):
Darwin later considered the nearly perfect function of male nipples in contrast to greatly reduced structures such as the
vesicula prostatica
The prostatic utricle (Latin for "small pouch of the prostate") is a small indentation in the prostatic urethra, at the apex of the urethral crest, on the seminal colliculus (''verumontanum''), laterally flanked by openings of the ejaculatory duct ...
, 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.
Evolution and biology
Male mammals of many species have been observed to lactate under unusual or pathogenic conditions, such as extreme stress, castration, and exposure to
phytoestrogens
A phytoestrogen is a plant-derived xenoestrogen (see estrogen) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it is a diverse group of naturally occurring nonster ...
, or
pituitary tumor
Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas.Dayak fruit bat (''
Dyacopterus spadiceus
The dayak fruit bat or dyak fruit bat (''Dyacopterus spadiceus'') is a relatively rare frugivorous megabat species found only on the Sunda Shelf of southeast Asia, specifically the Malay Peninsula south of the Isthmus of Kra, and the islands of ...
'') and the
Bismarck masked flying fox
The Bismarck masked flying fox (''Pteropus capistratus'') is a species of flying fox in the family Pteropodidae found in Papua New Guinea and named after the Bismarck Archipelago. It was once considered a subspecies of '' Pteropus temminckii'' be ...
(''Pteropus capistratus''). Lactating males may assist in the
nursing
Nursing is a profession within the health care sector focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life. Nurses may be differentiated from other health ...
of their infants. In addition, male goats are known to lactate on occasion.
Human male lactation
Spontaneous production of milk not associated with childbirth, known as
galactorrhea
Galactorrhea ( also spelled galactorrhoea) ( galacto- + -rrhea) or lactorrhea ( lacto- + -rrhea) is the spontaneous flow of milk from the breast, unassociated with childbirth or nursing.
Galactorrhea is reported to occur in 5–32% of women. M ...
, can occur in human males and females. Case reports of lactation induced in
transgender women
A trans woman or a transgender woman is a woman who was assigned male at birth. Trans women have a female gender identity, may experience gender dysphoria, and may transition; this process commonly includes hormone replacement therapy and so ...
Intersex
Intersex people are individuals born with any of several sex characteristics including chromosome patterns, gonads, or genitals that, according to the Office of the United Nations High Commissioner for Human Rights, "do not fit typical b ...
Milking the bull
Milking the bull is a proverb which uses the metaphor of milking a bull to indicate that an activity would be fruitless or futile.
In the 16th century, the German painter Hans Schäufelein illustrated the proverb on the eight of bells in a dec ...
*
* 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. Pyles