Production of milk (
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 pr ...
) 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 pr ...
s is well-documented in the
Dayak fruit bat and the
Bismarck masked flying fox. 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
Witch's milk or neonatal milk is milk secreted from the breasts of some newborn human infants of either sex. Neonatal milk secretion is considered a normal physiological occurrence and no treatment or testing is necessary. It is thought to be ca ...
(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 natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
, who commented on it in ''
The Descent of Man, and Selection in Relation to Sex'' (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 d ...
, 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, or
pituitary tumors. Therefore, it is hypothesized that while most male mammals could easily develop the ability to lactate, there is no selective advantage to male lactation. While male mammals could, in theory, improve their offspring's survival rate through the additional nourishment provided by lactation, most have developed other strategies to increase the number of surviving offspring, such as mating with additional partners. Presently, very few species are known where male lactation occurs and it is not well understood what evolutionary factors control the development of this trait.
Nonhuman animal male lactation
The phenomenon of male lactation occurs in some species, notably the
Dayak fruit bat (''
Dyacopterus spadiceus'') and the
Bismarck masked flying fox (''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 have been published.
See also
*
Galactagogue
*
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 ...
*
LGBT Reproduction
*
Milking the bull, a proverb that refers to the act of milking a male animal
*
Male egg
*
Male pregnancy
References
Citations
Sources
*
* 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
External links
''Sri Lanka Man nurses Daughter''
{{DEFAULTSORT:Male Lactation
Breastfeeding
Andrology