Other breast formation hypotheses may have then taken over as principal drivers.
Breast enlargement may for this purpose may have occurred as early as Homo ergaster (1.7-1.4 MYA). These contributed to human brain development and played a part in increasing brain size. The reason for this evolutionary change is unknown, several likely explanation have been put forward.Ī link has been proposed to processes for synthesizing the endogenous steroid hormone precursor dehydroepiandrosterone which takes place in fat rich regions of the body like the buttocks and breasts. Humans are the only mammals whose breasts become permanently enlarged after sexual maturity (known in humans as puberty). Some vulgar slang expressions may be considered to be derogatory or sexist to women. Ī large number of colloquial terms for breasts are used in English, ranging from fairly polite terms to vulgar or slang. The Merriam-Webster Dictionary states that " Middle English brest, from Old English brēost akin to Old High German brust., Old Irish brú, Russian bryukho" the first known usage of the term was before the 12th century. The breast spelling conforms to the Scottish and North English dialectal pronunciations. The English word breast derives from the Old English word brēost ('breast, bosom') from Proto-Germanic * breustam (breast), from the Proto-Indo-European base bhreus– (to swell, to sprout). Breasts, especially the nipples, are an erogenous zone. A number of cultures associate breasts with sexuality and tend to regard bare breasts in public as immodest or indecent. They can figure prominently in the perception of a woman's body and sexual attractiveness. Breasts have been featured in ancient and modern sculpture, art, and photography. During pregnancy, the breast responds to a complex interaction of hormones, including estrogens, progesterone, and prolactin, that mediate the completion of its development, namely lobuloalveolar maturation, in preparation of lactation and breastfeeding.Īlong with their major function in providing nutrition for infants, female breasts have social and sexual characteristics. At the ends of the ducts are lobules, or clusters of alveoli, where milk is produced and stored in response to hormonal signals. Subcutaneous fat covers and envelops a network of ducts that converge on the nipple, and these tissues give the breast its size and shape. Breast development in other primate females generally only occurs with pregnancy. At puberty, estrogens, in conjunction with growth hormone, cause breast development in female humans and to a much lesser extent in other primates. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and secretes milk to feed infants. The breast is one of two prominences located on the upper ventral region of a primate's torso.
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