[2] Subcutaneous fat covers and envelops a network of ducts that converge on the nipple, and these tissues give the breast its distinct size and globular shape.

[3] 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.

[8] Several hypotheses have been put forward: A 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.

[10][11][9] It has been suggested by zoologists Avishag and Amotz Zahavi that the size of the human breasts can be explained by the handicap theory of sexual dimorphism.

He therefore suggested enlarged sexual signals helped maintain the bond between a mated male and female even though they performed different duties and therefore were separated for lengths of time.

[16] Ashley Montague (1965) proposed that breasts came about as an adaptation for infant feeding for a different reason, as early human ancestors adopted bipedalism and the loss of body hair.

In addition to the milk glands, the breast is also composed of connective tissues (collagen, elastin), white fat, and the suspensory Cooper's ligaments.

Sensation in the breast is provided by the peripheral nervous system innervation by means of the front (anterior) and side (lateral) cutaneous branches of the fourth-, fifth-, and sixth intercostal nerves.

[31] The shape of the breasts is naturally determined by the support of the suspensory Cooper's ligaments, the underlying muscle and bone structures of the chest, and by the skin envelope.

In a 1952 article in Parents' Magazine, Frank H. Crowell erroneously reported that it was important for teen girls to begin wearing bras early.

[50] In menopausal women, HRT helps restore breast volume and skin elasticity diminished by declining estrogen levels, typically using oral or transdermal estradiol.

[51] In gender-affirming hormone therapy, breast development is induced through feminizing HRT, often combining estrogen with anti-androgens to suppress testosterone.

During the menstrual cycle, the breasts are enlarged by premenstrual water retention and temporary growth as influenced by changing hormone levels.

[67] Breast milk provides all necessary nutrients for the first six months of life, and then remains an important source of nutrition, alongside solid foods, until at least one or two years of age.

To avoid exercise-related discomfort and pain, medical experts suggest women wear a well-fitted sports bra during activity.

In boys and men, abnormal breast development is manifested as gynecomastia, the consequence of a biochemical imbalance between the normal levels of estrogen and testosterone in the male body.

[75] Breast reduction surgery more frequently leads to decreased sensation in the nipple-areola complex, and to low milk supply in women who choose to breastfeed.

[76] Femen is a feminist activist group which uses topless protests as part of their campaigns against sex tourism[77][78] religious institutions,[79] sexism, and homophobia.

[81] There is a long history of female breasts being used by comedians as a subject for comedy fodder (e.g., British comic Benny Hill's burlesque/slapstick routines).

Artifacts such as bowls, rock carvings and sacred statues with breasts have been recorded from 15,000 BC up to late antiquity all across Europe, North Africa and the Middle East.

Isis, an Egyptian goddess who represented, among many other things, ideal motherhood, was often portrayed as suckling pharaohs, thereby confirming their divine status as rulers.

Even certain male deities representing regeneration and fertility were occasionally depicted with breast-like appendices, such as the river god Hapy who was considered to be responsible for the annual overflowing of the Nile.

In Ancient Greece there were several cults worshipping the "Kourotrophos", the suckling mother, represented by goddesses such as Gaia, Hera and Artemis.

The popular adoration of female goddesses decreased significantly during the rise of the Greek city states, a legacy which was passed on to the later Roman Empire.

Women in art were covered in clothing from the neck down, including female goddesses like Athena, the patron of Athens who represented heroic endeavor.

However, even though the practice may be legal or socially accepted, some mothers may nevertheless be reluctant to expose a breast in public to breastfeed[93][94] due to actual or potential objections by other people, negative comments, or harassment.

"[99] Many people regard bare female breasts to be aesthetically pleasing or erotic, and they can elicit heightened sexual desires in men in many cultures.

In the ancient Indian work the Kama Sutra, light scratching of the breasts with nails and biting with teeth are considered erotic.

[101] A number of Western fashions include clothing which accentuate the breasts, such as the use of push-up bras and decollete (plunging neckline) gowns and blouses which show cleavage.

[102] Research conducted at the Victoria University of Wellington showed that breasts are often the first thing men look at, and for a longer time than other body parts.