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108-402: The nipple is a raised region of tissue on the surface of the breast from which, in lactating females, milk from the mammary gland leaves the body through the lactiferous ducts to nurse an infant. The milk can flow through the nipple passively, or it can be ejected by smooth muscle contractions that occur along with the ductal system. The nipple is surrounded by the areola , which

216-433: A "no nipples" policy with exceptions: material that is not allowed includes "some photos of female nipples, but photos of post- mastectomy scarring and women actively breastfeeding are allowed. Nudity in photos of paintings and sculptures is OK, too". Previously, Instagram had removed images of nursing mothers. Instagram removed images of Rihanna and had her account cancelled in 2014 when she posted selfies with nipples. This

324-500: A 1952 article in Parents' Magazine , Frank H. Crowell erroneously reported that it was important for teen girls to begin wearing bras early. According to Crowell, this would prevent sagging breasts, stretched blood vessels, and poor circulation later on. This belief was based on the false idea that breasts cannot anatomically support themselves. Sports bras are sometimes used for cardiovascular exercise, sports bras are designed to secure

432-401: A byproduct of some other constraint on adaptive evolution. In response to the position that spandrels are just small, unimportant byproducts, Gould and Lewontin argue that "we must not recognize that small means unimportant. Spandrels can be as prominent as primary adaptations". A main example used by Gould and Lewontin is the human brain. Many secondary processes and actions come in addition to

540-613: A family history of breast cancer. About five to ten percent of cases are the result of an inherited genetic predisposition, including BRCA mutations among others. Breast cancer most commonly develops in cells from the lining of milk ducts and the lobules that supply these ducts with milk. Cancers developing from the ducts are known as ductal carcinomas , while those developing from lobules are known as lobular carcinomas . There are more than 18 other sub-types of breast cancer. Some, such as ductal carcinoma in situ , develop from pre-invasive lesions . The diagnosis of breast cancer

648-625: A film entitled Free the Nipple , which is about "laws against female toplessness or restrictions on images of female, but not male, nipples", which Esco states is an example of sexism in society. Nipples can be sensitive to touch, and nipple stimulation can incite sexual arousal . Few women report experiencing orgasm from nipple stimulation. Before Komisaruk et al.'s functional magnetic resonance (fMRI) research on nipple stimulation in 2011, reports of women achieving orgasm from nipple stimulation relied solely on anecdotal evidence . Komisaruk's study

756-574: A forward-bending, self-protecting posture". A popular legend at the time was of the Amazons , a tribe of fierce female warriors who socialized with men only for procreation and even removed one breast to become better warriors (the idea being that the right breast would interfere with the operation of a bow and arrow). The legend was a popular motif in art during Greek and Roman antiquity and served as an antithetical cautionary tale. Many women regard their breasts as important to their sexual attractiveness , as

864-504: A goal such as long life, grandchildren, or accurate perception and prediction of the world", and "I suspect that music is auditory cheesecake, an exquisite confection crafted to tickle the sensitive spots of at least six of our mental faculties." Dunbar found this conclusion odd, and stated that "it falls foul of what we might refer to as the Spandrel Fallacy: 'I haven't really had time to determine empirically whether or not something has

972-420: A historical order from the distribution yielded by tabulation. The human chin has been proposed as an example of a spandrel, since modern humans ( Homo sapiens ) are the only species with a chin, an anatomical feature with no known function. Alternatively however, it has been suggested that chins may be the result of selection, based on an analysis of the rate of chin evolution in the fossil record. There

1080-406: A network of ducts that converge on the nipple , and these tissues give the breast its distinct size and globular shape. At the ends of the ducts are lobules , or clusters of alveoli , where milk is produced and stored in response to hormonal signals . During pregnancy, the breast responds to a complex interaction of hormones, including estrogens , progesterone , and prolactin , that mediate

1188-881: A nipple (also called mammary papilla or teat ) is a small projection of skin containing the outlets for 15–20 lactiferous ducts arranged cylindrically around the tip. Marsupials and eutherian mammals typically have an even number of nipples arranged bilaterally, from as few as 2 to as many as 19. The skin of the nipple is rich in a supply of special nerves that are sensitive to certain stimuli: these are slowly-adapting and rapidly-adapting cutaneous mechanoreceptors . Mechanoreceptors are identified respectively by Type I slowly-adapting with multiple Merkel corpuscle end-organs and Type II slowly-adapting with single Ruffini corpuscle end-organs , as well as Type I rapidly-adapting with multiple Meissner corpuscle end-organs and Type II rapidly-adapting with single Pacinian corpuscle end-organs . The dominant nerve supply to

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1296-400: A part in increasing brain size. Breast enlargement may for this purpose have occurred as early as Homo ergaster (1.7–1.4 MYA ). Other breast formation hypotheses may have then taken over as principal drivers. 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 . This would see

1404-402: A platter, signifying that they died as a martyr by having their breasts severed; one example of this is Saint Agatha of Sicily . Femen is a feminist activist group which uses topless protests as part of their campaigns against sex tourism religious institutions, sexism , and homophobia . Femen activists have been regularly detained by police in response to their protests. There

1512-405: A reluctance of the mother to continue to breastfeed. After birth, the milk supply increases based upon the continuous and increasing stimulation of the nipple by the infant. If the baby increases nursing time at the nipple, the mammary glands respond to this stimulation by increasing milk production. Nipple pain can be a disincentive for breastfeeding. Sore nipples that progress to cracked nipples

1620-434: A result of increased brain size and increasing complexity, though he provides no definitive answers as to what factors may have led to the brain attaining the size and complexity of which discrete infinity is a consequence. Steven Pinker and Ray Jackendoff say Chomsky's case is unconvincing. Pinker contends that the language faculty is not a spandrel, but rather a result of natural selection. Newmeyer (1998) instead views

1728-471: A sign of femininity that is important to their sense of self . A woman with smaller breasts may regard her breasts as less attractive. Spandrel (biology) The term " spandrel " originates from architecture, where it refers to the roughly triangular spaces between the top of an arch and the ceiling. The term was coined by paleontologist Stephen Jay Gould and population geneticist Richard Lewontin in their paper "The Spandrels of San Marco and

1836-435: A suite of secondary adaptations, thus the grounds of how well crafted a structure is for a function cannot be used as grounds for assigning or denying spandrel status. The nature of the current utility of a structure also does not provide a basis for assigning or denying spandrel status, nor does he see the origin of a structure as having any relationship to the extent or vitality of a later co-opted role, but places importance on

1944-1019: A terminological claim was offered that the "spandrels" of Basilica di San Marco were not spandrels at all, but rather were pendentives . Gould responded, "The term spandrel may be extended from its particular architectural use for two-dimensional byproducts to the generality of 'spaces left over', a definition that properly includes the San Marco pendentives." Other critics, such as Daniel Dennett , further claimed (in Darwin's Dangerous Idea and elsewhere) that these pendentives are not merely architectural by-products as Gould and Lewontin supposed. Dennett argues that alternatives to pendentives, such as corbels or squinches , would have served equally well from an architectural standpoint, but pendentives were deliberately selected due to their aesthetic value. Critics such as H. Allen Orr argued that Lewontin and Gould's oversight in this regard illustrates their underestimation of

2052-491: A thin needle is used for the biopsy. Receiving an injection to prevent pain from the biopsy may be more painful than the biopsy itself. Some men develop a condition known as gynecomastia , in which the breast tissue under the nipple develops and grows. Discharge from the nipple can occur. The nipple may swell in some men possibly due to increased levels of estrogen. Changes in appearance may be normal or related to disease. The average projection and size of human female nipples

2160-436: A well-fitted sports bra during activity. The breast is susceptible to numerous benign and malignant conditions. The most frequent benign conditions are puerperal mastitis , fibrocystic breast changes and mastalgia . Lactation unrelated to pregnancy is known as galactorrhea . It can be caused by certain drugs (such as antipsychotic medications), extreme physical stress, or endocrine disorders. Lactation in newborns

2268-453: A woman who goes topless is legally in the same boat as if she'd had sex in public. That may seem crazy, but in the US it's a permissible law." The legality around the exposure of nipples is inconsistently regulated throughout the US. Some states do not allow the visualization of any part of the breast. Other jurisdictions prohibit any female chest anatomy by banning anatomical structures that lie below

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2376-576: A woman's breasts are severely asymmetrical, surgery can be performed to either enlarge the smaller breast, reduce the size of the larger breast, or both. Breast augmentation surgery generally does not interfere with future ability to breastfeed. 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. Implants can interfere with mammography (breast x-rays images). In Christian iconography , some works of art depict women with their breasts in their hands or on

2484-451: Is a consensus that the male nipple exists because there is no particular advantage to males losing the trait. In consequence, some biologists would call the male nipple a spandrel . In humans, the nipples are often surrounded by body hair . The physiological purpose of nipples is to deliver milk , produced in the female mammary glands during lactation , to an infant . During breastfeeding, nipple stimulation by an infant will stimulate

2592-580: 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). In European pre-historic societies, sculptures of female figures with pronounced or highly exaggerated breasts were common. A typical example is the so-called Venus of Willendorf , one of many Paleolithic Venus figurines with ample hips and bosom. 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

2700-460: Is a serious and sometimes fatal infection. Transmission of Hepatitis C and B to the infant can occur if the nipples are cracked. Other infections can be transmitted through a break of the skin of the nipple and can infect the infant. A nipple-sparing/subcutaneous mastectomy is a surgical procedure where breast tissue is removed, but the nipple and areola are preserved. This procedure was historically done only prophylactically or with mastectomy for

2808-477: Is also considerable variation in size between individuals. Female humans are the only mammals which permanently develop breasts at puberty ; all other mammals develop their mammary tissue during the latter period of pregnancy; at puberty, estrogens , in conjunction with growth hormone , cause permanent breast growth . In females, the breast serves as the mammary gland , which produces and secretes milk to feed infants . Subcutaneous fat covers and envelops

2916-537: Is caused by hormones from the mother that crossed into the baby's bloodstream during pregnancy. Breast cancer is the most common cause of cancer death among women and it is one of the leading causes of death among women. Factors that appear to be implicated in decreasing the risk of breast cancer are regular breast examinations by health care professionals, regular mammograms , self-examination of breasts , healthy diet, exercise to decrease excess body fat, and breastfeeding . Both females and males develop breasts from

3024-431: Is committed when a person "knowingly or intentionally, ... appears in a state of nudity commits Public Indecency." Later in the statute, nudity is further described as an uncovered female nipple. But nipple exposure of a man was not regulated. An opinion column credited to Cecil Adams noted: "Ponder the significance of that. A man walks around bare-chested and the worst that happens is he won't get served in restaurants. But

3132-522: Is common, especially during the first trimester. By mid-pregnancy, the breast is physiologically capable of lactation and some women can express colostrum , a form of breast milk. Pregnancy causes elevated levels of the hormone prolactin , which has a key role in the production of milk. However, milk production is blocked by the hormones progesterone and estrogen until after delivery, when progesterone and estrogen levels plummet. At menopause, breast atrophy occurs. The breasts can decrease in size when

3240-400: Is confirmed by taking a biopsy of the concerning tissue. Once the diagnosis is made, further tests are carried out to determine if the cancer has spread beyond the breast and which treatments are most likely to be effective. The primary function of the breasts, as mammary glands, is the nourishing of an infant with breast milk . Milk is produced in milk-secreting cells in the alveoli. When

3348-401: Is considered a symptom of a disorder of the pituitary gland . Plastic surgery can be performed to augment or reduce the size of breasts, or reconstruct the breast in cases of deformative disease, such as breast cancer. Breast augmentation and breast lift ( mastopexy ) procedures are done only for cosmetic reasons, whereas breast reduction is sometimes medically indicated. In cases where

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3456-433: Is defined as a product of a dedicated genetic blueprint. Rudolph Botha counters that Chomsky has offered his conception of the feature of recursion but not a theory of the evolution of the language faculty as a whole. There is disagreement among experts as to whether music is a spandrel. Pinker has written that "As far as biological cause and effect are concerned, music is useless. It shows no signs of design for attaining

3564-445: Is disagreement among experts as to whether language is a spandrel. Linguist Noam Chomsky and Gould himself have both argued that human language may have originated as a spandrel. Chomsky writes that the language faculty , and the property of discrete infinity or recursion that plays a central role in his theory of universal grammar (UG), may have evolved as a spandrel. In this view, Chomsky initially pointed to language being

3672-406: Is localized to the area of the nipple. In some cases, the infection can progress to become a full-blown case of mastitis or breast infection. In some cases, if the mother has an infection with no nipple cracks or ulcerations, it is still safe to breastfeed the infant. Herpes infection of the nipple can go unnoticed because the lesions are small but usually are quite painful. Herpes in the newborn

3780-406: Is most often not cancer (benign), but rarely, it can be a sign of breast cancer. It is important to determine what is causing the discharge and to get treatment. Reasons for nipple discharge include: Sometimes, babies can have nipple discharge. This is caused by hormones from the mother before birth. It usually goes away in two weeks. Cancers such as Paget's disease (a rare type of cancer involving

3888-440: Is of concern since many women cease breastfeeding due to the pain . In some instances, an ulcer will form on the nipple. One reason for the development of cracked and sore nipples is the incorrect latching-on of the infant to the nipple. If a nipple appears to be wedge-shaped, white and flattened, this may indicate that the attachment of the infant is not good and there is a potential of developing cracked nipples. Herpes infection of

3996-605: Is often a darker colour than the surrounding skin. Male mammals also have nipples but without the same level of function or prominence. A nipple is often called a teat when referring to non-humans. "Nipple" or "teat" can also be used to describe the flexible mouthpiece of a baby bottle . In humans, the nipples of both males and females can be sexually stimulated as part of sexual arousal . In many cultures, female nipples are sexualized , or regarded as sex objects and evaluated in terms of their physical characteristics and sex appeal. Some cultures have little to no sexualization of

4104-455: Is slightly more than 3 ⁄ 8 inch (9.5 mm). Symptoms of breast cancer can often be seen first by changes of the nipple and areola, although not all women have the same symptoms, and some people do not have any signs or symptoms at all. A person may find out they have breast cancer after a routine mammogram . Warning signs can include: Changes in the nipple are not necessarily symptoms or signs of breast cancer. Other conditions of

4212-592: The Panglossian Paradigm: A Critique of the Adaptationist Programme" (1979). Evolutionary biologist Günter P. Wagner called the paper "the most influential structuralist manifesto". In their paper, Gould and Lewontin employed the analogy of spandrels in Renaissance architecture , such as the curved areas of masonry between arches supporting a dome that arise as a consequence of decisions about

4320-407: The axilla (armpit), and can reach as far to the back as the latissimus dorsi muscle , extending from the lower back to the humerus bone (the bone of the upper arm). As a mammary gland , the breast is composed of differing layers of tissue , predominantly two types: adipose tissue ; and glandular tissue , which affects the lactation functions of the breasts. The natural resonant frequency of

4428-629: The Middle East. Many female deities representing love and fertility were associated with breasts and breast milk. Figures of the Phoenician goddess Astarte were represented as pillars studded with breasts. 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

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4536-573: The anatomic breast. Normal breast tissue typically has a texture that feels nodular or granular, to an extent that varies considerably from woman to woman. The breasts are principally composed of adipose, glandular , and connective tissues. Because these tissues have hormone receptors, their sizes and volumes fluctuate according to the hormonal changes particular to thelarche (sprouting of breasts), menstruation (egg production), pregnancy (reproduction), lactation (feeding of offspring), and menopause (end of menstruation). The morphological structure of

4644-407: The apical axillary lymph nodes. The lymphatic drainage of the breasts is especially relevant to oncology because breast cancer is common to the mammary gland, and cancer cells can metastasize (break away) from a tumor and be dispersed to other parts of the body by means of the lymphatic system. The morphologic variations in the size, shape, volume, tissue density, pectoral locale, and spacing of

4752-407: The arteries. The lymphatic ducts that drain the nipple are the same for the breast. The axillary nodes are the apical axillary nodes, the lateral group and the anterior group. 75% of the lymph is drained through the axillary lymph nodes located near the armpit. The rest of the drainage leaves the nipple and breast through infroclavicular, pectoral, or parasternal nodes. Since nipples change throughout

4860-534: The benign disease over the fear of increased cancer development in retained areolar ductal tissue. Recent series suggest that it may be an oncologically sound procedure for tumours not in the subareolar position. The cultural tendency to hide the female nipple under clothing has existed in Western culture since the 1800s. As female nipples are often perceived an intimate part , covering them might have originated under Victorian morality as with riding side saddle. Exposing

4968-454: The breast. The chest ( thoracic cavity ) progressively slopes outwards from the thoracic inlet (atop the breastbone ) and above to the lowest ribs that support the breasts. The inframammary fold, where the lower portion of the breast meets the chest, is an anatomic feature created by the adherence of the breast skin and the underlying connective tissues of the chest; the IMF is the lower-most extent of

5076-411: The breasts are about 80 to 90% stromal tissue ( fat and connective tissue ), while epithelial or glandular tissue only accounts for about 10 to 20% of the volume of the breasts. The tissue composition ratios of the breast also vary among women. Some women's breasts have a higher proportion of glandular tissue than of adipose or connective tissues. The fat-to-connective-tissue ratio determines

5184-446: The breasts are stimulated by the suckling of her baby, the mother's brain secretes oxytocin . High levels of oxytocin trigger the contraction of muscle cells surrounding the alveoli, causing milk to flow along the ducts that connect the alveoli to the nipple. Full-term newborns have an instinct and a need to suck on a nipple, and breastfed babies nurse for both nutrition and for comfort. Breast milk provides all necessary nutrients for

5292-405: The breasts closely to the body to prevent movement during high-motion activity such as running. Studies have indicated sports bras which are overly tight may restrict respiratory function. The base of each breast is attached to the chest by the deep fascia over the pectoralis major muscles. The space between the breast and the pectoralis major muscle, called retromammary space , gives mobility to

5400-429: The breasts determine their natural shape, appearance, and position on a woman's chest. Breast size and other characteristics do not predict the fat-to-milk-gland ratio or the potential for the woman to nurse an infant. The size and the shape of the breasts are influenced by normal-life hormonal changes (thelarche, menstruation, pregnancy, menopause) and medical conditions (e.g. virginal breast hypertrophy ). The shape of

5508-420: 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. The suspensory ligaments sustain the breast from the clavicle (collarbone) and the clavico-pectoral fascia (collarbone and chest) by traversing and encompassing the fat and milk-gland tissues. The breast is positioned, affixed to, and supported upon

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5616-432: The breasts overlie the pectoralis major muscles and extend on average from the level of the second rib to the level of the sixth rib in the front of the rib cage ; thus, the breasts cover much of the chest area and the chest walls. At the front of the chest, the breast tissue can extend from the clavicle (collarbone) to the middle of the sternum (breastbone). At the sides of the chest, the breast tissue can extend into

5724-705: The chest wall, while its shape is established and maintained by the skin envelope. In most women, one breast is slightly larger than the other. More obvious and persistent asymmetry in breast size occurs in up to 25% of women. While it is a common belief that breastfeeding causes breasts to sag , researchers have found that a woman's breasts sag due to four key factors: cigarette smoking, number of pregnancies , gravity , and weight loss or gain. Women sometimes wear bras because they mistakenly believe they prevent breasts from sagging as they get older. Physicians, lingerie retailers, teenagers, and adult women used to believe that bras were medically required to support breasts. In

5832-518: The completion of its development, namely lobuloalveolar maturation, in preparation of lactation and breastfeeding . Along with their major function in providing nutrition for infants, several cultures ascribe social and sexual characteristics to female breasts, and may regard bare breasts in public as immodest or indecent . Breasts have been featured in ancient and modern sculpture, art, and photography. Breasts can represent fertility , femininity , or abundance . They can figure prominently in

5940-425: The density or firmness of the breast. During a woman's life, her breasts change size, shape, and weight due to hormonal changes during puberty , the menstrual cycle , pregnancy , breastfeeding, and menopause . The breast is an apocrine gland that produces the milk used to feed an infant. The nipple of the breast is surrounded by the areola (nipple-areola complex). The areola has many sebaceous glands, and

6048-488: The direct action of natural selection and that were later co-opted for a current use. Gould saw the term to be optimally suited for evolutionary biology for "the concept of a nonadaptive architectural by-product of definite and necessary form – a structure of particular size and shape that then becomes available for later and secondary utility". Gould and Lewontin's proposal generated a large literature of critique, which Gould characterised as being grounded in two ways. First,

6156-420: The discharge stop. Nipple discharge in a male is usually of more concern. Most of the time a mammogram and an examination of the fluid is done. A biopsy is often performed. A fine needle aspiration (FNA) biopsy can be fast and least painful. A very thin, hollow needle and slight suction will be used to remove a small sample from under the nipple. Using a local anesthetic to numb the skin may not be necessary since

6264-431: The disease , there may be bone pain , swollen lymph nodes , shortness of breath , or yellow skin . Risk factors for developing breast cancer include obesity , a lack of physical exercise , alcohol consumption, hormone replacement therapy during menopause , ionizing radiation , an early age at first menstruation , having children late in life (or not at all), older age, having a prior history of breast cancer, and

6372-425: The effects of estrogens in developing excessive breast tissue. 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. Around 70% of boys temporarily develop breast tissue during adolescence. The condition usually resolves by itself within two years. When male lactation occurs, it

6480-517: The entire breast and nipple is a form of protest for some and a crime for others. The exposure of nipples is usually considered immodest and in some instances is viewed as lewd or indecent behavior. A case in Erie, Pennsylvania, concerning the exposure of breasts and nipple proceeded to the United States Supreme Court . The Erie ordinance was regulating the nipple in public as an act that

6588-467: The evolutionary analysis of form in the history of life." Gould cites the masculinized genitalia of female hyenas and the brooding chamber of some snails as examples of evolutionary spandrels. Gould (1991) outlines some considerations for grounds for assigning or denying a structure the status of spandrel, pointing first to the fact that a structure originating as a spandrel through primary exaptation may have been further crafted for its current utility by

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6696-461: The explanation for larger breasts as them being an honest display of the women's health and ability to grow and carry them in her life. Prospective mates can then evaluate the genes of a potential mate for their ability to sustain her health even with the additional energy demanding burden she is carrying. The zoologist Desmond Morris describes a sociobiological approach in his science book The Naked Ape . He suggests, by making comparisons with

6804-411: The face, the woman's body compensated with round breasts. 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. Human upright stance meant infants must be carried at the hip or shoulder instead of on the back as in the apes. This gives the infant less opportunity to find

6912-510: The female breast in Greece became less common during the first millennium. 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 . During the middle of the first millennium BC, Greek culture experienced a gradual change in the perception of female breasts. Women in art were covered in clothing from

7020-701: The first known usage of the term was before the 12th century. "Breasts" is often used to refer to female breasts in particular, though the stricter anatomical term refers to the same region on members of either sex. Male breasts are sometimes referred to in the singular to mean the collective upper chest area, whereas female breasts are referred to in the plural unless speaking of a specific left or right breast. A large number of colloquial terms for female breasts are used in English, ranging from fairly polite terms to vulgar or slang. Some vulgar slang expressions may be considered to be derogatory or sexist to women. Humans are

7128-675: 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. Biomechanical studies have demonstrated that, depending on the activity and the size of a woman's breast, when she walks or runs braless, her breasts may move up and down by 4 to 18 centimetres (1.6 to 7.1 in) or more, and also oscillate side to side. Researchers have also found that as women's breast size increased, they took part in less physical activity, especially vigorous exercise. Few very-large-breasted women jogged, for example. To avoid exercise-related discomfort and pain, medical experts suggest women wear

7236-485: The five-stage Tanner scale . During thelarche , the developing breasts are sometimes of unequal size, and usually the left breast is slightly larger. This condition of asymmetry is transitory and statistically normal in female physical and sexual development. Medical conditions can cause overdevelopment (e.g., virginal breast hypertrophy, macromastia ) or underdevelopment (e.g., tuberous breast deformity , micromastia ) in girls and women. Approximately two years after

7344-400: The front (anterior) and side (lateral) cutaneous branches of the fourth-, fifth-, and sixth intercostal nerves . The T-4 nerve ( Thoracic spinal nerve 4 ), which innervates the dermatomic area , supplies sensation to the nipple-areola complex. Approximately 75% of the lymph from the breast travels to the axillary lymph nodes on the same side of the body, while 25% of the lymph travels to

7452-438: The human breast is about 2 hertz . Morphologically , the breast is tear-shaped. The superficial tissue layer ( superficial fascia ) is separated from the skin by 0.5–2.5 cm of subcutaneous fat (adipose tissue). The suspensory Cooper's ligaments are fibrous-tissue prolongations that radiate from the superficial fascia to the skin envelope. The female adult breast contains 14–18 irregular lactiferous lobes that converge at

7560-482: The human breast is identical in males and females until puberty . For pubescent girls in thelarche (the breast-development stage), the female sex hormones (principally estrogens) in conjunction with growth hormone promote the sprouting, growth, and development of the breasts. During this time, the mammary glands grow in size and volume and begin resting on the chest. These development stages of secondary sex characteristics (breasts, pubic hair, etc.) are illustrated in

7668-427: The increments and the decrements of the size and volume of a woman's breasts throughout the course of her life. Breast cancer is a cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection , fluid coming from the nipple , a newly inverted nipple, or a red or scaly patch of skin. In those with distant spread of

7776-452: The infant fastening onto the nipple to breastfeed. A good attachment is when the bottom of the areola (the area around the nipple) is in the infant's mouth and the nipple is drawn back inside his or her mouth. A poor latch results in insufficient nipple stimulation to create the let down reflex. The nipple is poorly stimulated when the baby latches on too close to the tip of the nipple. This poor attachment can cause sore and cracked nipples and

7884-488: The lack of symmetry, irregularity and idiosyncrasy that universal grammar tolerates and the widely different principles of organization of its various sub-components and consequent wide variety of linking rules relating them as evidence that such design features do not qualify as an exaptation. He suggests that universal grammar cannot be derivative and autonomous at the same time, and that Chomsky wants language to be an epiphenomenon and an "organ" simultaneously, where an organ

7992-405: The later evolutionary meaning of a structure. This seems to imply that the design and secondary utilization of spandrels may feed back into the evolutionary process and thus determine major features of the entire structure. The grounds Gould does accept to have validity in assigning or denying a structure the status of spandrel are historical order and comparative anatomy . Historical order involves

8100-437: The levels of circulating estrogen decline. The adipose tissue and milk glands also begin to wither. The breasts can also become enlarged from adverse side effects of combined oral contraceptive pills . The size of the breasts can also increase and decrease in response to weight fluctuations. Physical changes to the breasts are often recorded in the stretch marks of the skin envelope; they can serve as historical indicators of

8208-430: The life span in men and women, the anatomy of the nipple can change and this change may be expected and considered normal. Almost all mammals have nipples. Why males have nipples has been the subject of scientific research. Differences among the sexes (called sexual dimorphism ) within a given species are considered by evolutionary biologists to be mostly the result of sexual selection , directly or indirectly. There

8316-580: The main functions of the human brain. These secondary processes and thoughts can eventually turn into an adaptation or provide a fitness advantage to humans. Just because something is a secondary trait or byproduct of an adaptation does not mean it has no use. In 1982, Gould and Vrba introduced the term " exaptation " for characteristics that enhance fitness in their present role but were not built for that role by natural selection. Exaptations may be divided into two subcategories: pre-adaptations and spandrels. Spandrels are characteristics that did not originate by

8424-488: The menstrual cycle, the breasts are enlarged by premenstrual water retention and temporary growth. The breasts reach full maturity only when a woman's first pregnancy occurs. Changes to the breasts are among the first signs of pregnancy. The breasts become larger, the nipple-areola complex becomes larger and darker, the Montgomery's glands enlarge, and veins sometimes become more visible. Breast tenderness during pregnancy

8532-419: The milk from TDLUs into 4–18 lactiferous ducts, which drain to the nipple. The milk-glands-to-fat ratio is 2:1 in a lactating woman, and 1:1 in a non-lactating woman. 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

8640-513: The neck down, including female goddesses like Athena , the patron of Athens who represented heroic endeavor. There were exceptions: Aphrodite , the goddess of love, was more frequently portrayed fully nude, though in postures that were intended to portray shyness or modesty, a portrayal that has been compared to modern pin ups by historian Marilyn Yalom . Although nude men were depicted standing upright, most depictions of female nudity in Greek art occurred "usually with drapery near at hand and with

8748-400: The nipple can mimic the signs and symptoms of breast cancer. Some infections are transmitted through the nipple, especially if irritation or injury to the nipple has occurred. In these circumstances, the nipple itself can become infected with Candida that is present in the mouth of the breastfeeding infant. The infant will transmit the infection to the mother. Most of the time, this infection

8856-512: The nipple comes from the lateral cutaneous branches of fourth intercostal nerve . The nipple is also used as an anatomical landmark. It marks the T4 (fourth thoracic vertebra) dermatome and rests over the approximate level of the diaphragm. The arterial supply to the nipple and breast originates from the anterior intercostal branches of the internal thoracic (mammary) arteries; lateral thoracic artery; and thoracodorsal arteries. The venous vessels parallel

8964-399: The nipple during breastfeeding. Volatile compounds in these secretions may also serve as an olfactory stimulus for the newborn's appetite. The dimensions and weight of the breast vary widely among women. A small-to-medium-sized breast weighs 500 grams (1.1 pounds) or less, and a large breast can weigh approximately 750 to 1,000 grams (1.7 to 2.2 pounds) or more. In terms of composition,

9072-446: The nipple is painful. Nipple pain can also be caused by excessive friction of clothing against the nipple that causes a fissure . Nipple discharge refers to any fluid that seeps out of the nipple of the breast. Discharge from the nipple does not occur in lactating women. And discharge in non-pregnant women or women who are not breastfeeding may not cause concern. Men that have discharge from their nipples are not typical. Discharge from

9180-446: The nipple or the purchase to cling on to the mother's body hair. The mobility of the nipple on a large breast in most human females gives the infant more ability to find it, grasp it and feed. Other suggestions include simply that permanent breasts attracted mates, that "pendulous" breasts gave infants something to cling to, or that permanent breasts shared the function of a camel's hump , to store fat as an energy reserve. In women,

9288-407: The nipple, and going topless presents no barrier. The word "nipple" most likely originates as a diminutive of neb , an Old English word meaning "beak", "nose", or "face", and which is of Germanic origin . The words "teat" and "tit" share a Germanic ancestor. The second of the two, tit, was inherited directly from Proto-Germanic, while the first entered English via Old French . In mammals ,

9396-419: The nipple. The 2.0–4.5 mm milk ducts are immediately surrounded with dense connective tissue that support the glands. Milk exits the breast through the nipple, which is surrounded by a pigmented area of skin called the areola. The size of the areola can vary widely among women. The areola contains modified sweat glands known as Montgomery's glands . These glands secrete oily fluid that lubricate and protect

9504-433: The nipples of men or boys may indicate a problem. Discharge from the nipples can appear without squeezing or may only be noticeable if the nipples are squeezed. One nipple can have discharge while the other does not. The discharge can be clear, green, bloody, brown or straw-coloured. The consistency can be thick, thin, sticky or watery. Some cases of nipple discharge will clear on their own without treatment. Nipple discharge

9612-473: The only mammals whose breasts become permanently enlarged after sexual maturity (known in humans as puberty ). The reason for this evolutionary change is unknown. 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. These contributed to human brain development and played

9720-481: The onset of puberty (a girl's first menstrual cycle ), estrogen and growth hormone stimulate the development and growth of the glandular fat and suspensory tissues that compose the breast. This continues for approximately four years until the final shape of the breast (size, volume, density) is established at about the age of 21. Mammoplasia (breast enlargement) in girls begins at puberty, unlike all other primates, in which breasts enlarge only during lactation. During

9828-486: The other primates, that breasts evolved to replace swelling buttocks as a sex signal of ovulation. He notes how humans have, relatively speaking, large penises as well as large breasts. Furthermore, early humans adopted bipedalism and face-to-face coitus. 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. A 2001 study proposed that

9936-434: The parasternal nodes (beside the sternum bone). A small amount of remaining lymph travels to the other breast and to the abdominal lymph nodes. The subareolar region has a lymphatic plexus known as the "subareolar plexus of Sappey". The axillary lymph nodes include the pectoral (chest), subscapular (under the scapula), and humeral (humerus-bone area) lymph-node groups, which drain to the central axillary lymph nodes and to

10044-811: The perception of a woman's body and sexual attractiveness . Breasts, especially the nipples, can be an erogenous zone . 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). The breast spelling conforms to the Scottish and North English dialectal pronunciations. The Merriam-Webster Dictionary states that " Middle English brest , [comes] from Old English brēost ; akin to Old High German brust ..., Old Irish brú [belly], [and] Russian bryukho ";

10152-531: The pervasiveness of adaptations found in nature. Gould responded that critics ignore that later selective value is a separate issue from origination as necessary consequences of structure; he summarised his use of the term 'spandrel' in 1997: "Evolutionary biology needs such an explicit term for features arising as byproducts, rather than adaptations, whatever their subsequent exaptive utility ... Causes of historical origin must always be separated from current utilities; their conflation has seriously hampered

10260-415: The release of oxytocin from the hypothalamus . Oxytocin is a hormone that increases during pregnancy and acts on the breast to help produce the milk-ejection reflex . Oxytocin release from the nipple stimulation of the infant causes the uterus to contract even after childbirth. The strong uterine contractions that are caused by the stimulation of the mother's nipples help the uterus contract to clamp down

10368-562: The river god Hapy who was considered to be responsible for the annual overflowing of the Nile . Female breasts were also prominent in Minoan art in the form of the famous Snake Goddess statuettes, and a few other pieces, though most female breasts are covered. In Ancient Greece there were several cults worshipping the "Kourotrophos", the suckling mother, represented by goddesses such as Gaia , Hera and Artemis . The worship of deities symbolized by

10476-410: The rounded shape of a woman's breast evolved to prevent the sucking infant offspring from suffocating while feeding at the teat; that is, because of the human infant's small jaw, which did not project from the face to reach the nipple, they might block the nostrils against the mother's breast if it were of a flatter form (compare with the common chimpanzee ). Theoretically, as the human jaw receded into

10584-404: The same embryological tissues. Anatomically, male breasts do not normally contain lobules and acini that are present in females. In rare instances, it is possible for very few lobules to be present, this makes it possible for some men to develop lobular carcinoma of the breast. Normally, males produce lower levels of estrogens and higher levels of androgens , namely testosterone , which suppress

10692-416: The shape of the arches and the base of the dome, rather than being designed for the artistic purposes for which they were often employed. The authors singled out properties like the necessary number of four spandrels and their specific three-dimensional shape. At the time, it was widely thought in the scientific community that everything an animal has developed that has a positive effect on that animal's fitness

10800-423: The skin color varies from pink to dark brown. The basic units of the breast are the terminal duct lobular units (TDLUs), which produce the fatty breast milk. They give the breast its offspring-feeding functions as a mammary gland. They are distributed throughout the body of the breast. Approximately two-thirds of the lactiferous tissue is within 30 mm of the base of the nipple. The terminal lactiferous ducts drain

10908-415: The skin of the nipple) can also cause nipple discharge. Nipple discharge that is not normal is bloody, comes from only one nipple, or comes out on its own without squeezing or touching the nipple. Nipple discharge is more likely to be normal if it comes out of both nipples or happens when the nipples are squeezed. Squeezing the nipple to check for discharge can make it worse. Leaving the nipple alone may make

11016-509: The top of the areola or nipple. Such is the case in West Virginia and Massachusetts. West Virginia's regulation is very specific and is not likely to be misinterpreted, stating: "[The] display of 'any portion of the cleavage of the human female breast exhibited by a dress, blouse, skirt, leotard, bathing suit, or other wearing apparel [is permitted] provided the areola is not exposed, in whole or in part. ' " The Instagram social media site has

11124-406: The use of historical evidence to determine which feature arose as a primary adaptation and which one appeared subsequently as a co-opted by-product. In the absence of historical evidence, inferences are drawn about the evolution of a structure through comparative anatomy. Evidence is obtained by comparing current examples of the structure in a cladistic context and by subsequently trying to determine

11232-441: The uterine arteries. These contractions are necessary to prevent post-partum haemorrhage . When the infant suckles or stimulates the nipple, oxytocin levels rise and small muscles in the breast contract, moving the milk through the milk ducts. The result of nipple stimulation by the infant helps to move breast milk out through the ducts and to the nipple. This contraction of milk is called the "let-down reflex". Latching on refers to

11340-442: The word nipple or images of nipples to draw attention to their product or cause. Citations Bibliography Breast The breasts are two prominences located on the upper ventral region of the torso among humans and other primates . Both sexes develop breasts from the same embryological tissues. The relative size and development of the breasts is a major secondary sex distinction between females and males. There

11448-420: Was due to natural selection or some adaptation . Gould and Lewontin proposed an alternative hypothesis: that due to adaptation and natural selection, byproducts are also formed. Because these byproducts of adaptations that had no real relative advantage to survival, they were termed spandrels. In the biological sense, a "spandrel" might result from a requirement inherent in the body plan of an organism, or as

11556-472: Was incentive for the Twitter campaign #FreeTheNipple . In 2016, an Instagram page invited users to post images of nipples from both sexes; @genderless_nipples, which displays close ups of both the nipples of men and women for the purpose of spotlighting what may be inconsistency. Some contributors have circumvented the policy. Facebook has also been struggling to define its nipple policy. Filmmaker Lina Esco made

11664-444: Was the first to map the female genitals onto the sensory portion of the brain; it indicates that sensation from the nipples travels to the same part of the brain as sensations from the vagina, clitoris and cervix, and that these reported orgasms are genital orgasms caused by nipple stimulation, and may be directly linked to the genital sensory cortex ("the genital area of the brain"). Some companies and non-profit organisations have used

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