Cleavage, anatomically known as the intermammary cleft or the intermammary sulcus, is the space between a woman's breasts lying over the sternum. In popular culture, it is often defined by garments with low necklines, like ball gowns, evening gowns, lingerie and swimwear that expose or highlight cleavage.
Most people in Western culture, both male and female, consider breasts an important aspect of femininity and many women use cleavage to enhance their physical and sexual attractiveness and to improve their sense of femininity. Some people regard display of cleavage as a form of feminine flirting or seduction, within the confines of community, peer group and personal standards of modesty, as much as for its aesthetic or erotic effect. Some men derive erotic pleasure from seeing a woman's cleavage, and some people derive pleasure in their female partner exposing cleavage. Other groups, however, such as those subject to gymnophobia, may feel uncomfortable with the sight of a woman's cleavage or object to low-cut clothing for modesty or other reasons.
Cleavage terms 
The International Federation of Associations of Anatomists (IFAA) uses the terms "intermammary sulcus" or "intermammary cleft" when referring to the area of cleavage between the breasts not including the breasts. For legal purposes it was noted by the United States federal courts that "anal cleft or cleavage" and "cleavage of the female breast" are so imprecise as to provide no guidance in defining them.
Medically, the "width" of a woman's cleavage is determined by the attachment points of her breast tissue to the periosteal tissue covering breast bone. If a woman has breast implants positioned in the sub-muscular region, her cleavage is also defined to an extent by the medial attachments of the pectoralis major muscle. Implants do not by themselves make a woman's cleavage wider unless the physician overextended or stretched the lateral dissection from the contraction of the pectoralis major muscle.
Significant related terms are:
- Side cleavage: When the lateral aspects of the breasts are uncovered, it is known as side cleavage, sidewinders or sideboob.
- Bottom cleavage: Exposure of the underside of the breast, such as below an extremely short crop top, is known as neathage (a blend of underneath and cleavage), Australian cleavage (because of the reference to Australia as down-under), bottom cleavage, reverse cleavage or underboob.
In European society, décolletage was often a feature of the dress of the late Middle Ages. This continued through the Victorian period. Ball or evening gowns especially featured décolletage designed to display and emphasize cleavage.
In many European societies between the Renaissance and the 19th century, wearing low-cut dresses which exposed breasts was more acceptable than today; with a woman's bared legs, ankles, or shoulders being considered to be more risqué than exposed breasts.
In aristocratic and upper-class circles the display of breasts was at times regarded as a status symbol, as a sign of beauty, wealth or social position. The bared breast even invoked associations with nude sculptures of classical Greece that were exerting an influence on art, sculpture, and architecture of the period.
During the French Enlightenment, there was a debate as to whether a woman's breasts were merely a sensual enticement or rather a natural gift to be offered from mother to child. In Alexandre Guillaume Mouslier de Moissy's 1771 play The True Mother (La Vraie Mère), the title character rebukes her husband for treating her as merely an object for his sexual gratification: "Are your senses so gross as to look on these breasts – the respectable treasures of nature – as merely an embellishment, destined to ornament the chest of women?" Nearly a century later, also in France, a man from the provinces who attended a Court ball at the Tuilleries in Paris in 1855 was deeply shocked by the décolleté dresses and is said to have exclaimed in disgust: "I haven't seen anything like that since I was weaned!"
In 1884, John Singer Sargent painted a daring portrait of American-born Paris socialite, Virginie Amélie Avegno Gautreau. The original painting depicted the subject in a sleek black dress displaying what was considered scandalous cleavage and her right shoulder strap fallen off her shoulder. Sargent sought out Madame Gautreau as a subject. The controversy was so great that he reworked the painting to move the shoulder strap from her upper arm to her shoulder. Sargent left Paris for London in 1884 due to the controversy. He eventually sold it to the Museum of Modern Art in New York, and insisted that it be titled "Portrait of Madame X".
Some people became shocked when it became fashionable, around 1913, for dresses to be worn with a modest round or V-shaped neckline. In the German Empire, for example, all Roman Catholic bishops joined in issuing a pastoral letter attacking the new fashions. Fashions became more restrained in terms of décolletage, while exposure of the leg became more accepted in Western societies, during World War I and remained so for nearly half a century.
In 1953, Hollywood film The French Line was found objectionable under the Hays Code because of Jane Russell's "breast shots in bathtub, cleavage and breast exposure" while some of her décollete gowns were regarded to be "intentionally designed to give a bosom peep-show effect beyond even extreme decolletage."
From the 1960s onward, however, greater sexual permissiveness led to increasing displays of cleavage in films, on television, and in everyday life, and low-cut dress styles became very common, even for casual wear.
Cultural aspects 
Décolletage, which is a form of the neckline, is an aspect of women's fashion. As such, popular necklines change over time and for different occasions. Contemporary women's swimsuits and bikinis may sometimes have necklines which result in the tops and sides of breasts being exposed. Likewise evening dresses may have low necklines and yet be considered elegant and sophisticated, even on formal social occasions.
Enhancing cleavage 
Many women regard breasts as an important female secondary sex characteristic, and a factor in their sexual attractiveness. They identify their femininity and sense of self with their breasts. Historically women have, in appropriate situations, displayed their breasts and femininity with pride, within the limits of community and personal standards of modesty.
Various methods have been used by women in history to accentuate breasts. For example, corsets that enhanced cleavage were introduced in the mid-16th century. By the late 18th century cleavage-enhancing corsets grew more dramatic in pushing the breasts upwards. The tight lacing of corsets worn in the 19th and early 20th centuries emphasized both cleavage and the size of the bust and hips. Ball or evening gowns especially were designed to display and emphasize the décolletage.
More recently, after corsets became unfashionable, brassieres and padding have served to project, display and emphasize the breasts. Several brassiere manufacturers, among them Wonderbra and Victoria's Secret, produce push-up and other types of bras that enhance cleavage.
Some flat-chested women feel self-conscious about their small breasts and want to improve their sexual attractiveness by seeking breast augmentation. One flat-chested woman interviewed said, "It's the absolute worst being flat. You feel as though everyone is staring at your chest for all the wrong reasons. No men call you sexy, and you definitely don't get any wolf whistles. It brings down your entire self-esteem."
In 2006, British actress Keira Knightley wore a revealing Gucci dress at the European premiere of Pirates of the Caribbean: Dead Man's Chest that displayed her skinny body and flat chest. Her breasts were digitally enlarged on the U.S. theatrical version of the poster for both that movie and for the movie King Arthur. This practice angered Knightley, who said that it "comes from market research that clearly shows that other women refuse to look at famous actresses and stars with small breasts." Later in 2006, Knightley claimed she is "not allowed to be on a magazine cover in the US without at least a C cup because it 'turns people off'."
Low or plunging necklines expose the top or space between a woman's breasts. Showing the nipples or areolae is almost always considered immodest and in some instances is viewed as lewd or indecent behavior. In Western and some other societies, there are differences of opinion as to how much cleavage exposure is acceptable in public. In contemporary Western society, the extent to which a woman may expose her breasts depends on social and cultural context. Though displaying cleavage can be permissible in many settings, it may be prohibited by dress codes in settings such as workplaces, churches, and schools, where exposure of any part of female breasts may be considered inappropriate.
In the United States, in two separate incidents in 2007, Southwest Airlines crews asked female travelers to modify their clothing, to wear sweaters, or to leave the plane because the crew did not consider the amount of cleavage displayed acceptable.
In politics 
Vera Lengsfeld, the Conservative Christian Democratic Union candidate for Berlin's Friedrichshain-Kreuzberg district, used pictures of herself and German Chancellor Angela Merkel in low-cut dresses during her political campaign. Facing a tough campaign, she posted 750 provocative campaign posters accompanied by the slogan "We Have More to Offer." In a tough campaign, she wanted to draw attention to "serious election issues." The posters had a positive impact.
"If only a tenth of them also look at the content of my policies, I will have reached many more people than I could have done with classic street canvassing." Critics of Lengsfield — including some in her own party — accuse her of stooping too low to get votes. Some critics challenged Lengsfield's feminist credentials. Maria Boehmer, head of the women's arm of the Christian Democratic Union, said Lengsfield had engaged in an outdated "sex sells" campaign: "We don't need to do things like this any more."
Lengsfield said, "It's ridiculous to suggest that I'm being sexist or antifeminist," she says. "I'm a woman and I'm proud of that." The posters were featured on Japanese television and in Brazilian and Peruvian newspapers. Some of the posters were reportedly stolen as souvenirs according to the Agence France-Presse news agency.
Merkel originally generated a lot of attention when she wore a glamorous and very low-cut dress designed by Anna von Griesham to the opening of the Oslo Opera House on 12 April 2008. The photo of Merkel's cleavage alongside Norwegian Prime Minister Jens Stoltenberg was described by the British tabloid the Daily Mail as "Merkel's Weapons of Mass Destruction" and media gossip website Gawker, had a page entitled "German Chancellor Angela Merkel not Afraid to Show Her Breastesses." Lengsfield bought the rights to use the picture of Merkel but did not seek the Chancellor's permission.
U.S. Senator Hillary Clinton and British Home Secretary Jacqui Smith drew attention for wearing low-cut blouses that revealed a small amount of cleavage, resulting in comments in the Washington Post and the New York Times.
Cleavage theory 
British zoologist and ethologist Desmond Morris theorizes that cleavage is a sexual signal that imitates the image of the cleft between the buttocks, which according to Morris in The Naked Ape is also unique to humans, other primates as a rule having much flatter buttocks.
Evolutionary psychologists theorize that humans' permanently enlarged breasts, in contrast to other primates' breasts, which only enlarge during ovulation, allowed females to "solicit male attention and investment even when they are not really fertile", though Morris notes that in recent years there has been a trend toward reversing breast augmentations. According to social historian David Kunzle, waist confinement and décolletage are the primary sexualization devices of Western costume. Also, in South Africa, Wonderbra sponsors a National Cleavage Day during which women are encouraged to display their cleavage. Art historian James Laver argued that the changing standards of revealing the cleavage is more prominent in the evening dress than the day dress of women in the Western world.
See also 
- Breast fetishism
- Cleavage enhancement
- Cupless bra
- Erotic capital
- Mammary intercourse
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|Wikimedia Commons has media related to: Cleavage (breasts)|
- "Sargent's Portraits", an article including a mention of the scandal caused by the portrayal of cleavage in John Singer Sargent's "Portrait of Madame X".
- The Great Divide, a NY Times article on the cleavage