Cleavage is the cleft created by the partial exposure of a woman's breasts, especially when exposed by low-cut clothing. The neckline of a garment that exposes cleavage is known as décolletage (or décolleté in current French). Intermammary sulcus or intermammary cleft are the terms adopted by the International Federation of Associations of Anatomists for the area of cleavage between the breasts not including the breasts.
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." Popular 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 The Naked Ape is also unique to humans, other apes as a rule having much flatter buttocks.
In the United States there is controversy over how much cleavage exposure is acceptable in public. In two separate incidents in 2007 Southwest Airlines crews had asked travelers to modify their outfits, to wear sweaters, or to deplane. In the second case, dealing with two sorority sisters, the women were asked to leave because of their arrogance and lack of manners.
Exposure of the underside of the breast, such as below an extremely short crop top, is known as neathage, Australian cleavage, reverse cleavage or underboob. When the lateral aspects of the breasts are uncovered, it is known as side cleavage or sideboob.
On the first Friday of every April in South Africa, brassiere marketer Wonderbra sponsors a "National Cleavage Day". It is a day for women to celebrate not only their cleavage, but their independence.National Cleavage Day - Wonderbra
This article is based on "Cleavage (breasts)" from the free encyclopedia Wikipedia (http://en.wikipedia.org). It is licensed under the terms of the GNU Free Documentation Licencse. In the Wikipedia you can find a list of the authors by visiting the following address: http://en.wikipedia.org/w/index.php?title=Cleavage+%28breasts%29&action=history