A Hollywood censor borrowed a geology word and gave fashion the term cleavage
Geologists coined cleavage in the early 1800s for the way crystals and rocks split along neat planes. Then, reviewing Jane Russell's costumes in the 1943 film The Outlaw, the Hollywood censor Joseph Breen used it for the gap between the breasts, and the word never went back to the rocks.
Breen ran the Production Code Administration, the office that policed what American films could show. He applied the word to several British films too, including The Wicked Lady, and in August 1946 Time magazine explained it to readers as an industry trade term for the shadowed hollow dividing an actress's bosom. The root is the old verb cleave, to split. Before then, educated English speakers had said decolletage, a French word from a verb meaning to bare the neck, which strictly describes the neckline rather than the anatomy. Anatomists call the hollow itself the intermammary cleft.
How much of it may be shown has swung wildly. Low necklines flourished in mid-Tang China, Elizabethan England and post-revolutionary France, but were suppressed in Victorian England and again in the flapper era. Early English Puritans flattened the chest with tight bodices, and in the 17th century Spaniards reportedly strapped lead plates across girls' chests to stop them developing. Through the Middle Ages and into the Renaissance, the stomach rather than the breasts was often the main symbol of a woman's sexuality. Hollywood stars and push-up and underwired bras brought cleavage roaring back in the 1950s, a fascination strongest in the United States, and by the early 2020s its dramatisation was fading along with the big lingerie brands.
The attraction is far from universal. In their 1951 book Patterns of Sexual Behavior, Clellan Ford and Frank Beach reported that only 13 of 130 cultures surveyed saw breasts as sexually attractive. A documentary maker recalled an anthropologist in Mali, where women commonly go bare-chested while nursing, whose hosts were startled to hear that American men found breasts fascinating. The evolutionary psychologist David Buss judged Americans probably the most extreme in treating the breast as a sexual signal.
In India, traditional dress has often shown more midriff than chest, though by the 2010s low necklines were read as a fashion statement.
Source: Cleavage (breasts)
