Girls Drinking From Breasts Cleavage

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. Several brassiere manufacturers, among them Wonderbra and Victoria's Secret, have become known for marketing products that enhance the décolletage. On the first Friday of April in South Africa, Wonderbra sponsors a National Cleavage Day. According to social historian David Kunzle, waist confinement and the décolletage are the primary sexualization devices of Western costume. 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.