British zoologist Desmond Morris’ famous theory on the appeal of cleavage (I have a few theories of my own) is that it’s a sexual signifier of the cleft of the buttocks, known in less refined circles as the ass crack. Traditionally considered an unattractive sign of sloppiness, plumber’s butt is no longer a blue-collar syndrome, but naughty tease on par with the greatest sideboob. Anal cleavage has gained popularity this century with the rise of low-cut jeans (or should I say descent), the emergence of the whale tale, and most recently, posterior-revealing lingerie. Assless panties, if you will. Seven years ago, The Sun declared that “ass is the new tits,” and this new breed of underwear finally proves them right.