Matt Cardle, who is the winner of the most recent TV singing competition on the X Factor, flirts with an unknown woman in the Lobby of a Hotel in London. Whenever we walk away from another, out of a room, down a hall or across the street - they around us will check out our butts. This happens largely on an unconscious level and is more scrutinizing when it involves the opposite sex. Women are aware of this phenomenon more than men - although it's still occurs mostly subconsciously. Did you ever notice that before a woman gets out of her car, walks into a store/restaurant or stands up at a meeting - regardless of her size or shape, she straightens her clothes, particularly those covering her derrière? In both men and women, the size and shape of the buttocks are indicative of overall health and vitality - and thus the potential as a mate - and this biology is hardwired into our brains.