Historically, the beard was worn as a disguise - a simple way for men to change their faces without resorting to wearing make-up. It's not unusual for young men to try to cultivate growth in an attempt to look older (see Aaron Johnson's bewhiskered baby face, below), to appear more masculine, to command respect or to rebel. Even the best-looking men in the world get tired of being so damn clean-cut all the time. Take Brad Pitt, who in March 2010 grew an outrageous goatee and moustache that was still making an appearance, albeit trimmed, at Cannes this year. Brad told The Sun: 'I grew the beard out of boredom. No other reason than that.'