Barack Obama, who came into office in 2009 at the bright and sprightly age of 47, has been aging in front of our eyes. Over the past nearly seven years, the president has gone from dark-haired to salt-and-pepper to salt-and-darker-salt. Recently, he spilled the beans on his evolving looks."The first thing I want from young people is to stop calling me old," he joked to a Cambodian student, the BBC reports. But he defended his choice to grow old gracefully, telling the crowd that he’s looking his age naturally. “I don’t dye my hair — and a lot of world leaders do.”But that’s as far as he would go in the gentle ribbing on his international colleagues. “I won’t say who,” he demurred, “but their barbers know, their hairdressers.” Come on, Mr. President, not even a hint? We promise not to say who told us.