A girl attends Friday prayers in front of an army tank in Tahrir Square in Cairo February 18, 2011. Five years ago thousands of protesters took to the streets demanding the end of the 30-year reign of President Mubarak as Egypt became the second country to join the Arab Spring. After weeks of clashes, strikes and protests across Egypt, Mubarak resigned on February 11, 2011. (Photo by Suhaib Salem/Reuters)

A young Afghan vendor waits for customers to buy sheep's heads at a roadside stall at the busy market in Kabul on November 29, 2015. (Photo by Wakil Kohsar/AFP Photo)

Beach Policeman, Potomac River, 1922. (Photo by National Photo Company/Colorized by Patty Allison)

A US Marine feeds an orphan kitten found after a heavy mortar barrage near “Bunker Hill” during the Korean War. (Photo by Sgt Martin Riley/Getty Images). 1953

Two brown bear cubs born at Whipsnade Zoo. (Photo by Evening Standard/Getty Images). 1970

A Leyland lorry during the railway strike, “we supply both milk and baby” is chalked on the bonnet. (Photo by A. R. Coster/Topical Press Agency/Getty Images). 3rd October 1919

Father Christmas reading with three young children. (Photo by Spencer Arnold/Getty Images). Circa 1915

Festival goers wear Australia day attire at Big Day Out 2012 at the Sydney Showground on January 26, 2012 in Sydney, Australia. (Photo by Mark Metcalfe/Getty Images)