Riot police fire tear gas during a protest by supporters of Dilma Rousseff in Sao Paulo, Brazil August 31, 2016. (Photo by Paulo Whitaker/Reuters)

A ballet dancer stretches backstage during Nacho Duato's “The Nutcracker” at the Mikhailovsky Theatre in St. Petersburg, Russia November 21, 2015. For theatregoers in St Petersburg, Nacho Duato's “The Nutcracker” demonstrates the global appeal of a Christmas classic. When the curtain rises at the Mikhailovsky Theatre, among the oldest opera and ballet houses in Russia, it's the culmination of hundreds of hours of toil and sweat by dancers, costume makers, set designers and musicians playing the famous score by Pyotr Tchaikovsky. (Photo by Grigory Dukor/Reuters)

Anti-balaka militia originally sprang up to protect the Christian population of the Central African Republic, but now stand accused of human rights abuses themselves. Last month, the African Union branded militia targeting Muslims in Central African Republic as “terrorists” and said they would be treated as enemy combatants, a day after killing a Congolese peacekeeper and amid deepening international frustration at continuing violence in the impoverished and landlocked country. Photo: A female member of the anti-balaka, a Christian militia, patrols with other militiamen outside village of Zawa April 8, 2014. (Photo by Goran Tomasevic/Reuters)

Marshalls try to get their hands on a streaker as golfers Michael Campbell of New Zealand and Paul McGinley of Ireland play the World Match Play final at Wentworth golf club some 20 miles west of London, 18 September 2005. Campbell won the title at the 17th hole. (Photo by Odd Andersen/AFP Photo)

A British fan waits to enter the Malmo arena ahead of the finals of the 2013 Eurovision Song Contest on May 18, 2013. (Photo by John MacDougall/AFP Photo)

Six-month old female liliger cub Eva plays in snow with her mother Zita in the Zoo in Novosibirsk, Russia, Thursday, December 5, 2013. The cub's mother is Zita, a liger – half-lioness, half-tiger, and its father is a lion, Sam. (Photo by Ilnar Salakhiev/AP Photo)

Summit, an Australian shepherd, makes a leaping catch of a frisbee at the pet trade fair (Heimtiermesse) at Velodrom on November 2, 2012 in Berlin, Germany. Exhibitors are showing the latest trends in collars, snacks and other accessories for cats, dogs and other household pets. (Photo by Sean Gallup)

A man irrigating a rice paddy field using a traditional method. (Photo by Fox Photos/Getty Images). Japan, circa 1938