Chinese butchers catch a pig to slaughter on January 31, 2005 in Jinzhai County, Anhui Province, China. (Photo by Cancan Chu/GettyImages)

A smokejumper leaps from an airplane during a training flight above Winthrop, Washington, U.S., June 30, 2016. On a 100-degree day in early June, eight experienced firefighters did sit-ups in a semicircle training to parachute into a wildfire. Better known as “rookie candidates”, they were determined to make it through the five-week program at North Cascades Smokejumper Base in Winthrop, Washington, where the first experimental jumps occurred in 1939. (Photo by David Ryder/Reuters)

A woman waits at a polio immunisation health centre, in Maiduguri, Borno State, Nigeria, August 29, 2016. Nigeria's military has liberated large swathes of land from Boko Haram but a ride with an army convoy, all guns firing for fear of ambush, shows how far the northeast is from normality after a brutal Islamist insurgency that has displaced millions. (Photo by Afolabi Sotunde/Reuters)

Recording artists Demi Lovato (L) and Iggy Azalea perform on the Pepsi Stage, during the 2015 MTV Video Music Awards, at The Orpheum Theatre on August 30, 2015 in Los Angeles, California. (Photo by Frederick M. Brown/Getty Images for MTV)

A sculptural artwork depicting former Chilean dictator Augusto Pinochet and headless presidents shot by a hooded high school student (not pictured) is seen at the Contemporary Art Museum in Santiago, December 2, 2014. The artwork, part of the “El ladrillo angular” (The angular brick) exhibition, portrays a student fighting against the ongoing continuity of dictatorship because of a political and economic system which has been impossible to destroy, according to “Papas Fritas” the artwork's creator. (Photo by Ivan Alvarado/Reuters)

In this May 4, 2014 photo, a miner holds an amalgam of mercury and gold he mined after working a 28-hour shift at an illegal gold mining process, in La Pampa, in Peru's Madre de Dios region. Thousands of artisanal gold miners sweat through the long shifts and endure, for a few grams of gold, the perils of collapsing earth, limb-crushing machinery and the toxic mercury used to bind gold flecks. (Photo by Rodrigo Abd/AP Photo)

A female member of the Ahbab Al-Mustafa Battalion holds a gun as she undergoes military training in Aleppo's Salaheddine district, June 24, 2013. (Photo by Muzaffar Salman/Reuters)

An Australian athlete does a handstand as she arrives with her teammates during the opening ceremony for the Commonwealth Games 2014 in Glasgow, Scotland, Wednesday July 23, 2014. (Photo by Frank Augstein/AP Photo)