Humboldt Penguins swim in their pool as a keeper looks on through a spherical window during the annual stocktake press preview at London Zoo in Regents Park in London Monday, January 4, 2016. A requirement of ZSL London Zoo's license, the annual audit takes keepers a week to complete and all of the information is shared with zoos around the world via the International Species Information System, where it's used to manage the worldwide breeding programmes for endangered animals. (Photo by Alastair Grant/AP Photo)

A Munduruku Indian child is pictured at the Planalto Palace, where a meeting with Minister of the General Secretariat of the Presidency of Brazil Gilberto Carvalho was being held with other Munduruku Indians, in Brasilia, June 4, 2013. President Dilma Rousseff's government sought on Tuesday to defuse mounting conflicts with indigenous groups over its decision to stop setting aside farm land for Indians and plans to build more hydroelectric dams in the Amazon. The government flew 144 Munduruku Indians to Brasilia for talks to end a week-long occupation of the controversial Belo Monte dam on the Xingu river, a huge project aimed at feeding Brazil's fast-growing demand for electricity. (Photo by Ueslei Marcelino/Reuters)

Maudy – Kalulushi, Zambia. Maudy was born in a hut in a small village close to Kalulushi, in Zambia. She grew up playing in the street with the other children in the village, who all attend the same school, where students ages 3 to 10 years old are in the same class. The village has no shops, restaurants or hotels, and just a few children are lucky enough to have toys. Maudy and her friends found a box full of sunglasses on the street, which quickly became their favorite toys. “Toy Stories” project. (Photo and caption by Gabriele Galimberti)

Military vehicles surround a wreckage of a trolleybus, in Volgograd, Russia, Monday, December 30, 2013. A bomb blast tore through a trolleybus in the city of Volgograd on Monday morning, killing at least 10 people a day after a suicide bombing that killed at least 17 at the city's main railway station. Volgograd is about 650 kilometers (400 miles) northeast of Sochi, where the Olympics are to be held. (Photo by Denis Tyrin/AP Photo)

Liu Chunxia, a supporter of Xu Zhiyong, one of China's most prominent rights advocates, is detained by policemen while she gathers with other supporters nearby a court where Xu's trial is being held in Beijing January 22, 2014. When dozens of activists unfurled banners across the country last March and April calling for officials to disclose their assets, they did so at the urging of one of China's most prominent rights advocates, Xu Zhiyong. Xu, 40, stands trial on Wednesday on a charge of “gathering a crowd to disturb public order” punishable by up to five years in prison. His case will almost certainly spark fresh criticism from Western governments over Beijing's crackdown on dissent. (Photo by Kim Kyung-Hoon/Reuters)

Li Tingting, second from right, laughs as she is lifted off the ground by her wife Teresa Xu, right, outside of a beauty salon where the two were preparing for their wedding as clerks from an adjacent shop look on in Beijing, Thursday, July 2, 2015. Li, a 25-year-old prominent women's rights activist who was released from detention in April, held the wedding ceremony with her partner Teresa on Thursday and announced their marriage in an effort to push for LGBT (lesbian, gay, bisexual, and transgender) rights in China. (Photo by Mark Schiefelbein/AP Photo)

Austrian artist Erwin Wurm (R) stands next to an extra of his participation sculpture “Hose lueften, Haende hoch” (air out pants, hands high) at the garden of the Staedel Museum, in Frankfurt am Main, Germany, 06 May 2014. The series “Wurm: One Minute Sculptures” include painted or written instructions tell the person what they have to do and where for 60 seconds. The exhibition runs from 07 May to 13 July. (Photo by Arne Dedert/EPA)

A German Air Force Officer sits astride a dead boar outside a house where he is stationed near the Western Front, in this 1918 handout picture. This picture is part of a previously unpublished set of World War One (WWI) images from a private collection. The pictures offer an unusual view of varied and contrasting aspects of the conflict, from high tech artillery to mobile pigeon lofts, and from officers partying in their headquarters to the grim reality of life and death in the trenches. The year 2014 marks the centenary of the start of the war. (Photo by Reuters/Archive of Modern Conflict London)