Split-view of a killer whale at sunrise off the coast of Northern Norway. At least half of the world’s killer whale populations are doomed to extinction due to pollution of the oceans, a new study says. (Photo by Audun Rikardsen/Science)

A student of the Krasnoyarsk choreographic college prepares backstage before a dress rehearsal of a performance by graduates of the college at the State Theatre of Opera and Ballet in Russia's Siberian city of Krasnoyarsk, Russia, May 12, 2015. The annual performance showcases the work of students from across Russia who study or have studied at the well-known school. (Photo by Ilya Naymushin/Reuters)

Young Ian Archibald ponders the consequences of a complex critical study of beauty contestants during the Miss TV Times finals in London. (Photo by Central Press/Getty Images). 30 July 1971

Emily Hasler, an English Heritage employee at Charles Darwin's home, Down House, cleans a rabbit bone in his old study on April 2, 2011 in Downe, England. Staff at the house are cleaning and preparing the property ahead of their peak visitor season. The house contains the study where Darwin wrote “On the Origin of Species”, as well as family rooms and an extensive garden that inspired the renowned scientist. (Photo by Oli Scarff/Getty Images)

Sport category, winner: Yuan Peng. Liu Bingqing and Liu Yujie are twin sisters who have studied and trained in gymnastics since their early childhood in Jining, China. (Photo by Yuan Peng/Sony World Photography Awards)

Marine biologist Simon Pierce, who studies whale sharks, happened to be in the right place at the right time to capture amazing photo off Cancun, Mexico. (Photo by Simon Pierce/Mercury Press/Caters News)

A preparatory model of the Imperial State Crown of India worn in 1911 by King George V stands next to original ledgers dating from 1735 in Garrard's flagship store in Mayfair on April 6, 2011 in London, England. Garrard is the world's oldest jewellers having been founded by George Wickes in 1735 and soon after appointed as goldsmith to the Prince of Wales. For over 160 years Garrard held the title of Crown Jeweller, bestowed by Queen Victoria in 1843, Garrard have served six successive monarchs. They have produced several royal crowns as well as the engagement ring presented to Kate Middleton by Prince William and formerly Princess Diana's engagement ring. (Photo by Oli Scarff/Getty Images)

Iranian Kurdish female members of the Freedom Party of Kurdistan (PAK) hold a position on November 6, 2016 in an area near the town of Bashiqa, some 25 kilometres north east of Mosul, during an operation against Islamic State (IS) group jihadists to retake the main hub city. (Photo by Safin Hamed/AFP Photo)