A hippopotamus performs during a show at the circus in Krasnoyarsk, Siberia, Russia, July 7, 2016. (Photo by Ilya Naymushin/Reuters)

Princess Elizabeth with her husband Prince Philip Duke of Edinburgh and their children Prince Charles and Princess Anne. (Photo by Keystone/Getty Images). August 1951

A Cambodian girl goes through the garbage dump looking for things to recycle in order to survive July 26, 2003 in Phnom Penh, Cambodia. Rampant corruption in this impoverished country has lead to extreme poverty with many Cambodians living below the poverty line. (Photo by Paula Bronstein/Getty Images)

A pornographer posing as a fashion photographer sets up a photoshoot with an unsuspecting model, in the hope of getting some illicit footage. He suggests she try wearing something a little more suggestive. (Photo by Pryor/Three Lions/Getty Images). Circa 1955

The Queen Elizabeth Tower (Big Ben) is reflected in a puddle as a cyclist rides by in London, on 27 June 2016. Britain began preparations to leave the European Union on Monday but said it would not be rushed into a quick exit, as markets plunged in the wake of a seismic referendum despite attempts to calm jitters. (Photo by Leon Neal/AFP Photo)

A Palestinian youth demonstrates his parkour skills on a street in Gaza City, January 15, 2016. (Photo by Suhaib Salem/Reuters)

This picture taken on January 26, 2016 shows a monkey sitting on a bench during rehearsal at a monkey training school in a zoo in Dongying, eastern China's Shandong province. Shows featuring performing simians, popular in China and throughout Asia, are expecting a boost in the Lunar New Year of the monkey, which begins on February 8. But they are facing a growing backlash from Chinese people concerned about animal welfare. (Photo by Wang Zhao/AFP Photo)

Eurocopter's X³ high-speed hybrid helicopter demonstrator performs, September 6, 2010. The Eurocopter X³ (X-Cubed) is an experimental high-speed compound helicopter developed by Eurocopter (now Airbus Helicopters). A technology demonstration platform for Eurocopter “high-speed, long-range hybrid helicopter” or H³ concept, the X³ achieved 255 knots in level flight on 7 June 2013, setting an unofficial speed record for a helicopter. (Photo by Reuters/HO/Eurocopter/Penna)