An animal rights activist, wrapped in packaging labelled “carne humana” (human meat), participates in a protest against meat consumption to promote vegetarianism in central Barcelona, in Spain, May 22, 2016. (Photo by Albert Gea/Reuters)

Guests on the terrace of Shepheard's Hotel, Cairo, circa 1940. (Photo by Hulton Archive/Getty Images)

English comic actor and director Charlie Chaplin (Sir Charles Spencer Chaplin, 1889–1977) seated on straw bales during the filming of “The Circus” with his leading lady Merna Kennedy (1908–1944). (Photo by Margaret Chute/Getty Images). 1928

Aerial acrobat Schindler, notorious for his foolhardy stunts, practising one of his tricks listing out of the vertical, from a Klemp plane piloted by Richard Perlia. (Photo by General Photographic Agency/Getty Images). Circa 1927

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

New York City Deputy Police Commissioner John A. Leach, right, watching agents pour liquor into sewer following a raid during the height of prohibition, circa 1921. (Photo by Tom Marshall/Mediadrumworld)

Tibetan monks dressed as demons attend the Beating Ghost festival at the Yonghe Temple, also known as the Lama Temple, in Beijing on March 19, 2015. The Beating Ghost festival, or Da Gui festival in Chinese, is an important ritual of Tibetan Buddhism and is believed to expel evil spirits and shake off troubles. (Photo by Wang Zhao/AFP Photo)

A woman dancing on the Sphinx. A pyramid can be seen in the background. (Photo by Fox Photos/Getty Images). 1928