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)

Getting her tongue pierced was “exciting and scary” says a teen who succumbed to pressure from her best friend in Austin, Texas, February 22, 2008. This image is featured in National Geographic's exhibition “Women of Vision: National Geographic Photographers on Assignment”, on view at the Palm Beach Photographic Centre, Jan. 22 - Mar. 22, 2015. (Photo by Kitra Cahana/National Geographic)

Coca growers chew coca leaves during a celebration for the reincorporation of Bolivia to the UN Convention Against Illicit Traffic in Narcotic Drugs in La Paz on January 14, 2013. “The coca leaf is not any more seen as cocaine (...), it is a victory of our identity” said Bolivian President Evo Morales. (Photo by Jorge Bernal/AFP Photo)

In this November 9, 2014 photo, a man sits on the rope holding his bull by the neck as he waits to enter it in a bull fight in Leogane, Haiti. The obscure Haitian practice of fighting bulls is brutal like a cock or dog fight, but on a larger scale. A casual pastime for some rural men, it is serious business for others looking to pay their children's school fees or even buy a car. (Photo by Dieu Nalio Chery/AP Photo)

Men at work at the Cardiff Institute, making huge baskets, unique in size and construction, for loading oil cake in South Africa. (Photo by Maeers/Getty Images). 1938

Winston Leonard Spencer Churchill (1874–1965), British Statesman and Prime Minister inspecting the boys from a training ship. (Photo by Hulton Archive/Getty Images). 1912

In this Friday, January 6, 2017, photo, a North Korean woman working at the Kim Jong Suk Silk Mill looks up from her workstation in Pyongyang, North Korea. The silk mill, named after North Korean leader Kim Jong Un's grandmother, is where 1,600 workers – mostly women – sort and process silkworms to produce silk thread that officials at the Pyongyang factory say is made into roughly 200 tons of silk a year. (Photo by Wong Maye-E/AP Photo)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)