“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

Models prepare backstage before a presentation as part of Fashion Weekend Plus Size Summer 2015 collection show in Sao Paulo, July 25, 2015. (Photo by Nacho Doce/Reuters)

Beauty contestants prepare backstage before the fashion show of Miss Tiffany's Universe 2016 transvestite contest in Bangkok, Thailand, April 20, 2016. (Photo by Athit Perawongmetha/Reuters)

Revellers dressed as zombies take part in an enactment of the running of the bulls a day before the start of the San Fermin festival in Pamplona, northern Spain, July 5, 2016. (Photo by Eloy Alonso/Reuters)

Snow blows off the Svalbard Global Seed Vault before being inaugurated at sunrise, Tuesday, February 26, 2008. (Photo by John McConnico/AP Photo)

Models get prepared backstage before Wagner Kallieno Winter Collection 2016 show during Sao Paulo Fashion Week in Sao Paulo, Brazil, October 23, 2015. (Photo by Paulo Whitaker/Reuters)

Residents of the Brussels suburb of Molenbeek are searched by police before taking part in a memorial gathering to honour the victims of the recent deadly Paris attacks, in Brussels, Belgium, November 18, 2015. (Photo by Yves Herman/Reuters)

Models get ready backstage before the presentation of the Etam Live Show Lingerie at the Fashion Week in Paris, France, September 27, 2016. (Photo by Charles Platiau/Reuters)