A Turkana boy herds cows as he carries a rifle in north western Kenya near the town of Kibish inside the Turkana region of the Ilemy Triangle September 26, 2014. The Turkana people have historically clashed over ethnic differences and precious resources such as fishing, pasture and fresh water with other tribes bordering their territory, such as the Dassanach from southern Ethiopia. (Photo by Goran Tomasevic/Reuters)

For centuries the Highlands peoples of Papua New Guinea fought over land, women and pigs. Sorcery and battle skills could elevate a clan to Bigmanship, where the bigger the “presentation”, the bigger the man. Clans therefore would paint their bodies and create fearsome masks as part of their psy. Here: These are the terrifying tribe of “mudmen” from a remote part of Papua New Guinea. (Photo by Jeremy Hunter/Exclusivepix Media)

Revellers with their bodies and faces painted attend the "Zombie Walk" parade in Sao Paulo, Brazil, November 2, 2015. (Photo by Paulo Whitaker/Reuters)

A burning tree is seen during a fire in an area of the Amazon rainforest in Itapua do Oeste, Rondonia State, Brazil, September 11, 2019. (Photo by Bruno Kelly/Reuters)

A model walks the runway during the Neon Sao Paulo Fashion Week Spring/Summer 2013 Collections Show on June 14, 2012 in Sao Paulo, Brazil. (Photo by Fernanda Calfat)

Models present creations from Vislumbre during Fashion Weekend Plus Size in Sao Paulo, Brazil, March 19, 2017. (Photo by Paulo Whitaker/Reuters)

Competitors pose backstage during the Arnold Classic South America bodybuilding event in Sao Paulo, Brazil, April 22, 2017. (Photo by Nacho Doce/Reuters)

A girl reacts as she is tattooed during the third International Tattoo Week Rio 2016 festival in Rio de Janeiro, Brazil, January 22, 2016. (Photo by Pilar Olivares/Reuters)