Bonobo apes, primates unique to Congo and humankind's closest relative, groom one another at a sanctuary just outside the capital Kinshasa, Congo on October 31, 2006. (Photo by Finbarr O'Reilly/Reuters)

A group of men play Myanmar's traditional sport of chinlone in Naypyitaw, Myanmar, Friday, November 18, 2016. (Photo by Aung Shine Oo/AP Photo)

A man stands on a mountain summit as he looks over the Inntal valley in the western Austrian village of Gnadenwald, Austria on July 18, 2017. (Photo by Dominic Ebenbichler/Reuters)

Shortlisted: “Two big eyes” by Miao Yong (Zejiang province, China). Damselflies look over the leaves. “I was photographing insects in a park near my home when suddenly I found two damselflies in the grass. They kept flying and it was very difficult to focus until suddenly they parked behind a leaf”. (Photo by Miao Yong/2017 Royal Society of Biology Photographer of the Year)

This photo taken on August 7, 2016 shows mahjong enthusiasts playing mahjong under water in a swimming pool at a diving club in the Chinese city of Chongqing. Only participants with proper diving certification were allowed to take part in the underwater competition. (Photo by AFP Photo/Stringer)

A woman, covered in mud, dances during the traditional “Bloco da Lama” or “Mud Block” carnival party, in Paraty, Brazil, Saturday, February 14, 2015. Revelers in the seaside colonial town threw themselves into deposits of black, mineral-rich slime, emerging covered head-to-toe in the sludge. Bikinis and trunks disappeared beneath the mud, which highlights both gym-pumped pectorals and beer-fed guts. (Photo by Leo Correa/AP Photo)

Beach Policeman, Potomac River, 1922. (Photo by National Photo Company/Colorized by Patty Allison)