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

A woman smokes marijuana during the annual 4/20 marijuana rally on Parliament Hill in Ottawa, Ontario, Canada, April 20, 2017. (Photo by Chris Wattie/Reuters)

Warriors from the Suri tribe in Ethiopia still stage the savage “Donga” battles – even after many fighters have been died from their injuries. Donga stick fights take place after the harvests, the Surmas count days owing to knots on a long stem of grass or jags on the trunk of a tree dedicated to that specific use. Here: A tribeswoman sporting a huge lip plate and wearing a skinned animal carcass on her head. (Photo by Eric Lafforgue/Exclusivepix Media)

Sport category, winner: Yuan Peng. Liu Bingqing and Liu Yujie are twin sisters who have studied and trained in gymnastics since their early childhood in Jining, China. (Photo by Yuan Peng/Sony World Photography Awards)

This picture taken on April 12, 2017 shows men carrying bamboo through a forest near Dashan village near the city of Lin'an, Zhejiang Province. Lin'an is in a area of eastern Zhejiang province whose rich bamboo forests are estimated to supply up to two-thirds of China's bamboo shoots, plus a range of other products derived from the fast-growing plant that are produced both for domestic and overseas markets. (Photo by Johannes Eisele/AFP Photo)

In this Sunday, March 11, 2017 photo, children fight in a boxing ring in Chitungwiza, Zimbabwe. Zimbabwean boys as young as 10 hurry every weekend to a boxing ring whose nickname, Wafa Wafa, in the local Shona language suggests that whoever enters will be lucky to come out alive. (Photo by Tsvangirayi Mukwazhi/AP Photo)

Riot police officers in position to crack down on demonstrators during a protest against Venezuelan President Nicolas Maduro, in Caracas on April 20, 2017. Venezuelan riot police fired tear gas Thursday at groups of protesters seeking to oust President Nicolas Maduro, who have vowed new mass marches after a day of deadly unrest. Police in western Caracas broke up scores of opposition protesters trying to join a larger march, though there was no immediate repeat of Wednesday's violent clashes, which left three people dead. (Photo by Juan Barreto/AFP Photo)

In this April 20, 2017 photo, a woman is aided by fellow demonstrators after falling, overcome by tear gas, during anti-government protests in Caracas, Venezuela. Tens of thousands of protesters asking for the resignation of President Nicolas Maduro flooded the streets again, one day after three people were killed and hundreds arrested in the biggest anti-government demonstrations in years. (Photo by Ariana Cubillos/AP Photo)