Riot policemen launch tears gas canisters during clashes with coca growers from Yungas in La Paz, Bolivia February 21, 2017. (Photo by David Mercado/Reuters)

View of an American marine as he lies in a foxhole and whistles at a husky, one of the scouting dogs used during the landing on Guam, August 1944. (Photo by W. Eugene Smith/Time & Life Pictures/Getty Images)

Members of the New Orleans Baby Doll Ladies march during the Krewe of Zulu parade at Mardi Gras in New Orleans, Louisiana U.S., February 28, 2017. (Photo by Shannon Stapleton/Reuters)

Two women wearing bejewelled bras kiss during the annual Sydney Gay and Lesbian Mardi Gras festival in Sydney, Australia March 4, 2017. (Photo by Jason Reed/Reuters)

A dancer prays before she performs as land activists gather to commemorate the upcoming Women's Day in Phnom Penh, Cambodia, March 7, 2017. (Photo by Samrang Pring/Reuters)

A young woman employee of North American Aviation Incorporated, working over the landing gear mechanism of a P-51 fighter plane, Inglewood, California, 1942. (Photo by Alfred T. Palmer/Buyenlarge/Getty Images)

An Orchid Mantis (Hymenopus coronatus) is perched on the head of a frog hanging from a tree branch on March 15, 2017 in Padang, Indonesia. (Photo by Riau Images/Barcroft Images)

A man dressed as Darth Vader goes through the turnstile at Lermontovsky Prospekt station on the Moscow metro in Moscow, Russia on May 4, 2017. (Photo by Vyacheslav Prokofyev/TASS)