Nazi dictator Adolf Hitler greets supporters at a May Day gathering in the Olympic Stadium, Berlin. (Photo by Keystone). 1st May 1938

Armed women attend a rally to show support to the Houthi movement in Sanaa, Yemen January 13, 2018. (Photo by Khaled Abdullah/Reuters)

A supporter of the Houthi movement attends a rally marking the birth anniversary of Prophet Mohammed, in Sanaa, Yemen December 11, 2016. (Photo by Khaled Abdullah/Reuters)

Women loyal to the Houthi movement parade to show support to the movement in Sanaa, Yemen January 17, 2017. (Photo by Khaled Abdullah/Reuters)

A female hippopotamus named “Mali”, which means Jasmine, eats fruits arranged to look like a cake during her 50th birthday celebration at Dusit Zoo in Bangkok, Thailand September 23, 2016. (Photo by Chaiwat Subprasom/Reuters)

Buns are stamped the Chinese characters “Ping An”, meaning peaceful and safe, inside a bakery, at Hong Kong's Cheung Chau island, China May 17, 2015, ahead of the upcoming Bun Festival on May 25. The festival celebrates the islanders' deliverance from famine many centuries ago and is meant to placate ghosts and restless spirits. (Photo by Tyrone Siu/Reuters)

Drastic inequality is by no means new in New York. Jacob A. Riis was called a muckraker after he chose to spotlight the city’s poverty at the turn of the 20th century by photographing it. Here: Sweatshop in Hester Street, 1889-1890. (Photo by Jacob A. Riis/Museum of the City of New York, Gift of Roger William Riis)

A reveller holds her dog dressed in costume, during the Rio Dog Carnival, known as the Blocao – with “bloco” meaning street party and “cao” dog, during pre- carnival celebrations at Copacabana beach in Rio de Janeiro, Brazil, on February 19, 2017. (Photo by Yasuyoshi Chiba/AFP Photo)