A man drinks at a "colored" water cooler in a streetcar terminal in Oklahoma City, July 1939. (Photo by Reuters/Library of Congress)

A patient buried in the hot sand looks out from under a shade that protects his face from the sun in Siwa, Egypt, August 12, 2015. In the searing heat of summer in western Egypt, at the hottest time of the day, sufferers of rheumatism, joint pain, infertility or impotence lie buried neck-deep in the sand of Siwa near Dakrour Mountain. Locals say taking a sand bath is a natural therapy with powers to cure many medical conditions. (Photo by Asmaa Waguih/Reuters)

This photo taken on April 16, 2014 shows ethnic Kayan women wearing traditional clothes and bronze rings around tbeir neck in Panpet village, Demoso township in Kayah state, eastern Myanmar. Some ethnic Kayan women, also known as Padaung, begin wearing the bronze rings on their neck and legs from a young age. Usually they start wearing six to ten rings when they are five to ten-years-old and then they put on one more ring a year for years after then. (Photo by Ye Aung Thu/AFP Photo)

A man in “Red Army” garb hits the pavement during a simulated attack during a re-staging of part of the Long March in Jinggangshan September 14, 2017. The scene brings alive an extraordinary chapter in China's history that established the supremacy of Chairman Mao Zedong and the Communist Party. Deep in the mountains of Jinggangshan in the southeastern province of Jiangxi, a classroom of bank tellers participates in an ideological boot camp that plays into Chinese President Xi Jinping's drive to further consolidate his grip on power. (Photo by Thomas Peter/Reuters)

Long-tailed mayflies (Palingenia longicauda) at Tisza river near Tiszainoka 135km (84 miles) southeast of Budapest, June 23, 2013. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

A devotee is carried around town in a vessel as part of rituals during the Swasthani Bratakatha festival at Thecho in Lalitpur, Nepal, February 19, 2016. During the month long festival, devotees recite one chapter of a Hindu tale daily from the 31-chapter sacred Swasthani Brata Katha book that is dedicated to God Madhavnarayan and Goddess Swasthani, alongside various other gods and goddess and the miraculous feats performed by them. (Photo by Navesh Chitrakar/Reuters)

A polar bear fast asleep at London Zoo. (Photo by Fox Photos/Getty Images). 1961