A mahout splashes water on his elephant in the river Sabarmati on a hot summer day in Ahmedabad, India, May 20, 2015. (Photo by Amit Dave/Reuters)

Saraa Mutawkil (R), 18, practises boxing at Al Rabie club in Omdurman May 10, 2016. (Photo by Mohamed Nureldin Abdallah/Reuters)

A Tibetan woman with horses in a remote area of the Yushu Autonomous Prefecture of the Tibetan Plateau on May 31, 2016. (Photo by Giulia Marchi/The Washington Post)

A child sleeps under a table at the Jorkpan market in Sinkor district in Monrovia, Liberia on May 2, 2016. (Photo by Marco Longari/AFP Photo)

A rainbow is seen near a cloud south of Corvallis, Ore., Monday, May 19, 2014. (Photo by Andy Cripe/AP Photo/The Corvallis Gazette-Times)

A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

A lizard is seen hunting for fish during the daytime on May 04, 2017 in West Sumatra, Indonesia. (Photo by Riau Images/Barcroft Images)

Model Ashley Graham is seen walking in Soho on May 9, 2017 in New York City. (Photo by Raymond Hall/GC Images)