Young girls carry containers filled with drinking water beside the railway station in Agartala, India, April 20, 2016. (Photo by Jayanta Dey/Reuters)

Girls rest on stairs at the China Digital Entertainment Expo and Conference (ChinaJoy) in Shanghai, China July 27, 2017. (Photo by Aly Song/Reuters)

Girls ride on a donkey cart with grass for animals on the outside of Nangarhar province, Afghanistan May 19, 2015. (Photo by Reuters/Parwiz)

A girl reacts during a rehearsal for the Independence Day military parade in central Kiev, Ukraine, August 19, 2016. (Photo by Valentyn Ogirenko/Reuters)

Students celebrate their A-level results at King Edward VI High School for Girls in Birmingham, England on August 18, 2016. The proportion of top grades achieved by A-level students across the UK has fallen for a fifth year in a row, and girls have caught up with boys in attaining A* grades. (Photo by Joe Giddens/PA Wire)

A young Hindu girl sits for a ceremony where she and other girls are worshipped as “Kumari”, or living goddess, during Ram Navami festival, at a temple in Kolkata, India, Saturday, March 28, 2015. Ram Navami marks the birth of Hindu God Rama. (Photo by Bikas Das/AP Photo)

A woman runs through the early morning mist on Hampstead Heath on September 30, 2011 in London, England. Much of the UK is enjoying a spell of unseasonably hot weather which is expected to last into next week. (Photo by Dan Kitwood/Getty Images)

American artists have drawn criticism after making stunning, intricate sculptures by pouring hot liquid aluminium into anthills.