A competitor shouts as he takes part in the “Tough Guy” adventure race near Wolverhampton, central England, on January 29, 2017. The Tough Guy event, which is being held for the final time in its 30th year, challenges thousands of competitors to run a gruelling course whilst negotiating over 200 obstacles including: water, fire, and tunnels. (Photo by Oli Scarff/AFP Photo)

Egyptian bootblacks cleaning a European's shoes in Cairo. (Photo by Hulton Archive/Getty Images). Circa 1870

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

Figure Skating, ISU Grand Prix Rostelecom Cup 2016/2017, Ice Dance Short Dance, Moscow, Russia on November 4, 2016. Kaitlyn Weaver and Andrew Poje of Canada compete. (Photo by Grigory Dukor/Reuters)

American model and television personality Kendall Jenner attends the Tiffany & Co. Paper Flowers event and Believe In Dreams campaign launch on May 3, 2018 in New York City. (Photo by Jamie McCarthy/Getty Images for Tiffany & Co.)

A British policewoman chasing after a group of naked street boys by the Serpentine in Hyde Park, London. (Photo by Reg Speller/Getty Images). 1926

Sergei Bobkov, 59, paints Siberian cedar nut oil onto a life-size sculpture of Pallas's Cat, also known in Russia as Manul Cat, which he made from Siberian cedar wood shavings using more than 700 thousand pieces over four years, in the village of Kozhany, southwest of the Siberian city of Krasnoyarsk, Russia, April 28, 2017. (Photo by Ilya Naymushin/Reuters)

Figure Skating, ISU Grand Prix of Figure Skating NHK Trophy 2016/2017, Ice Dance Short Dance, Sapporo, Japan on November 26, 2016. Kaitlin Hawayek and Jean-Luc Baker of the U.S. compete. (Photo by Issei Kato/Reuters)