Chinese butchers catch a pig to slaughter on January 31, 2005 in Jinzhai County, Anhui Province, China. (Photo by Cancan Chu/GettyImages)

A Flemish demonstrator, one of thousands who gathered for a march through Brussels to protest against what the Flemings call their subjucation by the French-speaking Walloons, draws back as he is jeered by a crowd of Walloons on the pavement in a Brussels Street, on October 14, 1962. The Flemish demonstrators clashed with Walloon counter demonstrators as riot police sought to maintain order. The Flemings claim that although they form 60% of the population in Belgium, they are inadequately represented in the government, and they say, the Walloons get most of the top jobs in the armed forces and the diplomatic service. (Photo by AP Photo)

A robot named “Robovie-II”, developed by Japanese robotics research institution ATR, moves around at a grocery store during a shopping assisting experiment by utilizing the robot in an ubiquitous network technology platform in Kyoto, western Japan January 6, 2010. (Photo by Yuriko Nakao/Reuters)

A thirsty timber wolf, Lithuania, 2018. (Photo by Erikas Plucas/Alamy Stock Photo)

A tourist stands on a paddle boat near soldiers taking part on a military and police drill in preparation for the temporary closure of the holiday island Boracay in Philippines on April 24, 2018. (Photo by Erik De Castro/Reuters)

The front wheels of a tractor lift off the ground as the driver moves a heavy trailer outside Peshawar, Pakistan February 19, 2018. (Photo by Fayaz Aziz/Reuters)

A swimmer competes in Le Defi Monte-Cristo (Monte Cristo Challenge) swimming event at the Chateau d'If, off the coast of Marseille, southern France, on June 21, 2019. Created in 1999 and inspired by Alexandre Dumas' character of Edmond Dantes, the Monte Cristo Challenge will take place from June 21 to 23, 2019. (Photo by Boris Horvat/AFP Photo)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)