Competitors in costume cross a water obstacle during the Wildsau Dirt Run (Wild Boar Dirt Run) obstacle course fun race at Hellsklamm ravine in Obertriesting, Austria, October 22, 2016. (Photo by Heinz-Peter Bader/Reuters)

A gory fight to the death between snarling dogs and captured wild boars. Gathered around a bamboo-walled arena, Indonesians in this remote part of Java island seem eager to watch the blood-curdling contests, known locally as “adu bagong” (boar fighting). Not surprisingly, animal rights activists are up in arms against the regular spectacle, which began in the 1960s when wild pig numbers in this area in West Java soared and they were hunted to protect crops. Here: Women share a joke as they walk to a paddy field in Cikawao village of Majalaya, West Java province, Indonesia, October 12, 2017. (Photo by Reuters/Beawiharta)

A firefighter recovers after climbing the 1800 steps of the Costanera Centre Tower as part of the “Race for Life” aimed at encouraging organ donation in Chile, in Santiago, on October 16, 2016. More than 500 volunteer firefighters are expected to climb the 1800 steps of the tallest building in South America to promote and encourage organ donation in the country. (Photo by Claudio Reyes/AFP Photo)

Dustin Murley (L) and Jessey Sisson race on their ostriches during the annual Ostrich Festival in Chandler, Arizona March 10, 2013. (Photo by Joshua Lott/Reuters)

Participants take part in an extreme run “Bison race” near the town of Logoisk, Belarus September 17, 2016. (Photo by Vasily Fedosenko/Reuters)

A participant competes in the “Farinato Race” winter extreme run competition in Gijon, northern Spain, January 31, 2016. (Photo by Eloy Alonso/Reuters)

Racing driver J. Gaal at the wheel of car number 26 at the RAC Tourist Trophy, run, for the first time, over the Four Inch Course on the Isle of Man, 17th September 1908. Gaal is racing in waterproofs. (Photo by Topical Press Agency/Hulton Archive/Getty Images)

People take part in the "Bison Race" winter extreme run competition in Zhodino, Belarus, December 5, 2015. (Photo by Vasily Fedosenko/Reuters)