The front wheels of a tractor, pulling a trailer overloaded with sugarcane, are seen lifted off the ground as it passes through the streets of Karor Lan Esan, Pakistan December 6, 2015. (Photo by Caren Firouz/Reuters)

A Ka'apor Indian warrior (L) chases a logger who tried to escape after they captured him during a jungle expedition to search for and expel loggers from the Alto Turiacu Indian territory, near the Centro do Guilherme municipality in the northeast of Maranhao state in the Amazon basin, August 7, 2014. Tired of what they say is a lack of sufficient government assistance in keeping loggers off their land, the Ka'apor Indians, who along with four other tribes are the legal inhabitants and caretakers of the territory, have sent their warriors out to expel all loggers they find and set up monitoring camps in the areas that are being illegally exploited. (Photo by Lunae Parracho/Reuters)

An art installation formed with milk churns, made by land art artist Gerard Benoit a la Guillaume, is seen at the Chenau de Mayen in the resort of Leysin, Switzerland August 7, 2015. More than 80 milk churns were placed between the Tour d'Ai and the Tour de Mayen summits at an altitude of 2,000 meters (6,561 feet) above sea level under the direction of the artist, to be photographed for his ongoing art project entitled “Milk churns without borders”. (Photo by Denis Balibouse/Reuters)

A masked reveller parades through the streets on the first day of the carnival season in Lucerne, Switzerland, 12 February 2015. In the background the well known Kappellbruecke bridge. (Photo by Alexandra Wey/EPA)

A mahout rides on an elephant in the city of Amritsar, India, 08 November 2015. Such elephants are often accompanied by their caretakers who ask for alms from people in the streets. (Photo by Raminder Pal Singh/EPA)

People ride a motorcycle near Koudoukou Mosque where Pope Francis meets Imam Tidiani Moussa Naibi in Bangui, Central African Republic, November 30, 2015. (Photo by Stefano Rellandini/Reuters)

A three-seater Toyota Kikai concept car is displayed during the 2016 CES trade show in Las Vegas, Nevada January 8, 2016. (Photo by Steve Marcus/Reuters)