A commuter gestures to Boris Johnson as he rides across Vauxhall Bridge in London, England on November 19, 2015. The London mayor was opening a cycle superhighway. (Photo by John Stillwell/PA Wire)

A woman carries a piglet as she runs on ice during a running challenge in Changsha, Hunan province February 8, 2015. A total of 20 people participated in the challenge requiring them to choose a pig ranging between 15 kg and 115 kg in weight, and carrying it while running on a 20.15-metre-long ice track. The participants that complete the challenge will be rewarded with the pig they carried, local media reported. (Photo by Darwin Zhou/Reuters)

An animal advocate lays in fake blood in a replica of a meat package with a label that reads “meat” during a protest “The meat is murder” in the Bulgarian capital Sofia on May 8, 2016. (Photo by Nikolay Doychinov/AFP Photo)

A boy runs with a burning barrel soaked in tar at the annual Ottery St Mary tar barrel festival on November 5, 2015 in Ottery St. Mary, England. The tradition, which is over 400 years old, sees competitors (who must have been born in the town to take part) running with burning barrels on their backs through the village, until the heat becomes too unbearable or the barrel breaks down, starting with junior barrels carried by children and continuing all evening with ever larger and larger barrels. The event, which has been threatened with closure on previous years due to increasing public liability insurance costs, raises thousands of pounds for charity and attracts spectators from around the world. (Photo by Matt Cardy/Getty Images)

Galapagos – Rocking the Cradle: Four major ocean currents converge along the Galapagos archipelago, creating the conditions for an extraordinary diversity of animal life, April 25, 2016. The islands are home to at least 7,000 flora and fauna species, of which 97 percent of the reptiles, 80 percent of the land birds, 50 percent of the insects and 30 percent of the plants are endemic. (Photo by Thomas P. Peschak for National Geographic/World Press Photo)

The Villarrica Volcano is seen at night from Pucon town, Chile, July 12, 2015. Villarrica, located near the popular tourist resort of Pucon, is among the most active volcanoes in South America. (Photo by Cristobal Saavedra/Reuters)

Crowds look on as the super moon rises behind the Fremantle War Memorial at Monument Hill on November 14, 2016 in Fremantle, Australia. A super moon occurs when a full moon passes closes to earth than usual, with the November 14th moon expected to be closer than it has been in over 70 years. (Photo by Paul Kane/Getty Images)

People make their way on an algae-covered beach in Qingdao, Shandong province, China, July 19, 2015. (Photo by Reuters/Stringer)