“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

A woman rides the world's longest urban zip line, with a speed of up to 80 kilometers per hour on a one kilometer run from 170 meter to ground level, in the Marina district of Dubai, United Arab Emirates, Tuesday, December 5, 2017. (Photo by Kamran Jebreili/AP Photo)

This picture taken on December 31, 2017 shows an Indian sadhu preparing food at a camp at Sangam, ahead of the Magh Mela festival, in Allahabad. The Magh Mela, which is known as a mini-Kumbh Mela, is scheduled to start January 2 and continue until February 13 with auspicious bathing dates throughout the 45 day period. (Photo by Sanjay Kanojia/AFP Photo)

A man crosses Canal Street in the wind and rain from Hurricane Isaac August 29, 2012. (Photo by David J. Phillip/Associated Press)

A horse-drawn cart passing through a section cut out of the base of a giant sequoia tree in the Mariposa groves of Yosemite Park, California. (Photo by Carleton E Watkins/Getty Images). 1870

Against the scorching sun, a hungry jackal chases a flock of birds looking for a quick morning snack. Taken in South Africa's Kgalagadi Transfrontier National Park, these images capture the moment a lone hunter tries, and then succeeds, in his pursuit. (Photo by John Mullineux/Solent News)

Nikki Reed is seen shopping at American Rag in Los Angeles, CA., on May 14, 2014. (Photo by Bauergriffin.com)

Fireworks explode over Elizabeth Tower housing the Big Ben clock in London. (Photo by Kirsty Wigglesworth/Associated Press)