“A Mothers Tail”. A baby cub pulls on his mother's tail to get attention. Photo location: Masai Mara, Kenya. (Photo and caption by Tori Marsh/National Geographic Photo Contest)

Lilly Caron, 8, of Bridgeton, Maine, Jason Homchick, of San Diego, and Lilly's father Jason Caron, (obscured), ride the Sky Swing at Seacoast Adventure, Thursday, July 14, 2016, in Wyndham, Maine. The 100-foot-tall swing gives riders the combined thrills of sky diving and hang gliding. (Photo by Robert F. Bukaty/AP Photo)

A reveller takes part in an annual block party known as “Cordao de Prata Preta”, one of the many carnival parties to take place in the neighbourhoods of Rio de Janeiro, February 6, 2016. (Photo by Pilar Olivares/Reuters)

An employee of a bakery talks on his mobile while balancing on his head a tray of freshly baked bread from a local bakery in a street in Cairo, Egypt, January 12, 2016. (Photo by Asmaa Waguih/Reuters)

Actors reenact the famous picture of a sailor kissing a nurse on the 70th anniversary of Victory over Japan Day, near a replica sculpture in New York's Times Square August 14, 2015. The replica is being displayed to celebrate the 70th anniversary of the iconic photograph of the most famous kiss in American history that was captured between an American sailor and nurse on August 14, 1945, marking the end of World War Two. The actors are hired by a tour bus company to pose for groups to photograph. (Photo by Brendan McDermid/Reuters)

Ethnic Miao men wearing traditional masks smear dust on a woman's face to wish her good luck during local celebration event for Lunar New Year in Liuzhou, Guangxi Zhuang Autonomous Region, China, February 16, 2016. (Photo by Reuters/Stringer)

A pro-Russian rebel guards a captured former Ukrainian Army checkpoint outside Vuhlehirsk, Donetsk region, eastern Ukraine, Thursday, February 5, 2015. The rebels have closed in around the town in a strategy they triumphantly refer to as the Debaltseve cauldron. Separatists recently burst through government lines in the rural settlement of Vuhlehirsk. (Photo by Vadim Braydov/AP Photo)

A street performer dressed up as a waiter performs for at Marques de Larios street in downtown Malaga, Spain, July 4, 2016. (Photo by Jon Nazca/Reuters)