“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 group of men play Myanmar's traditional sport of chinlone in Naypyitaw, Myanmar, Friday, November 18, 2016. (Photo by Aung Shine Oo/AP Photo)

A dirty thunderstorm occurs over Mount Sakurajima as the volcano erupts violently at 12:03 am on July 26, 2016 in Tarumizu, Kagoshima, Japan. The eruption occurred at the mountain's Showa crater. This is the first time that the active volcano in southern Kyushu has spewed out a smokestack that high since an eruption on August 18, 2013, according to the Kagoshima Meteorological Office. (Photo by The Asahi Shimbun via Getty Images)

A man assist trucks carry palm oil fruit on a damaged road at Mesuji Raya village in Ogan Komering Ilir, South Sumatra province, Indonesia, January 11, 2017. (Photo by Budi Candra Setya/Reuters/Antara Foto)

A Somali Armed Forces member carries her ammunition during fighting between the military and police backed by intelligence forces in the Dayniile district of Mogadishu, Somalia September 16, 2017. (Photo by Feisal Omar/Reuters)

Russian soldiers rehearse ahead of a forthcoming parade on Red Square in Moscow on November 5, 2017 The event will take place on November 7, marking the 76 th anniversary of a 1941 parade, when Red Army soldiers marched past the Kremlin walls towards the front line to fight Nazi Germany troops during World War Two. (Photo by Mladen Antonov/AFP Photo)

In a handout picture released by the British Ministry of Defence via their Defence News Imagery website on August 22, 2016, Nils Olav the penguin inspects the Guard of Honour formed by His Majesty the King of Norway's Guard on August 22, 2016 at Edinburgh Zoo in Scotland. His Majesty the King of Norway's Guard paid a very special visit to RZSS Edinburgh Zoo to bestow a unique honour upon resident king penguin Sir Nils Olav. Already a knight, the most famous king penguin in the world was given the new title of “Brigadier Sir Nils Olav”. (Photo by Mark Owens/AFP Photo)

A woman offers a prayer at Pashupatinath Temple during the Teej festival in Kathmandu, Nepal September 4, 2016. During this festival, married Hindu women observe day-long fast and pray for a happy married life while those unmarried pray for a good husband. (Photo by Navesh Chitrakar/Reuters)