Luke Personius, 12, waits for a wave as he surfs before school at sunrise in Hermosa Beach, California April 2, 2015. The group of friends surf at sunrise most mornings, then shower outside and walk to school. (Photo by Lucy Nicholson/Reuters)

An indigenous girl carries a monkey inside her house in their village at Xingu national park in Mato Grosso, Brazil, October 2, 2015. The Kamayura tribe consists of around 300 people, and is one of the 16 ethnic groups living in the indigenous Xingu national park. (Photo by Paulo Whitaker/Reuters)

Houthi followers perform the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. The nothern-based Houthis, a Shi'ite Muslim group, took control of Sanaa last September. Arab countries intervened in the conflict in March to halt a Houthi advance into the south which caused the Saudi-backed government to flee to Riyadh from its refuge in the southern port of Aden. (Photo by Khaled Abdullah/Reuters)

A person dressed as the Krampus performs during the 9th Krampus meeting show in Serfaus, Tyrol, Austria, 12 November 2016. Several thousand people watched the parade of about 27 artists groups from Austria and South Tyrol, Italy. The Krampus is a folklorical figure who, during the Christmas season, punishes children who have misbehaved. (Photo by Christian Bruna/EPA)

A visitor kneels down nex to an iCub robot made by the Italian Institute of Technology at the scientists congress IROS 2015 in Hamburg, Germany October 2, 2015. The robot congress is organized by TAMS group (Technical Aspects of Multimodal Systems) of Hamburg's university. (Photo by Fabian Bimmer/Reuters)

Hikers walk to reach the top of Naqba Rum area in South Sinai, Egypt, November 20, 2015. Bedouins in the "Sinai is Safe" group guided more than 100 hikers over a 25 km (15 mile) trek over the trails of the White Canyon and the Closed Canyon. The NGO aims to challenge mainstream perceptions of the area by encouraging Nile Valley residents to explore the untamed wilderness with the Bedouin tribes. (Photo by Asmaa Waguih/Reuters)

A member of “Laughter Doctors of Ciudad Juarez” performs at a children's hospital in Ciudad Juarez March 11, 2015. Through clown performances, music and interactive activities, the group of doctors visit different hospitals throughout the border city, using laughter to help aid the recovery of young and elderly patients suffering from serious illness or injury, as well as provide hope for the hospitalized patients and their families, local media reported. (Photo by Jose Luis Gonzalez/Reuters)

Members of the local Cossack community undergo military training at a boot camp set up by the Russkiye Vityazi (Russian Knights) military patriotic club in the village of Sengileyevskoye, south of Stavropol, March 22, 2015. A group of cossacks from the village of Kazanskaya, who are planning a professional career at the military intelligence service, has arrived at a camp for training under the leadership of professional instructors. (Photo by Eduard Korniyenko/Reuters)