A street cleaner demonstrates his martial arts skills in front of a closed shop near Beijing's Tiananmen Square September 2, 2015 as the capital prepares for tomorrow's parade. (Photo by Damir Sagolj/Reuters)

Bison along the Bitterroot Valley's Eastside Highway north of Stevensville, Montana, are covered in snow following a blizzard on November 23, 2010. (Photo by Perry Backus/The Missoulian)

Framed by the setting sun, an American Bison grazes at the Tallgrass Prairie National Preserve on Tuesday, April 28, 2015, near Strong City, Kan. The buffalo herd at Tallgrass is one of the few herds of wild bison left in the United States. (Photo by Travis Heying/The Wichita Eagle via AP Photo)

Kambeba Indian, Dream Braga, 18, aims his arrow in a jungle near the village Tres Unidos, Amazon state May 9, 2015. Dream Braga has been shooting fish with a bow and arrow for most of his life. In the Amazonian village where he grew up, that was what kids did for food and fun. He participated in the Indigenous Archery Project which recruits Amazon native children to compete with modern archery equipment and try for a place on the national team, with the 2016 Olympics in Rio de Janeiro as their ultimate goal. After training with Olympic coaches for three months, he has now been promoted to Brazil's national team. (Photo by Bruno Kelly/Reuters)

A child plays with a soap bubble on the city hall plaza on March 14, 2015 in Paris. (Photo by Dominique Faget/AFP Photo)

Young Japanese women dressed in colourful Kimonos take a photo of themselves as they gather for a ceremony marking the “Coming of Age Day” at the Toshimaen Amusement Park in Tokyo, Japan, 11 January 2016. The Coming of Age Day is the day to celebrate young people who turn 20 years old while the age of 20 is considered the beginning of adulthood and is the minimum legal age for voting, drinking and smoking in Japan. (Photo by Kiyoshi Ota/EPA)

Syrian refugee girl Nur El-Huda, 9, shows a drawing of her home in Syria, in her classroom in Yayladagi refugee camp in Hatay province near the Turkish-Syrian border, Turkey, December 16, 2015. Syria's conflict has left hundreds of thousands dead, pushed millions more into exile, and had a profound effect on children who lost their homes or got caught up in the bloodletting. The drawings of young refugees living in Turkey show their memories of home and hopes for its future. The pictures also point to the mental scars borne by 2.3 million Syrian refugees living in Turkey, more than half of them children. (Photo by Umit Bektas/Reuters)

A bakery worker rides a bicycle as he carries fresh bread on his head in Cairo, Egypt, February 9, 2016. (Photo by Asmaa Waguih/Reuters)