Girls of University of Cincinnati Stage Grecian Games on April 29, 1921. Garbed in costumes of ancient Greece, fair students of the University of Cincinnati, Ohio arranged a set of Grecian Games for the benefit of the University athletic fund. All of the girl students of the University, who take a great interest in outdoor games and athletics, took part in the games. The fund was greatly increased through the staging of the unique attraction and the girls purpose to give a return engagement. The accompanying photographs show the girl contestants in their Grecian costumes. Photo shows the start of the 100 yard dash. (Photo by Bettmann Archive/Getty Images)

Eight-year-old Niu Dongfang trains at the No. 2 Beijing Shuangqiao School January 13, 2005 in Beijing, China. Most of students in the gymnastics school have to study more than five years from as young as age six before they become athletes. (Photo by Guang Niu/Getty Images)

Revellers participate in a parade on the street during a carnival in the village of Vevcani, south of Skopje, Macedonia January 13, 2016. Vevcani village marks the annual Orthodox St. Vasilij Day with a carnival that features a 1,400-year-old celebration with pagan roots. The highlights of the carnival include a political satire where masked villagers act out current events. (Photo by Ognen Teofilovski/Reuters)

A women sell food under the wing of a plane wreckage being used as housing in M'Poko Internally Displaced Persons camp in Bangui, Central African Republic on Saturday, February 13, 2016. The M'Poko IDP camp, just outside the capitol's airport, currently houses close to 20,000 people displaced due to the ongoing conflict in Central African Republic. (Photo by Jane Hahn/The Washington Post)

People walk along the Dune du Pilat (Dune of Pilat), the tallest sand dune in Europe, in La Teste de Buch, near Bordeaux, France, June 15, 2016. The dune has a volume of about 60,000,000 m³, measuring around 500 m wide from east to west and 2.7 km in length from north to south. Its height is currently 110 meters above sea level. (Photo by Sergio Perez/Reuters)

On the western side of Mount Hood lies the longest glacier cave system in the contiguous United States. In 2012, these caves were mapped to a combined length of 7,166.8 feet by cave explorers Brent McGregor and Eddy Cartaya. Currently, the total passage length is hundreds of feet less. Glaciers are frozen rivers; they are always moving and changing... (Photo and caption by Josh Hydeman)

In this photo taken on Saturday, April, 4, 2015, a bear chews on a corncob at a shelter that attracts hundreds of visitors and volunteers from around the world every year, in Kutarevo, Croatia. Over a decade ago, Ivan Crnkovic-Pavenka, a retired Croatian social worker decided to help bears become “ambassadors of the wilderness” among people and set up a unique shelter for brown bears in the idyllic mountain village of Kutarevo in central Croatia, where eight bears currently live in two huge enclosures. (Photo by Amel Emric/AP Photo)

Competitors perform at the World Irish Dance Championship on April 13, 2014 in London, England. The 44th World Irish Dance Championship is currently running at London's Hilton London Metropole hotel, and will host approximately 5,000 dancers competing in solo, Ceili, modern figure choreography and dance drama categories during the week long event. (Photo by Dan Kitwood/Getty Images)