Two Herens cows lock horns during the qualification round of the annual “Battle of the Queens” cow fight finals in Aproz, in the western Alpine canton of Valais May 5, 2013. Each year when taken to the alpine pastures, the cows test their strength and fight for the herd's leadership. The competition continues until a new queen has forced all the other cows to retreat. (Photo by Valentin Flauraud/Reuters)

These Arab recruits line up in a barracks square in the British Mandate of Palestine, on December 28, 1940, for their first drill under a British solider. Some 6,000 Palestinian Arabs signed up with the British Army during the course of World War II. (AP Photo)

Costumed participants are seen during an Irish tradition of Hunting of the Wren festival held every St. Stephen's Day in Dingle, Ireland, December 26, 2016. Wren Day, also known as Wren's Day, Day of the Wren, or Hunt the Wren Day is celebrated on 26 December, St. Stephen's Day. The tradition consists of “hunting” a fake wren and putting it on top a decorated pole. (Photo by Clodagh Kilcoyne/Reuters)

Workers clean empty cooking oil containers at a roadside recycling workshop in Kolkata, India, July 13, 2016. (Photo by Rupak De Chowdhuri/Reuters)

Cambodian children sleep on a pavement at a park in Phnom Penh on July 8, 2016. (Photo by Tang Chhin Sothy/AFP Photo)

Children play football in Bujumbura, Burundi on March 19, 2015. (Photo by Carl de Souza/AFP Photo)

Participants pass an egg using their mouths during a religious ritual as they play the role of traditional fighters in a parade during the Popo (Mask) Carnival of Bonoua, in the east of Abidjan, April 18, 2015. The carnival has its origins in the changes that Aboure youths in Bonoua introduced to the annual festival of yams. (Photo by Luc Gnago/Reuters)

In this May 8, 2015 photo, sisters Zoraida Infante, left, and Graciela Trujillo pray on Fishermen's Beach before therapeutic swimming in the Pacific Ocean in Lima, Peru. Under overcast skies, the bathers practice thalassotherapy, which derives from the Greek “thalasso”, for “sea”, and draws on the ocean's healing properties. (Photo by Rodrigo Abd/AP Photo)