Ten-year-old Macy Friday, front left, reacts as she looks back at her family after meeting Hillary Clinton, front right, as she campaigns for U.S. Sen. Mark Udall, D-Colo., back, during a stop in the newly-renovated Union Station in Denver on Monday, October 13, 2014. Clinton appeared at an event to raise money for Udall's current re-election campaign and then headed to Las Vegas for another appearance on Monday night. (Photo by David Zalubowski/AP Photo)

Women Wrestlers, Bolivia. Lucha libre (Bolivian wrestling) is one of the most popular sports in the country. Women wrestlers are known as cholitas and have in the last ten years become popular in the sport. Here, Carmen Rosa and Yulia la Pacena perform in a benefit show to raise money for the bathrooms of a school in La Paz, Bolivia, 26 June 2011. (Photo by Daniele Tamagni)

A Tibetan rider fires his weapon as he perfoms his riding skills at the Qinghai Yushu Horse Racing Festival on July 27, 2007 in Yushu County of Yushu Tibetan Autonomous Prefecture, Qinghai Province, northwest China. The Horse Racing Festival of Tibetan nomads in Yushu Prefecture falls in late July and early August on the Tibetan calendar. During the festival, various equestrian skills will be performed along with singing, dancing and costume shows. (Photo by China Photos/Getty Images)

Trick rider Kendel Sampson performs during the trick riding session of the RAM Rodeo in Warkworth, Ontario, on August 1, 2013. The teenage Encore Presentation Trick Riders perform daring stunts every rodeo season in towns throughout Canada. (Photo by Norm Betts/Barcroft Media)

Arctic wolves in their new enclosure in the wildlife park in Hanau, Germany, 10 February 2015. The pack is one of the park's main attractions, which specializes in local and European breeds. (Photo by Boris Roessler/EPA)

Chinese aids activists hand out condoms in a subway train in Wuhan, central China's Hubei province on December 1, 2014. The World Health Organization issued a call to action to China on December 1, 2014 over HIV/AIDS as government figures said nearly half a million people are living with the disease or its precursor, with hundreds of thousands more thought to be undiagnosed. (Photo by AFP Photo)

A ring-tailed lemur is pictured at Zoom Torino, a zoological park in Cumiana near Turin, on April 22, 2015. Zoom Torino is a new immersive zoological park, where animals can be seen without bars or cages, only natural barriers ensure the visit. (Photo by Marco Bertorello/AFP Photo)