Cattle keepers from the Dinka tribe perform a traditional dance after a prayer session for peace and good health along the route to Rajaf Payam outside the capital Juba October 18, 2014. (Photo by Jok Solomon/Reuters)

Female North Korean traffic police officers gather in front of bronze statues of the late leaders Kim Il Sung and Kim Jong Il to pay their respects in Pyongyang, North Korea on Saturday, February 16, 2013. North Koreans turned out to commemorate what would have been the 71th birthday of Kim Jong Il who died on December 17, 2011. (Photo by David Guttenfelder/AP Photo)

In this undated photo made available by journal Nature on January 15, 2014, a northern bald ibis (Geronticus eremita) flies in Tuscany, Italy. A new study released Wednesday, January 15, 2014 says the birds choreograph the flapping of their wings, getting a boost from an updraft of air in the wake of the flapping wings by flying behind the first bird and off to the side. When a flock of birds take advantage of these aerodynamics, they form a V. (Photo by Markus Unsöld/AP Photo)

An animal rights activist washes herself with red dye to mimic blood during a protest against the testing of shampoo on animals in Barcelona. April 24, 2012. (Photo by Raul Albaledo/AFP Photo)

Girls suffering from dwarfism take part in the disability pride parade in New York, July 12, 2015. The parade grand marshal was former U.S. Sen. Tom Harkin, the Iowa Democrat who 25 years ago sponsored the Americans With Disabilities Act. (Photo by Eduardo Munoz/Reuters)

Children eat watermelons to meet the “beginning of autumn” at a kindergarten in Handan, China on August 7, 2015. Chinese tradition to eat watermelons or peaches before that day symbolises “biting away summer”. The solar term ‘beginning of autumn’ falls on 8 August this year. (Photo by Xinhua/REX Shutterstock)

A chicken seller carries his chickens on his head in the market in Peshawar, Pakistan, August 20, 2015. (Photo by Khuram Parvez/Reuters)

Revelers march in the Lower Ninth Ward during a second line parade marking the 10th anniversary of Hurricane Katrina on August 29, 2015 in New Orleans, Louisiana. (Photo by Mario Tama/Getty Images)