Bonobo apes, primates unique to Congo and humankind's closest relative, groom one another at a sanctuary just outside the capital Kinshasa, Congo on October 31, 2006. (Photo by Finbarr O'Reilly/Reuters)

Rebecca Bailey rides a unicycle during a winter nor'easter snow storm in Boston, Massachusetts, U.S. February 9, 2017. (Photo by Brian Snyder/Reuters)

US freestyler, gold medalist Mcrae Williams competes during the men' s SlopeStyle (SS) finals at the FIS Snowboard and Freestyle Ski World Championships 2017 in Sierra Nevada on March 19, 2017. (Photo by Albert Gea/Reuters)

A Romanian female soldier adjusts her helmet before taking part in weapons training with US Marines female counterparts at the Capu Midia Surface to Air Firing Range, on the Black Sea coast in Romania, Monday, March 20, 2017. About 1,200 US and Romanian troops take part in the Spring Storm 17 exercise, meant to simulate defense of the Romanian Black Sea coastline and urban areas. (Photo by Vadim Ghirda/AP Photo)

A Palestinian man rides his horse on a beach in Gaza City February 17, 2017. (Photo by Mohammed Salem/Reuters)

Girls rest on stairs at the China Digital Entertainment Expo and Conference (ChinaJoy) in Shanghai, China July 27, 2017. (Photo by Aly Song/Reuters)

Ashley Ward kayaks down a flooded street that has been inundated with water from Hurricane Harvey on August 27, 2017 in Houston, Texas. Harvey, which made landfall north of Corpus Christi late Friday evening, is expected to dump upwards to 40 inches of rain in areas of Texas over the next couple of days. (Photo by Scott Olson/Getty Images)

A model gets ready backstage during the Tbilisi Fashion Week in Tbilisi, Georgia, on October 27, 2017. The presentation of the Spring/Summer 2018 collections runs from 27 to 30 October. (Photo by David Mdzinarishvili/Reuters)