Then U.S. Army First Lieutenant Kirsten Griest (C) and fellow soldiers participate in combatives training during the Ranger Course on Fort Benning, Georgia, in this handout photograph taken on April 20, 2015 and obtained on August 20, 2015. When Griest and another woman completed the daunting U.S. Army Ranger school this week they helped end questions about whether women can serve as combat leaders, as the Pentagon is poised to open new roles, including elite Navy SEALs, to women in coming months. The feat by Griest and First Lieutenant Shaye Haver followed a re-evaluation of the role of women after their frontline involvement in Iraq and Afghanistan and the end of a rule barring them from combat roles in 2013. (Photo by Spc. Nikayla Shodeen/Reuters/U.S. Army)

Partially demolished houses stand in the Vila Autodromo slum with the Rio 2016 Olympic Park in the background in Rio de Janeiro, Brazil, February 25, 2016. (Photo by Ricardo Moraes/Reuters)

Residents of the Brussels suburb of Molenbeek are searched by police before taking part in a memorial gathering to honour the victims of the recent deadly Paris attacks, in Brussels, Belgium, November 18, 2015. (Photo by Yves Herman/Reuters)

Going toe-to-toe, these fighting primates could give Floyd Mayweather a run for his money. The amazing images – captured by Australian tourist Julie Rathbone on the banks of the Zambezi river in Africa – show the pair engaging in a few fisticuffs. The Chacma baboons appeared to settle a disagreement by fighting – before a senior baboon plays referee and steps in to break it up. Nurse unit manager Julie Rathbone, 59, from New South Wales, was on a cruise down the river when she spotted the fracas unfolding. (Photo by Julie Rathbone/Caters News)

A three-seater Toyota Kikai concept car is displayed during the 2016 CES trade show in Las Vegas, Nevada January 8, 2016. (Photo by Steve Marcus/Reuters)

Martin Lacey Jr. with a lion during the premiere of the Circus Krone program “Circus der Preistraeger” at Circus Krone on February 2, 2016 in Munich, Germany. (Photo by Hannes Magerstaedt/Getty Images)

A receptionist dinosaur robot performs at the new robot hotel, aptly called Henn na Hotel or Weird Hotel, in Sasebo, southwestern Japan, Wednesday, July 15, 2015. From the receptionist that does the check-in and check-out to the porter that’s a stand-on-wheels taking luggage up to the room, the hotel, that is run as part of Huis Ten Bosch amusement park, is “manned” almost totally by robots to save labor costs. (Photo by Shizuo Kambayashi/AP Photo)

An art installation formed with milk churns, made by land art artist Gerard Benoit a la Guillaume, is seen at the Chenau de Mayen in the resort of Leysin, Switzerland August 7, 2015. More than 80 milk churns were placed between the Tour d'Ai and the Tour de Mayen summits at an altitude of 2,000 meters (6,561 feet) above sea level under the direction of the artist, to be photographed for his ongoing art project entitled “Milk churns without borders”. (Photo by Denis Balibouse/Reuters)