A baby rhesus macaque (Macaca mulatta) looks up as it plays with a tiger cub at a zoo in Hefei, Anhui province, August 2, 2012. (Photo by Jianan Yu/Reuters)

Two stags fight in a wildlife park in Aurach near Kitzbuehel, in the Austrian province of Tyrol. (Photo by Kerstin Joensson/Associated Press)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

A rebel fighter carries his weapon as he moves through a hole in a wall in the old city of Aleppo near the frontline against forces loyal to Syria's President Bashar al-Assad December 28, 2014. (Photo by Jalal Al-Mamo/Reuters)

In this photo taken Saturday, February 14, 2015, Benjamin Miller, 20, from Georgia, in the US, is gored by a bull during the “Carnaval del Toro” in Ciudad Rodrigo, Spain. An American youth is recovering in the intensive-care unit of a hospital in western Salamanca after being savagely gored during a bullfighting festival celebrating Carnival, officials said Sunday. Surgeon Enrique Crespo said he was called to operate on 20-year-old Benjamin Miller from Georgia, who had been gored and tossed by a large fighting bull on Saturday, the first day of nearby Ciudad Rodrigo's “Carnaval del Toro”. (Photo by Jose Vicente/AP Photo)

The villas of Marabe Al Dhafra in Abu Dhabi, United Arab Emirates are home to approximately 2,000 people. Located in one of the hottest regions of the world, the record high temperature here is 49.2C° (120.6F°). (Photo by Benjamin Grant/Penguin Random House)

Employees of a food stand take pictures of Titan, a robot created by England Cyberstein Robots, performing at the Danilovsly market in downtown of Moscow, Russia, 12 May 2014. Titan visited to Moscow to attend “Bal Robotov”, an interactive exhibition of the most recent advances in robotics which will be opened on 15 May in Artplay Moscow exhibition center. Titan worked alongside superstars including Will.i.am, Rihanna, Will Smith and Jackie Chan. (Photo by Sergei Ilnitsky/EPA)

A visitor takes a photo of a boulder plastic made of synthetic material called “To be in Limbo” hangs from the ceiling of the 20 meter high Jesuit Church in Vienna, Austria, Tuesday, November 25, 2014. The eight meter high, hollow and 700 kilogram heavy sculpture from the artists group Steinbrener/Dempf and Huber is supposed to symbolize faith and its threatening moments. The installation will remain until April 19, 2015 and then move to a church in Hamburg, Germany. (Photo by Ronald Zak/AP Photo)