Mario Huettenhofer, chief of the German company 3D Fab, presents his own face as 3d print during the international fairs FabCon 3.D and Rapid.Tech in Erfurt, Germany, Thursday, May 15, 2014. 130 exhibitors from all over the world present the entire world of 3D printing. The trade fairs are accompanied by specialist programs featuring 80 scientists, practitioners and trend analysts from ten countries, who will explain the latest findings, trends and applications for additive processes in industry and for 3D printing in the private sector to newcomers, experts and consumers alike. (Photo by Jens Meyer/AP Photo)

A photo taken on August 29, 2014, shows Mount Tavurvur erupting in eastern Papua New Guinea, spewing rocks and ash into the air, forcing the evacuation of local communities and international flights to be re-routed. Mount Tavurvur, which destroyed the town of Rabaul when it erupted simultaneously with nearby Mount Vulcan in 1994, rumbled to life early in the morning on the tip of the remote island of New Britain. (Photo by Oliver Bluett/AFP Photo)

Shamans perform a ritual of predictions for the upcoming US election with posters of presidential candidates Donald Trump and Hilary Clinton at the Agua Dulce beach in Lima on November 7, 2016. Hillary Clinton and Donald Trump launched into the frenzied final day of their historic fight for the White House Monday, with blow-out rallies in the handful of swing states that will decide who leads the United States. (Photo by Ernesto Benavides/AFP Photo)

A street actor dressed as a devil frightens children in downtown Prague in Prague, Czech Republic, Monday, December 5, 2016. On the eve of St. Nicholas, Czechs traditionally celebrate by dressing up as Devils, Angels and St. Nicholas, and visiting children in their homes handing out small presents, coal, potatoes or other gifts. (Photo by Petr David Josek/AP Photo)

A swimmer disguised as Superman dives into the lake during the 78th “Coupe de Noel” (Christmas cup) swimming race in the Lake Geneva, on December 18, 2016 in Geneva. More than 1800 participants took part in the event, a 12-meter-long swimming off the Geneva's bank in the 7 degrees Celsius cold water. (Photo by Fabrice Coffrini/AFP Photo)

A man holds a cow at the cattle market in Maiduguri, Nigeria, March 9, 2016. A Nigerian government push to strangle the Boko Haram insurgency has shut down the cattle trade that sustained the city of Maiduguri, leaving many residents with no livelihood, including many of the two million people displaced by the war. In recent months the army has taken back much of the territory lost to the jihadists during the five-year insurgency. (Photo by Afolabi Sotunde/Reuters)

A guide dangles a live chicken in front of a crocodile in the village of Bazoule, Burkina Faso, December 4, 2015. The villagers believe the crocodiles that live there are sacred. (Photo by Joe Penney/Reuters)

From house breaking in Johannesburg to hippos on the loose in Tbilisi to rioters attacking a policewoman in Burundi, Reuters photographers tell the story behind some of the most iconic pictures of the year. Here: Protesters drag a female police officer accused of shooting a protester in the Buterere neighbourhood of Bujumbura, Burundi, May 12, 2015. Goran Tomasevic: Protesters started throwing stones at a group of police, who then started to run away. The policewoman in the photo, Medikintos Inabeza, 33, got left behind and then some protesters started to push her, saying that she had shot a female protestor in the stomach with an AK47 rifle. I didn't see anything of that. There were 5 or 10 protesters pushing the policewoman at first, then others came and joined in. Up to 20 or 30 protesters were surrounding her at one point. The protesters kicked and beat her very badly; I also saw a couple of knives. I thought they were going to kill her... (Photo by Goran Tomasevic/Reuters)