Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

A female Kurdistan Workers Party (PKK) fighter stands near a security position in Sinjar, March 13, 2015. Women fighters at a Kurdistan Workers Party (PKK) base on Mount Sinjar in northwest Iraq, just like their male counterparts, have to be ready for action at any time. Smoke from the front line, marking their battle against Islamic State, which launched an assault on northern Iraq last summer, is visible from the base. Many of the women have cut links with their families back home; the fighters come from all corners of the Kurdish region. (Photo by Asmaa Waguih /Reuters)

In this photo taken Saturday, January 24, 2015, a child makes a face while having her photo taken with the snow covered slopes of the Nanshan ski resort behind her in Beijing. As Beijing makes a final push in its bid for the 2022 Winter Olympics, Chinese President Xi Jinping says winning the bid will encourage over 300 million Chinese to take up winter sports by 2022, according to state-run Xinhua News agency. (Photo by Ng Han Guan/AP Photo)

A volunteer photographs a woman as she kisses a volunteer wearing a condom costume during marking the International Condom Day in Kiev, Ukraine, 13 February 2015. The event was organized to promote and create awareness towards “Safe s*x” and the use of condoms to control and prevent Human Immunodeficiency Virus (HIV) and other sexually transmitted diseases on the occasion of the International Condom day. (Photo by Roman Pilipey/EPA)

Riot Police form a cordon as a Police car burns on the opening day of the European Central Bank (ECB) in Frankfurt am Main, western Germany, on March 18, 2015. Supporters of the so-called Blockupy alliance consisting of social movements, activists, workers, trade unions and parties are expected to stage large protests against austerity and the authority of the European Central Bank when the bank's new headquarters officially will be on March 18, 2015. (Photo by Odd Andersen/AFP Photo)

Revelers, covered in coloured powder, celebrate, during a Holi Run Festival in Madrid, Spain, Sunday, April 12, 2015. Thousands of revelers took part in the festival that includes a mini marathon. The festivals are fashioned after the Hindu spring festival Holi, which is mainly celebrated in the north and east of India. (Photo by Andres Kudacki/AP Photo)

A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

Emilia Pechinkova, a 24-years-old Bulgarian Pomak (Bulgarian speaking Muslims) bride poses for a photograph following the “gelina” or face painting ceremony carried out by female guests and relatives in preparation for her three-day wedding ceremony in the village of Draginovo, 100 kms southeast of Sofia on April 22, 2016. Bulgaria's Muslim population is one of the highest in the European Union. During the Communist regime religious rituals were not tolerated, and Muslims were forced to abandon wearing their traditional wedding outfits. Recently, more young Pomak women want to include traditional wedding customs that were forbidden during the regime, regardless of their secular lifestyles and the high cost of such a wedding. (Photo by Nikolay Doychinov/AFP Photo)