The painted nails of a Kurdish Peshmerga female fighter are seen as she takes up a position during combat skills training before being deployed to fight Islamic State militants, at their military camp in Sulaimaniya, northern Iraq September 18, 2014. (Photo by Ahmed Jadallah/Reuters)

Marines finish a 10 kilometer training hike carrying 55 pound (25 kg) packs during Marine Combat Training (MCT) on February 22, 2013 at Camp Lejeune, North Carolina. Since 1988 all non-infantry enlisted male Marines have been required to complete 29 days of basic combat skills training at MCT after graduating from boot camp. MCT has been required for all enlisted female Marines since 1997. About six percent of enlisted Marines are female. (Photo by Scott Olson/AFP Photo)

FaceResearch.org, a site run by two psychologists at the University of Aberdeen in Scotland, features software that can average together faces from thousands of photos. These images purportedly show the average face of women from 40 different nationalities.

Dove Jo (L) and HJ Kim kiss beneath a 26-foot statue inspired by the iconic kiss between a nurse and a sailor in Times Square August 12, 2010 in New York City. Alfred Eisenstaedt took the famous photograph on V-J Day marking the end of World War II. (Photo by Mario Tama/Getty Images)

In this photo distributed by the Israeli Defense Forces (IDF) May 23, 2005, woman soldiers wear branches in their helmets as their infantry instructors' course learns about camouflage during the field craft week of their training May 19, 2005 at an army base near Beersheva in Israel's southern desert. It takes the IDF more than 2 months to teach these 18-year-old female recruits the basic arts of warfare before they assigned to pass on their newly-acquired skills to the army's male and female draftees. (Photo by Abir Sultan/IDF via Getty Images)

An Israeli soldier takes part in during a rehearsal for a ceremony to mark Israel's Memorial Day for fallen soldiers at the Mount of Olives cemetery in east Jerusalem, Tuesday, May 10, 2016. Israel will mark the annual Memorial Day in remembrance of soldiers who died in the nation's conflicts, beginning at dusk Tuesday until Wednesday evening. (Photo by Oded Balilty/AP Photo)

South Korea's Amry Special Warfare Command (SWC) soldiers aim their machine guns in a frozen river during a winter exercise in Pyeongchang, South Korea, Thursday, January 8, 2015. About 200 SWC soldiers participated in this routine two-week winter drill. (Photo by Ahn Young-joon/AP Photo)

Underwater photographer Sarah Lee uses a technique known as “duck diving” to capture these stunning photos of surfers in Hawaii. Surfers “duck dive” under the water to avoid incoming waves so they can get further out to sea. Photo: A surfer comes free from her surfboard. (Photo by Sarah Lee/Caters News)