Ayesha Farooq, 26, Pakistan's only female war-ready fighter pilot watches an airforce jet about to take off at Mushaf base in Sargodha, north Pakistan June 7, 2013. Farooq, from Punjab province's historic city of Bahawalpur, is one of 19 women who have become pilots in the Pakistan Air Force over the last decade – there are five other female fighter pilots, but they have yet to take the final tests to qualify for combat. A growing number of women have joined Pakistan's defence forces in recent years as attitudes towards women change. (Photo by Zohra Bensemra/Reuters)

A girl jumps over a campfire while celebrating Ivan Kupala Night, a traditional Slavic holiday not far from Kiev on July 6, 2013. During the celebration, originating in pagan times, people plait wreaths, jump over fires, and swim naked. (Photo by Sergei Supinsky/AFP Photo)

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Old Heidelberg, Dog with Pipe, 1905. (Photo by Detroit Publishing Company)

Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

“Entwined Lives”. Tim Laman, US Winner, Wildlife photographer of the year. A young male orangutan makes the 30-metre climb up the thickest root of the strangler fig high above the canopy in Gunung Palung national park, one of the few protected orangutan strongholds in Indonesian Borneo. Laman had to do three days of climbing to position several GoPro cameras that he could trigger remotely. This shot was the one he had long visualised, looking down on the orangutan within its forest home. (Photo by Tim Laman/2016 Wildlife Photographer of the Year)

Actress Marilyn Monroe poses for a portrait in a bathing suit and high heels with a bottle of Coca-Cola in a glass on a table behind her in circa 1953. (Photo by Michael Ochs Archives/Getty Images)