Two women lighting cigarettes on a tennis court in Essex, England circa 1930's. (Photo by Keystone View/FPG/Getty Images)

Princess Elizabeth with her husband Prince Philip Duke of Edinburgh and their children Prince Charles and Princess Anne. (Photo by Keystone/Getty Images). August 1951

A Burmese worker sets up Christmas lights inside a woman's clothing store inside a shopping mall December 6, 2011 in Nay Pyi Taw, Myanmar. (Photo by Paula Bronstein/Getty Images)

An activist of the anti-G8 forum “Block G8” shows his middle finger to a police helicopter passing overhead June 07, 2007 at Bollhagen, near Heiligendamm, Germany. (Photo by Carsten Koall/Getty Images)

Festival goers wear Australia day attire at Big Day Out 2012 at the Sydney Showground on January 26, 2012 in Sydney, Australia. (Photo by Mark Metcalfe/Getty Images)

This combination of two photos taken on July 5, 2014, shows the Aazzab family waiting to break their fast, top, and their meal, bottom, during the holy month of Ramadan in Casablanca, Morocco. For the millions of Muslims abstaining from food and drink from sunrise to sunset every day during Islam's holiest month of Ramadan, that first sip of water after a grueling fast is by far the most anticipated moment of the day. (Photo by Abdeljalil Bounhar/AP Photo)

A new species of monkey found in the Democratic Republic of the Congo and identified as Lesula (Cercopithecus lomamiensis) is seen in this undated photograph from an article published September 12, 2012 in the science journal PLOS One. The monkey was first seen in 2007 by researchers John and Terese Hart of the Peabody Museum of Natural History at Yale Research Project. The finding of C. lomamiensis represents only the second new species of African monkey to be discovered in the past 28 years, according to the research article. (Photo by Hart J. A., Detwiler K. M., Gilbert C. C./Reuters)

Robot couple Xiaolan (L) and Xiaotao carry trays of food at a restaurant in Jinhua, Zhejiang province, China, May 18, 2015. The restaurant, which opened on Monday, has two robots delivering food for customers. The robots were designed as a couple, Xiaolan and Xiaotao, according to local media. (Photo by Reuters/Stringer)