Egyptian bootblacks cleaning a European's shoes in Cairo. (Photo by Hulton Archive/Getty Images). Circa 1870

Model Luma Grothe poses on red carpet as he arrives for the screening of the film “Julieta” in competition at the 69th Cannes Film Festival in Cannes, France, May 17, 2016. (Photo by Regis Duvignau/Reuters)

(L-R) Miss Universe 2015 Pia Wurtzbach, Miss USA 2015 Olivia Jordan and Miss Teen USA 2015 Katherine Haik attend the 2016 Miss USA pageant at T-Mobile Arena on June 5, 2016 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

A PETA (People for the Ethical Treatment of Animals) activist with her body painted promotes veganism in Bangkok April 21, 2016. (Photo by Jorge Silva/Reuters)

An Oakland Raiders cheerleader performs during the second half of an NFL football game against the Pittsburgh Steelers in Oakland, Calif., Sunday, October 27, 2013. (Photo by Marcio Jose Sanchez/AP Photo)

Lightning strikes the Willis Tower (formerly Sears Tower) in downtown on June 12, 2013 in Chicago, Illinois. (Photo by Scott Olson/Getty Images)

A Syrian man rides his bicycle past a man selling grains during a halt in fighting on February 29, 2016 in Douma, in the Eastern Ghouta region, east of the capital Damascus. A UN-backed ceasefire deal took hold across parts of Syria, bringing relative calm to areas where the Islamic State group and Al-Qaeda's local affiliate are not present. (Photo by Sameer Al-Doumy/AFP Photo)

Artist Kong Ning wears a wedding dress made from respirators to highlight concerns about air quality and pollution in Beijing, China on December 1, 2015. (Photo by Luo Xiaoguang/Xinhua Press/Corbis)