Two men using an electric power saw to fell a tree circa 1940's. (Photo by Keystone View/FPG/Getty Images)

A German Shepard bares its teeth during Schutzhund attack dog training at Witmer-Tyson Imports February 14, 2002 in Newark, CA. (Photo by Justin Sullivan/Getty Images)

South Korean prostitutes hide their identities as they participate in a rally on September 22, 2005 in Seoul, South Korea. Prostitutes rallied against government law aimed at the s*x industry. (Photo by Chung Sung-Jun/Getty Images)

A model poses at the Le Silla Spring/Summer 2012 presentation as part Milan Womenswear Fashion Week on September 23, 2011 in Milan, Italy. (Photo by Vincenzo Lombardo/Getty Images for Le Silla)

Clouds float over an open field January 3, 2007 in Shirley Heights, Antigua. (Photo by Joe Raedle/Getty Images)

Hjalmar kneads the raw candy paste on a table on October 12, 2007 in Berlin, Germany. The Berlin based candy store produces 30 different kinds of handmade candies according traditional recipes. (Photo by Andreas Rentz/Getty Images)

Soldiers, including two recruits who have brought some chickens, at Victoria prepare to board the train for the battle front. (Photo by Hulton Archive/Getty Images)

A recruitment drive during the First World War at Trafalgar Square, London. (Photo by Central Press/Getty Images)