A boy doing chin-ups as he takes entrance exams at the Moscow Suvorov Military School in Moscow, Russia on July 11, 2019. (Photo by Sergei Karpukhin/Russian News Agency TASS via Getty Images)

Members of a dance troupe participate in the Cabildo de Getsemani parade as part of the 208th Independence celebrations in Carta​gena, Colombia, 10 November 2019. (Photo by Ricardo Maldonado Rozo/EPA/EFE)

Dancers at the Windmill Theatre in London, England practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)

In the mountains of central Vietnam, a colossal pair of hands lifts a golden thread of walkway high above the clifftops, as if the mountain itself has sprouted limbs. Here: A giant hand structure at the Gold Bridge is seen on Ba Na hill near Danang city, Vietnam on August 1, 2018. (Photo by Reuters/Kham)

A gold mine worker displays gold in a local mine in Al-Ibedia locality at River Nile State, July 30, 2013. (Photo by Mohamed Nureldin Abdallah/Reuters)

Japanese researchers have sparked hopes of finding a cure for human baldness after successfully growing hair on hairless mice by implanting follicles created from stem cells, Agence France Presse reports. A picture taken on April 13, 2012 and released by the Tsuji Lab Research Institute for Science and Technology of the Tokyo University of Science shows a hairless mouse with black hair on its back at the laboratory in Noda, Chiba Prefecture. (Photo by Tokyo University of Science via AFP)

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)

7th August 1941: A Soviet sniper targets the enemy with the telescopic sight on his rifle.