Women sing and dance as children gather in the background during the so-called parade of children's troops in Rostov-on-Don, southern Russia, May 14, 2015. About 500 children aged from 4 to 10, members of youth military patriotic clubs, honor guards and paratroopers took part in the event, which was organized under the guidance of Commander of Southern Military District Colonel-General Alexander Galkin and was held to honor World War Two veterans and mark the 70th anniversary of the victory over Nazi Germany, according to local media. (Photo by Eduard Korniyenko/Reuters)

Tanzania, 1964. A touching moment between primatologist and National Geographic grantee Jane Goodall and young chimpanzee Flint at Tanzania's Gombe Stream Reserve. (Photo by Hugo van Lawick via National Geographic)

NATO and U.S. flags flutter as U.S. Air Force F-22 Raptor fighter flies over the military air base in Siauliai, Lithuania, April 27, 2016. (Photo by Ints Kalnins/Reuters)

A woman, covered in coloured powder, takes part in the 2019 Colour Run, a 5 km run around the Luzhniki Olympic Complex, in Moscow, Russia on June 02, 2019. (Photo by Sefa Karacan/Anadolu Agency/Getty Images)

A plane battling the Ferguson Fire passes the setting sun in unincorporated Mariposa County Calif., near Yosemite National Park on Sunday, July 15, 2018. (Photo by Noah Berger/AP Photo)

This photo taken on November 4, 2019 shows people taking part in a fish catching competition in a paddy field in Leishan county in China's southwestern Guizhou province, to celebrate the new year festival Miao people. (Photo by AFP Photo/China Stringer Network)

A medical worker wearing a full protective outfit tests a man for Covid-19 symptoms in a street in Wuhan, China, 01 April 2020. Wuhan, the epicenter of the coronavirus outbreak, partly lifted the lockdown allowing people to enter the city after more than two months. According to Chinese government figures over 2,500 people have died of Covid-19 in Wuhan since the outbreak began. (Photo by Roman Pilipey/EPA/EFE)

A reveler takes part of the Light Festival parade in San Jose, Costa Rica on December 14, 2019. (Photo by Ezequiel Becerra/AFP Photo)